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1

Discontinuity stresses in metallic pressure vessels  

NASA Technical Reports Server (NTRS)

The state of the art, criteria, and recommended practices for the theoretical and experimental analyses of discontinuity stresses and their distribution in metallic pressure vessels for space vehicles are outlined. The applicable types of pressure vessels include propellant tanks ranging from main load-carrying integral tank structure to small auxiliary tanks, storage tanks, solid propellant motor cases, high pressure gas bottles, and pressurized cabins. The major sources of discontinuity stresses are discussed, including deviations in geometry, material properties, loads, and temperature. The advantages, limitations, and disadvantages of various theoretical and experimental discontinuity analysis methods are summarized. Guides are presented for evaluating discontinuity stresses so that pressure vessel performance will not fall below acceptable levels.

1971-01-01

2

Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifting Philosophy  

NASA Technical Reports Server (NTRS)

The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle s Kevlar-49 (DuPont) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed nonconservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23 percent lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

Thesken, John C.; Murthy, Pappu L. N.; Phoenix, S. L.

2009-01-01

3

Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifing Philosophy  

NASA Technical Reports Server (NTRS)

The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle's Kevlar-49 fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed non-conservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic-plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23% lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

Thesken, John C.; Murthy, Pappu L. N.; Phoenix, Leigh

2007-01-01

4

Residual stresses in weld deposited clad pressure vessels and nozzles  

SciTech Connect

Results of through-thickness residual stress measurements are provided for a variety of samples of weld deposited 308/309L stainless steel and Alloy 600 cladding on low-alloy pressure vessel ferritic steels. Clad thicknesses between 5 and 9mm on samples that vary in thickness from 45 to 200mm were studied. The samples were taken from flat plates, from a spherical head of a pressure vessel, from a ring-segment of a nozzle bore, and from the transition radius between a nozzle and a pressure vessel shell. A layer removal method was used to measure the residual stresses. The effects of uncertainties in elastic constants (Young`s modulus and Poisson`s ratio) as well as experimental error are assessed. All measurements were done at room temperature. The results of this work indicate that curvature plays a significant role in cladding residual stress and that tensile residual stresses as high as the yield stress can be measured in the cladding material. Since the vessel from which the spherical and nozzle corner samples were taken was hydrotested, and the flat plate specimens were taken from specimens used in mechanical fatigue testing, these results suggest that rather high tensile residual stresses can be retained in the cladding material even after some mechanical loading associated with hydrotesting and that higher levels of hydrotest loading would be required to alter the cladding residual stresses.

Jones, D.P.; Mabe, W.R. [Westinghouse Electric Co., West Mifflin, PA (United States); Shadley, J.R.; Rybicki, E.F. [Univ. of Tulsa, OK (United States)

1998-04-01

5

Composite Overwrapped Pressure Vessels (COPV) Stress Rupture Test  

NASA Technical Reports Server (NTRS)

One of the major concerns for the aging Space Shuttle fleet is the stress rupture life of composite overwrapped pressure vessels (COPVs). Stress rupture life of a COPV has been defined as the minimum time during which the composite maintains structural integrity considering the combined effects of stress levels and time. To assist in the evaluation of the aging COPVs in the Orbiter fleet an analytical reliability model was developed. The actual data used to construct this model was from testing of COPVs constructed of similar, but not exactly same materials and pressure cycles as used on Orbiter vessels. Since no actual Orbiter COPV stress rupture data exists the Space Shuttle Program decided to run a stress rupture test to compare to model predictions. Due to availability of spares, the testing was unfortunately limited to one 40" vessel. The stress rupture test was performed at maximum operating pressure at an elevated temperature to accelerate aging. The test was performed in two phases. The first phase, 130 F, a moderately accelerated test designed to achieve the midpoint of the model predicted point reliability. The more aggressive second phase, performed at 160 F was designed to determine if the test article will exceed the 95% confidence interval of the model. This paper will discuss the results of this test, it's implications and possible follow-on testing.

Russell, Richard; Flynn, Howard; Forth, Scott; Greene, Nathanael; Kezian, Michael; Varanauski, Don; Yoder, Tommy; Woodworth, Warren

2009-01-01

6

Stress Rupture Life Reliability Measures for Composite Overwrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

Composite Overwrapped Pressure Vessels (COPVs) are often used for storing pressurant gases onboard spacecraft. Kevlar (DuPont), glass, carbon and other more recent fibers have all been used as overwraps. Due to the fact that overwraps are subjected to sustained loads for an extended period during a mission, stress rupture failure is a major concern. It is therefore important to ascertain the reliability of these vessels by analysis, since the testing of each flight design cannot be completed on a practical time scale. The present paper examines specifically a Weibull statistics based stress rupture model and considers the various uncertainties associated with the model parameters. The paper also examines several reliability estimate measures that would be of use for the purpose of recertification and for qualifying flight worthiness of these vessels. Specifically, deterministic values for a point estimate, mean estimate and 90/95 percent confidence estimates of the reliability are all examined for a typical flight quality vessel under constant stress. The mean and the 90/95 percent confidence estimates are computed using Monte-Carlo simulation techniques by assuming distribution statistics of model parameters based also on simulation and on the available data, especially the sample sizes represented in the data. The data for the stress rupture model are obtained from the Lawrence Livermore National Laboratories (LLNL) stress rupture testing program, carried out for the past 35 years. Deterministic as well as probabilistic sensitivities are examined.

Murthy, Pappu L. N.; Thesken, John C.; Phoenix, S. Leigh; Grimes-Ledesma, Lorie

2007-01-01

7

Stress distribution in continuously heterogeneous thick laminated pressure vessels  

SciTech Connect

Stress analysis of multilayered pressure vessels possessing cylindrical anisotropy and under internal, external and interlaminar pressure is given. The special case when the axis of anisotropy coincides with the axis of symmetry Oz and the stresses do not vary long the generator is investigated. In this case there exists a plane of elastic symmetry normal to this axis at every point of the cylinder so that each layer may be considered s orthotropic. However, elastic properties can vary through the thickness of a layer. Exact elasticity solutions are obtained for both open-ended and closed-ended cylinders using a stress function approach. The method of solution allows the forces on the layer interfaces to be taken into account with relative ease. Numerical results are presented for thick cylinders with isotropic and orthotropic layers, and stress distributions across the thickness are given.

Verijenko, V.E.; Adali, S.; Tabakov, P.Y. [Univ. of Natal, Durban (South Africa). Dept. of Mechanical Engineering

1995-11-01

8

Stresses in reactor pressure vessel nozzles -- Calculations and experiments  

SciTech Connect

Reactor pressure vessel nozzles are characterized by a high stress concentration which is critical in their low-cycle fatigue assessment. Program of experimental verification of stress/strain field distribution during elastic-plastic loading of a reactor pressure vessel WWER-1000 primary nozzle model in scale 1:3 is presented. While primary nozzle has an ID equal to 850 mm, the model nozzle has ID equal to 280 mm, and was made from 15Kh2NMFA type of steel. Calculation using analytical methods was performed. Comparison of results using different analytical methods -- Neuber`s, Hardrath-Ohman`s as well as equivalent energy ones, used in different reactor Codes -- is shown. Experimental verification was carried out on model nozzles loaded statically as well as by repeated loading, both in elastic-plastic region. Strain fields were measured using high-strain gauges, which were located in different distances from center of nozzle radius, thus different stress concentration values were reached. Comparison of calculated and experimental data are shown and compared.

Brumovsky, M. [Nuclear Research Institute Rez plc (Czech Republic); Polachova, H. [Nuclear Machinery, Ltd. Plzen (Czech Republic)

1995-11-01

9

The inclusion of weld residual stress in fracture margin assessments of embrittled nuclear reactor pressure vessels  

Microsoft Academic Search

Analyses were performed to determine the impact of weld residual stresses in a reactor pressure vessel (RPV) on (1) the generation of pressure temperature (P-T) curves required for maintaining specified fracture prevention margins during nuclear plant startup and shutdown, and (2) the conditional probability of vessel failure due to pressurized thermal shock (PTS) loading. The through wall residual stress distribution

T. L. Dickson; B. R. Bass; W. J. McAfee

1998-01-01

10

Strain measurements using FBG on composite over wrap pressure vessels (COPV) in stress rupture test  

NASA Astrophysics Data System (ADS)

Thirty six Fiber Optic Braggs Grating sensors were used during an ambient temperature hydrostatic pressurization testing of a Space Transportation System (STS) 40-inch Kevlar Composite Over-wrapped Pressure Vessel (COPV). The 40-inch vessel was of the same design and approximate age as the STS Main Propulsion System (MPS) and Orbiter Maneuvering System (OMS) vessels. The sensors were surfaces mounted to on the vessel to measure strain during a stress rupture event. The Bragg signals were linear with the applied pressure. The results indicated that the vessel was under an uneven force distribution at various locations on the vessel.

Grant, Joseph; Banks, Curtis

2007-04-01

11

Comparison between hot surface stress and effective stress acting at notch-like defect tip in a pressure vessel  

Microsoft Academic Search

In this study, we have compared effective stress obtained by the Volumetric Method (VM) and hot surface stress (HS) obtained by linear or quadratic extrapolations for a longitudinal or transversal surface defect stress distribution in a pressure vessel.It appears clearly that the definition of hot surface stress through linear extrapolation characterises the gross stress distribution affected by stress concentration.It has

M. Allouti; S. Jallouf; C. Schmitt; G. Pluvinage

2011-01-01

12

RESIDUAL STRESS DISTRIBUTIONS FOR MULTI-PASS WELDS IN PRESSURE VESSEL AND PIPING COMPONENTS  

E-print Network

RESIDUAL STRESS DISTRIBUTIONS FOR MULTI-PASS WELDS IN PRESSURE VESSEL AND PIPING COMPONENTS distributions in common pressure vessel and piping components is generated by using the multi-pass finite-walled pipes with various radius to thickness ratios. Both single- and double-V weld joints are investigated

Michaleris, Panagiotis

13

ADDITIONAL STRESS AND FRACTURE MECHANICS ANALYSES OF PRESSURIZED WATER REACTOR PRESSURE VESSEL NOZZLES  

SciTech Connect

In past years, the authors have undertaken various studies of nozzles in both boiling water reactors (BWRs) and pressurized water reactors (PWRs) located in the reactor pressure vessel (RPV) adjacent to the core beltline region. Those studies described stress and fracture mechanics analyses performed to assess various RPV nozzle geometries, which were selected based on their proximity to the core beltline region, i.e., those nozzle configurations that are located close enough to the core region such that they may receive sufficient fluence prior to end-of-life (EOL) to require evaluation of embrittlement as part of the RPV analyses associated with pressure-temperature (P-T) limits. In this paper, additional stress and fracture analyses are summarized that were performed for additional PWR nozzles with the following objectives: To expand the population of PWR nozzle configurations evaluated, which was limited in the previous work to just two nozzles (one inlet and one outlet nozzle). To model and understand differences in stress results obtained for an internal pressure load case using a two-dimensional (2-D) axi-symmetric finite element model (FEM) vs. a three-dimensional (3-D) FEM for these PWR nozzles. In particular, the ovalization (stress concentration) effect of two intersecting cylinders, which is typical of RPV nozzle configurations, was investigated. To investigate the applicability of previously recommended linear elastic fracture mechanics (LEFM) hand solutions for calculating the Mode I stress intensity factor for a postulated nozzle corner crack for pressure loading for these PWR nozzles. These analyses were performed to further expand earlier work completed to support potential revision and refinement of Title 10 to the U.S. Code of Federal Regulations (CFR), Part 50, Appendix G, Fracture Toughness Requirements, and are intended to supplement similar evaluation of nozzles presented at the 2008, 2009, and 2011 Pressure Vessels and Piping (PVP) Conferences. This work is also relevant to the ongoing efforts of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code, Section XI, Working Group on Operating Plant Criteria (WGOPC) efforts to incorporate nozzle fracture mechanics solutions into a revision to ASME B&PV Code, Section XI, Nonmandatory Appendix G.

Walter, Matthew [Structural Integrity Associates, Inc.; Yin, Shengjun [ORNL; Stevens, Gary [U.S. Nuclear Regulatory Commission; Sommerville, Daniel [Structural Integrity Associates, Inc.; Palm, Nathan [Westinghouse Electric Company, Cranberry Township, PA; Heinecke, Carol [Westinghouse Electric Company, Cranberry Township, PA

2012-01-01

14

Stress and Fracture Mechanics Analyses of Boiling Water Reactor and Pressurized Water Reactor Pressure Vessel Nozzles  

SciTech Connect

This paper describes stress analysis and fracture mechanics work performed to assess boiling water reactor (BWR) and pressurized water reactor (PWR) nozzles located in the reactor pressure vessel (RPV) adjacent to the core beltline region. Various RPV nozzle geometries were investigated: 1. BWR recirculation outlet nozzle; 2. BWR core spray nozzle3 3. PWR inlet nozzle; ; 4. PWR outlet nozzle; and 5. BWR partial penetration instrument nozzle. The above nozzle designs were selected based on their proximity to the core beltline region, i.e., those nozzle configurations that are located close enough to the core region such that they may receive sufficient fluence prior to end-of-license (EOL) to require evaluation as part of establishing the allowed limits on heatup, cooldown, and hydrotest (leak test) conditions. These nozzles analyzed represent one each of the nozzle types potentially requiring evaluation. The purpose of the analyses performed on these nozzle designs was as follows: To model and understand differences in pressure and thermal stress results using a two-dimensional (2-D) axi-symmetric finite element model (FEM) versus a three-dimensional (3-D) FEM for all nozzle types. In particular, the ovalization (stress concentration) effect of two intersecting cylinders, which is typical of RPV nozzle configurations, was investigated; To verify the accuracy of a selected linear elastic fracture mechanics (LEFM) hand solution for stress intensity factor for a postulated nozzle corner crack for both thermal and pressure loading for all nozzle types; To assess the significance of attached piping loads on the stresses in the nozzle corner region; and To assess the significance of applying pressure on the crack face with respect to the stress intensity factor for a postulated nozzle corner crack.

Yin, Shengjun [ORNL; Bass, Bennett Richard [ORNL; Stevens, Gary [U.S. Nuclear Regulatory Commission; Kirk, Mark [NRC

2011-01-01

15

Residual stress analysis in BWR pressure vessel attachments  

SciTech Connect

Residual stresses from welding processes can be the primary driving force for stress corrosion cracking (SCC) in BWR components. Thus, a better understanding of the causes and nature of these residual stresses can help assess and remedy SCC. Numerical welding simulation software, such as SYSWELD, and material property data have been used to quantify residual stresses for application to SCC assessments in BWR components. Furthermore, parametric studies using SYSWELD have revealed which variables significantly affect predicted residual stress. Overall, numerical modeling techniques can be used to evaluate residual stress for SCC assessments of BWR components and to identify and plan future SCC research.

Dexter, R.J.; Leung, C.P. (Southwest Research Inst., San Antonio, TX (United States)); Pont, D. (FRAMASOFT+CSI, 69 - Lyon (France). Div. of Framatome)

1992-06-01

16

Composite Overwrapped Pressure Vessels (COPV) Stress Rupture Test: Part 2. Part 2  

NASA Technical Reports Server (NTRS)

One of the major concerns for the aging Space Shuttle fleet is the stress rupture life of composite overwrapped pressure vessels (COPVs). Stress rupture life of a COPY has been defined as the minimum time during which the composite maintains structural integrity considering the combined effects of stress levels and time. To assist in the evaluation of the aging COPVs in the Orbiter fleet an analytical reliability model was developed. The actual data used to construct this model was from testing of COPVs constructed of similar, but not exactly same materials and pressure cycles as used on Orbiter vessels. Since no actual Orbiter COPV stress rupture data exists the Space Shuttle Program decided to run a stress rupture test to compare to model predictions. Due to availability of spares, the testing was unfortunately limited to one 40" vessel. The stress rupture test was performed at maximum operating pressure at an elevated temperature to accelerate aging. The test was performed in two phases. The first phase, 130 F, a moderately accelerated test designed to achieve the midpoint of the model predicted point reliability. A more aggressive second phase, performed at 160 F, was designed to determine if the test article will exceed the 95% confidence interval ofthe model. In phase 3, the vessel pressure was increased to above maximum operating pressure while maintaining the phase 2 temperature. After reaching enough effectives hours to reach the 99.99% confidence level of the model phase 4 testing began when the temperature was increased to greater than 170 F. The vessel was maintained at phase 4 conditions until it failed after over 3 million effect hours. This paper will discuss the results of this test, it's implications and possible follow-on testing.

Russell, Richard; Flynn, Howard; Forth, Scott; Greene, Nathanael; Kezirian, Michael; Varanauski, Don; Leifeste, Mark; Yoder, Tommy; Woodworth, Warren

2010-01-01

17

A mathematical model for the stressed state analysis of cylindrical laminated-composite pressure vessels  

NASA Astrophysics Data System (ADS)

An algorithm and a computer program have been developed for calculating the strength of pressure vessels made of laminated composites. Numerical results for pressure vessels of Kevlar 49 laminates are compared with experimental data in the literature.

Bak, Roman; Matyja, Tomasz

18

Strain measurements using FBG on composite over wrap pressure vessels (COPV) in stress rupture test  

Microsoft Academic Search

Thirty six Fiber Optic Braggs Grating sensors were used during an ambient temperature hydrostatic pressurization testing of a Space Transportation System (STS) 40-inch Kevlar Composite Over-wrapped Pressure Vessel (COPV). The 40-inch vessel was of the same design and approximate age as the STS Main Propulsion System (MPS) and Orbiter Maneuvering System (OMS) vessels. The sensors were surfaces mounted to on

Joseph Grant; Curtis Banks

2007-01-01

19

Pressure vessel integrity 1991  

SciTech Connect

This volume contains papers relating to the structural integrity assessment of pressure vessels and piping, with special emphasis on nuclear industry applications. The papers were prepared for technical sessions developed under the sponsorship of the ASME Pressure Vessels and Piping Division Committees for Codes and Standards, Computer Technology, Design and Analysis, and Materials Fabrication. They were presented at the 1991 Pressure Vessels and Piping Division Conference in San Diego, California, June 23-27. The primary objective of the sponsoring organization is to provide a forum for the dissemination and discussion of information on development and application of technology for the structural integrity assessment of pressure vessels and piping. This publication includes contributions from authors from Australia, France, Japan, Sweden, Switzerland, the United Kingdom, and the United States. The papers here are organized in six sections, each with a particular emphasis as indicated in the following section titles: Fracture Technology Status and Application Experience; Crack Initiation, Propagation and Arrest; Ductile Tearing; Constraint, Stress State, and Local-Brittle-Zones Effects; Computational Techniques for Fracture and Corrosion Fatigue; and Codes and Standards for Fatigue, Fracture and Erosion/Corrosion.

Bhandari, S. (Framatome (FR)); Doney, R.O.; McDonald, M.S. (ABB Combustion Engineering Nuclear Power (US)); Jones, D.P.; Wilson, W.K. (Westinghouse Bettis Atomic Power Laboratory (US)); Pennell, W.E. (Oak Ridge National Laboratory (US))

1991-01-01

20

Stress Rupture Testing and Analysis of the NASA WSTF-JPL Carbon Overwrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

Carbon composite overwrapped pressure vessels (COPVs) are widely used in applications from spacecraft to life support. COPV technology provides a pressurized media storage advantage over amorphous technology with weight savings on the order of 30 percent. The National Aeronautics and Space Administration (NASA) has been supporting the development of this technology since the early 1970's with an interest in safe application of these components to reduce mass to orbit. NASA White Sands Test Facility (WSTF) has been testing components in support of this objective since the 1980s and has been involved in test development and analysis to address affects of impact, propellant and cryogenic fluids exposure on Kevlar and carbon epoxy. The focus of this paper is to present results of a recent joint WSTF-Jet Propulsion Laboratories (JPL) effort to assess safe life of these components. The WSTF-JPL test articles consisted of an aluminum liner and a carbon fiber overwrap in an industry standard epoxy resin system. The vessels were specifically designed with one plus-minus helical wrap and one hoop wrap over the helical and they measured 4.23 x 11.4 in. long. 120 test articles were manufactured in August of 1998 of one lot fiber and resin and the 110 test articles were delivered to WSTF for test. Ten of the 120 test articles were burst tested at the manufacturer to establish the delivered fiber stress. Figure 1 shows a test article in a pre burst condition and with a hoop fiber failure (no leak of pressurized media) and post burst (failure of liner and loss of pressurized media).

Greene, Nathanael; Yoder, Tommy; Saulsberry, Regor; Grimes, Lorie; Thesken, John; Phoenix, Leigh

2007-01-01

21

Stress Corrosion Cracking and Fatigue Crack Growth Studies Pertinent to Spacecraft and Booster Pressure Vessels  

NASA Technical Reports Server (NTRS)

This experimental program was divided into two parts. The first part evaluated stress corrosion cracking in 2219-T87 aluminum and 5Al-2.5Sn (ELI) titanium alloy plate and weld metal. Both uniform height double cantilever beam and surface flawed specimens were tested in environments normally encountered during the fabrication and operation of pressure vessels in spacecraft and booster systems. The second part studied compatibility of material-environment combinations suitable for high energy upper stage propulsion systems. Surface flawed specimens having thicknesses representative of minimum gage fuel and oxidizer tanks were tested. Titanium alloys 5Al-2.5Sn (ELI), 6Al-4V annealed, and 6Al-4V STA were tested in both liquid and gaseous methane. Aluminum alloy 2219 in the T87 and T6E46 condition was tested in fluorine, a fluorine-oxygen mixture, and methane. Results were evaluated using modified linear elastic fracture mechanics parameters.

Hall, L. R.; Finger, R. W.

1972-01-01

22

A Comparison of Various Stress Rupture Life Models for Orbiter Composite Pressure Vessels and Confidence Intervals  

NASA Technical Reports Server (NTRS)

In conjunction with a recent NASA Engineering and Safety Center (NESC) investigation of flight worthiness of Kevlar Overwrapped Composite Pressure Vessels (COPVs) on board the Orbiter, two stress rupture life prediction models were proposed independently by Phoenix and by Glaser. In this paper, the use of these models to determine the system reliability of 24 COPVs currently in service on board the Orbiter is discussed. The models are briefly described, compared to each other, and model parameters and parameter uncertainties are also reviewed to understand confidence in reliability estimation as well as the sensitivities of these parameters in influencing overall predicted reliability levels. Differences and similarities in the various models will be compared via stress rupture reliability curves (stress ratio vs. lifetime plots). Also outlined will be the differences in the underlying model premises, and predictive outcomes. Sources of error and sensitivities in the models will be examined and discussed based on sensitivity analysis and confidence interval determination. Confidence interval results and their implications will be discussed for the models by Phoenix and Glaser.

Grimes-Ledesma, Lorie; Murthy, Pappu L. N.; Phoenix, S. Leigh; Glaser, Ronald

2007-01-01

23

A Comparison of Various Stress Rupture Life Models for Orbiter Composite Pressure Vessels and Confidence Intervals  

NASA Technical Reports Server (NTRS)

In conjunction with a recent NASA Engineering and Safety Center (NESC) investigation of flight worthiness of Kevlar Ovenvrapped Composite Pressure Vessels (COPVs) on board the Orbiter, two stress rupture life prediction models were proposed independently by Phoenix and by Glaser. In this paper, the use of these models to determine the system reliability of 24 COPVs currently in service on board the Orbiter is discussed. The models are briefly described, compared to each other, and model parameters and parameter error are also reviewed to understand confidence in reliability estimation as well as the sensitivities of these parameters in influencing overall predicted reliability levels. Differences and similarities in the various models will be compared via stress rupture reliability curves (stress ratio vs. lifetime plots). Also outlined will be the differences in the underlying model premises, and predictive outcomes. Sources of error and sensitivities in the models will be examined and discussed based on sensitivity analysis and confidence interval determination. Confidence interval results and their implications will be discussed for the models by Phoenix and Glaser.

Grimes-Ledesma, Lorie; Murthy, Pappu, L. N.; Phoenix, S. Leigh; Glaser, Ronald

2006-01-01

24

Dual shell pressure balanced vessel  

DOEpatents

A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

Fassbender, Alexander G. (West Richland, WA)

1992-01-01

25

46 CFR 197.462 - Pressure vessels and pressure piping.  

Code of Federal Regulations, 2014 CFR

... (5) When pressure tests are conducted on pressure vessels or pressure piping, the test pressure shall be maintained for a period of time sufficient...examination of all joints, connections and high stress areas. [CGD 95-028, 62 FR...

2014-10-01

26

46 CFR 197.462 - Pressure vessels and pressure piping.  

Code of Federal Regulations, 2013 CFR

... (5) When pressure tests are conducted on pressure vessels or pressure piping, the test pressure shall be maintained for a period of time sufficient...examination of all joints, connections and high stress areas. [CGD 95-028, 62 FR...

2013-10-01

27

46 CFR 197.462 - Pressure vessels and pressure piping.  

Code of Federal Regulations, 2012 CFR

... (5) When pressure tests are conducted on pressure vessels or pressure piping, the test pressure shall be maintained for a period of time sufficient...examination of all joints, connections and high stress areas. [CGD 95-028, 62 FR...

2012-10-01

28

46 CFR 197.462 - Pressure vessels and pressure piping.  

Code of Federal Regulations, 2011 CFR

... (5) When pressure tests are conducted on pressure vessels or pressure piping, the test pressure shall be maintained for a period of time sufficient...examination of all joints, connections and high stress areas. [CGD 95-028, 62 FR...

2011-10-01

29

46 CFR 197.462 - Pressure vessels and pressure piping.  

Code of Federal Regulations, 2010 CFR

... (5) When pressure tests are conducted on pressure vessels or pressure piping, the test pressure shall be maintained for a period of time sufficient...examination of all joints, connections and high stress areas. [CGD 95-028, 62 FR...

2010-10-01

30

Pressure vessel bottle mount  

NASA Technical Reports Server (NTRS)

A mounting assembly for mounting a composite pressure vessel to a vehicle includes a saddle having a curved surface extending between two pillars for receiving the vessel. The saddle also has flanged portions which can be bolted to the vehicle. Each of the pillars has hole in which is mounted the shaft portion of an attachment member. A resilient member is disposed between each of the shaft portions and the holes and loaded by a tightening nut. External to the holes, each of the attachment members has a head portion to which a steel band is attached. The steel band circumscribes the vessel and translates the load on the springs into a clamping force on the vessel. As the vessel expands and contracts, the resilient members expand and contract so that the clamping force applied by the band to the vessel remains constant.

Wingett, Paul (Inventor)

2001-01-01

31

Strain measurement during stress rupture of composite over-wrapped pressure vessel with fiber Bragg gratings sensors  

NASA Astrophysics Data System (ADS)

Fiber optic Bragg gratings were used to measure strain fields during Stress Rupture (SSM) test of Kevlar Composite Over-Wrapped Pressure Vessels (COPVs). The sensors were embedded under the over-wrapped attached to the liner released from the Kevlar and attached to the Kevlar released from the liner. Additional sensors (foil gages and fiber bragg gratings) were surface mounted on the COPV liner.

Banks, Curtis E.; Grant, Joseph; Russell, Sam; Arnett, Shawn

2008-03-01

32

Strain Measurement during Stress Rupture of Composite Over-Wrapped Pressure Vessel with Fiber Bragg Gratings Sensors  

NASA Technical Reports Server (NTRS)

Fiber optic Bragg gratings were used to measure strain fields during Stress Rupture (SSM) test of Kevlar Composite Over-Wrapped Pressure Vessels (COPV). The sensors were embedded under the over-wrapped attached to the liner released from the Kevlar and attached to the Kevlar released from the liner. Additional sensors (foil gages and fiber bragg gratings) were surface mounted on the COPY liner.

Banks, Curtis E.; Grant, Joseph; Russell, Sam; Arnett, Shawn

2008-01-01

33

A THREE-DIMENSIONAL PHOTOELASTIC STUDY OF STRESSES AROUND REINFORCED OUTLETS IN PRESSURE VESSELS  

Microsoft Academic Search

The three-dimensional photoelastic determination of the stresses around ; cylindrical outlets in spherical and cylindrical shells loaded by internal ; pressure is described. Several sizes and shapes of reinforcement were tested to ; study the effects of certain variables and to determine an optimum design. The ; results are tabulated in the form of stress-concentration factors. Distribution ; of the

C. E. Taylor; N. C. Lind; J. W. Schweiker

1959-01-01

34

Reactor pressure vessel nozzle  

DOEpatents

A nozzle for joining a pool of water to a nuclear reactor pressure vessel includes a tubular body having a proximal end joinable to the pressure vessel and a distal end joinable in flow communication with the pool. The body includes a flow passage therethrough having in serial flow communication a first port at the distal end, a throat spaced axially from the first port, a conical channel extending axially from the throat, and a second port at the proximal end which is joinable in flow communication with the pressure vessel. The inner diameter of the flow passage decreases from the first port to the throat and then increases along the conical channel to the second port. In this way, the conical channel acts as a diverging channel or diffuser in the forward flow direction from the first port to the second port for recovering pressure due to the flow restriction provided by the throat. In the backflow direction from the second port to the first port, the conical channel is a converging channel and with the abrupt increase in flow area from the throat to the first port collectively increase resistance to flow therethrough.

Challberg, Roy C. (Livermore, CA); Upton, Hubert A. (Morgan Hill, CA)

1994-01-01

35

Reactor pressure vessel nozzle  

DOEpatents

A nozzle for joining a pool of water to a nuclear reactor pressure vessel includes a tubular body having a proximal end joinable to the pressure vessel and a distal end joinable in flow communication with the pool. The body includes a flow passage therethrough having in serial flow communication a first port at the distal end, a throat spaced axially from the first port, a conical channel extending axially from the throat, and a second port at the proximal end which is joinable in flow communication with the pressure vessel. The inner diameter of the flow passage decreases from the first port to the throat and then increases along the conical channel to the second port. In this way, the conical channel acts as a diverging channel or diffuser in the forward flow direction from the first port to the second port for recovering pressure due to the flow restriction provided by the throat. In the backflow direction from the second port to the first port, the conical channel is a converging channel and with the abrupt increase in flow area from the throat to the first port collectively increase resistance to flow therethrough. 2 figs.

Challberg, R.C.; Upton, H.A.

1994-10-04

36

High pressure storage vessel  

DOEpatents

Disclosed herein is a composite pressure vessel with a liner having a polar boss and a blind boss a shell is formed around the liner via one or more filament wrappings continuously disposed around at least a substantial portion of the liner assembly combined the liner and filament wrapping have a support profile. To reduce susceptible to rupture a locally disposed filament fiber is added.

Liu, Qiang

2013-08-27

37

Hybrid Inflatable Pressure Vessel  

NASA Technical Reports Server (NTRS)

Figure 1 shows a prototype of a large pressure vessel under development for eventual use as a habitable module for long spaceflight (e.g., for transporting humans to Mars). The vessel is a hybrid that comprises an inflatable shell attached to a rigid central structural core. The inflatable shell is, itself, a hybrid that comprises (1) a pressure bladder restrained against expansion by (2) a web of straps made from high-strength polymeric fabrics. On Earth, pressure vessels like this could be used, for example, as portable habitats that could be set up quickly in remote locations, portable hyperbaric chambers for treatment of decompression sickness, or flotation devices for offshore platforms. In addition, some aspects of the design of the fabric straps could be adapted to such other items as lifting straps, parachute straps, and automotive safety belts. Figure 2 depicts selected aspects of the design of a vessel of this type with a toroidal configuration. The bladder serves as an impermeable layer to keep air within the pressure vessel and, for this purpose, is sealed to the central structural core. The web includes longitudinal and circumferential straps. To help maintain the proper shape upon inflation after storage, longitudinal and circumferential straps are indexed together at several of their intersections. Because the web is not required to provide a pressure seal and the bladder is not required to sustain structural loads, the bladder and the web can be optimized for their respective functions. Thus, the bladder can be sealed directly to the rigid core without having to include the web in the seal substructure, and the web can be designed for strength. The ends of the longitudinal straps are attached to the ends of the rigid structural core by means of clevises. Each clevis pin is surrounded by a roller, around which a longitudinal strap is wrapped to form a lap seam with itself. The roller is of a large diameter chosen to reduce bending of the fibers in the strap. The roller also serves to equalize the load in the portions of the strap on both sides of the clevis pin. The lap seam is formed near the clevis by use of a tapered diamond stitch: This stitch is designed specifically to allow fibers in the stitch and strap to relax under load in such a manner that the load becomes more nearly evenly distributed among all fibers in the stitch region. Thus, the tapered diamond stitch prevents load concentrations that could cause premature failure of the strap and thereby increases the strength of the strap/structural-core joint. The lap seam can be rated at >90 percent of the strength of the strap material.

Raboin, Jasen; Valle, Gerard D.; Edeen, Gregg; DeLaFuente, Horacio M.; Schneider, William C.; Spexarth, Gary R.; Johnson, Christopher J.; Pandya, Shalini

2004-01-01

38

Apollo experience report: Pressure vessels  

NASA Technical Reports Server (NTRS)

The Apollo spacecraft pressure vessels, associated problems and resolutions, and related experience in evaluating potential problem areas are discussed. Information is provided that can be used as a guideline in the establishment of baseline criteria for the design and use of lightweight pressure vessels. One of the first practical applications of the use of fracture-mechanics technology to protect against service failures was made on Apollo pressure vessels. Recommendations are made, based on Apollo experience, that are designed to reduce the incidence of failure in pressure-vessel operation and service.

Ecord, G. M.

1972-01-01

39

Stress State of Pipe Couplings in the Cylindrical Walls of Pressure Vessels  

Microsoft Academic Search

The “principle of area compensation” (GOST 24755?83) is used in designing pipe couplings; in conformity with this principle, additional metal should be added to the wall of the vessel housing in order that the sectional area of the metal removed from the opening, which requires reinforcement, be compensated by the sectional area of the additional metal. Problems of the strength

P. G. Pimshtein; G. M. Mordina; L. P. Barabanova

2003-01-01

40

Graphite filament wound pressure vessels  

NASA Technical Reports Server (NTRS)

Filament wound NOL rings, 4-inch and 8-inch diameter closed-end vessels involving three epoxy resin systems and three graphite fibers were tested to develop property data and fabrication technology for filament wound graphite/epoxy pressure vessels. Vessels were subjected to single-cycle burst tests at room temperature. Manufacturing parameters were established for tooling, winding, and curing that resulted in the development of a pressure/vessel performance factor (pressure x volume/weight) or more than 900,000 in. for an oblate spheroid specimen.

Feldman, A.; Damico, J. J.

1972-01-01

41

Image-based biomechanical modeling of aortic wall stress and vessel deformation: response to pulsatile arterial pressure simulations  

NASA Astrophysics Data System (ADS)

Image-based modeling of cardiovascular biomechanics may be very helpful for patients with aortic aneurysms to predict the risk of rupture and evaluate the necessity of a surgical intervention. In order to generate a reliable support it is necessary to develop exact patient-specific models that simulate biomechanical parameters and provide individual structural analysis of the state of fatigue and characterize this to the potential of rupture of the aortic wall. The patient-specific geometry used here originates from a CT scan of an Abdominal Aortic Aneurysm (AAA). The computations are based on the Finite Element Method (FEM) and simulate the wall stress distribution and the vessel deformation. The wall transient boundary conditions are based on real time-dependent pressure simulations obtained from a previous computational fluid dynamics study. The physiological wall material properties consider a nonlinear hyperelastic constitutive model, based on realistic ex-vivo analysis of the aneurismal arterial tissue. The results showed complex deformation and stress distribution on the AAA wall. The maximum stresses occurred at the systole and are found around the aneurismal bulge in regions close to inflection points. Biomechanical modeling based on medical images and coupled with patient-specific hemodynamics allows analysing and quantifying the effects of dilatation of the arterial wall due to the pulsatile aortic pressure. It provides a physical and realistic insight into the wall mechanics and enables predictive simulations of AAA growth and assessment of rupture. Further development integrating endovascular models would help evaluating non-invasively individual treatment strategies for optimal placement and improved device design.

Hazer, Dilana; Bauer, Miriam; Unterhinninghofen, Roland; Dillmann, Rüdiger; Richter, Götz-M.

2008-03-01

42

Critical fracture stress and fracture strain models for the prediction of lower and upper shelf toughness in nuclear pressure vessel steels  

Microsoft Academic Search

Critical fracture stress and stress modified fracture strain models are utilized to describe the variation of lower and upper shelf fracture toughness with temperature and strain rate for two alloy steels used in the manufacture of nuclear pressure vessels, namely SA533B-1 (HSST Plate 02) and SA302B (Surveillance correlation heat). Both steels have been well characterized with regard to static and

R. O. Ritchie; W. L. Server; R. A. Wullaert

1979-01-01

43

Critical fracture stress and fracture strain models for the prediction of lower and upper shelf toughness in nuclear pressure vessel steels  

Microsoft Academic Search

Critical fracture stress and stress modified fracture strain models are utilized to describe the variation of lower and upper\\u000a shelf fracture toughness with temperature and strain rate for two alloy steels used in the manufacture of nuclear pressure\\u000a vessels, namely SA533B-1 (HSST Plate 02) and SA302B (Surveillance correlation heat). Both steels have been well characterized\\u000a with regard to static and

R. O. Ritchie; W. L. Server; R. A. Wullaert

1979-01-01

44

Multilayer Composite Pressure Vessels  

NASA Technical Reports Server (NTRS)

A method has been devised to enable the fabrication of lightweight pressure vessels from multilayer composite materials. This method is related to, but not the same as, the method described in gMaking a Metal- Lined Composite-Overwrapped Pressure Vessel h (MFS-31814), NASA Tech Briefs, Vol. 29, No. 3 (March 2005), page 59. The method is flexible in that it poses no major impediment to changes in tank design and is applicable to a wide range of tank sizes. The figure depicts a finished tank fabricated by this method, showing layers added at various stages of the fabrication process. In the first step of the process, a mandrel that defines the size and shape of the interior of the tank is machined from a polyurethane foam or other suitable lightweight tooling material. The mandrel is outfitted with metallic end fittings on a shaft. Each end fitting includes an outer flange that has a small step to accommodate a thin layer of graphite/epoxy or other suitable composite material. The outer surface of the mandrel (but not the fittings) is covered with a suitable release material. The composite material is filament- wound so as to cover the entire surface of the mandrel from the step on one end fitting to the step on the other end fitting. The composite material is then cured in place. The entire workpiece is cut in half in a plane perpendicular to the axis of symmetry at its mid-length point, yielding two composite-material half shells, each containing half of the foam mandrel. The halves of the mandrel are removed from within the composite shells, then the shells are reassembled and bonded together with a belly band of cured composite material. The resulting composite shell becomes a mandrel for the subsequent steps of the fabrication process and remains inside the final tank. The outer surface of the composite shell is covered with a layer of material designed to be impermeable by the pressurized fluid to be contained in the tank. A second step on the outer flange of each end fitting accommodates this layer. Depending on the application, this layer could be, for example, a layer of rubber, a polymer film, or an electrodeposited layer of metal. If the fluid to be contained in the tank is a gas, then the best permeation barrier is electrodeposited metal (typically copper or nickel), which can be effective at a thickness of as little as 0.005 in (.0.13 mm). The electrodeposited metal becomes molecularly bonded to the second step on each metallic end fitting. The permeation-barrier layer is covered with many layers of filament-wound composite material, which could be the same as, or different from, the composite material of the inner shell. Finally, the filament-wound composite material is cured in an ov

DeLay, Tom

2005-01-01

45

Mechanical characteristics of filament-wound pressure vessel (burst pressure)  

NASA Technical Reports Server (NTRS)

The finite element method is used to analyze the mechanical characteristics of a pressurized filament-wound (FW) pressure vessel, and to predict its burst pressure. The analysis takes into account the bending moment, the stretch-bend coupling effect, nonlinear stress-strain relations, and finite deflection. The analysis is based on two initial failure criteria for laminae, and two ultimate fracture criteria for laminated structures. The numerical results, obtained by applying the load incremental method to the isotensoid CFRP pressure vessel used in the launching of the Zikiken satellite, are in good agreement with the experimental burst pressure and fracture behaviors.

Iida, H.; Uemura, M.

1987-01-01

46

Modeling flow stress constitutive behavior of SA508-3 steel for nuclear reactor pressure vessels  

NASA Astrophysics Data System (ADS)

Based on the measured stress-strain curves under different temperatures and strain rates, a series of flow stress constitutive equations for SA508-3 steel were firstly established through the classical theories on work hardening and softening. The comparison between the experimental and modeling results has confirmed that the established constitutive equations can correctly describe the mechanical responses and microstructural evolutions of the steel under various hot deformation conditions. We further represented a successful industrial application of this model to simulate a forging process for a large conical shell used in a nuclear steam generator, which evidences its practical and promising perspective of our model with an aim of widely promoting the hot plasticity processing for heavy nuclear components of fission reactors.

Sun, Mingyue; Hao, Luhan; Li, Shijian; Li, Dianzhong; Li, Yiyi

2011-11-01

47

A test method to evaluate stress corrosion cracking in pressure vessels  

Microsoft Academic Search

An accelerated laboratory test method was developed to evaluate the stress corrosion cracking (SCC) of kraft continuous digesters. The method uses circular patch test welds made from 38-mm-thick ASTM A516 Grade 70 steel plate. The specimens were exposed to a 110 C solution containing 40 gLNaOH and 20 gLNaâS at a controlled electrochemical potential. Several different welding procedures were evaluated

D. Singbeil; A. Garner

1988-01-01

48

A test method to evaluate stress corrosion cracking in pressure vessels  

SciTech Connect

An accelerated laboratory test method was developed to evaluate the stress corrosion cracking (SCC) of kraft continuous digesters. The method uses circular patch test welds made from 38-mm-thick ASTM A516 Grade 70 steel plate. The specimens were exposed to a 110 C solution containing 40 gLNaOH and 20 gLNa/sub 2/S at a controlled electrochemical potential. Several different welding procedures were evaluated for resistance to SCC, along with stress relief, shotpeening, sealed thermal spray coatings, and weld overlays of Inconel/sup (1)/ 82 and AISI 309L stainless steel (SS). Stress relief, shotpeening, and sealed thermal spray coatings prevented SCC during the test. Compared to a control specimen, SCC was less severe after temper-bead welding and after welding with an E6010 capping pass. Severe SCC occurred in a specimen welded with the worst-case welding procedure. Deep, circumferential SCC occurred in the carbon steel at the edge of the Inconel 82 weld overlay. SCC was also observed at the interface between the AISI 309L SS weld overlay and the base plate.

Singbeil, D.; Garner, A.

1988-02-01

49

Susceptibility of Conventional Pressure Vessel Steel to Hydrogen-Induced Cracking and Stress Oriented Hydrogen-Induced Cracking in Hydrogen Sulfide-Containing Diglycolamine Solutions  

Microsoft Academic Search

Hydrogen-induced cracking (HIC) and stress-oriented hydrogen-induced cracking (SOHIC) tests were conducted on a conventional type A516-70 (UNS K02700) pressure vessel steel exposed to hydrogen sulfide (HâS)-containing diglycolamine (DGA) gas-sweetening environments. Base-line HIC and SOHIC tests were conducted in NACE TM0284-96 Solution A. For the SOHIC tests, four-point double-beam specimens were stressed to 60%, 80%, or 100% of the yield strength

M. A. Al-Anezi; A. K. Agrawal; G. S. Frankel

1999-01-01

50

Pressure vessel having continuous sidewall  

NASA Technical Reports Server (NTRS)

A spacecraft pressure vessel has a tub member. A sidewall member is coupled to the tub member so that a bottom section of the sidewall member extends from an attachment intersection with the tub member and away from the tub member. The bottom section of the sidewall member receives and transfers a load through the sidewall member.

Simon, Xavier D. (Inventor); Barackman, Victor J. (Inventor)

2011-01-01

51

Ultrasonic pressure measurement in pressure vessels  

NASA Astrophysics Data System (ADS)

Based on the reflected longitudinal wave, a new non-intrusive method for pressure measurement is proposed. The acoustoelastic theory and the thin-shell theory are introduced to develop the pressure measurement model in cylindrical pressure vessels. And a pressure measurement system is constructed to evaluate the effectiveness of the proposed method. The pressure measurement is implemented by measuring the travel-time change between two received ultrasonic sensors. The experimental results verify the feasibility and effectiveness of this new non-intrusive method. Compared with the non-intrusive pressure measurement method based on the critically refracted longitudinal wave (LCR wave), the proposed non-intrusive pressure measurement method has the advantages of higher sensitivity and higher signal-to-noise ratio.

Bi, Yao; Zhou, Hongliang; Huang, Zhiyao; Zhou, Hanhua; Yang, Xianglong

2014-12-01

52

Static-stress analysis of dual-axis safety vessel  

NASA Astrophysics Data System (ADS)

An 8 ft diameter safety vessel, made of HSLA-100 steel, is evaluated to determine its ability to contain the quasi-static residual pressure from a high explosive (HE) blast. The safety vessel is designed for use with the Dual-Axis Radiographic Hydrotest (DARHT) facility being developed at Los Alamos National Laboratory. A smaller confinement vessel fits inside the safety vessel and contains the actual explosion, and the safety vessel functions as a second layer of containment in the unlikely case of a confinement vessel leak. The safety vessel is analyzed as a pressure vessel based on the ASME Boiler and Pressure Vessel Code, Section 8, Division 1, and the Welding Research Council Bulletin, WRC107. Combined stresses that result from internal pressure and external loads on nozzles are calculated and compared to the allowable stresses for HSLA-100 steel. Results confirm that the shell and nozzle components are adequately designed for a static pressure of 830 psi, plus the maximum expected external loads. Shell stresses at the 'shell to nozzle' interface, produced from external loads on the nozzles, were less than 700 psi. The maximum combined stress resulting from the internal pressure plus external loads was 17,384 psi, which is significantly less than the allowable stress of 42,375 psi for HSLA-100 steel.

Bultman, D. H.

1992-11-01

53

Development of Residual Stress Improvement for Nuclear Pressure Vessel Instrumentation Nozzle Weld Joint (P-43+P-8) by Means of Induction Heating  

SciTech Connect

As a counter measurement of intergranular stress corrosion cracking (IGSCC) in boiling water reactors, the induction heating stress improvement (IHSI) has been developed as a method to improve the stress factor, especially residual stresses in affected areas of pipe joint welds. In this method, a pipe is heated from the outside by an induction coil and cooled from the inside with water simultaneously. By thermal stresses to produce a temperature differential between the inner and outer pipe surfaces, the residual stress inside the pipe is improved compression. IHSI had been applied to weld joints of austenitic stainless steel pipes (P-8+P-8). However IHSI had not been applied to weld joints of nickel-chromium-iron alloy (P-43) and austenitic stainless steel (P-8). This weld joint (P-43+P-8) is used for instrumentation nozzles in nuclear power plants' reactor pressure vessels. Therefore for the purpose of applying IHSI to this one, we studied the following: Investigation of IHSI conditions (Essential Variables); Residual stresses after IHSI; Mechanical properties after IHSI. This paper explains that IHSI is sufficiently effective in improvement of the residual stresses for this weld joint (P-43+P-8), and that IHSI does not cause negative effects by results of mechanical properties, and IHSI is verified concerning applying it to this kind of weld joint. (authors)

Takuro Terajima; Takashi Hirano [Ishikawajima-Harima Heavy Industies Co., Ltd (Japan)

2006-07-01

54

Static-stress analysis of dual-axis confinement vessel  

NASA Astrophysics Data System (ADS)

This study evaluates the static-pressure containment capability of a 6-ft-diameter, spherical vessel, made of HSLA-100 steel, to be used for high-explosive (HE) containment. The confinement vessel is designed for use with the Dual-Axis Radiographic Hydrotest Facility (DARHT) being developed at Los Alamos National Laboratory. Two sets of openings in the vessel are covered with x-ray transparent covers to allow radiographic imaging of an explosion as it occurs inside the vessel. The confinement vessel is analyzed as a pressure vessel based on the ASME Boiler and Pressure Vessel Code, Section 8, Division 1, and the Welding Research Council Bulletin, WRC-107. Combined stresses resulting from internal pressure and external loads on nozzles are calculated and compared with the allowable stresses for HSLA-100 steel. Results confirm that the shell and nozzles of the confinement vessel are adequately designed to safely contain the maximum residual pressure of 1675 psi that would result from an HE charge of 24.2 kg detonated in a vacuum. Shell stresses at the shell-to-nozzle interface, produced from external loads on the nozzles, were less than 400 psi. The maximum combined stress resulting from the internal pressure plus external loads was 16,070 psi, which is less than half the allowable stress of 42,375 psi for HSLA-100 steel.

Bultman, D. H.

1992-11-01

55

Material Selection for a Pressure Vessel  

NSDL National Science Digital Library

Pressure vessels are designed to contain pressure and withstand the operating mechanical and thermal transients for a specified design life. In addition they are designed to safety to leak before break (LBB). LBB describes the situation in which a leak occurs before a complete double-ended break of a component. Ductile and tough materials are widely used in nuclear pressure vessels, because of their high resistance to catastrophic rupture. The design process involves fatigue analysis to demonstrate that there is insignificant crack growth a postulated surface crack during the entire design life. However in terms of LBB the significant parameter is the elastic-plastic fracture toughness, and the material strength. However based on assessment based on linear elastic fracture mechanics, the candidate materials are carbon steels, low alloy steels and stainless steels, which interestingly are the materials that are used for pressure vessels. In terms of the fatigue crack initiation, the appropriate parameters are the threshold stress intensity factor range and the endurance limit and the material selection is based on these parameters.

Chattopadhyay, Sonnath

56

Reactor pressure vessel vented head  

DOEpatents

A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell.

Sawabe, James K. (San Jose, CA)

1994-01-11

57

Failure analysis of a 300M steel pressure vessel  

Microsoft Academic Search

A failure analysis was made in a 300M steel pressure vessel which has failed during hydrotest. The rupture occurred suddenly at a pressure level lower than what has been expected for the proof pressure. According to the results of various examinations it was concluded that hydrogen assisted stress corrosion cracking was the mechanism responsible for the failure. The root causes

M. L. A. Graça; C. Y. Hoo; O. M. M. Silva; N. J. Lourenço

2009-01-01

58

Stiffness Study of Wound-Filament Pressure Vessels  

NASA Technical Reports Server (NTRS)

Report presents theoretical and experimental study of stiffness of lightweight, jointed pressure vessels made of wound graphite fibers and epoxy. Specimens fabricated from layers of graphite fibers, wet with epoxy, on aluminum mandrel. Segment ends thickened with interspersed layers of axially oriented fibers to reduce pinhole bearing stresses and local deformations. Segments cured at 390 degrees F (199 degrees C). Report presents results of vibrational tests of one-quarter-scale models of wound-filament pressure vessels.

Verderaime, V.

1986-01-01

59

Reactor pressure vessel vented head  

DOEpatents

A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell. 6 figures.

Sawabe, J.K.

1994-01-11

60

LPT. EBOR reactor vessel in TAN 646. Pressure vessel head ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

LPT. EBOR reactor vessel in TAN 646. Pressure vessel head being installed in vault. Refueling port extension (right) and control rod nozzles (center). Camera facing northwest. Photographer: Comiskey. Date: January 20, 1965. INEEL negative no. 65-241 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

61

Steel pressure vessels for hydrostatic pressures to 50 kilobars.  

PubMed

Cylindrical steel pressure vessels are described that can be used for hydrostatic pressures up to 50 kilobars. Monoblock vessels of 350 maraging steel can be used to 40 kilobars and compound vessels with an inner vessel of 350 maraging steel and an outer vessel of 300 maraging steel to 50 kilobars. Neither requires the cylinder to be end loaded, and so they are much easier to use than the more usual compound vessels with a tungsten carbide inner and steel outer vessel. PMID:18699223

Lavergne, A; Whalley, E

1978-07-01

62

Optimization of multilayered composite pressure vessels using exact elasticity solution  

SciTech Connect

An approach for the optimal design of thick laminated cylindrical pressure vessels is given. The maximum burst pressure is computed using an exact elasticity solution and subject to the Tsai-Wu failure criterion. The design method is based on an accurate 3-D stress analysis. Exact elasticity solutions are obtained using the stress function approach where the radial, circumferential and shear stresses are determined taking the closed ends of the cylindrical shell into account. Design optimization of multilayered composite pressure vessels are based on the use of robust multidimensional methods which give fast convergence. Two methods are used to determine the optimum ply angles, namely, iterative and gradient methods. Numerical results are given for optimum fiber orientation of each layer for thick and thin-walled multilayered pressure vessels.

Adali, S.; Verijenko, V.E.; Tabakov, P.Y. [Univ. of Natal, Durban (South Africa). Dept. of Mechanical Engineering; Walker, M. [Technicon Natal, Durban (South Africa)

1995-11-01

63

Thick-wall Kevlar 49/Epoxy pressure vessels  

SciTech Connect

The feasibility of thick-wall composite vessels for very high pressure applications is demonstrated. Prototype vessels, in both spherical and cylindrical geometries, were designed, fabricated and burst tested. It is shown that experimental burst pressures are in excellent agreement with predicted values for burst pressures up to 60 ksi. Each unit consisted of a thin, seamless, copper liner with stainless steel fill stems and a filament-wound Kevlar 49/epoxy outer shell. Analysis of vessel performance accounted for liner thickness and yield strengths, composite thickness, mechanical properties and fiber volume fraction, and stress concentrations caused by the fill stem. Spherical vessels of three different sizes (inside diameters of 2.15 inches, 4.0 inches and 5.3 inches) with either 30 ksi or 60 ksi design burst pressure are discussed. Also, cylindrical vessels with identical liners but of two different composite thicknesses are described. These vessels achieved 50 ksi and 57 ksi burst pressures, respectively. In addition to the design considerations alluded to throughout the paper, the stress state in a thin metal liner during cyclic loading and the life prediction of composite vessels under sustained loading are discussed.

Guess, T.R.

1984-01-01

64

Lightweight bladder lined pressure vessels  

DOEpatents

A lightweight, low permeability liner for graphite epoxy composite compressed gas storage vessels. The liner is composed of polymers that may or may not be coated with a thin layer of a low permeability material, such as silver, gold, or aluminum, deposited on a thin polymeric layer or substrate which is formed into a closed bladder using torispherical or near torispherical end caps, with or without bosses therein, about which a high strength to weight material, such as graphite epoxy composite shell, is formed to withstand the storage pressure forces. The polymeric substrate may be laminated on one or both sides with additional layers of polymeric film. The liner may be formed to a desired configuration using a dissolvable mandrel or by inflation techniques and the edges of the film seamed by heat sealing. The liner may be utilized in most any type of gas storage system, and is particularly applicable for hydrogen, gas mixtures, and oxygen used for vehicles, fuel cells or regenerative fuel cell applications, high altitude solar powered aircraft, hybrid energy storage/propulsion systems, and lunar/Mars space applications, and other applications requiring high cycle life.

Mitlitsky, Fred (1125 Canton Ave., Livermore, CA 94550); Myers, Blake (4650 Almond Cir., Livermore, CA 94550); Magnotta, Frank (1206 Bacon Way, Lafayette, CA 94549)

1998-01-01

65

Lightweight bladder lined pressure vessels  

DOEpatents

A lightweight, low permeability liner is described for graphite epoxy composite compressed gas storage vessels. The liner is composed of polymers that may or may not be coated with a thin layer of a low permeability material, such as silver, gold, or aluminum, deposited on a thin polymeric layer or substrate which is formed into a closed bladder using tori spherical or near tori spherical end caps, with or without bosses therein, about which a high strength to weight material, such as graphite epoxy composite shell, is formed to withstand the storage pressure forces. The polymeric substrate may be laminated on one or both sides with additional layers of polymeric film. The liner may be formed to a desired configuration using a dissolvable mandrel or by inflation techniques and the edges of the film sealed by heat sealing. The liner may be utilized in most any type of gas storage system, and is particularly applicable for hydrogen, gas mixtures, and oxygen used for vehicles, fuel cells or regenerative fuel cell applications, high altitude solar powered aircraft, hybrid energy storage/propulsion systems, and lunar/Mars space applications, and other applications requiring high cycle life. 19 figs.

Mitlitsky, F.; Myers, B.; Magnotta, F.

1998-08-25

66

Organic fiber/epoxy pressure vessels  

NASA Technical Reports Server (NTRS)

We evaluated the performance of an organic fiber in an epoxy matrix by winding 20-cm diam spherical and cylindrical pressure vessels of various designs. For the spherical vessels, we used soft aluminum liners 0.76 mm thick for a double boss design and 2 mm thick for a single boss design. For the cylindrical vessels, we used both 0.5-mm rubber liners and 0.76-mm soft aluminum liners. Vessels of both types were tested for burst pressure and cyclic fatigue at room temperature and liquid hydrogen temperature. The effects of temperature and vessel shape on the vessel performance factor were negligible. Our vessel fatigue data were marred by premature failure of the liners.

Chiao, T. T.; Hamstad, M. A.; Marcon, M. A.

1974-01-01

67

Nonsymmetric buckling of plate-end pressure vessels  

SciTech Connect

Small cylindrical pressure vessels are often constructed with a circular flat plate end closure. The end-plate undergoes large deformations under working loads. High local stresses develop at the junction between the cylinder and end-plate, causing yield under proof loading. The compressive circumferential stresses at the junction may lead to bifurcation into a nonsymmetric deformation mode. This study explores the geometrically nonlinear elastic-plastic behavior of plate-end pressure vessels. The form of the axisymmetric prebuckling path is investigated, showing the strongly stiffening nature of the response. Bifurcation of the closure into a nonsymmetric mode is studied.

Teng, J.G. (School of Civil and Mining Engineering, Univ. of Sydney, NSW (AU)); Rotter, J.M. (Dept. of Civil Engineering and Building Science, Univ. of Edinburgh, The King's Buildings, Edinburgh (GB))

1989-08-01

68

Method of manufacturing an overwrapped pressure vessel  

NASA Technical Reports Server (NTRS)

A pressure vessel of the type wherein a metallic liner in the shape of a cylindrical portion with a dome-shaped portion at each end thereof is overwrapped by a plurality of layers of resin coated, single fiberglass filaments. A four-step wrapping technique reinforces the vessel with overwrap material at the most likely areas for vessel failure. Overwrapping of the vessel is followed by a sizing pressurization cycle which induces a compressive prestress into the liner and thereby permits the liner to deform elastically through an increased strain range.

Beck, Emory J. (Inventor)

1976-01-01

69

Steel - Structural, reinforcing; Pressure vessel, railway  

SciTech Connect

This book contains specifications for structural steel used in various constructions; concrete reinforcement; plate and forgings for boilers and pressure vesseles; rails, axles, wheels and other accessories for railway service.

Not Available

1986-01-01

70

A scattered-light three-dimensional photoelastic stress analysis of a thick-walled pressure vessel  

E-print Network

is plane-polarized in a direction that is mutually perpendicular to both the axis of propagation before scattering and the axis of propagation after scattering. Thus, in Figure 1, an observer at A would see the beam at maximum intensity, and an observer... of polarization of the incident light beam and the direction of the maximum secondary I -0- Plane Polarized Light Source Figure 1. Scattered-Light Intensity principal stress & and a is the angle between the direction of observation and the maximum secondary...

Lednicky, Edward Frank

1971-01-01

71

Pure Niobium as a Pressure Vessel Material  

NASA Astrophysics Data System (ADS)

Physics laboratories around the world are developing niobium superconducting radio frequency (SRF) cavities for use in particle accelerators. These SRF cavities are typically cooled to low temperatures by direct contact with a liquid helium bath, resulting in at least part of the helium container being made from pure niobium. In the U.S., the Code of Federal Regulations allows national laboratories to follow national consensus pressure vessel rules or use of alternative rules which provide a level of safety greater than or equal to that afforded by ASME Boiler and Pressure Vessel Code. Thus, while used for its superconducting properties, niobium ends up also being treated as a material for pressure vessels. This report summarizes what we have learned about the use of niobium as a pressure vessel material, with a focus on issues for compliance with pressure vessel codes. We present results of a literature search for mechanical properties and tests results, as well as a review of ASME pressure vessel code requirements and issues.

Peterson, T. J.; Carter, H. F.; Foley, M. H.; Klebaner, A. L.; Nicol, T. H.; Page, T. M.; Theilacker, J. C.; Wands, R. H.; Wong-Squires, M. L.; Wu, G.

2010-04-01

72

Failure analysis of a fiberglass-reinforced plastic pressure vessel  

SciTech Connect

A fiberglass-reinforced plastic (FRP) pressure vessel containing sulfuric acid failed catastrophically in service. Preliminary investigations ruled out failure due to sabotage and chemical or mechanical overpressure. Subsequent examination of the fiber fracture surfaces and measurements of mirror radii indicated that fiber failure had occurred at stresses significantly below the fibers` expected strength. Further examination by scanning electron microscopy and energy dispersive spectroscopy indicated that the glass fibers had been exposed to sulfuric acid, a reagent that corrodes this type of glass and degrades its strength. Finite element analysis indicated stresses in an exposed region of the vessel that exceeded the strengths of the FRP during normal vessel operation. Numerous cracks were detected in this region using a vicinal optical illumination technique. We concluded that vessel failure was caused by progressive degradation and rupture of fibers starting at the outer surface of the FRP and extending inwards and laterally, until a crack of critical size was produced.

Glass, S.J.; Beauchamp, E.K.; Carr, M.; Guess, T.R.; Monroe, S.L.; Moore, R.J.; Slavin, A.; Sorenson, N.R.

1995-09-01

73

Summary of Activities for Health Monitoring of Composite Overwrapped Pressure Vessels Updated January 2014  

NASA Technical Reports Server (NTRS)

This three year project (FY12-14) will design and demonstrate the ability of new Magnetic Stress Gages for the measurement of stresses on the inner diameter of a Composite Overwrapped Pressure Vessel overwrap.

Skow, Miles G.

2014-01-01

74

Flexible Composite-Material Pressure Vessel  

NASA Technical Reports Server (NTRS)

A proposed lightweight pressure vessel would be made of a composite of high-tenacity continuous fibers and a flexible matrix material. The flexibility of this pressure vessel would render it (1) compactly stowable for transport and (2) more able to withstand impacts, relative to lightweight pressure vessels made of rigid composite materials. The vessel would be designed as a structural shell wherein the fibers would be predominantly bias-oriented, the orientations being optimized to make the fibers bear the tensile loads in the structure. Such efficient use of tension-bearing fibers would minimize or eliminate the need for stitching and fill (weft) fibers for strength. The vessel could be fabricated by techniques adapted from filament winding of prior composite-material vessels, perhaps in conjunction with the use of dry film adhesives. In addition to the high-bias main-body substructure described above, the vessel would include a low-bias end substructure to complete coverage and react peak loads. Axial elements would be overlaid to contain damage and to control fiber orientation around side openings. Fiber ring structures would be used as interfaces for connection to ancillary hardware.

Brown, Glen; Haggard, Roy; Harris, Paul A.

2003-01-01

75

Liquid Nitrogen Subcooler Pressure Vessel Engineering Note  

SciTech Connect

The normal operating pressure of this dewar is expected to be less than 15 psig. This vessel is open to atmospheric pressure thru a non-isolatable vent line. The backpressure in the vent line was calculated to be less than 1.5 psig at maximum anticipated flow rates.

Rucinski, R.; /Fermilab

1997-04-24

76

Proactive life extension of pressure vessels  

NASA Astrophysics Data System (ADS)

For a company to maintain its competitive edge in today's global market every opportunity to gain an advantage must be exploited. Many companies are strategically focusing on improved utilization of existing equipment as well as regulatory compliance. Abbott Laboratories is no exception. Pharmaceutical companies such as Abbott Laboratories realize that reliability and availability of their production equipment is critical to be successful and competitive. Abbott Laboratories, like many of our competitors, is working to improve safety, minimize downtime and maximize the productivity and efficiency of key production equipment such as the pressure vessels utilized in our processes. The correct strategy in obtaining these objectives is to perform meaningful inspection with prioritization based on hazard analysis and risk. The inspection data gathered in Abbott Laboratories pressure vessel program allows informed decisions leading to improved process control. The results of the program are reduced risks to the corporation and employees when operating pressure retaining equipment. Accurate and meaningful inspection methods become the cornerstone of a program allowing proper preventative maintenance actions to occur. Successful preventative/predictive maintenance programs must utilize meaningful nondestructive evaluation techniques and inspection methods. Nondestructive examination methods require accurate useful tools that allow rapid inspection for the entire pressure vessel. Results from the examination must allow the owner to prove compliance of all applicable regulatory laws and codes. At Abbott Laboratories the use of advanced NDE techniques, primarily B-scan ultrasonics, has provided us with the proper tools allowing us to obtain our objectives. Abbott Laboratories uses B-scan ultrasonics utilizing a pulse echo pitch catch technique to provide essential data on our pressure vessels. Equipment downtime is reduced because the nondestructive examination usually takes place while our vessels are in service. As the inspection takes place we are able to view a real time image of detected discontinuities on a video monitor. The B-scan ultrasonic technique is allowing us to perform fast accurate examinations covering up to 95% of the surface area of each pressure vessel. Receiving data on 95% of a pressure vessel provides us with a lot of useful information. We use this data to determine the condition of each pressure vessel. Once the condition is known the vessels are classed by risk. The risk level is then managed by making decisions related to repair, operating parameters, accepting and monitoring or replacement of the equipment. Inspection schedules are set at maximum intervals and reinspection is minimized for the vessels that are not at risk. The remaining life of each pressure vessel is determined, mechanical integrity is proven and regulatory requirements are met. Abbott Laboratories is taking this proactive approach because we understand that our process equipment is a critical element for successful operation. A run to failure practice would never allow Abbott Laboratories to achieve the corporation's objective of being the world's leading health care company. Nondestructive state of the art technology and the understanding of its capabilities and limitations are key components of a proactive program for life extension of pressure vessels. 26

Mager, Lloyd

1998-03-01

77

A Survey of Pressure Vessel Code Compliance for Superconducting RF Cryomodules  

SciTech Connect

Superconducting radio frequency (SRF) cavities made from niobium and cooled with liquid helium are becoming key components of many particle accelerators. The helium vessels surrounding the RF cavities, portions of the niobium cavities themselves, and also possibly the vacuum vessels containing these assemblies, generally fall under the scope of local and national pressure vessel codes. In the U.S., Department of Energy rules require national laboratories to follow national consensus pressure vessel standards or to show ''a level of safety greater than or equal to'' that of the applicable standard. Thus, while used for its superconducting properties, niobium ends up being treated as a low-temperature pressure vessel material. Niobium material is not a code listed material and therefore requires the designer to understand the mechanical properties for material used in each pressure vessel fabrication; compliance with pressure vessel codes therefore becomes a problem. This report summarizes the approaches that various institutions have taken in order to bring superconducting RF cryomodules into compliance with pressure vessel codes. In Japan, Germany, and the U.S., institutions building superconducting RF cavities integrated in helium vessels or procuring them from vendors have had to deal with pressure vessel requirements being applied to SRF vessels, including the niobium and niobium-titanium components of the vessels. While niobium is not an approved pressure vessel material, data from tests of material samples provide information to set allowable stresses. By means of procedures which include adherence to code welding procedures, maintaining material and fabrication records, and detailed analyses of peak stresses in the vessels, or treatment of the vacuum vessel as the pressure boundary, research laboratories around the world have found methods to demonstrate and document a level of safety equivalent to the applicable pressure vessel codes.

Peterson, Thomas; Klebaner, Arkadiy; Nicol, Tom; Theilacker, Jay; /Fermilab; Hayano, Hitoshi; Kako, Eiji; Nakai, Hirotaka; Yamamoto, Akira; /KEK, Tsukuba; Jensch, Kay; Matheisen, Axel; /DESY; Mammosser, John; /Jefferson Lab

2011-06-07

78

Pressurized wet digestion in open vessels.  

PubMed

The High Pressure Asher (HPA-S) was adapted with a Teflon liner for pressurized wet digestion in open vessels. The autoclave was partly filled with water containing 5% (vol/vol) hydrogen peroxide. The digestion vessels dipped partly into the water or were arranged on top of the water by means of a special rack made of titanium or PTFE-coated stainless steel. The HPA-S was closed and pressurized with nitrogen up to 100 bars. The maximum digestion temperature was 250 degrees C for PFA vessels and 270 degrees C for quartz vessels. Digestion vessels made of quartz or PFA-Teflon with volumes between 1.5 mL (auto sampler cups) and 50 mL were tested. The maximum sample amount for quartz vessels was 0.5-1.5 g and for PFA vessels 0.2-0.5 g, depending on the material. Higher sample intake may lead to fast reactions with losses of digestion solution. The samples were digested with 5 mL HNO(3) or with 2 mL HNO(3)+6 mL H(2)O+2 mL H(2)O(2). The total digestion time was 90-120 min and 30 min for cooling down to room temperature. Auto sampler cups made of PFA were used as digestion vessels for GFAAS. Sample material (50 mg) was digested with 0.2 mL HNO(3)+0.5 mL H(2)O+0.2 mL H(2)O(2). The analytical data of nine certified reference materials are also within the confidential intervals for volatile elements like mercury, selenium and arsenic. No cross contamination between the digestion vessels could be observed. Due to the high gas pressure, the diffusion rate of volatile species is low and losses of elements by volatilisation could be observed only with diluted nitric acid and vessels with large cross section. In addition, cocoa, walnuts, nicotinic acid, pumpkin seeds, lubrication oil, straw, polyethylene and coal were digested and the TOC values measured. The residual carbon content came to 0.2-10% depending on the sample matrix and amount. PMID:12802569

Maichin, B; Zischka, M; Knapp, G

2003-07-01

79

Cavity closure arrangement for high pressure vessels  

DOEpatents

A closure arrangement for a pressure vessel such as the pressure vessel of a high temperature gas-cooled reactor wherein a liner is disposed within a cavity penetration in the reactor vessel and defines an access opening therein. A closure is adapted for sealing relation with an annular mounting flange formed on the penetration liner and has a plurality of radially movable locking blocks thereon having outer serrations adapted for releasable interlocking engagement with serrations formed internally of the upper end of the penetration liner so as to effect high strength closure hold-down. In one embodiment, ramping surfaces are formed on the locking block serrations to bias the closure into sealed relation with the mounting flange when the locking blocks are actuated to locking positions.

Amtmann, Hans H. (San Diego, CA)

1981-01-01

80

Reactor pressure vessel with forged nozzles  

DOEpatents

Inlet nozzles for a gravity-driven cooling system (GDCS) are forged with a cylindrical reactor pressure vessel (RPV) section to which a support skirt for the RPV is attached. The forging provides enhanced RPV integrity around the nozzle and substantial reduction of in-service inspection costs by eliminating GDCS nozzle-to-RPV welds.

Desai, Dilip R. (Fremont, CA)

1993-01-01

81

Structural design, analysis, and code evaluation of an odd-shaped pressure vessel  

NASA Astrophysics Data System (ADS)

An effort to design, analyze, and evaluate a rectangular pressure vessel is described. Normally pressure vessels are designed in circular or spherical shapes to prevent stress concentrations. In this case, because of operational limitations, the choice of vessels was limited to a rectangular pressure box with a removable cover plate. The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code is used as a guideline for pressure containments whose width or depth exceeds 15.24 cm (6.0 in.) and where pressures will exceed 103.4 KPa (15.0 lbf/in(sup 2)). This evaluation used Section 8 of this Code, hereafter referred to as the Code. The dimensions and working pressure of the subject vessel fall within the pressure vessel category of the Code. The Code design guidelines and rules do not directly apply to this vessel. Therefore, finite-element methodology was used to analyze the pressure vessel, and the Code then was used in qualifying the vessel to be stamped to the Code. Section 8, Division 1 of the Code was used for evaluation. This action was justified by selecting a material for which fatigue damage would not be a concern. The stress analysis results were then checked against the Code, and the thicknesses adjusted to satisfy Code requirements. Although not directly applicable, the Code design formulas for rectangular vessels were also considered and presented.

Rezvani, M. A.; Ziada, H. H.

1992-12-01

82

Material Issues in Space Shuttle Composite Overwrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

Composite Overwrapped Pressure Vessels (COPV) store gases used in four subsystems for NASA's Space Shuttle Fleet. While there are 24 COPV on each Orbiter ranging in size from 19-40", stress rupture failure of a pressurized Orbiter COPV on the ground or in flight is a catastrophic hazard and would likely lead to significant damage/loss of vehicle and/or life and is categorized as a Crit 1 failure. These vessels were manufactured during the late 1970's and into the early 1980's using Titanium liners, Kevlar 49 fiber, epoxy matrix resin, and polyurethane coating. The COPVs are pressurized periodically to 3-5ksi and therefore experience significant strain in the composite overwrap. Similar composite vessels were developed in a variety of DOE Programs (primarily at Lawrence Livermore National Laboratories or LLNL), as well as for NASA Space Shuttle Fleet Leader COPV program. The NASA Engineering Safety Center (NESC) formed an Independent Technical Assessment (ITA) team whose primary focus was to investigate whether or not enough composite life remained in the Shuttle COPV in order to provide a strategic rationale for continued COPV use aboard the Space Shuttle Fleet with the existing 25-year-old vessels. Several material science issues were examined and will be discussed in this presentation including morphological changes to Kevlar 49 fiber under stress, manufacturing changes in Kevlar 49 and their effect on morphology and tensile strength, epoxy resin strain, composite creep, degradation of polyurethane coatings, and Titanium yield characteristics.

Sutter, James K.; Jensen, Brian J.; Gates, Thomas S.; Morgan, Roger J.; Thesken, John C.; Phoenix, S. Leigh

2006-01-01

83

Codes and standards and applications for design and analysis of pressure vessel and piping components 1991  

Microsoft Academic Search

Pressure technology and nuclear Codes and Standards address the entire spectrum of requirements for safety and reliability of pressure vessels and piping-materials, design, analysis, construction, fabrication, welding, nondestructive examination, acceptance testing, inservice inspection, inservice testing, repair, replacement and modification. Topics covered in this book included reactor vessel design, production reactors, safety standards, stress analyses, and seismic effects.

Sammataro

1991-01-01

84

Cracking progress and mechanism of 16MNR pressure vessel material  

SciTech Connect

A new testing device has been developed to test the antifatigue abilities of several pressure vessel materials. Crack initiation and propagation through grain boundaries can be seen clearly by the optical microscope and computer multi-media system at the microscopic level. It has been determined that the shear stress plays subtle effects to the first stage of crack initiation. The effects of small defects to fatigue lives are also discussed.

Pan, J.Z.; Sun, X.M. [East China Univ. of Science and Technology, Shanghai (China); Jin, L. [Shanghai Inst. of Chemical Technology (China)

1996-12-01

85

Corrosion of steel tendons used in prestressed concrete pressure vessels  

Microsoft Academic Search

The corrosion behavior of a high-strength steel (Specifications for Uncoated Seven-Wire-Stress-Relieved Strand for Prestressed Concrete (ASTM A 416-74, Grade 270)), typical of those used as tensioning tendons in prestressed concrete pressure vessels was measured in several corrosive environments. The protection obtained by coating the steel with two commercial petroleum-base greases or with Portland cement grout was evaluated. The few reported

J. C. Griess; D. J. Naus

1980-01-01

86

(Irradiation embrittlement of reactor pressure vessels)  

SciTech Connect

The traveler served as a member of the two-man US Nuclear Regulatory Commission sponsored team who visited the Prometey Complex in Leningrad to assess the potential for expanded cooperative research concerning integrity of the primary pressure boundary in commercial light-water reactors. The emphasis was on irradiation embrittlement, structural analysis, and fracture mechanics research for reactor pressure vessels. At the irradiation seminar in Cologne, presentations were made by German, French, Finnish, Russian, and US delegations concerning many aspects of irradiation of pressure vessel steels. The traveler made presentations on mechanisms of irradiation embrittlement and on important aspects of the Heavy-Section Steel Irradiation Program results of irradiated fracture mechanics tests.

Corwin, W.R.

1990-09-24

87

Experimental Investigation of Composite Pressure Vessel Performance and Joint Stiffness for Pyramid and Inverted Pyramid Joints  

NASA Technical Reports Server (NTRS)

The focus of this study is on the suitability in the application of classical laminate theory analysis tools for filament wound pressure vessels with adhesive laminated joints in particular: pressure vessel wall performance, joint stiffness and failure prediction. Two 18-inch diameter 12-ply filament wound pressure vessels were fabricated. One vessel was fabricated with a 24-ply pyramid laminated adhesive double strap butt joint. The second vessel was fabricated with the same number of plies in an inverted pyramid joint. Results from hydrostatic tests are presented. Experimental results were used as input to the computer programs GENLAM and Laminate, and the output compared to test. By using the axial stress resultant, the classical laminate theory results show a correlation within 1% to the experimental results in predicting the pressure vessel wall pressure performance. The prediction of joint stiffness for the two adhesive joints in the axial direction is within 1% of the experimental results. The calculated hoop direction joint stress resultant is 25% less than the measured resultant for both joint configurations. A correction factor is derived and used in the joint analysis. The correction factor is derived from the hoop stress resultant from the tank wall performance investigation. The vessel with the pyramid joint is determined to have failed in the joint area at a hydrostatic pressure 33% value below predicted failure. The vessel with the inverted pyramid joint failed in the wall acreage at a hydrostatic pressure within 10% of the actual failure pressure.

Verhage, Joseph M.; Bower, Mark V.; Gilbert, Paul A. (Technical Monitor)

2001-01-01

88

Composite Overwrapped Pressure Vessels (COPV) Materials Aging Issues  

NASA Technical Reports Server (NTRS)

This slide presentation reviews some of the issues concerning the aging of the materials in a Composite Overwrapped Pressure Vessels (COPV). The basic composition of the COPV is a Boss, a composite overwrap, and a metallic liner. The lifetime of a COPV is affected by the age of the overwrap, the cyclic fatigue of the metallic liner, and stress rupture life, a sudden and catastrophic failure of the overwrap while holding at a stress level below the ultimate strength for an extended time. There is information about the coupon tests that were performed, and a test on a flight COPV.

2010-01-01

89

Guide for certifying pressure vessels and systems  

NASA Astrophysics Data System (ADS)

This guide is intended to provide methodology and describe the intent of the Pressure Vessel and System (PV/S) Certification program. It is not meant to be a mandated document, but is intended to transmit a basic understanding of the PV/S program, and include examples. After the reader has familiarized himself with this publication, he should have a basic understanding of how to go about developing a PV/S certification program.

Lundy, Floyd; Krusa, Paul W.

1992-07-01

90

Guide for certifying pressure vessels and systems  

NASA Technical Reports Server (NTRS)

This guide is intended to provide methodology and describe the intent of the Pressure Vessel and System (PV/S) Certification program. It is not meant to be a mandated document, but is intended to transmit a basic understanding of the PV/S program, and include examples. After the reader has familiarized himself with this publication, he should have a basic understanding of how to go about developing a PV/S certification program.

Lundy, Floyd; Krusa, Paul W.

1992-01-01

91

Composite Pressure Vessel Including Crack Arresting Barrier  

NASA Technical Reports Server (NTRS)

A pressure vessel includes a ported fitting having an annular flange formed on an end thereof and a tank that envelopes the annular flange. A crack arresting barrier is bonded to and forming a lining of the tank within the outer surface thereof. The crack arresting barrier includes a cured resin having a post-curing ductility rating of at least approximately 60% through the cured resin, and further includes randomly-oriented fibers positioned in and throughout the cured resin.

DeLay, Thomas K. (Inventor)

2013-01-01

92

Tailoring Topology Optimization to Composite Pressure Vessel Design with Simultaneous  

E-print Network

;Introduction ­ CNG Pressure Vessels Compressed Natural Gas (CNG) Pressure Vessels CNG Cargo Containment System$160/ship Comparison of CNG and LNG (Liquefied Natural Gas) Introduction ­ CNG Pressure Vessels MM for compression, loading and unloading CNG inside cars and buses #12;Size of investment for a 500MMscf/d plant CNG

Paulino, Glaucio H.

93

A utility perspective on management of reactor pressure vessel embrittlement  

SciTech Connect

A utility perspective on evaluating and managing radiation embrittlement of pressure vessels is presented in this paper. Included are observations and experiences gained from pressure vessel surveillance capsule programs, and activities on flux reduction through the use of low-leakage core-loading patterns. Also included are pressure vessel embrittlement considerations relating to plant regenerating and plant life extension.

Perrin, J.S. [Public Service Electric and Gas Co., Hancocks Bridge, NJ (United States)

1993-12-01

94

Reliability Considerations for Composite Overwrapped Pressure Vessels on Spacecraft  

NASA Technical Reports Server (NTRS)

Composite Overwrapped Pressure Vessels (COPVs) are used to store gases under high pressure onboard spacecraft. These are used for a variety of purposes such as propelling liquid fuel etc, Kevlar, glass, Carbon and other more recent fibers have all been in use to overwrap the vessels. COPVs usually have a thin metallic liner with the primary purpose of containing the gases and prevent any leakage. The liner is overwrapped with filament wound composite such as Kevlar, Carbon or Glass fiber. Although the liner is required to perform in the leak before break mode making the failure a relatively benign mode, the overwrap can fail catastrophically under sustained load due to stress rupture. It is this failure mode that is of major concern as the stored energy of such vessels is often great enough ta cause loss of crew and vehicle. The present paper addresses some of the reliability concerns associated specifically with Kevlar Composite Overwrapped Pressure Vessels. The primary focus of the paper is on how reliability of COPV's are established for the purpose of deciding in general their flight worthiness and continued use. Analytical models based on existing design data will be presented showing how to achieve the required reliability metric to the end of a specific period of performance. Uncertainties in the design parameters and how they affect reliability and confidence intervals will be addressed as well. Some trade studies showing how reliability changes with time during a program period will be presented.

Murthy, Pappu L. N.; Gyekenyesi, John P.; Grimes-Ledesma, Lorie; Phoenix, S. L.

2007-01-01

95

Modeling Scala Media as a Pressure Vessel  

NASA Astrophysics Data System (ADS)

The clinical condition known as endolymphatic hydrops is the swelling of scala media and may result in loss in hearing sensitivity consistent with other forms of low-frequency biasing. Because outer hair cells (OHCs) are displacement-sensitive and hearing levels tend to be preserved despite large changes in blood pressure and CSF pressure, it seems unlikely that the OHC respond passively to changes in static pressures in the chambers. This suggests the operation of a major feedback control loop which jointly regulates homeostasis and hearing sensitivity. Therefore the internal forces affecting the cochlear signal processing amplifier cannot be just motile responses. A complete account of the cochlear amplifier must include static pressures. To this end we have added a third, pressure vessel to our 1-D 140-segment, wave-digital filter active model of cochlear mechanics, incorporating the usual nonlinear forward transduction. In each segment the instantaneous pressure is the sum of acoustic pressure and global static pressure. The object of the model is to maintain stable OHC operating point despite any global rise in pressure in the third chamber. Such accumulated pressure is allowed to dissipate exponentially. In this first 3-chamber implementation we explore the possibility that acoustic pressures are rectified. The behavior of the model is critically dependent upon scaling factors and time-constants, yet by initial assumption, the pressure tends to accumulate in proportion to sound level. We further explore setting of the control parameters so that the accumulated pressure either stays within limits or may rise without bound.

Lepage, Eric; Olofsson, A.?Ke

2011-11-01

96

Neural Network Burst Pressure Prediction in Composite Overwrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

Acoustic emission data were collected during the hydroburst testing of eleven 15 inch diameter filament wound composite overwrapped pressure vessels. A neural network burst pressure prediction was generated from the resulting AE amplitude data. The bottles shared commonality of graphite fiber, epoxy resin, and cure time. Individual bottles varied by cure mode (rotisserie versus static oven curing), types of inflicted damage, temperature of the pressurant, and pressurization scheme. Three categorical variables were selected to represent undamaged bottles, impact damaged bottles, and bottles with lacerated hoop fibers. This categorization along with the removal of the AE data from the disbonding noise between the aluminum liner and the composite overwrap allowed the prediction of burst pressures in all three sets of bottles using a single backpropagation neural network. Here the worst case error was 3.38 percent.

Hill, Eric v. K.; Dion, Seth-Andrew T.; Karl, Justin O.; Spivey, Nicholas S.; Walker, James L., II

2007-01-01

97

Midland reactor pressure vessel flaw distribution  

SciTech Connect

The results of laboratory nondestructive examination (NDE), and destructive cross-sectioning of selected weldment sections of the Midland reactor pressure vessel were analyzed per a previously developed methodology in order to develop a flaw distribution. The flaw distributions developed from the NDE results obtained by two different ultrasonic test (UT) inspections (Electric Power Research Institute NDE Center and Pacific Northwest Laboratories) were not statistically significantly different. However, the distribution developed from the NDE Center`s (destructive) cross-sectioning-based data was found to be significantly different than those obtained through the UT inspections. A fracture mechanics-based comparison of the flaw distributions showed that the cross-sectioning-based data, conservatively interpreted (all defects considered as flaws), gave a significantly lower vessel failure probability when compared with the failure probability values obtained using the UT-based distributions. Given that the cross-sectioning data were reportedly biased toward larger, more significant-appearing (by UT) indications, it is concluded that the nondestructive examinations produced definitively conservative results. In addition to the Midland vessel inspection-related analyses, a set of twenty-seven numerical simulations, designed to provide a preliminary quantitative assessment of the accuracy of the flaw distribution method used here, were conducted. The calculations showed that, in more than half the cases, the analysis produced reasonably accurate predictions.

Foulds, J.R.; Kennedy, E.L. [Failure Analysis Associates, Inc., Menlo Park, CA (United States)] [Failure Analysis Associates, Inc., Menlo Park, CA (United States); Rosinski, S.T. [Sandia National Labs., Albuquerque, NM (United States)] [Sandia National Labs., Albuquerque, NM (United States)

1993-12-01

98

Plating Repair Of Nickel-Alloy Pressure Vessels  

NASA Technical Reports Server (NTRS)

Procedure for localized electrodeposition of nickel enables repair of small damaged nickel-based pressure vessels. Electrodeposition restores weakened areas of vessel wall to at least their former strength.

Ricklefs, Steve K.; Chagnon, Kevin M.

1989-01-01

99

Acoustic emission testing of 12-nickel maraging steel pressure vessels  

NASA Technical Reports Server (NTRS)

Acoustic emission data were obtained from three point bend fracture toughness specimens of 12-nickel maraging steel, and two pressure vessels of the same material. One of the pressure vessels contained a prefabricated flaw which was extended and sharpened by fatigue cycling. It is shown that the flawed vessel had similar characteristics to the fracture specimens, thereby allowing estimates to be made of its nearness to failure during a proof test. Both the flawed and unflawed pressure vessel survived the proof pressure and 5 cycles to the working pressure, but it was apparent from the acoustic emission response during the proof cycle and the 5 cycles to the working pressure that the flawed vessel was very near failure. The flawed vessel did not survive a second cycle to the proof pressure before failure due to flaw extension through the wall (causing a leak).

Dunegan, H. L.

1973-01-01

100

Three-Dimensional Digital Image Correlation of a Composite Overwrapped Pressure Vessel During Hydrostatic Pressure Tests  

NASA Technical Reports Server (NTRS)

Ambient temperature hydrostatic pressurization tests were conducted on a composite overwrapped pressure vessel (COPV) to understand the fiber stresses in COPV components. Two three-dimensional digital image correlation systems with high speed cameras were used in the evaluation to provide full field displacement and strain data for each pressurization test. A few of the key findings will be discussed including how the principal strains provided better insight into system behavior than traditional gauges, a high localized strain that was measured where gages were not present and the challenges of measuring curved surfaces with the use of a 1.25 in. thick layered polycarbonate panel that protected the cameras.

Revilock, Duane M., Jr.; Thesken, John C.; Schmidt, Timothy E.

2007-01-01

101

Finite element analysis of filament-wound composite pressure vessel under internal pressure  

NASA Astrophysics Data System (ADS)

In this study, finite element analysis (FEA) of composite overwrapped pressure vessel (COPV), using commercial software ABAQUS 6.12 was performed. The study deals with the simulation of aluminum pressure vessel overwrapping by Carbon/Epoxy fiber reinforced polymer (CFRP). Finite element method (FEM) was utilized to investigate the effects of winding angle on filament-wound pressure vessel. Burst pressure, maximum shell displacement and the optimum winding angle of the composite vessel under pure internal pressure were determined. The Laminae were oriented asymmetrically for [00,00]s, [150,-150]s, [300,-300]s, [450,-450]s, [550,-550]s, [600,-600]s, [750,-750]s, [900,-900]s orientations. An exact elastic solution along with the Tsai-Wu, Tsai-Hill and maximum stress failure criteria were employed for analyzing data. Investigations exposed that the optimum winding angle happens at 550 winding angle. Results were compared with the experimental ones and there was a good agreement between them.

Sulaiman, S.; Borazjani, S.; Tang, S. H.

2013-12-01

102

Hydroide Storage Vessel wall stress measurements  

SciTech Connect

Holographic Interferometry and strain gauge measurements were used to determine whether a prototype Hydride Storage Vessel (HSV) swelled while it was loaded in eleven stages with hydrogen. Bed swelling is inferred from deformation of the surface of the HSV. No swelling was detected, even after saturating the hydride material inside the HSV. The large chunky morphology of the titanium is likely responsible for the lack of wall stress. This morphology also implies that decay helium that remains in the titanium hydride (that is, helium that is not released as gas to the free volume) should not cause significant wall stresses when the HSV is used for long-term tritium storage. Holographic interferometry proved to be an extremely sensitive technique to measure swelling, having a detection limit of about 3 microns surface displacement.

Clark, E.A. [Westinghouse Savannah River Company, AIKEN, SC (United States); Pechersky, M.J.

1997-07-31

103

Asymmetric Bulkheads for Cylindrical Pressure Vessels  

NASA Technical Reports Server (NTRS)

Asymmetric bulkheads are proposed for the ends of vertically oriented cylindrical pressure vessels. These bulkheads, which would feature both convex and concave contours, would offer advantages over purely convex, purely concave, and flat bulkheads (see figure). Intended originally to be applied to large tanks that hold propellant liquids for launching spacecraft, the asymmetric-bulkhead concept may also be attractive for terrestrial pressure vessels for which there are requirements to maximize volumetric and mass efficiencies. A description of the relative advantages and disadvantages of prior symmetric bulkhead configurations is prerequisite to understanding the advantages of the proposed asymmetric configuration: In order to obtain adequate strength, flat bulkheads must be made thicker, relative to concave and convex bulkheads; the difference in thickness is such that, other things being equal, pressure vessels with flat bulkheads must be made heavier than ones with concave or convex bulkheads. Convex bulkhead designs increase overall tank lengths, thereby necessitating additional supporting structure for keeping tanks vertical. Concave bulkhead configurations increase tank lengths and detract from volumetric efficiency, even though they do not necessitate additional supporting structure. The shape of a bulkhead affects the proportion of residual fluid in a tank that is, the portion of fluid that unavoidably remains in the tank during outflow and hence cannot be used. In this regard, a flat bulkhead is disadvantageous in two respects: (1) It lacks a single low point for optimum placement of an outlet and (2) a vortex that forms at the outlet during outflow prevents a relatively large amount of fluid from leaving the tank. A concave bulkhead also lacks a single low point for optimum placement of an outlet. Like purely concave and purely convex bulkhead configurations, the proposed asymmetric bulkhead configurations would be more mass-efficient than is the flat bulkhead configuration. In comparison with both purely convex and purely concave configurations, the proposed asymmetric configurations would offer greater volumetric efficiency. Relative to a purely convex bulkhead configuration, the corresponding asymmetric configuration would result in a shorter tank, thus demanding less supporting structure. An asymmetric configuration provides a low point for optimum location of a drain, and the convex shape at the drain location minimizes the amount of residual fluid.

Ford, Donald B.

2007-01-01

104

Designing of a Fleet-Leader Program for Carbon Composite Overwrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

Composite Overwrapped Pressure Vessels (COPVs) are often used for storing pressurant gases on board spacecraft when mass saving is a prime requirement. Substantial weight savings can be achieved compared to all metallic pressure vessels. For example, on the space shuttle, replacement of all metallic pressure vessels with Kevlar COPVs resulted in a weight savings of about 30 percent. Mass critical space applications such as the Ares and Orion vehicles are currently being planned to use as many COPVs as possible in place of all-metallic pressure vessels to minimize the overall mass of the vehicle. Due to the fact that overwraps are subjected to sustained loads during long periods of a mission, stress rupture failure is a major concern. It is, therefore, important to ascertain the reliability of these vessels by analysis, since it is practically impossible to show by experimental testing the reliability of flight quality vessels. Also, it is a common practice to set aside flight quality vessels as "fleet leaders" in a test program where these vessels are subjected to slightly accelerated operating conditions so that they lead the actual flight vessels both in time and load. The intention of fleet leaders is to provide advanced warning if there is a serious design flaw in the vessels so that a major disaster in the flight vessels can be averted with advance warning. On the other hand, the accelerating conditions must be not so severe as to be prone to false alarms. The primary focus of the present paper is to provide an analytical basis for designing a viable fleet leader program for carbon COPVs. The analysis is based on a stress rupture behavior model incorporating Weibull statistics and power-law sensitivity of life to fiber stress level.

Murthy, Pappu L.N.; Phoenix, S. Leigh

2009-01-01

105

Fracture analysis of surface and through-cracks in cylindrical pressure vessels  

NASA Technical Reports Server (NTRS)

A previously developed fracture criterion was applied to surface- and through-cracked cylindrical pressure vessels to see how well the criterion can correlate fracture data. Fracture data from the literature on surface cracks in aluminum alloy, steel, and epoxy vessels and on through cracks in aluminum alloy, titanium alloy, steel, and brass vessels were analyzed using the fracture criterion. The criterion correlated the failure stresses to within + or - 10 percent for either surface or through cracks over a wide range of crack size and vessel diameter. The fracture criterion was also found to correlate failure stresses from flat plates (center-crack or double-edge-crack tension specimens) and cylindrical pressure vessels containing through - cracks within + or - 10 percent.

Newman, J. C., Jr.

1976-01-01

106

Fracture analysis of surface and through cracks in cylindrical pressure vessels  

NASA Technical Reports Server (NTRS)

A previously developed fracture criterion was applied to fracture data for surface- and through-cracked cylindrical pressure vessels to see how well the criterion can correlate fracture data. Fracture data from the literature on surface cracks in aluminum alloy, steel, and epoxy vessels, and on through cracks in aluminum alloy, titanium alloy steel, and brass vessels were analyzed by using the fracture criterion. The criterion correlated the failure stresses to within + or - 10 percent for either surface or through cracks over a wide range of crack size and vessel diameter. The fracture criterion was also found to correlate failure stresses to within + or - 10 percent for flat plates (center-crack or double-edge-crack tension specimens) and cylindrical pressure vessels containing through cracks.

Newman, J. C., Jr.

1976-01-01

107

Radiation effects on reactor pressure vessel supports  

SciTech Connect

The purpose of this report is to present the findings from the work done in accordance with the Task Action Plan developed to resolve the Nuclear Regulatory Commission (NRC) Generic Safety Issue No. 15, (GSI-15). GSI-15 was established to evaluate the potential for low-temperature, low-flux-level neutron irradiation to embrittle reactor pressure vessel (RPV) supports to the point of compromising plant safety. An evaluation of surveillance samples from the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) had suggested that some materials used for RPV supports in pressurized-water reactors could exhibit higher than expected embrittlement rates. However, further tests designed to evaluate the applicability of the HFIR data to reactor RPV supports under operating conditions led to the conclusion that RPV supports could be evaluated using traditional method. It was found that the unique HFIR radiation environment allowed the gamma radiation to contribute significantly to the embrittlement. The shielding provided by the thick steel RPV shell ensures that degradation of RPV supports from gamma irradiation is improbable or minimal. The findings reported herein were used, in part, as the basis for technical resolution of the issue.

Johnson, R.E. [Nuclear Regulatory Commission, Washington, DC (United States). Div. of Engineering Technology; Lipinski, R.E. [Idaho National Engineering Lab., Rockville, MD (United States)

1996-05-01

108

Autogenous pressurization of cryogenic vessels using submerged vapor injection  

Microsoft Academic Search

Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet, a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency with pressurant gas requirements

Robert J. Stochl; Neil T. van Dresar; Raymond F. Lacovic

1991-01-01

109

Large boron--epoxy filament-wound pressure vessels  

NASA Technical Reports Server (NTRS)

Advanced composite material used to fabricate pressure vessel is prepeg (partially cured) consisting of continuous, parallel boron filaments in epoxy resin matrix arranged to form tape. To fabricate chamber, tape is wound on form which must be removable after composite has been cured. Configuration of boron--epoxy composite pressure vessel was determined by computer program.

Jensen, W. M.; Bailey, R. L.; Knoell, A. C.

1973-01-01

110

Local stress factors of a pipe-nozzle under internal pressure  

Microsoft Academic Search

A comprehensive study of local pressure stresses at the juncture of a pipe-nozzle is presented. Currently, neither experimental nor analytical data exists that is sufficient for pressure vessel designers to analyze the local pressure stresses at the juncture of a pipe-nozzle. In order to provide a comprehensive database to calculate these pressure stresses, this paper, through a finite element technique,

J. L. Ha; B. C. Sun; B. Koplik

1995-01-01

111

Predicting Structural Behavior of Filament Wound Composite Pressure Vessel Using Three Dimensional Shell Analysis  

NASA Astrophysics Data System (ADS)

Fiber reinforced polymer composite materials with their higher specific strength, moduli and tailorability characteristics will result in reduction of weight of the structure. The composite pressure vessels with integrated end domes develop hoop stresses that are twice longitudinal stresses and when isotropic materials like metals are used for development of the hardware and the material is not fully utilized in the longitudinal/meridional direction resulting in over weight components. The determination of a proper winding angles and thickness is very important to decrease manufacturing difficulties and to increase structural efficiency. In the present study a methodology is developed to understand structural characteristics of filament wound pressure vessels with integrated end domes. Progressive ply wise failure analysis of composite pressure vessel with geodesic end domes is carried out to determine matrix crack failure, burst pressure values at various positions of the shell. A three dimensional finite element analysis is computed to predict the deformations and stresses in the composite pressure vessel. The proposed method could save the time to design filament wound structures, to check whether the ply design is safe for the given input conditions and also can be adapted to non-geodesic structures. The results can be utilized to understand structural characteristics of filament wound pressure vessels with integrated end domes. This approach can be adopted for various applications like solid rocket motor casings, automobile fuel storage tanks and chemical storage tanks. Based on the predictions a composite pressure vessel is designed and developed. Hydraulic test is performed on the composite pressure vessel till the burst pressure.

Madhavi, M.; Venkat, R.

2014-01-01

112

Neutron fluence determination for light water reactor pressure vessels  

SciTech Connect

A general description of limitations that exist in pressure vessel neutron fluence determinations for commercial light water reactors is presented. Complexity factors that arise in light water reactor pressure vessel neutron fluence calculations are identified and used to analyze calculational limitations. Two broad categories of calculational limitations are introduced, namely benchmark field limitations and deep penetration limitations. Explicit examples of limitations that can arise in each of these two broad categories are presented. These limitations are used to show that the recent draft regulatory guide for the determination of pressure vessel neutron fluence, developed by the Nuclear Regulatory Commission, is based upon procedures and assumptions that are not valid. To eliminate the complexity and limitations of calculational methods, it is recommended that the determination of light water reactor pressure vessel neutron fluence be based upon experiment. Recommendations for improved methods of pressure vessel surveillance neutron dosimetry are advanced.

Gold, R. [Metrology Control Corp., Richland, WA (United States)

1994-12-31

113

Reactor Pressure Vessel Head Packaging & Disposal  

SciTech Connect

Reactor Pressure Vessel (RPV) Head replacements have come to the forefront due to erosion/corrosion and wastage problems resulting from the susceptibility of the RPV Head alloy steel material to water/boric acid corrosion from reactor coolant leakage through the various RPV Head penetrations. A case in point is the recent Davis-Besse RPV Head project, where detailed inspections in early 2002 revealed significant wastage of head material adjacent to one of the Control Rod Drive Mechanism (CRDM) nozzles. In lieu of making ASME weld repairs to the damaged head, Davis-Besse made the decision to replace the RPV Head. The decision was made on the basis that the required weld repair would be too extensive and almost impractical. This paper presents the packaging, transport, and disposal considerations for the damaged Davis-Besse RPV Head. It addresses the requirements necessary to meet Davis Besse needs, as well as the regulatory criteria, for shipping and burial of the head. It focuses on the radiological characterization, shipping/disposal package design, site preparation and packaging, and the transportation and emergency response plans that were developed for the Davis-Besse RPV Head project.

Wheeler, D. M.; Posivak, E.; Freitag, A.; Geddes, B.

2003-02-26

114

Transportable, small high-pressure preservation vessel for cells  

Microsoft Academic Search

We have previously reported that the survival rate of astrocytes increases under high-pressure conditions at 4°C. However, pressure vessels generally have numerous problems for use in cell preservation and transportation: (1) they cannot be readily separated from the pressurizing pump in the pressurized state; (2) they are typically heavy and expensive due the use of materials such as stainless steel;

N. Kamimura; S. Sotome; K. Nakajima; Y. Yoshimura; A. Shimizu

2010-01-01

115

Fatigue life improvement of an autofrettage thick-walled pressure vessel with an external groove  

NASA Astrophysics Data System (ADS)

This report presents an investigation into a fatigue life improvement of an autofrettaged thick-walled pressure vessel with an external groove subjected to pulsating internal pressure, along with mean strain and mean stress effects on strain-controlled low cycle fatigue behavior. Linear elastic stress analysis of an autofrettaged thick-walled pressure vessel with an external groove is done using a finite element method. Autofrettage loading is performed using a thermal loading analogy. Change of external groove geometry is made using a quasi-optimization technique and finite element method to achieve longer fatigue life by relieving the stress concentration at the groove root. Surface treatment using shot peening is employed to produce compressive residual stresses at the vulnerable surface of the groove root to counteract the high tensile stresses. An evaluation of the fatigue life of an autofrettaged thick-walled pressure vessel with an external groove is done through a series of simulation fatigue tests using C-shaped specimens taken from the thick-walled pressure vessel.

Koh, Seung K.; Stephens, Ralph I.

1992-01-01

116

Journal of Pressure Vessel Technology, Vol. 131, 2009, 041401 The Effects of Filler Metal Transformation Temperature on Residual Stresses in a  

E-print Network

investigated. Three single-pass groove welds were deposited by manual- metal-arc welding on 12 mm thick steel Transformation Temperature on Residual Stresses in a High Strength Steel Weld J. A. Francis School of Materials be adjusted to engineer the residual stress distribution in a bainitic-martensitic steel weld has been

Cambridge, University of

117

Firefighter's compressed air breathing system pressure vessel development program  

NASA Technical Reports Server (NTRS)

The research to design, fabricate, test, and deliver a pressure vessel for the main component in an improved high-performance firefighter's breathing system is reported. The principal physical and performance characteristics of the vessel which were required are: (1) maximum weight of 9.0 lb; (2) maximum operating pressure of 4500 psig (charge pressure of 4000 psig); (3) minimum contained volume of 280 in. 3; (4) proof pressure of 6750 psig; (5) minimum burst pressure of 9000 psig following operational and service life; and (6) a minimum service life of 15 years. The vessel developed to fulfill the requirements described was completely sucessful, i.e., every category of performence was satisfied. The average weight of the vessel was found to be about 8.3 lb, well below the 9.0 lb specification requirement.

Beck, E. J.

1974-01-01

118

Transient evolution of inter vessel gap pressure due to relative thermal expansion between two vessels  

NASA Astrophysics Data System (ADS)

In a typical liquid metal cooled fast breeder reactor (LMFBR), a cylindrical sodium filled main vessel, which carries the internals such as reactor core, pumps, intermediate heat exchangers etc. is surrounded by another vessel called safety vessel. The inter vessel gap is filled with nitrogen. During a thermal transient in the pool sodium, because of the relative delay involved in the thermal diffusion between MV and SV, they are subjected to relative thermal expansion or contraction between them. This in turn results in pressurisation and depressurisation of inter vessel gap nitrogen respectively. In order to obtain the external pressurization for the buckling design of MV, transient thermal models for obtaining the evolutions of MV, SV and inter gap nitrogen temperatures and hence their relative thermal expansion and inter vessel gap pressure have been developed. This paper gives the details of the mathematical model, assumptions made in the calculation and the results of the analysis.

Natesan, K.; Selvaraj, P.; Chellapandi, P.; Chetal, S. C.

2002-08-01

119

46 CFR 54.01-17 - Pressure vessel for human occupancy (PVHO).  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Pressure vessel for human occupancy (PVHO...SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54.01-17 Pressure vessel for human occupancy...

2014-10-01

120

10 CFR 50.66 - Requirements for thermal annealing of the reactor pressure vessel.  

Code of Federal Regulations, 2011 CFR

...thermal annealing of the reactor pressure vessel. 50.66 Section...thermal annealing of the reactor pressure vessel. (a...detailed description of the pressure vessel and all structures...The effects of localized high temperatures on...

2011-01-01

121

10 CFR 50.66 - Requirements for thermal annealing of the reactor pressure vessel.  

Code of Federal Regulations, 2014 CFR

...thermal annealing of the reactor pressure vessel. 50.66 Section...thermal annealing of the reactor pressure vessel. (a...detailed description of the pressure vessel and all structures...The effects of localized high temperatures on...

2014-01-01

122

10 CFR 50.66 - Requirements for thermal annealing of the reactor pressure vessel.  

Code of Federal Regulations, 2012 CFR

...thermal annealing of the reactor pressure vessel. 50.66 Section...thermal annealing of the reactor pressure vessel. (a...detailed description of the pressure vessel and all structures...The effects of localized high temperatures on...

2012-01-01

123

10 CFR 50.66 - Requirements for thermal annealing of the reactor pressure vessel.  

Code of Federal Regulations, 2013 CFR

...thermal annealing of the reactor pressure vessel. 50.66 Section...thermal annealing of the reactor pressure vessel. (a...detailed description of the pressure vessel and all structures...The effects of localized high temperatures on...

2013-01-01

124

46 CFR 50.05-5 - Existing boilers, pressure vessels or piping systems.  

Code of Federal Regulations, 2014 CFR

...Existing boilers, pressure vessels or piping systems. 50.05-5 Section 50...Existing boilers, pressure vessels or piping systems. (a) Whenever doubt exists...existing boiler, pressure vessel, or piping system, the marine inspector...

2014-10-01

125

29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2012 CFR

...Portable air receivers and other unfired pressure vessels. 1915.172 Section 1915...SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other...Portable air receivers and other unfired pressure vessels. (a) Portable,...

2012-07-01

126

29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2011 CFR

...Portable air receivers and other unfired pressure vessels. 1915.172 Section 1915...SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other...Portable air receivers and other unfired pressure vessels. (a) Portable,...

2011-07-01

127

46 CFR 54.01-17 - Pressure vessel for human occupancy (PVHO).  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Pressure vessel for human occupancy (PVHO...SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54.01-17 Pressure vessel for human occupancy...

2010-10-01

128

29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2013 CFR

...Portable air receivers and other unfired pressure vessels. 1915.172 Section 1915...SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other...Portable air receivers and other unfired pressure vessels. (a) Portable,...

2013-07-01

129

29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2014 CFR

...Portable air receivers and other unfired pressure vessels. 1915.172 Section 1915...SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other...Portable air receivers and other unfired pressure vessels. (a) Portable,...

2014-07-01

130

46 CFR 54.01-17 - Pressure vessel for human occupancy (PVHO).  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Pressure vessel for human occupancy (PVHO...SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54.01-17 Pressure vessel for human occupancy...

2013-10-01

131

77 FR 59408 - Finding of Equivalence; Alternate Pressure Relief Valve Settings on Certain Vessels Carrying...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Finding of Equivalence; Alternate Pressure Relief Valve Settings on Certain Vessels...Policy Letter 04-12, ``Alternative Pressure Relief Valve Settings on Vessels Carrying...Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Section VIII...

2012-09-27

132

29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2010 CFR

...Portable air receivers and other unfired pressure vessels. 1915.172 Section 1915...SHIPYARD EMPLOYMENT Portable, Unfired Pressure Vessels, Drums and Containers, Other...Portable air receivers and other unfired pressure vessels. (a) Portable,...

2010-07-01

133

46 CFR 54.01-17 - Pressure vessel for human occupancy (PVHO).  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Pressure vessel for human occupancy (PVHO...SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54.01-17 Pressure vessel for human occupancy...

2011-10-01

134

46 CFR 54.01-17 - Pressure vessel for human occupancy (PVHO).  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Pressure vessel for human occupancy (PVHO...SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54.01-17 Pressure vessel for human occupancy...

2012-10-01

135

On the optimal pretensioning of cylindrical and spherical pressure vessels  

SciTech Connect

Filament winding of pressure vessels and pipes is always realized with some pretensioning, and some external loads may be applied. It is important to determine such an optimal preload regime that ensures the maximum load-carrying capacity of the vessel subject to internal pressure. In the present study, the optimal preload distribution is analyzed in the filament winding fabrication of the cylindrical or spherical pressure vessels that are treated as growing elastic solids subjected to aging. In the case of cylindrical vessels, the dependence of the optimal preload intensity versus the polar radius is obtained for both nonaging and aging material of the fibers. In the case of spherical pressure vessels, the optimal regime of internal pressure applied during the winding process is obtained. The optimal loading of a spherical vessel at both infinitesimal and finite strains is analyzed. The new solutions obtained and the recommendations formulated are of a special practical importance for the optimal design and fabrication of the composite pressure vessels and pipes.

Kalamkarov, A.L.; Drozdov, A.D. [Technical Univ. of Nova Scotia, Halifax, Nova Scotia (Canada). Dept. of Mechanical Engineering

1995-11-01

136

Lightweight cryogenic-compatible pressure vessels for vehicular fuel storage  

DOEpatents

A lightweight, cryogenic-compatible pressure vessel for flexibly storing cryogenic liquid fuels or compressed gas fuels at cryogenic or ambient temperatures. The pressure vessel has an inner pressure container enclosing a fuel storage volume, an outer container surrounding the inner pressure container to form an evacuated space therebetween, and a thermal insulator surrounding the inner pressure container in the evacuated space to inhibit heat transfer. Additionally, vacuum loss from fuel permeation is substantially inhibited in the evacuated space by, for example, lining the container liner with a layer of fuel-impermeable material, capturing the permeated fuel in the evacuated space, or purging the permeated fuel from the evacuated space.

Aceves, Salvador; Berry, Gene; Weisberg, Andrew H.

2004-03-23

137

Neutron shielding panels for reactor pressure vessels  

DOEpatents

In a nuclear reactor neutron panels varying in thickness in the circumferential direction are disposed at spaced circumferential locations around the reactor core so that the greatest radial thickness is at the point of highest fluence with lesser thicknesses at adjacent locations where the fluence level is lower. The neutron panels are disposed between the core barrel and the interior of the reactor vessel to maintain radiation exposure to the vessel within acceptable limits.

Singleton, Norman R. (Murrysville, PA)

2011-11-22

138

Design of Semi-composite Pressure Vessel using Fuzzy and FEM  

NASA Astrophysics Data System (ADS)

The present study attempts to present a new method to design a semi-composite pressure vessel (known as hoop-wrapped composite cylinder) using fuzzy decision making and finite element method. A metal-composite vessel was designed based on ISO criteria and then the weight of the vessel was optimized for various fibers of carbon, glass and Kevlar in the cylindrical vessel. Failure criteria of von-Mises and Hoffman were respectively employed for the steel liner and the composite reinforcement to characterize the yielding/ buckling of the cylindrical pressure vessel. The fuzzy decision maker was used to estimate the thickness of the steel liner and the number of composite layers. The ratio of stresses on the composite fibers and the working pressure as well as the ratio of stresses on the composite fibers and the burst (failure) pressure were assessed. ANSYS nonlinear finite element solver was used to analyze the residual stress in the steel liner induced due to an auto-frettage process. Result of analysis verified that carbon fibers are the most suitable reinforcement to increase strength of cylinder while the weight stayed appreciably low.

Sabour, Mohammad H.; Foghani, Mohammad F.

2010-04-01

139

46 CFR 58.60-3 - Pressure vessel.  

Code of Federal Regulations, 2014 CFR

...HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Industrial Systems and Components on Mobile Offshore...pressure vessel that is a component in an industrial system under this subpart must...

2014-10-01

140

46 CFR 61.10-5 - Pressure vessels in service.  

Code of Federal Regulations, 2014 CFR

...for certification: all tubular heat exchangers, hydraulic accumulators, and...twice every 5 years: all tubular heat exchangers, hydraulic accumulators, and...hydrostatic test: (1) Tubular heat exchangers. (2) Pressure vessels...

2014-10-01

141

46 CFR 58.60-3 - Pressure vessel.  

Code of Federal Regulations, 2013 CFR

...HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Industrial Systems and Components on Mobile Offshore...pressure vessel that is a component in an industrial system under this subpart must...

2013-10-01

142

46 CFR 58.60-3 - Pressure vessel.  

Code of Federal Regulations, 2012 CFR

...HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Industrial Systems and Components on Mobile Offshore...pressure vessel that is a component in an industrial system under this subpart must...

2012-10-01

143

46 CFR 61.10-5 - Pressure vessels in service.  

Code of Federal Regulations, 2011 CFR

...for certification: all tubular heat exchangers, hydraulic accumulators, and...twice every 5 years: all tubular heat exchangers, hydraulic accumulators, and...hydrostatic test: (1) Tubular heat exchangers. (2) Pressure vessels...

2011-10-01

144

46 CFR 61.10-5 - Pressure vessels in service.  

Code of Federal Regulations, 2012 CFR

...for certification: all tubular heat exchangers, hydraulic accumulators, and...twice every 5 years: all tubular heat exchangers, hydraulic accumulators, and...hydrostatic test: (1) Tubular heat exchangers. (2) Pressure vessels...

2012-10-01

145

46 CFR 61.10-5 - Pressure vessels in service.  

Code of Federal Regulations, 2010 CFR

...for certification: all tubular heat exchangers, hydraulic accumulators, and...twice every 5 years: all tubular heat exchangers, hydraulic accumulators, and...hydrostatic test: (1) Tubular heat exchangers. (2) Pressure vessels...

2010-10-01

146

46 CFR 61.10-5 - Pressure vessels in service.  

Code of Federal Regulations, 2013 CFR

...for certification: all tubular heat exchangers, hydraulic accumulators, and...twice every 5 years: all tubular heat exchangers, hydraulic accumulators, and...hydrostatic test: (1) Tubular heat exchangers. (2) Pressure vessels...

2013-10-01

147

46 CFR 58.60-3 - Pressure vessel.  

Code of Federal Regulations, 2010 CFR

...HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Industrial Systems and Components on Mobile Offshore...pressure vessel that is a component in an industrial system under this subpart must...

2010-10-01

148

46 CFR 58.60-3 - Pressure vessel.  

Code of Federal Regulations, 2011 CFR

...HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Industrial Systems and Components on Mobile Offshore...pressure vessel that is a component in an industrial system under this subpart must...

2011-10-01

149

Structural Health Monitoring of Composite Wound Pressure Vessels  

NASA Technical Reports Server (NTRS)

The increasing use of advanced composite materials in the wide range of applications including Space Structures is a great impetus to the development of smart materials. Incorporating these FBG sensors for monitoring the integrity of structures during their life cycle will provide valuable information about viability of the usage of such material. The use of these sensors by surface bonding or embedding in this composite will measure internal strain and temperature, and hence the integrity of the assembled engineering structures. This paper focuses on such a structure, called a composite wound pressure vessel. This vessel was fabricated from the composite material: TRH50 (a Mitsubishi carbon fiber with a 710-ksi tensile strength and a 37 Msi modulus) impregnated with an epoxy resin from NEWPORT composites (WDE-3D-1). This epoxy resin in water dispersed system without any solvents and it cures in the 240-310 degrees F range. This is a toughened resin system specifically designed for pressure applications. These materials are a natural fit for fiber sensors since the polyimide outer buffer coating of fiber can be integrated into the polymer matrix of the composite material with negligible residual stress. The tank was wound with two helical patterns and 4 hoop wraps. The order of winding is: two hoops, two helical and two hoops. The wall thickness of the composite should be about 80 mil or less. The tank should burst near 3,000 psi or less. We can measure the actual wall thickness by ultrasonic or we can burst the tank and measure the pieces. Figure 1 shows a cylinder fabricated out of carbon-epoxy composite material. The strain in different directions is measured with a surface bonded fiber Bragg gratings and with embedded fiber Bragg gratings as the cylinder is pressurized to burst pressures. Figure 2 shows the strain as a function of pressure of carbon-epoxy cylinder as it is pressurized with water. Strain is measured in different directions by multiple gratings oriented in both axial and hoops directions.

Grant, Joseph; Kaul, Raj; Taylor, Scott; Jackson, Kurt; Myers, George; Sharma, A.

2002-01-01

150

Crashworthy sealed pressure vessel for plutonium transport  

SciTech Connect

A rugged transportation package for the air shipment of radioisotopic materials was recently developed. This package includes a tough, sealed, stainless steel inner containment vessel of 1460 cc capacity. This vessel, intended for a mass load of up to 2 Kg PuO/sub 2/ in various isotopic forms (not to exceed 25 watts thermal activity), has a positive closure design consisting of a recessed, shouldered lid fastened to the vessel body by twelve stainless-steel bolts; sealing is accomplished by a ductile copper gasket in conjunction with knife-edge sealing beads on both the body and lid. Follow-on applications of this seal in newer, smaller packages for international air shipments of plutonium safeguards samples, and in newer, more optimized packages for greater payload and improved efficiency and utility, are briefly presented.

Andersen, J.A.

1980-01-01

151

Progressive Fracture and Damage Tolerance of Composite Pressure Vessels  

NASA Technical Reports Server (NTRS)

Structural performance (integrity, durability and damage tolerance) of fiber reinforced composite pressure vessels, designed for pressured shelters for planetary exploration, is investigated via computational simulation. An integrated computer code is utilized for the simulation of damage initiation, growth, and propagation under pressure. Aramid fibers are considered in a rubbery polymer matrix for the composite system. Effects of fiber orientation and fabrication defect/accidental damages are investigated with regard to the safety and durability of the shelter. Results show the viability of fiber reinforced pressure vessels as damage tolerant shelters for planetary colonization.

Chamis, Christos C.; Gotsis, Pascal K.; Minnetyan, Levon

1997-01-01

152

Low-Cost, Lightweight Pressure Vessel Proof Test  

NASA Astrophysics Data System (ADS)

This experiment seeks to determine the burst strength of the low-cost, lightweight pressure vessel fabricated by the Suborbital Center of Excellence (SCE). Moreover, the test explores the effects of relatively large gage pressures on material strain for ‘pumpkin-shaped' pressure vessels. The SCE team used pressure transducers and analog gauges to measure the gage pressure while a video camera assembly recorded several gores in the shell for strain analysis. The team loaded the vessel in small intervals of pressure until the structure failed. Upon test completion, the pressure readings and video recordings were analyzed to determine the burst strength and material strain in the shell. The analysis yielded a burst pressure of 13.5 psi while the strain analysis reported in the shell. While the results of this proof test are encouraging, the structure's factor of safety must be increased for actual balloon flights. Furthermore, the pressure vessel prototype must be subjected to reliability tests to show the design can sustain gage pressures for the length of a balloon flight.

Chanez, Eric

153

Heavy wall pressure vessels for energy systems  

SciTech Connect

Modifications of steels currently accepted in the Code appear to provide improved mechanical properties. These steels may permit the fabrication of larger diameter vessels with thinner section sizes and improved reliability and integrity. Adapting current specifications should expedite Code approval. Finally the challenge of improving welding procedures and adapting processes for field applications will result in higher quality weldments.

Canonico, D.A.

1980-06-17

154

Time-dependent response of filamentary composite spherical pressure vessels  

NASA Technical Reports Server (NTRS)

A filamentary composite spherical pressure vessel is modeled as a pseudoisotropic (or transversely isotropic) composite shell, with the effects of the liner and fill tubes omitted. Equations of elasticity, macromechanical and micromechanical formulations, and laminate properties are derived for the application of an internally pressured spherical composite vessel. Viscoelastic properties for the composite matrix are used to characterize time-dependent behavior. Using the maximum strain theory of failure, burst pressure and critical strain equations are formulated, solved in the Laplace domain with an associated elastic solution, and inverted back into the time domain using the method of collocation. Viscoelastic properties of HBFR-55 resin are experimentally determined and a Kevlar/HBFR-55 system is evaluated with a FORTRAN program. The computed reduction in burst pressure with respect to time indicates that the analysis employed may be used to predict the time-dependent response of a filamentary composite spherical pressure vessel.

Dozier, J. D.

1983-01-01

155

Autogenous pressurization of cryogenic vessels using submerged vapor injection  

NASA Technical Reports Server (NTRS)

Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet; a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency, with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurent requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed.

Stochl, Robert J.; Vandresar, Neil T.; Lacovic, Raymond F.

1991-01-01

156

Autogenous pressurization of cryogenic vessels using submerged vapor injection  

NASA Technical Reports Server (NTRS)

Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet, a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurant requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed.

Stochl, Robert J.; Van Dresar, Neil T.; Lacovic, Raymond F.

1991-01-01

157

Autogenous pressurization of cryogenic vessels using submerged vapor injection  

NASA Astrophysics Data System (ADS)

Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet, a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurant requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed.

Stochl, Robert J.; van Dresar, Neil T.; Lacovic, Raymond F.

158

Summary of Activities for Health Monitoring of Composite Overwrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

This three-year project (FY12-14) will design and demonstrate the ability of new Magnetic Stress Gages for the measurement of stresses on the inner diameter of a Composite Overwrapped Pressure Vessel overwrap. The sensors are being tested at White Sands Testing Facility (WSTF) where the results will be correlated with a known nondestructive technique acoustic emission. The gages will be produced utilizing Meandering Winding Magnetometer (MWM) and/or MWM array eddy current technology. The ultimate goal is to utilize this technology for the health monitoring of Composite Overwrapped Pressure Vessels for all future flight programs. The first full-scale pressurization test was performed at WSTF in June 2012. The goals of this test were to determine adaptations of the magnetic stress gauge instrumentation that would be necessary to allow multiple sensors to monitor the vessel's condition simultaneously and to determine how the sensor response changes with sensor selection and orientation. The second full scale pressurization test was performed at WSTF in August 2012. The goals of this test were to monitor the vessel's condition with multiple sensors simultaneously, to determine the viability of the multiplexing units (MUX) for the application, and to determine if the sensor responses in different orientations are repeatable. For both sets of tests the vessel was pressured up to 6,000 psi to simulate maximum operating pressure. Acoustic events were observed during the first pressurization cycle. This suggested that the extended storage period prior to use of this bottle led to a relaxation of the residual stresses imparted during auto-frettage. The pressurization tests successfully demonstrated the use of multiplexers with multiple MWM arrays to monitor a vessel. It was discovered that depending upon the sensor orientation, the frequencies, and the sense element, the MWM arrays can provide a variety of complementary information about the composite overwrapped pressure vessel load conditions. For example, low frequency measurements can be used to monitor the overwrap thickness and changes associated with pressure level. High frequency data is dominated by the properties of the overwrap, including the fiber orientations and lay-up of the layers.

Russell, Rick; Skow, Miles

2013-01-01

159

Proceedings of the 13. international conference on NDE in the nuclear and pressure vessel industries  

SciTech Connect

This book is divided into the following sections: plenary session; role of NDE (nondestructive evaluation) 1; x-ray technology; role of NDE 2; piping and major components; reactor pressure vessel inspection; advanced ultrasonic inspection technologies 1; performance demonstration initiative and inspection qualification approaches; electromagnetic technologies; advanced ultrasonic inspection technologies 2; advanced inspection technologies 1; advanced inspection technologies 2; material characterization 1; material characterization 2; steam generators 1; steam generators 2; BWR reactor pressure vessel inspection; modelling of NDE inspections; turbine inspection; stress measurement; and control rod drive mechanism. Separate abstracts were prepared for 66 papers in this book.

Iida, Kunihiro [ed.] [Shibaura Inst. of Technology, Tokyo (Japan); Light, G.M [ed.] [Southwest Research Inst., San Antonio, TX (United States); Whittle, M.J. [ed.] [John Whittle and Associates, Cheshire (United Kingdom)

1995-08-01

160

Transportable, small high-pressure preservation vessel for cells  

NASA Astrophysics Data System (ADS)

We have previously reported that the survival rate of astrocytes increases under high-pressure conditions at 4°C. However, pressure vessels generally have numerous problems for use in cell preservation and transportation: (1) they cannot be readily separated from the pressurizing pump in the pressurized state; (2) they are typically heavy and expensive due the use of materials such as stainless steel; and (3) it is difficult to regulate pressurization rate with hand pumps. Therefore, we developed a transportable high-pressure system suitable for cell preservation under high-pressure conditions. This high-pressure vessel has the following characteristics: (1) it can be easily separated from the pressurizing pump due to the use of a cock-type stop valve; (2) it is small and compact, is made of PEEK and weighs less than 200 g; and (3) pressurization rate is regulated by an electric pump instead of a hand pump. Using this transportable high-pressure vessel for cell preservation, we found that astrocytes can survive for 4 days at 1.6 MPa and 4°C.

Kamimura, N.; Sotome, S.; Nakajima, K.; Yoshimura, Y.; Shimizu, A.

2010-03-01

161

Surveillance of WWER-440C reactor pressure vessels  

SciTech Connect

In Czechoslovakia there are six units of Water-Water Power Reactor (WWER)-440 C type reactors (pressurized water reactor [PWR] type) incorporated with pressure vessel surveillance specimens. These sets of specimens are kept for carrying out static tensile testing, impact notch toughness testing, and static fracture toughness testing, and are supplemented by necessary sets of neutron flux monitors. Results of mechanical testing of these specimens evaluated after one to five years of reactor operation are summarized and discussed with respect to the effect of individual heats and welding joints, radiation embrittlement laws, and lead factor and pressure vessel lifetime assessment.

Brumovsky, M. [Nuclear Research Inst., Rez (Czechoslovakia). Div. of Integrity; Pav, T. [Nuclear Research Inst., Rez (Czechoslovakia). Dept. of Nuclear Materials

1993-12-01

162

Calibrating Droplet Generator for Pressurized Testing Vessel  

NASA Technical Reports Server (NTRS)

Device helps to aline laser for droplet-sizing interferometer. Monodispersing Droplet Generator creates uniformly sized droplets. Laser source and receiver of interferometer alined and focused on droplets. MDG mounted in high-pressure flange on tank. Line extensions pass through flange to outside. Flange allows MDG to operate at high injector back pressures used for tests.

Defever, G. J.; Exposito, T.

1985-01-01

163

High performance universal test system for pressure vessel sealing property  

Microsoft Academic Search

Based on a general control plan, from 0.1MPa to 45MPa of pressure resistance value, the various pressure vessel's sealing property examination was completed with high intellectualization; the real-time display , the storage of data acquisition, as well as curve analysis were fulfilled. Using the micro motor and the encoder in the system, the high pressure hand operated valve has successfully

Yonghua Wang; Hao Jiang; Xiali Liu

2011-01-01

164

Report of the terawatt laser pressure vessel committee  

SciTech Connect

In 1995 the ATF project sent out an RFP for a CO2 Laser System having a TeraWatt output. Eight foreign and US firms responded. The Proposal Evaluation Panel on the second round selected Optoel, a Russian firm based in St. Petersburg, on the basis of the technical criteria and cost. Prior to the award, BNL representatives including the principal scientist, cognizant engineer and a QA representative visited the Optoel facilities to assess the company's capability to do the job. The contract required Optoel to provide a x-ray preionized high pressure amplifier that included: a high pressure cell, x-ray tube, internal optics and a HV pulse forming network for the main discharge and preionizer. The high-pressure cell consists of a stainless steel pressure vessel with various ports and windows that is filled with a gas mixture operating at 10 atmospheres. In accordance with BNL Standard ESH 1.4.1 ''Pressurized Systems For Experimental Use'', the pressure vessel design criteria is required to comply with the ASME Boiler and Pressure Vessel Code In 1996 a Preliminary Design Review was held at BNL. The vendor was requested to furnish drawings so that we could confirm that the design met the above criteria. The vendor furnished drawings did not have all dimensions necessary to completely analyze the cell. Never the less, we performed an analysis on as much of the vessel as we could with the available information. The calculations concluded that there were twelve areas of concern that had to be addressed to assure that the pressure vessel complied with the requirements of the ASME code. This information was forwarded to the vendor with the understanding that they would resolve these concerns as they continued with the vessel design and fabrication. The assembled amplifier pressure vessel was later hydro tested to 220 psi (15 Atm) as well as pneumatically to 181 psi (12.5 Atm) at the fabricator's Russian facility and was witnessed by a BNL engineer. The unit was shipped to the US and installed at the ATF. As part of the commissioning of the device the amplifier pressure vessel was disassembled several times at which time it became apparent that the vendor had not addressed 7 of the 12 issues previously identified. Closer examination of the vessel revealed some additional concerns including quality of workmanship. Although not required by the contract, the vendor furnished radiographs of a number of pressure vessel welds. A review of the Russian X-rays revealed radiographs of both poor and unreadable quality. However, a number of internal weld imperfections could be observed. All welds in question were excavated and then visually and dye penetrant inspected. These additional inspections confirmed that the weld techniques used to make some of these original welds were substandard. The applicable BNL standard, ESH 1.4.1, addresses the problem of pressure vessel non-compliance by having a committee appointed by the Department Chairman review the design and provide engineering solutions to assure equivalent safety. On January 24, 2000 Dr. M. Hart, the NSLS Chairman, appointed this committee with this charge. This report details the engineering investigations, deliberations, solutions and calculations which were developed by members of this committee to determine that with repairs, new components, appropriate NDE, and lowering the design pressure, the vessel can be considered safe to use.

Woodle, M.H.; Beauman, R.; Czajkowski, C.; Dickinson, T.; Lynch, D.; Pogorelsky, I.; Skjaritka, J.

2000-09-25

165

ESPI with synchronized pressure stressing  

NASA Astrophysics Data System (ADS)

Optical detection of disbonds in aluminum composites is demonstrated using electronic speckle pattern interferometry combined with synchronized pressure stressing. The surface on the test specimen is periodically pressure stressed in synchronization with the image acquisition rate of an image processor. This is achieved by using a two-port, low volume, transparent vacuum chamber mounted on the specimen. One of the ports of the vacuum chamber is connected to a constant vacuum source, and the other is connected to the ambient via a solenoid valve that is periodically opened and closed in synchronization with the image acquisition. Furthermore, illumination of the specimen is also synchronized with the stressing. Speckle images of the surface of the specimen undergoing high and low pressure stressing are combined with a reference speckle image and acquired at the image acquisition frequency of the detecting CCD camera. Every two consecutive images are then subtracted in the image processor and displayed in real-time. In this manner, excellent noise reduction is achieved, rejecting the effects of low frequency noise contributions such as slow object drift, air current, and thermal gradients in/around the specimen found in typical industrial environments.

Chatters, Thomas C.; Pouet, Bruno F.; Krishnaswamy, Sridhar

1993-05-01

166

Study on the development of composite CNG pressure vessels  

NASA Astrophysics Data System (ADS)

The development of composite CNG (compressed natural gas) pressure vessels with HDPE (high density polyethylene) liner and metal end nozzles was studied. The CNG environmental tests carried out for HDPE, resins and reinforcing fibres showed no significant damages. The metal end nozzles and the dome contour of the liner were designed, respectively. The stacking sequence was analysed and applied in filament winding of the pressure vessels. They showed satisfactory results when subjected to burst tests. The fibre volume fractions, Vf, were obtained by image analyser and the average Vfs were 54.09% and 53.49% in hoop and helical regions, respectively.

Kim, B. S.; Kim, B. H.; Kim, J. B.; Joe, C. R.

167

Maine Yankee dosimetry capsule and pressure vessel neutron fluence calculations  

SciTech Connect

In-house capability for deterministic neutron and gamma transport analyses has been implemented at Yankee Atomic Electric Company (YAEC). A detailed R-Theta (R-{theta}) calculational model of Maine Yankee was developed to help in validation of the methods and to establish appropriate models for support of the ongoing Maine Yankee pressure vessel surveillance program. Several data and modeling sensitivity studies were performed and comparisons to measured dosimetry capsule data were emphasized. The calculated results establish confidence in the YAEC in-house computational methodology for general pressure vessel fluence analyses.

White, J.R. [Univ. of Massachusetts, Lowell, MA (United States). Chemical and Nuclear Engineering Dept.; Spinney, K.B.; Morrissey, K.J.; Cacciapouti, R.J. [Yankee Atomic Electric Co., Bolton, MA (United States)

1994-12-31

168

Interaction of defects with dislocations in reactor pressure vessel steels  

SciTech Connect

The radiation embrittlement of reactor pressure vessel steels may be partially explained by the creation of irradiation-induced defects that interact with the moving dislocations during plastic deformation. This research studies the nature of the interaction mechanisms and the microstructural properties and the mobility of the dislocations. Internal friction measurements, torsional plastic deformation tests, and transmission electron microscopy observations have been performed in ferritic steels used for reactor pressure vessels, more precisely the JRQ (Japanese Reference Quality) steel (International Atomic Energy Agency [IAEA] correlation monitoring material). The influence of neutron irradiation and of annealing treatments is discussed.

Munier, A.; Schaller, R. [Ecole Polytechnique Federale de Lausanne (Switzerland). Dept. of Physique; Mercier, O.; Waeber, W.B. [Paul Scherrer Inst., Villigen (Switzerland)

1993-12-01

169

Technical Appendix to Cryogenic Pressure Vessels  

SciTech Connect

The 20,000 gls. Liquid Argon dewar stores up to 15,000 gls. of high purity (<1.0 ppm O{sub 2}, 0.999995) LAr for use in the Liquid Argon calorimeters of E740, the D0 collider detector, at elevation 707-feet. The dewar provides for the total detector volume of 11,000 gls and a 4,000 gls. storage inventory. The large gas volume ({ge}5,000 gls.) serves operational needs and guards against overfill concerns. The LAr dewar functions in two modes: (1) low pressure (16 psi relief) storage, and liquid and gas transfer operations to and from the low pressure (13 psi relief) detector cryostats, and (2) high pressure (65 psi relief) liquid transfer operations to and from a delivery trailer at elevation 743-feet. The storage function is intended to be long term and nonventing. The dewar is equipped with a 40 kW LN{sub 2} condenser that operates to maintain the pressure constant in the storage mode. This service exactly parallels the NeH{sub 2} and D{sub 2} storage dewar services provided at the 15-feet bubble chamber for its operation.

Mulholland, G.T.; Rucinski, R.A; /Fermilab

1990-02-22

170

Neural network/acoustic emission burst pressure prediction for impact damaged composite pressure vessels  

SciTech Connect

Acoustic emission signal analysis has been used to measure the effect impact damage has on the burst pressure of 146 mm (5.75 in.) diameter graphite/epoxy and the organic polymer, Kevlar/epoxy filament wound pressure vessels. Burst pressure prediction models were developed by correlating the differential acoustic emission amplitude distribution collected during low level hydroproof tests to known burst pressures using backpropagation artificial neural networks. Impact damage conditions ranging from barely visible to obvious fiber breakage, matrix cracking, and delamination were included in this work. A simulated (inert) propellant was also cast into a series of the vessels from each material class, before impact loading, to provide boundary conditions during impact that would simulate those found on solid rocket motors. The results of this research effort demonstrate that a quantitative assessment of the effects that impact damage has on burst pressure can be made for both organic polymer/epoxy and graphite/epoxy pressure vessels. Here, an artificial neural network analysis of the acoustic emission parametric data recorded during low pressure hydroproof testing is used to relate burst pressure to the vessel`s acoustic signature. Burst pressure predictions within 6.0% of the actual failure pressure are demonstrated for a series of vessels.

Walker, J.L.; Workman, G.L. [Univ. of Alabama, Huntsville, AL (United States); Russell, S.S. [National Aeronautics and Space Administration, Huntsville, AL (United States). Marshall Space Flight Center; Hill, E.V.K. [Embry-Riddle Aeronautical Univ., Daytona Beach, FL (United States)

1997-08-01

171

SMART composite high pressure vessels with integrated optical fiber sensors  

NASA Astrophysics Data System (ADS)

In this paper application of integrated Optical Fiber Sensors for strain state monitoring of composite high pressure vessels is presented. The composite tanks find broad application in areas such as: automotive industry, aeronautics, rescue services, etc. In automotive application they are mainly used for gaseous fuels storage (like CNG or compressed Hydrogen). In comparison with standard steel vessels, composite ones have many advantages (i.e. high mechanical strength, significant weight reduction, etc). In the present work a novel technique of vessel manufacturing, according to this construction, was applied. It is called braiding technique, and can be used as an alternative to the winding method. During braiding process, between GFRC layers, two types of optical fiber sensors were installed: point sensors in the form of FBGs as well as interferometric sensors with long measuring arms (SOFO®). Integrated optical fiber sensors create the nervous system of the pressure vessel and are used for its structural health monitoring. OFS register deformation areas and detect construction damages in their early stage (ensure a high safety level for users). Applied sensor system also ensured a possibility of strain state monitoring even during the vessel manufacturing process. However the main application of OFS based monitoring system is to detect defects in the composite structure. An idea of such a SMART vessel with integrated sensor system as well as an algorithm of defect detection was presented.

Blazejewski, Wojciech; Czulak, Andrzej; Gasior, Pawel; Kaleta, Jerzy; Mech, Rafal

2010-04-01

172

A PRELIMINARY REVIEW OF THE DESIGN AND FEASIBILITY OF PRESTRESSED CONCRETE PRESSURE VESSELS FOR NUCLEAR REACTORS  

Microsoft Academic Search

The design of prestressed concrete pressure vessels is discussed, and ; some approximate design formulas are developed. The design and performance of ; vessels reported in the literature are reviewed, and an approximate comparison is ; made of steel and concrete pressure vessels for a particular case. Concrete ; vessels are attractive for moderate temperatures and pressures because of the

Holt

1963-01-01

173

Multilayer Pressure Vessel Materials Testing and Analysis. Phase 1  

NASA Technical Reports Server (NTRS)

To provide NASA a comprehensive suite of materials strength, fracture toughness and crack growth rate test results for use in remaining life calculations for aging multilayer pressure vessels, Southwest Research Institute (R) (SwRI) was contracted in two phases to obtain relevant material property data from a representative vessel. This report describes Phase 1 of this effort which includes a preliminary material property assessment as well as a fractographic, fracture mechanics and fatigue crack growth analyses of an induced flaw in the outer shell of a representative multilayer vessel that was subjected to cyclic pressure test. SwRI performed this Phase 1 effort under contract to the Digital Wave Corporation in support of their contract to Jacobs ATOM for the NASA Ames Research Center.

Cardinal, Joseph W.; Popelar, Carl F.; Page, Richard A.

2014-01-01

174

Filament-reinforced cylindrical pressure vessels: analysis and numerical evaluation  

Microsoft Academic Search

The response to internal pressure of a cylindrical vessel consisting of a metal liner reinforced with a circumferentially wound filament-epoxy composite has been analyzed. Expressions for pressures required to produce the onset of yielding and complete yielding in the liner, failure of the composite, and efficiencies are derived for all combinations of three liner materials (HP-9-4-20 steel, 6061-T6 Al, and

1977-01-01

175

Modeling of irradiation embrittlement of reactor pressure vessel steels  

Microsoft Academic Search

A model to describe the change in the inelastic and fracture properties of reactor pressure vessel steels due to neutron irradiation in the ductile region (i.e., irradiation embrittlement) is developed. First, constitutive equations for unirradiated elastic-viscoplastic-damaged materials are developed within the framework of the irreversible thermodynamics theory. To take into account the effect of hydrostatic pressure on the nucleation and

S. Murakami; A. Miyazaki; M. Mizuno

2000-01-01

176

Irradiation Effects in Strain-aged Pressure Vessel Steel  

Microsoft Academic Search

BOTH neutron irradiation and normal ageing phenomena may separately cause deterioration in the properties of mild steels by increasing the brittle-ductile transition temperature. In the case of reactor pressure vessels, the effects of neutron irradiation alone may increase this transition temperature to values well above room temperature. For purposes of reactor design, as well as for estimating the permissible service-life

M. Grounes; H. P. Myers

1962-01-01

177

Creep of A508/533 Pressure Vessel Steel  

SciTech Connect

ABSTRACT Evaluation of potential Reactor Pressure Vessel (RPV) steels has been carried out as part of the pre-conceptual Very High Temperature Reactor (VHTR) design studies. These design studies have generally focused on American Society of Mechanical Engineers (ASME) Code status of the steels, temperature limits, and allowable stresses. Initially, three candidate materials were identified by this process: conventional light water reactor (LWR) RPV steels A508 and A533, 2¼Cr-1Mo in the annealed condition, and Grade 91 steel. The low strength of 2¼Cr-1Mo at elevated temperature has eliminated this steel from serious consideration as the VHTR RPV candidate material. Discussions with the very few vendors that can potentially produce large forgings for nuclear pressure vessels indicate a strong preference for conventional LWR steels. This preference is based in part on extensive experience with forging these steels for nuclear components. It is also based on the inability to cast large ingots of the Grade 91 steel due to segregation during ingot solidification, thus restricting the possible mass of forging components and increasing the amount of welding required for completion of the RPV. Grade 91 steel is also prone to weld cracking and must be post-weld heat treated to ensure adequate high-temperature strength. There are also questions about the ability to produce, and very importantly, verify the through thickness properties of thick sections of Grade 91 material. The availability of large components, ease of fabrication, and nuclear service experience with the A508 and A533 steels strongly favor their use in the RPV for the VHTR. Lowering the gas outlet temperature for the VHTR to 750°C from 950 to 1000°C, proposed in early concept studies, further strengthens the justification for this material selection. This steel is allowed in the ASME Boiler and Pressure Vessel Code for nuclear service up to 371°C (700°F); certain excursions above that temperature are allowed by Code Case N-499-2 (now incorporated as an appendix to Section III Division 5 of the Code). This Code Case was developed with a rather sparse data set and focused primarily on rolled plate material (A533 specification). Confirmatory tests of creep behavior of both A508 and A533 are described here that are designed to extend the database in order to build higher confidence in ensuring the structural integrity of the VHTR RPV during off-normal conditions. A number of creep-rupture tests were carried out at temperatures above the 371°C (700°F) Code limit; longer term tests designed to evaluate minimum creep behavior are ongoing. A limited amount of rupture testing was also carried out on welded material. All of the rupture data from the current experiments is compared to historical values from the testing carried out to develop Code Case N-499-2. It is shown that the A508/533 basemetal tested here fits well with the rupture behavior reported from the historical testing. The presence of weldments significantly reduces the time to rupture. The primary purpose of this report is to summarize and record the experimental results in a single document.

Richard Wright

2014-08-01

178

Evaluation of Acoustic Emission NDE of Kevlar Composite Over Wrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

Pressurization and failure tests of small Kevlar/epoxy COPV bottles were conducted during 2006 and 2007 by Texas Research Institute Austin, Inc., at TRI facilities. This is a report of the analysis of the Acoustic Emission (AE) data collected during those tests. Results of some of the tests indicate a possibility that AE can be used to track the stress-rupture degradation of COPV vessels.

Horne, Michael R.; Madaras, Eric I.

2008-01-01

179

Age, Blood Pressure, and Retinal Vessel Diameter: Separate Effects and Interaction of Blood Pressure and Age  

Microsoft Academic Search

PURPOSE. The association of age and blood pressure (BP) with retinal vessel change is widely reported, with inverse relation- ships between retinal arteriolar and venular diameter and in- creasing age and elevated BP. No previous studies have dis- sected the separate effects of age and BP on the diameter of retinal vessels. METHODS. This was a population-based, cross-sectional study comprising

Shweta Kaushik; Annette Kifley; Paul Mitchell; Jie Jin Wang

180

Monster pressure vessel proves low-emission power plant technology  

SciTech Connect

After almost a decade of near dormancy, the Babcock and Wilcox plant in Mt. Vernon, Ind., sprang back to life in the late 1980s to give birth to one of the world`s largest pressure vessels. The vessel, which was completely shop-fabricated and assembled, is 69 ft 3 in. high and 44 ft 5 in. in diameter. With walls of 2-7/8-in.-thick steel, more than 100 nozzles, and a gross weight of 1250 tons, it called for creativity in fabrication and some of the best welding technology and craftsmanship available at the time. This was appropriate for a vessel destined to become a part of some of the most promising new technology in power generation. Known as pressurized fluidized bed combustion (PFBC), the method makes it possible to burn high-sulfur coal while meeting stringent environmental standards. American Electric Power (AEP) installed the completed PFBC module, with 200-MW thermal input, at the Ohio Power Tidd Plant in Brilliant, Ohio. The demonstration plant, which began operating in 1990, was planned to show off the combined-cycle PFBC technology and establish it as a viable alternative to conventional coal-fired plants. The paper describes how the PFBC method works, the fabrication of the pressure vessel, and the successful four years at the Tidd Plant.

Roberts, B. [Lincoln Electric Co., Cleveland, OH (United States)

1995-04-01

181

Design by analysis of ductile failure and buckling in torispherical pressure vessel heads  

Microsoft Academic Search

Thin shell torispherical pressure vessel heads are known to exhibit complex elastic–plastic deformation and buckling behaviour under static pressure. In pressure vessel Design by Analysis, the designer is required to assess both of these behaviour modes when specifying the allowable static load. The EN and ASME boiler and pressure vessel codes permit the use of inelastic analysis in design by

Donald Mackenzie; Duncan Camilleri; Robert Hamilton

2008-01-01

182

Fabrication of toroidal composite pressure vessels. Final report  

SciTech Connect

A method for fabricating composite pressure vessels having toroidal geometry was evaluated. Eight units were fabricated using fibrous graphite material wrapped over a thin-walled aluminum liner. The material was wrapped using a machine designed for wrapping, the graphite material was impregnated with an epoxy resin that was subsequently thermally cured. The units were fabricated using various winding patterns. They were hydrostatically tested to determine their performance. The method of fabrication was demonstrated. However, the improvement in performance to weight ratio over that obtainable by an all metal vessel probably does not justify the extra cost of fabrication.

Dodge, W.G.; Escalona, A.

1996-11-24

183

High pressure, high-temperature vessel, especially for nuclear reactors  

SciTech Connect

A pressure vessel susceptible to high temperatures, especially for containment of a nuclear-reactor core, is constituted of a cylindrical shell from a cast material such as cast steel, cast iron or concrete, and is prestressed by vertical cables which extend parallel to generatrices of the shell. Peripheral (Circumferential) prestressing cables are provided around the shell which can be externally insulated. The peripheral tensioning cables are exposed externally of the insulation material and bear upon the shell of the vessel with heatresistant elements of high compressive strength which extend through the external insulation.

Mitterbacher, P.; Schoning, J.; Schwiers, H.G.

1980-09-23

184

Stress analysis of hydride bed vessels used for tritium storage  

SciTech Connect

A prototype hydride storage bed, using LaNi{sub 4.25}Al{sub 0.75} as the storage material, was fitted with strain gages to measure strains occurring in the stainless steel bed vessel caused by expansion of the storage powder upon uptake of hydrogen. The strain remained low in the bed as hydrogen was added, up to a bed loading of about 0.5 hydrogen to metal atom ratio (H/M). The strain then increased with increasing hydrogen loading ({approximately} 0.8 H/M). Different locations exhibited greatly different levels of maximum strain. In no case was the design stress of the vessel exceeded.

McKillip, S.T.; Bannister, C.E.; Clark, E.A.

1991-12-31

185

Stress analysis of hydride bed vessels used for tritium storage  

SciTech Connect

A prototype hydride storage bed, using LaNi{sub 4.25}Al{sub 0.75} as the storage material, was fitted with strain gages to measure strains occurring in the stainless steel bed vessel caused by expansion of the storage powder upon uptake of hydrogen. The strain remained low in the bed as hydrogen was added, up to a bed loading of about 0.5 hydrogen to metal atom ratio (H/M). The strain then increased with increasing hydrogen loading ({approximately} 0.8 H/M). Different locations exhibited greatly different levels of maximum strain. In no case was the design stress of the vessel exceeded.

McKillip, S.T.; Bannister, C.E.; Clark, E.A.

1991-01-01

186

Evaluation of Agency Non-Code Layered Pressure Vessels (LPVs)  

NASA Technical Reports Server (NTRS)

In coordination with the Office of Safety and Mission Assurance and the respective Center Pressure System Managers (PSMs), the NASA Engineering and Safety Center (NESC) was requested to formulate a consensus draft proposal for the development of additional testing and analysis methods to establish the technical validity, and any limitation thereof, for the continued safe operation of facility non-code layered pressure vessels. The PSMs from each NASA Center were asked to participate as part of the assessment team by providing, collecting, and reviewing data regarding current operations of these vessels. This report contains the outcome of the assessment and the findings, observations, and NESC recommendations to the Agency and individual NASA Centers.

Prosser, William H.

2014-01-01

187

Lessons Learned From Developing Reactor Pressure Vessel Steel Embrittlement Database  

SciTech Connect

Materials behaviors caused by neutron irradiation under fission and/or fusion environments can be little understood without practical examination. Easily accessible material information system with large material database using effective computers is necessary for design of nuclear materials and analyses or simulations of the phenomena. The developed Embrittlement Data Base (EDB) at ORNL is this comprehensive collection of data. EDB database contains power reactor pressure vessel surveillance data, the material test reactor data, foreign reactor data (through bilateral agreements authorized by NRC), and the fracture toughness data. The lessons learned from building EDB program and the associated database management activity regarding Material Database Design Methodology, Architecture and the Embedded QA Protocol are described in this report. The development of IAEA International Database on Reactor Pressure Vessel Materials (IDRPVM) and the comparison of EDB database and IAEA IDRPVM database are provided in the report. The recommended database QA protocol and database infrastructure are also stated in the report.

Wang, Jy-An John [ORNL

2010-08-01

188

Lightweight pressure vessels and unitized regenerative fuel cells  

SciTech Connect

Energy storage systems have been designed using lightweight pressure vessels with unitized regenerative fuel cells (URFCs). The vessels provide a means of storing reactant gases required for URFCs; they use lightweight bladder liners that act as inflatable mandrels for composite overwrap and provide a permeation barrier. URFC systems have been designed for zero emission vehicles (ZEVs); they are cost competitive with primary FC powered vehicles that operate on H/air with capacitors or batteries for power peaking and regenerative braking. URFCs are capable of regenerative braking via electrolysis and power peaking using low volume/low pressure accumulated oxygen for supercharging the power stack. URFC ZEVs can be safely and rapidly (<5 min.) refueled using home electrolysis units. Reversible operation of cell membrane catalyst is feasible without significant degradation. Such systems would have a rechargeable specific energy > 400 Wh/kg.

Mitlitsky, F.; Myers, B.; Weisberg, A.H.

1996-09-06

189

An Acoustic Emission and Acousto-Ultrasonic Analysis of Impact Damaged Composite Pressure Vessels  

NASA Technical Reports Server (NTRS)

The research presented herein summarizes the development of acoustic emission (AE) and acousto-ultrasonic (AU) techniques for the nondestructive evaluation of filament wound composite pressure vessels. Vessels fabricated from both graphite and kevlar fibers with an epoxy matrix were examined prior to hydroburst using AU and during hydroburst using AE. A dead weight drop apparatus featuring both blunt and sharp impactor tips was utilized to produce a single known energy 'damage' level in each of the vessels so that the degree to which the effects of impact damage could be measured. The damage levels ranged from barely visible to obvious fiber breakage and delamination. Independent neural network burst pressure prediction models were developed from a sample of each fiber/resin material system. Here, the cumulative AE amplitude distribution data collected from low level proof test (25% of the expected burst for undamaged vessels) were used to measure the effects of the impact on the residual burst pressure of the vessels. The results of the AE/neural network model for the inert propellant filled graphite/epoxy vessels 'IM7/3501-6, IM7/977-2 and IM7/8553-45' demonstrated that burst pressures can be predicted from low level AE proof test data, yielding an average error of 5.0%. The trained network for the IM7/977-2 class vessels was also able to predict the expected burst pressure of taller vessels (three times longer hoop region length) constructed of the same material and using the same manufacturing technique, with an average error of 4.9%. To a lesser extent, the burst pressure prediction models could also measure the effects of impact damage to the kevlar/epoxy 'Kevlar 49/ DPL862' vessels. Here though, due to the higher attenuation of the material, an insufficient amount of AE amplitude information was collected to generate robust network models. Although, the worst case trial errors were less than 6%, when additional blind predictions were attempted, errors as high as 50% were produced. An acousto-ultrasonic robotic evaluation system (AURES) was developed for mapping the effects of damage on filament wound pressure vessels prior to hydroproof testing. The AURES injects a single broadband ultrasonic pulse into each vessel at preprogrammed positions and records the effects of the interaction of that pulse on the material volume with a broadband receiver. A stress wave factor in the form of the energy associated with the 750 to 1000 kHz and 1000 to 1250 kHz frequency bands were used to map the potential failure sites for each vessel. The energy map associated with the graphite/epoxy vessels was found to decrease in the region of the impact damage. The kevlar vessels showed the opposite trend, with the energy values increasing around the damage/failure sites.

Walker, James L.; Workman, Gary L.; Workman, Gary L.

1996-01-01

190

Pressure vessel steel embrittlement monitoring by magnetic properties measurements  

Microsoft Academic Search

The magnetic properties of specimens of one heat of A533B nuclear pressure vessel grade steel have been examined in the as-received condition and after neutron irradiation to various fluence levels up to 4 [times] 10[sup 18] cm[sup [minus]2] (E > 0.1 MeV) in the University of Illinois Advanced TRIGA reactor core at two temperatures, approximately 120 and 260[degrees]C. The effect

J. F. Stubbins; W. J. Shong; M. Giacobbe; A. M. Ougouag; J. G. Williams

1992-01-01

191

Pressure vessel steel embrittlement monitoring by magnetic properties measurements  

Microsoft Academic Search

The magnetic properties of specimens of one heat of A533B nuclear pressure vessel grade steel have been examined in the as-received condition and after neutron irradiation to various fluence levels up to 4 à 10¹⁸ cm⁻² (E > 0.1 MeV) in the University of Illinois Advanced TRIGA reactor core at two temperatures, approximately 120 and 260°C. The effect of some

J. F. Stubbins; W. J. Shong; M. Giacobbe; A. M. Ougouag; J. G. Williams

1992-01-01

192

Corrosion of steel tendons used in prestressed concrete pressure vessels  

Microsoft Academic Search

The purpose of this investigation was to determine the corrosion behavior of a high strength steel (ASTM A416-74 grade 270), typical of those used as tensioning tendons in prestressed concrete pressure vessels, in several corrosive environments and to demonstrate the protection afforded by coating the steel with either of two commercial petroleum-base greases or Portland Cement grout. In addition, the

J. C. Griess; D. J. Naus

2009-01-01

193

Composite Pressure Vessel Variability in Geometry and Filament Winding Model  

NASA Technical Reports Server (NTRS)

Composite pressure vessels (CPVs) are used in a variety of applications ranging from carbon dioxide canisters for paintball guns to life support and pressurant storage on the International Space Station. With widespread use, it is important to be able to evaluate the effect of variability on structural performance. Data analysis was completed on CPVs to determine the amount of variation that occurs among the same type of CPV, and a filament winding routine was developed to facilitate study of the effect of manufacturing variation on structural response.

Green, Steven J.; Greene, Nathanael J.

2012-01-01

194

46 CFR 38.05-3 - Design and construction of pressure vessel type cargo tanks-TB/ALL.  

Code of Federal Regulations, 2010 CFR

... false Design and construction of pressure vessel type cargo tanks-TB/ALL...05-3 Design and construction of pressure vessel type cargo tanks—TB/ALL. (a) Cargo tanks of pressure vessel configuration...

2010-10-01

195

46 CFR 38.05-3 - Design and construction of pressure vessel type cargo tanks-TB/ALL.  

Code of Federal Regulations, 2014 CFR

... false Design and construction of pressure vessel type cargo tanks-TB/ALL...05-3 Design and construction of pressure vessel type cargo tanks—TB/ALL. (a) Cargo tanks of pressure vessel configuration...

2014-10-01

196

46 CFR 38.05-3 - Design and construction of pressure vessel type cargo tanks-TB/ALL.  

Code of Federal Regulations, 2011 CFR

... false Design and construction of pressure vessel type cargo tanks-TB/ALL...05-3 Design and construction of pressure vessel type cargo tanks—TB/ALL. (a) Cargo tanks of pressure vessel configuration...

2011-10-01

197

46 CFR 38.05-3 - Design and construction of pressure vessel type cargo tanks-TB/ALL.  

Code of Federal Regulations, 2012 CFR

... false Design and construction of pressure vessel type cargo tanks-TB/ALL...05-3 Design and construction of pressure vessel type cargo tanks—TB/ALL. (a) Cargo tanks of pressure vessel configuration...

2012-10-01

198

46 CFR 38.05-3 - Design and construction of pressure vessel type cargo tanks-TB/ALL.  

Code of Federal Regulations, 2013 CFR

... false Design and construction of pressure vessel type cargo tanks-TB/ALL...05-3 Design and construction of pressure vessel type cargo tanks—TB/ALL. (a) Cargo tanks of pressure vessel configuration...

2013-10-01

199

Neutron flux reduction programs for reactor pressure vessel  

SciTech Connect

The objective of this work is to implement various fast neutron flux reduction programs on the belt-line region of the reactor pressure vessel to reduce the increasing rate of reference temperature for pressurized thermal shock (RT PTS) for Korea Nuclear Unit 1. A pressurized thermal shock (PTS) event is an event or transient in pressurized water reactors (PWRs) causing severe overcooling (thermal shock) concurrent with or followed by significant pressure in the reactor vessel. A PTS concern arises if one of these transients acts in the belt-line region of a reactor vessel where a reduced fracture resistance exists because of neutron irradiation. Generally, the RT PTS value is continuously increasing according to the fast neutron irradiation during the reactor operation, and it can reach the screening criterion prior to the expiration of the operating license. To reduce the increasing rate of RT PTS, various neutron flux reduction programs can be implemented, which are focused on license renewal. In this paper, neutron flux reduction programs, such as low leakage loading pattern strategy, loading of neutron absorber rods, and dummy fuel assembly loading are considered for Korea Nuclear Unit 1, of which the RT PTS value of the leading material (circumferential weld) is going to reach the screening criterion in the near future. To evaluate the effects of the neutron flux reduction programs, plant and cycle specific forward neutron transport calculations for the various neutron flux reduction programs were carried out. For the analysis, all transport calculations were carried out by using the DORT 3.1 discrete ordinate code and BUGLE-96 cross-section library. (authors)

Yoo, C.S. [Korea Atomic Energy Research Inst. KAERI, 150 Deogjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, B.C. [Korea Reactor Integrity Surveillance Technology KRIST, 150 Deogjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

2011-07-01

200

Prevention of non-ductile fracture in 6061-T6 aluminum nuclear pressure vessels  

SciTech Connect

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Committee has approved rules for the use of 6061-T6 and 6061-T651 aluminum for the construction of Class 1 welded nuclear pressure vessels for temperatures not exceeding 149 C (300 F). Nuclear Code Case N-519 allows the use of this aluminum in the construction of low temperature research reactors such as the Advanced Neutron Source. The rules for protection against non-ductile fracture are discussed. The basis for a value of 25.3 MPa {radical}m (23 ksi {radical}in.) for the critical or reference stress intensity factor for use in the fracture analysis is presented. Requirements for consideration of the effects of neutron irradiation on the fracture toughness are discussed.

Yahr, G.T. [Oak Ridge National Lab., TN (United States). Engineering Technology Div.

1995-06-01

201

High performance filament wound composites for pressure vessel applications.  

NASA Technical Reports Server (NTRS)

A new high modulus fiber was evaluated as a reinforcement for filament wound pressure vessels. Based on preliminary data it offers significant specific strength and modulus improvements over an S-glass reinforcement. Winding parameters and design data were established for the fiber with two different epoxy resin systems. NOL composite rings were evaluated for tensile strength, modulus and interlaminar shear strength at +70 F, -320 F and -423 F. Results showed that the fiber reinforced composite exhibited a specific strength of 4,100,000 inches and a specific modulus of 290,000,000 inches compared to 3,260,000 inches and 110,000,000 inches respectively for S-glass. Utilizing this data to design small filament wound pressure vessels, a performance factor of 806,000 inches was obtained experimentally with PRD 49-1 fiber compared to values of 632,000 inches and 501,000 inches for S-glass and high modulus graphite vessels, respectively.

Hoggatt, J. T.

1971-01-01

202

Evaluation of Data-Logging Transducer to Passively Collect Pressure Vessel p/T History  

NASA Technical Reports Server (NTRS)

Pressure vessels owned and operated by NASA are required to be regularly certified per agency policy. Certification requires an assessment of damage mechanisms and an estimation of vessel remaining life. Since detail service histories are not typically available for most pressure vessels, a conservative estimate of vessel pressure/temperature excursions is typically used in assessing fatigue life. This paper details trial use of a data-logging transducer to passively obtain actual pressure and temperature service histories of pressure vessels. The approach was found to have some potential for cost savings and other benefits in certain cases.

Wnuk, Stephen P.; Le, Son; Loew, Raymond A.

2013-01-01

203

Jam proof closure assembly for lidded pressure vessels  

DOEpatents

An expendable closure assembly is provided for use (in multiple units) with a lockable pressure vessel cover along its rim, such as of an autoclave. This assembly is suited to variable compressive contact and locking with the vessel lid sealing gasket. The closure assembly consists of a thick walled sleeve insert for retention in the under bores fabricated in the cover periphery and the sleeve is provided with internal threading only. A snap serves as a retainer on the underside of the sleeve, locking it into an under bore retention channel. Finally, a standard elongate externally threaded bolt is sized for mating cooperation with the so positioned sleeve, whereby the location of the bolt shaft in the cover bore hole determines its compressive contact on the underlying gasket.

Cioletti, Olisse C. (Pittsburgh, PA)

1992-01-01

204

PRESSURIZATION OF CONTAINMENT VESSELS FROM PLUTONIUM OXIDE CONTENTS  

SciTech Connect

Transportation and storage of plutonium oxide is typically done using a convenience container to hold the oxide powder which is then placed inside a containment vessel. Intermediate containers which act as uncredited confinement barriers may also be used. The containment vessel is subject to an internal pressure due to several sources including; (1) plutonium oxide provides a heat source which raises the temperature of the gas space, (2) helium generation due to alpha decay of the plutonium, (3) hydrogen generation due to radiolysis of the water which has been adsorbed onto the plutonium oxide, and (4) degradation of plastic bags which may be used to bag out the convenience can from a glove box. The contributions of these sources are evaluated in a reasonably conservative manner.

Hensel, S.

2012-03-27

205

Modeling of Ductile Crack Growth in Reactor Pressure-Vessel Steels and Determination of J R Curves  

Microsoft Academic Search

A method is presented for predicting JR curves for reactor pressure-vessel steels. The authors propose a procedure for determining the ductile fracture model parameters from the test results for smooth and notched cylindrical specimens. The stress and strain fields at the tip of a stationary and propagating cracks are studied by the finite-element method. The predicted JR curves are compared

B. Z. Margolin; V. I. Kostylev; A. I. Minkin; A. V. Il'in

2002-01-01

206

Testing of Full Scale Flight Qualified Kevlar Composite Overwrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

Many decades ago NASA identified a need for low-mass pressure vessels for carrying various fluids aboard rockets, spacecraft, and satellites. A pressure vessel design known as the composite overwrapped pressure vessel (COPV) was identified to provide a weight savings over traditional single-material pressure vessels typically made of metal and this technology has been in use for space flight applications since the 1970's. A typical vessel design consisted of a thin liner material, typically a metal, overwrapped with a continuous fiber yarn impregnated with epoxy. Most designs were such that the overwrapped fiber would carry a majority of load at normal operating pressures. The weight advantage for a COPV versus a traditional singlematerial pressure vessel contributed to widespread use of COPVs by NASA, the military, and industry. This technology is currently used for personal breathing supply storage, fuel storage for auto and mass transport vehicles and for various space flight and aircraft applications. The NASA Engineering and Safety Center (NESC) was recently asked to review the operation of Kevlar 2 and carbon COPVs to ensure they are safely operated on NASA space flight vehicles. A request was made to evaluate the life remaining on the Kevlar COPVs used on the Space Shuttle for helium and nitrogen storage. This paper provides a review of Kevlar COPV testing relevant to the NESC assessment. Also discussed are some key findings, observations, and recommendations that may be applicable to the COPV user community. Questions raised during the investigations have revealed the need for testing to better understand the stress rupture life and age life of COPVs. The focus of this paper is to describe burst testing of Kevlar COPVs that has been completed as a part of an the effort to evaluate the effects of ageing and shelf life on full scale COPVs. The test articles evaluated in this discussion had a diameter of 22 inches for S/N 014 and 40 inches for S/N 011. The time between manufacture and burst was 28 and 22 years. Visual inspection, shearography, heat soak thermography and borescope inspection were performed on vessel S/N 011 and all but shearography was performed on S/N 014 before they were tested and details of this work can be found in a companion paper titled, "Nondestructive Methods and Special Test Instrumentation Supporting NASA Composite Overwrapped Pressure Vessel Assessments." The vessels were instrumented so that measurements could be made to aid in the understanding of vessel response. Measurements made on the test articles included girth, boss displacement, internal volume, multiple point strain, full field strain, eddy current, acoustic emission (AE) pressure and temperature. The test article before and during burst is shown with the pattern used for digital image correlation full field strain measurement blurring as the vessel fails.

Greene, Nathanael; Saulsberry, Regor; Yoder, Tommy; Forsyth, Brad; Thesken, John; Phoenix, Leigh

2007-01-01

207

Design and analysis of piping, pressure vessels, and components  

SciTech Connect

This book contains 26 selections. Some of the titles are: Pipe rupture hardware minimization in pressurized water reactor systems; Development of shell and tube LNG vaporizers using titanium heat transfer tubes; Design improvements of an in-line process gas desuperheater in high temperature service; and Modes of failure-primary and secondary stresses.

Short, W.E.; Dermenjian, A.A.; McGrattan, R.J.; Bhandari, S.K.

1987-01-01

208

Elevated temperature mechanical properties of a reactor pressure vessel steel  

NASA Astrophysics Data System (ADS)

A testing program is in progress to define the tensile and creep properties of SA533 Grade B Class 1 steel at temperatures from 371 to 538 °C. The overall objective is to provide the data necessary to obtain ASME Code approval for use of this material for the Modular High-Temperature Gas-Cooled Reactor (MHTGR) vessel during short-term temperature excursions above 371 °C. Testing and evaluation involve three heats of base metal, two submerged arc welds, and a shielded metal arc weld. The creep strengths of the base metal heats and the weldments were found to be equivalent; the weld metal itself is slightly stronger. The data obtained indicate that stress to produce 1% strain will likely be the controlling factor in setting the allowable stresses for design.

McCoy, H. E.; Rittenhouse, P. L.

1990-04-01

209

A Theoretical Investigation of Composite Overwrapped Pressure Vessel (COPV) Mechanics Applied to NASA Full Scale Tests  

NASA Technical Reports Server (NTRS)

A theoretical investigation of the factors controlling the stress rupture life of the National Aeronautics and Space Agency's (NASA) composite overwrapped pressure vessels (COPVs) continues. Kevlar(TradeMark) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar(TradeMark) filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However, due to the presence of a load sharing liner, the manufacturing induced residual stresses and the complex mechanical response, the state of actual fiber stress in flight hardware and test articles is not clearly known. This paper is a companion to the experimental investigation reported in [1] and develops a theoretical framework necessary to design full-scale pathfinder experiments and accurately interpret the experimentally observed deformation and failure mechanisms leading up to static burst in COPVs. The fundamental mechanical response of COPVs is described using linear elasticity and thin shell theory and discussed in comparison to existing experimental observations. These comparisons reveal discrepancies between physical data and the current analytical results and suggest that the vessel's residual stress state and the spatial stress distribution as a function of pressure may be completely different from predictions based upon existing linear elastic analyses. The 3D elasticity of transversely isotropic spherical shells demonstrates that an overly compliant transverse stiffness relative to membrane stiffness can account for some of this by shifting a thin shell problem well into the realm of thick shell response. The use of calibration procedures are demonstrated as calibrated thin shell model results and finite element results are shown to be in good agreement with the experimental results. The successes reported here have lead to continuing work with full scale testing of larger NASA COPV hardware.

Greene, N.; Thesken, J. C.; Murthy, P. L. N.; Phoenix, S. L.; Palko, J.; Eldridge, J.; Sutter, J.; Saulsberry, R.; Beeson, H.

2006-01-01

210

A Theoretical Investigation of Composite Overwrapped Pressure Vessel (COPV) Mechanics Applied to NASA Full Scale Tests  

NASA Technical Reports Server (NTRS)

A theoretical investigation of the factors controlling the stress rupture life of the National Aeronautics and Space Administration's (NASA) composite overwrapped pressure vessels (COPVs) continues. Kevlar (DuPont) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of a load sharing liner, the manufacturing induced residual stresses and the complex mechanical response, the state of actual fiber stress in flight hardware and test articles is not clearly known. This paper is a companion to a previously reported experimental investigation and develops a theoretical framework necessary to design full-scale pathfinder experiments and accurately interpret the experimentally observed deformation and failure mechanisms leading up to static burst in COPVs. The fundamental mechanical response of COPVs is described using linear elasticity and thin shell theory and discussed in comparison to existing experimental observations. These comparisons reveal discrepancies between physical data and the current analytical results and suggest that the vessel s residual stress state and the spatial stress distribution as a function of pressure may be completely different from predictions based upon existing linear elastic analyses. The 3D elasticity of transversely isotropic spherical shells demonstrates that an overly compliant transverse stiffness relative to membrane stiffness can account for some of this by shifting a thin shell problem well into the realm of thick shell response. The use of calibration procedures are demonstrated as calibrated thin shell model results and finite element results are shown to be in good agreement with the experimental results. The successes reported here have lead to continuing work with full scale testing of larger NASA COPV hardware.

Thesken, John C.; Murthy, Pappu L. N.; Phoenix, S. L.; Greene, N.; Palko, Joseph L.; Eldridge, Jeffrey; Sutter, James; Saulsberry, R.; Beeson, H.

2009-01-01

211

NEUTRON DAMAGE IN REACTOR PRESSURE-VESSEL STEEL EXAMINED WITH POSITRON ANNIHILATION LIFETIME SPECTROSCOPY  

E-print Network

NEUTRON DAMAGE IN REACTOR PRESSURE-VESSEL STEEL EXAMINED WITH POSITRON ANNIHILATION LIFETIME-vessel steels. We irradiated samples ofASTM A508 nuclear reactor pressure-vessel steel to fast neutron 17 2 (PALS) to study the effects of neutron damage in the steels on positron lifetimes. Non

Motta, Arthur T.

212

Fluole:. a New Relevant Experiment for Pwr Pressure Vessel Surveillance  

NASA Astrophysics Data System (ADS)

FLUOLE is a new benchmark-type experiment dedicated to PWR vessel surveillance dosimetry. It provides precise experimental data for the validation of the neutron spectrum propagation calculation from the core to the vessel. The square core is surrounded by a stainless steel baffle and internals with innovative design: the PWR barrel is simulated by two half-cylindrical steel structures, leading to different steel-water slides; two steel components stand for a surveillance capsule and for a part of the pressure vessel. Measurement locations are available on the whole experimental structure. The experimental knowledge of the core sources is obtained by integral gamma scanning measurements on fuel pins. Reaction rates measured by calibrated fission chambers and a large set of dosimeters give information on the neutron energy and spatial distributions with uncertainties comprised between 1.7% to 10% (2?). Due to the weak level of the EOLE neutron flux a special, high efficiency, calibrated gamma spectrometry device has been used for some dosimeters, allowing measuring an activity as low as 2. 10-2 Bq per sample. 103Rhm activities have been measured on an absolute calibrated X spectrometry device. The FLUOLE experiment goal is to usefully complete the current experimental benchmarks database used for the validation of neutron calculation codes.

Beretz, D.; Bourganel, S.; Blaise, P.; Destouches, C.; Huot, N.; Girard, J.-M.; Domergue, C.; Philibert, H.; Brissot, R.; Dumont, M.

2009-08-01

213

Relationship between target organ damage and blood pressure, retinal vessel calibre, oxidative stress and polymorphisms in VAV-2 and VAV-3 genes in patients with hypertension: a case–control study protocol (LOD-Hipertensión)  

PubMed Central

Introduction Target organ damage (TOD) is associated with increased cardiovascular risk. The study objectives were to analyse the relationship of TOD to blood pressure, size of retinal arteries and veins, oxidative stress and different polymorphisms in the VAV-2 and VAV-3 genes in participants with hypertension. Methods and analysis A case–control study to analyse the relationship between clinical, biochemical and genetic parameters and presence of cardiac, vascular and renal TOD in 486 patients with hypertension. Participants with TOD will be considered as cases, and those without TOD will be enrolled as controls. This will be a collaborative study conducted by the groups of Primary Care, Cardiovascular and Metabolic and Degenerative Diseases of the Instituto de Investigación Biomédica of Salamanca (IBSAL). Assessment of cardiac, renal and vascular TOD. Measurement of peripheral and central blood pressure, size of eye fundus arteries and veins, and oxidative stress, and polymorphisms in the VAV-2 and VAV-3 genes. Ethics and dissemination The study will be conducted after approval is obtained from the Ethics Committee of Hospital Clínico Universitario of Salamanca. All study participants will sign an informed consent to agree to participate in the study, and another consent to agree on the genetic study, in compliance with the Declaration of Helsinki and the WHO standards for observational studies. The results of this study will allow for an understanding of the relationship of the different TODs with blood pressure, retinal artery and vein diameters, oxidative stress and polymorphisms in VAV-2 and VAV-3 genes. Trial registration number Clinical Trials. gov Identifier: NCT02022618. PMID:24699462

Gomez-Marcos, Manuel A; Gonzalez-Sarmiento, Rogelio; Recio-Rodríguez, José I; Agudo-Conde, Cristina; Gamella-Pozuelo, Luis; Perretta-Tejedor, Nuria; Martínez-Salgado, Carlos; García-Ortiz, Luis

2014-01-01

214

Design of a standalone-type beryllium vessel for high-pressure protein crystallography  

Microsoft Academic Search

A standalone-type beryllium (Be) high-pressure crystallography vessel has been developed. Using a coupler-joint unit and a pressure valve, we could keep the pressure in the vessel constant at 100+\\/-1 MPa for more than 24 h without connecting to a pressure-generating apparatus. Diffraction spots of a glucose isomerase (GI) crystal under 100 MPa were collected using the vessel and a rotating

Yoshihisa Suzuki; Masayuki Tsukamoto; Haruhiko Sakuraba; Masamitsu Matsumoto; Makoto Nagasawa; Katsuhiro Tamura

2010-01-01

215

Improved fireman's compressed air breathing system pressure vessel development program  

NASA Technical Reports Server (NTRS)

Prototype high pressure glass filament-wound, aluminum-lined pressurant vessels suitable for use in a fireman's compressed air breathing system were designed, fabricated, and acceptance tested in order to demonstrate the feasibility of producing such high performance, lightweight units. The 4000 psi tanks have a 60 standard cubic foot (SCF) air capacity, and have a 6.5 inch diamter, 19 inch length, 415 inch volume, weigh 13 pounds when empty, and contain 33 percent more air than the current 45 SCF (2250 psi) steel units. The current steel 60 SCF (3000 psi) tanks weigh approximately twice as much as the prototype when empty, and are 2 inches, or 10 percent shorter. The prototype units also have non-rusting aluminum interiors, which removes the hazard of corrosion, the need for internal coatings, and the possibility of rust particles clogging the breathing system.

King, H. A.; Morris, E. E.

1973-01-01

216

Effective materials for reducing damage rates to PWR pressure vessels  

SciTech Connect

Among the proposed measures for reducing the damage rate to pressurized water reactor (PWR) pressure vessels are the following: 1. replacement of fuel rods in peripheral fuel assemblies with dummy rods-the [open quotes]fuel replacement[close quotes] (FR) approach; 2. insertion of neutron reflecting and attenuating materials between the core baffle and the core barrel-the [open quotes]reflector-shield[close quotes] (RS) approach; 3. attachment of shielding patches to the thermal shield-the [open quotes]thermal shield[close quotes] approach. The material commonly proposed for all three approaches is stainless steel (SS). While searching for optimal compact shield compositions, Gilai et al. found that a combination of tungsten and titanium hydride is significantly more effective than SS for attenuating fusion and fission neutrons. A preliminary feasibility study later indicated that tungsten and titanium-hydride can, indeed, make a more effective reflector shield than SS.

Greenspan, E.; Abrefah, J.; Olander, D.; Shayer, Z. (Univ. of California, Berkeley (United States))

1993-01-01

217

Stress anisotropy and concentration effects in high pressure measurements. [sodium chloride  

NASA Technical Reports Server (NTRS)

Sodium chloride is used as an internal pressure standard in high pressure research. Possible corrections are discussed which are needed in the calibration of this standard due to the independent effects of stress anisotropy and stress concentration in pressure vessels. The first is due to the lack of a truly hydrostatic state of stress in solid state pressure vessels. The second is due to the difference in the compressibilities between the pressure transmitting substances (sodium chloride) and a stiffer test specimen. These two corrections are then combined and a total correction, as a function of measured pressure, is discussed for two systems presently in use. The predicted value of the combined effect is about 5-10% of the pressure at 30 GPa.

Nelson, D. A., Jr.; Ruoff, A. L.

1974-01-01

218

Flux effect analysis in WWER-440 reactor pressure vessel steels  

NASA Astrophysics Data System (ADS)

The results of long term research programme concerning the determination of irradiation embrittlement dependence on fast neutron flux for WWER-440 reactor pressure vessel steels before and after annealing are presented in this paper. The study of flux effect was carried out on commercial WWER-440 steels which differ significantly in phosphorous (0.013-0.036 wt%) and copper (0.08-0.20 wt%) contents. All specimens were irradiated in surveillance channel positions under similar conditions at high ˜4 × 1012 ?m-2 s-1 and low ˜6 × 1011 ?m-2 s-1 fluxes (E > 0.5 MeV) at a temperature of 270 °?. The radiation embrittlement was evaluated by transition temperature shift on the basis of Charpy specimens test results. In case of low flux, the measured Tk shifts could be 25-50 °C bigger than the Tk shifts obtained from high flux data. A significant flux effect is observed in WWER-440 reactor pressure vessel steels with higher copper content (>0.13 wt%).

Kryukov, A.; Blagoeva, D.; Debarberis, L.

2013-11-01

219

Fatigue of weldments in nuclear pressure vessels and piping  

SciTech Connect

Current (ASME) Code fatigue design rules for nuclear pressure vessels and piping include no special considerations for weldments other than purely geometric factors. Research programs aimed at nonnuclear applications have found weldments to display fatigue behavior inferior to that of pure base material. Available information on fatigue of weldments relevant to nuclear pressure vessels and piping was reviewed and determined changes in the current design rules appear to be dictated by the available information. Information was obtained and summarized and stored in a computerized data management system to facilitate correlation of facts and development of conclusions. Significant areas where development of additional data would substantially increase the ability to judge the adequacy of the current ASME design rules include: a better understanding of the relative importance of crack initiation and crack propagation to fatigue life; additional fatigue data for prototypic commercial weldments, including cumulative damage; properties of repair welds; significance of reheat cracks; quantitative effect of Code-allowable weld defects; and the effect of variable microstructure across the weld joint. Based on the information that is available, there is no evidence that the ASME Code fatigue design procedures need to be changed at this time. The current ASME design procedures, which form the general basis for fatigue evaluation both in the US and abroad are reviewed. Included is a review of various factors that influence the fatigue of weldments and of service experience with nuclear systems regarding fatigue of weldments. Research programs that may contribute to available information are reviewed.

Booker, M.K.; Booker, B.L.P.; Meieran, H.B.; Heuschkel J.

1980-03-01

220

46 CFR 50.05-5 - Existing boilers, pressure vessels or piping systems.  

Code of Federal Regulations, 2013 CFR

...of recalculating the maximum allowable working pressure of boilers, pressure vessels, or piping which have deteriorated...formulas in this subchapter does not permit a higher pressure than that originally allowed by the...

2013-10-01

221

46 CFR 50.05-5 - Existing boilers, pressure vessels or piping systems.  

Code of Federal Regulations, 2010 CFR

...of recalculating the maximum allowable working pressure of boilers, pressure vessels, or piping which have deteriorated...formulas in this subchapter does not permit a higher pressure than that originally allowed by the...

2010-10-01

222

46 CFR 50.05-5 - Existing boilers, pressure vessels or piping systems.  

Code of Federal Regulations, 2012 CFR

...of recalculating the maximum allowable working pressure of boilers, pressure vessels, or piping which have deteriorated...formulas in this subchapter does not permit a higher pressure than that originally allowed by the...

2012-10-01

223

46 CFR 50.05-5 - Existing boilers, pressure vessels or piping systems.  

Code of Federal Regulations, 2011 CFR

...of recalculating the maximum allowable working pressure of boilers, pressure vessels, or piping which have deteriorated...formulas in this subchapter does not permit a higher pressure than that originally allowed by the...

2011-10-01

224

Simply actuated closure for a pressure vessel - Design for use to trap deep-sea animals  

NASA Technical Reports Server (NTRS)

A pressure vessel is described that can be closed by a single translational motion within 1 sec. The vessel is a key component of a trap for small marine animals and operates automatically on the sea floor. As the vessel descends to the sea floor, it is subjected both internally and externally to the high pressures of the deep sea. The mechanism for closing the pressure vessel on the sea floor is activated by the timed release of the ballast which was used to sink the trap. As it rises to the sea surface, the internal pressure of the vessel remains near the value present on the sea floor. The pressure vessel has been used in simulated ocean deployments and in the deep ocean (9500 m) with a 75%-85% retention of the deep-sea pressure. Nearly 100% retention of pressure can be achieved by using an accumulator filled with a gas.

Yayanos, A. A.

1977-01-01

225

Burst prediction by acoustic emission in filament-wound pressure vessels  

NASA Technical Reports Server (NTRS)

Acoustic emission in 51-cm diameter graphite/epoxy pressure vessels was monitored during pressurization (hydrotesting). Several vessels were subjected to impact by a blunt impactor, but only after the vessels had been proofed; that is, pressurized to 80 percent of nominal burst pressure as determined from control (unimpacted) vessels. AE activity was then monitored throughout a series of successively higher pressure cycles ranging from 10 to 60 percent of ultimate. Each cycle included a ramp up to pressure followed by a 4-min hold period and then pressure unload. The event rate was high, and especially modified AE analyzers had to be used to acquire the data. This paper presents the AE event count versus pressure history of these tests and demonstrates the ability of the AE technique to monitor the growth of damage and to estimate the effect on ultimate strength. The number of events that occurred during pressure holds proved to be a reasonable estimator of vessel performance.

Gorman, Michael R.

1990-01-01

226

Thin-metal lined PRD 49-III composite vessels. [evaluation of pressure vessels for burst strength and fatigue performance  

NASA Technical Reports Server (NTRS)

Filament wound pressure vessels of various configurations were evaluated for burst strength and fatigue performance. The dimensions and characteristics of the vessels are described. The types of tests conducted are explained. It was determined that all vessels leaked in a relatively few cycles (20 to 60 cycles) with failure occurring in all cases in the metallic liner. The thin liner would de-bond from the composite and buckling took place during depressurization. No composite failures or indications of impeding composite failures were obtained in the metal-lined vessels.

Hoggatt, J. T.

1974-01-01

227

Crack arrest in pressure vessel steels in a K- gradient and at low K Ia levels  

NASA Astrophysics Data System (ADS)

A simple theoretical model is used to examine the effect of the gradient of the crack tip stress intensity K on crack arrest in a nuclear reactor pressure vessel which is subject to a hypothetical thermal transient. Attention is focussed on the case where arrest occurs at the lower end of the transition temperature regime, when crack propagation and arrest are not accompanied by the formation of ductile ligaments. The analysis shows that the arrest K values depend on the gradient of K, and this leads to variability in the arrest values. In particular the arrest K value should be lower when the K gradient is positive than when it is negative; this prediction is reconciled with recent experimental results on crack arrest in model vessel tests.

Smith, E.

1986-10-01

228

Transmitted Ultrasound Pressure Variation in Micro Blood Vessel Phantoms  

PubMed Central

Silica, cellulose, and polymethylmethacrylate tubes with inner diameters of ten to a few hundred microns are commonly used as blood vessel phantoms in in vitro studies of microbubble or nanodroplet behavior during insonation. However, a detailed investigation of the ultrasonic fields within these micro-tubes has not yet been performed. This technical note provides a theoretical analysis of the ultrasonic fields within micro-tubes. Numerical results show that for the same tube material, the interaction between the micro-tube and megaHertz-frequency ultrasound may vary drastically with incident frequency, tube diameter, and wall thickness. For 10 MHz ultrasonic insonation of a polymethylmethacrylate (PMMA) tube with an inner diameter of 195 ?m and an outer diameter of 260 ?m, the peak pressure within the tube can be up to 300% of incident pressure amplitude. However, using 1 MHz ultrasound and a silica tube with an inner diameter of 12 ?m and an outer diameter of 50 ?m, the peak pressure within the tube is only 12% of the incident pressure amplitude, and correspondingly the spatial-average-time-average intensity within the tube is only 1% of the incident intensity. PMID:18395962

Qin, Shengping; Kruse, Dustin E.; Ferrara, Katherine W.

2008-01-01

229

Recent advances in lightweight, filament-wound composite pressure vessel technology  

NASA Technical Reports Server (NTRS)

A review of recent advances is presented for lightweight, high performance composite pressure vessel technology that covers the areas of design concepts, fabrication procedures, applications, and performance of vessels subjected to single cycle burst and cyclic fatigue loading. Filament wound fiber/epoxy composite vessels were made from S glass, graphite, and Kevlar 49 fibers and were equipped with both structural and nonstructural liners. Pressure vessels structural efficiencies were attained which represented weight savings, using different liners, of 40 to 60 percent over all titanium pressure vessels. Significant findings in each area are summarized.

Lark, R. F.

1977-01-01

230

Polymer-lined filament-wound pressure vessels for nitrogen containment  

NASA Technical Reports Server (NTRS)

A program has been started to develop fatigue-resistant polymeric liners for a filament-wound pressure vessel to contain nitrogen gas at room temperature. First, nitrogen permeation of butyl rubber sheet coated with Saran and Parylene C was studied in flat specimens. Then four 10-cm-diam cylindrical pressure vessels were prepared with chlorobutyl rubber liners coated with the same materials. These vessels were valved off after nitrogen gas pressurization to approximately 65% of their expected failure pressure. One vessel leaked. The other three vessels showed an average pressure loss of less than 1% per month. These pressure vessels have an average performance factor of about 370 kPa x cu m/kg based on composite mass.

Hamstad, M. A.; Chiao, T. T.; Jessop, E. S.

1974-01-01

231

Polymer-lined filament-wound pressure vessels for nitrogen containment  

NASA Technical Reports Server (NTRS)

A program has been started to develop fatigue-resistant polymeric liners for a filament-wound pressure vessel to contain nitrogen gas at room temperature. First, nitrogen permeation of butyl rubber sheet coated with Saran and Parylene C was studied in flat specimens. Then four 10-cm-diam cylindrical pressure vessels were prepared with chlorobutyl rubber liners coated with the same materials. These vessels were valved off after nitrogen gas pressurization to approximately 65% (approximately 11.7 MPa or 1700 psig) of their expected failure pressure. One vessel leaked. The other three vessels showed an average pressure loss of less than 1% per month. These pressure vessels have an average performance factor of approximately 370 kPa-cu m/kg (1,500,000 in.) based on composite mass.

Hamstad, M. A.; Chiao, T. T.; Jessop, E. S.

1974-01-01

232

Pressurized thermal shock probabilistic fracture mechanics sensitivity analysis for Yankee Rowe reactor pressure vessel  

SciTech Connect

The Nuclear Regulatory Commission (NRC) requested Oak Ridge National Laboratory (ORNL) to perform a pressurized-thermal-shock (PTS) probabilistic fracture mechanics (PFM) sensitivity analysis for the Yankee Rowe reactor pressure vessel, for the fluences corresponding to the end of operating cycle 22, using a specific small-break-loss- of-coolant transient as the loading condition. Regions of the vessel with distinguishing features were to be treated individually -- upper axial weld, lower axial weld, circumferential weld, upper plate spot welds, upper plate regions between the spot welds, lower plate spot welds, and the lower plate regions between the spot welds. The fracture analysis methods used in the analysis of through-clad surface flaws were those contained in the established OCA-P computer code, which was developed during the Integrated Pressurized Thermal Shock (IPTS) Program. The NRC request specified that the OCA-P code be enhanced for this study to also calculate the conditional probabilities of failure for subclad flaws and embedded flaws. The results of this sensitivity analysis provide the NRC with (1) data that could be used to assess the relative influence of a number of key input parameters in the Yankee Rowe PTS analysis and (2) data that can be used for readily determining the probability of vessel failure once a more accurate indication of vessel embrittlement becomes available. This report is designated as HSST report No. 117.

Dickson, T.L.; Cheverton, R.D.; Bryson, J.W.; Bass, B.R.; Shum, D.K.M.; Keeney, J.A. [Oak Ridge National Lab., TN (United States)

1993-08-01

233

Evaluation of embedded FBGs in composite overwrapped pressure vessels for strain based structural health monitoring  

NASA Astrophysics Data System (ADS)

The increased use of composite overwrapped pressure vessels (COPVs) in space and commercial applications, and the explosive nature of pressure vessel ruptures, make it crucial to develop techniques for early condition based damage detection. The need for a robust health monitoring system for COPVs is a high priority since the mechanisms of stress rupture are not fully understood. Embedded Fiber Bragg Grating (FBG) sensors have been proposed as a potential solution that may be utilized to anticipate and potentially avoid catastrophic failures. The small size and light weight of optical fibers enable manufactures to integrate FBGs directly into composite structures for the purpose of structural health monitoring. A challenging aspect of embedding FBGs within composite structures is the risk of potentially impinging the optical fiber while the structure is under load, thus distorting the optical information to be transferred. As the COPV is pressurized, an embedded optical sensor is compressed between the expansion of the inner bottle, and the outer overwrap layer of composite. In this study, FBGs are installed on the outer surface of a COPV bottle as well as embedded underneath a composite overwrap layer for comparison of strain measurements. Experimental data is collected from optical fibers containing multiple FBGs during incremental pressurization cycles, ranging from 0 to 10,000 psi. The graphical representations of high density strain maps provide a more efficient process of monitoring structural integrity. Preliminary results capture the complex distribution of strain, while furthering the understanding of the failure mechanisms of COPVs.

Pena, Francisco; Strutner, Scott M.; Richards, W. Lance; Piazza, Anthony; Parker, Allen R.

2014-03-01

234

Techniques for Embedding Instrumentation in Pressure Vessel Test Articles  

NASA Technical Reports Server (NTRS)

Many interesting structural and thermal events occur in materials that are housed within a surrounding pressure vessel. In order to measure the environment during these events and explore their causes instrumentation must be installed on or in the material. Transducers can be selected that are small enough to be embedded within the test material but these instruments must interface with an external system in order to apply excitation voltages and output the desired data. The methods for installing the instrumentation and creating an interface are complicated when the material is located in a case or housing containing high pressures and hot gases. Installation techniques for overcoming some of these difficulties were developed while testing a series of small-scale solid propellant and hybrid rocket motors at Marshall Space Flight Center. These techniques have potential applications in other test articles where data are acquired from materials that require containment due to the severe environment encountered during the test process. This severe environment could include high pressure, hot gases, or ionized atmospheres. The development of these techniques, problems encountered, and the lessons learned from the ongoing testing process are summarized.

Cornelius, Michael

2006-01-01

235

ASTM Standards for Reactor Dosimetry and Pressure Vessel Surveillance  

SciTech Connect

The ASTM standards provide guidance and instruction on how to field and interpret reactor dosimetry. They provide a roadmap towards understanding the current ''state-of-the-art'' in reactor dosimetry, as reflected by the technical community. The consensus basis to the ASTM standards assures the user of an unbiased presentation of technical procedures and interpretations of the measurements. Some insight into the types of standards and the way in which they are organized can assist one in using them in an expeditious manner. Two example are presented to help orient new users to the breadth and interrelationship between the ASTM nuclear metrology standards. One example involves the testing of a new ''widget'' to verify the radiation hardness. The second example involves quantifying the radiation damage at a pressure vessel critical weld location through surveillance dosimetry and calculation.

GRIFFIN, PATRICK J.

1999-09-14

236

Continuous Cooling Transformations in Nuclear Pressure Vessel Steels  

NASA Astrophysics Data System (ADS)

A class of low-alloy steels often referred to as SA508 represent key materials for the manufacture of nuclear reactor pressure vessels. The alloys have good properties, but the scatter in properties is of prime interest in safe design. Such scatter can arise from microstructural variations but most studies conclude that large components made from such steels are, following heat treatment, fully bainitic. In the present work, we demonstrate with the help of a variety of experimental techniques that the microstructures of three SA508 Gr.3 alloys are far from homogeneous when considered in the context of the cooling rates encountered in practice. In particular, allotriomorphic ferrite that is expected to lead to a deterioration in toughness, is found in the microstructure for realistic combinations of austenite grain size and the cooling rate combination. Parameters are established to identify the domains in which SA508 Gr.3 steels transform only into the fine bainitic microstructures.

Pous-Romero, Hector; Bhadeshia, Harry K. D. H.

2014-10-01

237

Macrosegregation and Microstructural Evolution in a Pressure-Vessel Steel  

NASA Astrophysics Data System (ADS)

This work assesses the consequences of macrosegregation on microstructural evolution during solid-state transformations in a continuously cooled pressure-vessel steel (SA508 Grade 3). Stark spatial variations in microstructure are observed following a simulated quench from the austenitization temperature, which are found to deliver significant variations in hardness. Partial-transformation experiments are used to show the development of microstructure in segregated material. Evidence is presented which indicates the bulk microstructure is not one of upper bainite, as it has been described in the past, but one comprised of Widmanstätten ferrite and pockets of lower bainite. Segregation is observed on three different length scales, and the origins of each type are proposed. Suggestions are put forward for how the segregation might be minimized, and its detrimental effects suppressed by heat treatments.

Pickering, E. J.; Bhadeshia, H. K. D. H.

2014-06-01

238

Structural considerations in design of lightweight glass-fiber composite pressure vessels  

NASA Technical Reports Server (NTRS)

The development of structurally efficient, metal-lined, glass-fiber composite pressure vessels. Both the current state-of-the-art and current problems are discussed along with fracture mechanics considerations for the metal liner. The design concepts used for metal-lined, glass-fiber, composite pressure vessels are described and the structural characteristics of the composite designs are compared with each other and with homogeneous metal pressure vessels. Specific design techniques and available design data are identified. Results of a current program to evaluate flaw growth and fracture characteristics of the metal liners are reviewed and the impact of these results on composite pressure vessel designs is discussed.

Faddoul, J. R.

1973-01-01

239

The behavior of shallow flaws in reactor pressure vessels  

SciTech Connect

Both analytical and experimental studies have shown that the effect of crack length, a, on the elastic-plastic toughness of structural steels is significant. The objective of this report is to recommend those research investigations that are necessary to understand the phenomenon of shallow behavior as it affects fracture toughness so that the results can be used properly in the structural margin assessment of reactor pressure vessels (RPVs) with flaws. Preliminary test results of A 533 B steel show an elevated crack-tip-opening displacement (CTOD) toughness similar to that observed for structural steels tested at the University of Kansas. Thus, the inherent resistance to fracture initiation of A 533 B steel with shallow flaws appears to be higher than that used in the current American Society of Mechanical Engineers (ASME) design curves based on testing fracture mechanics specimens with deep flaws. If this higher toughness of laboratory specimens with shallow flaws can be transferred to a higher resistance to failure in RPV design or analysis, then the actual margin of safety in nuclear vessels with shallow flaws would be greater than is currently assumed on the basis of deep-flaw test results. This elevation in toughness and greater resistance to fracture would be a very desirable situation, particularly for the pressurized-thermal shock (PTS) analysis in which shallow flaws are assumed to exist. Before any advantage can be taken of this possible increase in initiation toughness, numerous factors must be analyzed to ensure the transferability of the data. This report reviews those factors and makes recommendations of studies that are needed to assess the transferability of shallow-flaw toughness test results to the structural margin assessment of RPV with shallow flaws. 14 refs., 8 figs.

Rolfe, S.T. (Kansas Univ., Lawrence, KS (United States))

1991-11-01

240

Sustained load behavior of graphite/epoxy metal-lined pressure vessels for long-life space applications  

NASA Technical Reports Server (NTRS)

Tests were performed on candidate graphite yarns for the overwraps to be used on the Space Station Freedom's pressure vessels. The objective was to determine the performance and ranking of these overwraps to ensure that sustained loads would not be a problem during their 30-yr life in space. Tests were conducted at high stress levels for short time periods on subscale composite bottles. The average delivered fiber stresses were determined from the measured burst pressures via SCI analysis that accounts for both geometry and the properties of the resin and yarn.

Babel, H. W.; Vickers, B. D.; Thomas, D. A.

1989-01-01

241

D-Zero Central Calorimeter Pressure Vessel and Vacuum Vessel Safety Notes  

SciTech Connect

The relief valve and relief piping capacity was calculated to be 908 sefm air. This exceeds all relieving conditions. The vessel also has a rupture disc with a 2640 scfm air stamped capacity. In order to significantly decrease the amount of time required to fill the cryostats, it is desired to raise the setpoint of the 'operating' relief valve on the argon storage dewar to 20 psig from its existing 16 psig setting. This additional pressure increases the flow to the cryostats and will overwhelm the relief capacity if the temperature of the modules within these vessels is warm enough. Using some conservative assumptions and simple calculations within this note, the maximum average temperature that the modules within each cryostat can be at prior to filling from the storage dewar with liquid argon is at least 290 K. The average temperature of the module mass for any of the three cryostats can be as high as 290 K prior to filling that particular cryostat. This should not be confused with the average temperature of a single type or location which is useful in protecting the modules-not necessarily the vessel itself. A few modules of each type and at different elevations should be used in an average which would account for the different weights of each module. Note that at 290 K, the actual flow of argon through the relief valve and the rupture disk was under the maximum theoretical flows for each relief device. This means that the bulk temperature could actually have been raised to flow argon through the reliefs at their maximum capacity. Therefore, the temperature of 290 K is a conservative value for the calculated flow rate of 12.3 gpm. Safeguards in addition to and used in conjunction with operating procedures shall be implemented in such a way so that the above temperature limitation is not exceeded and such that it is exclusive of the programmable logic controller (PLC). One suggestion is using a toggle switch for each cryostat mounted in the PLC I/O box which would maintain control of the signals to open the cold fill valves of each cryostat. With the safeguards in place while carefully monitoring the temperatures during a cooldown cycle in each cryostat, the set pressure in the argon storage dewar can safely be increased to 20 psig.

Rucinski, R.; Luther, R.; /Fermilab

1990-10-25

242

Stress concentration factors for circular, reinforced penetrations in pressurized cylindrical shells. Ph.D. Thesis - Virginia Univ.  

NASA Technical Reports Server (NTRS)

The effect on stresses in a cylindrical shell with a circular penetration subject to internal pressure was investigated in thin, shallow linearly, elastic cylindrical shells. Results provide numerical predictions of peak stress concentration factors around nonreinforced and reinforced penetrations in pressurized cylindrical shells. Analytical results were correlated with published formulas, as well as theoretical and experimental results. An accuracy study was made of the finite element program for each of the configurations considered important in pressure vessel technology. A formula is developed to predict the peak stress concentration factor for analysis and/or design in conjunction with the ASME Boiler and Pressure Vessel Code.

Ramsey, J. W., Jr.

1975-01-01

243

Composite Overwrapped Pressure Vessels (COPV): Flight Rationale for the Space Shuttle Program  

NASA Technical Reports Server (NTRS)

Each Orbiter Vehicle (Space Shuttle Program) contains up to 24 Kevlar49/Epoxy Composite Overwrapped Pressure Vessels (COPV) for storage of pressurized gases. In the wake of the Columbia accident and the ensuing Return To Flight (RTF) activities, Orbiter engineers reexamined COPV flight certification. The original COPV design calculations were updated to include recently declassified Kevlar COPV test data from Lawrence Livermore National Laboratory (LLNL) and to incorporate changes in how the Space Shuttle was operated as opposed to orinigially envisioned. 2005 estimates for the probability of a catastrophic failure over the life of the program (from STS-1 through STS-107) were one-in-five. To address this unacceptable risk, the Orbiter Project Office (OPO) initiated a comprehensive investigation to understand and mitigate this risk. First, the team considered and eventually deemed unfeasible procuring and replacing all existing flight COPVs. OPO replaced the two vessels with the highest risk with existing flight spare units. Second, OPO instituted operational improvements in ground procedures to signficiantly reduce risk, without adversely affecting Shuttle capability. Third, OPO developed a comprehensive model to quantify the likelihood of occurrance. A fully-instrumented burst test (recording a lower burst pressure than expected) on a flight-certified vessel provided critical understanding of the behavior of Orbiter COPVs. A more accurate model was based on a newly-compiled comprehensive database of Kevlar data from LLNL and elsewhere. Considering hardware changes, operational improvements and reliability model refinements, the mean reliability was determined to be 0.998 for the remainder of the Shuttle Program (from 2007, for STS- 118 thru STS-135). Since limited hardware resources precluded full model validation through multiple tests, additional model confidence was sought through the first-ever Accelerated Stress Rupture Test (ASRT) of a flown flight article. A Bayesian statistical approach was developed to interpret possible test results. Since the lifetime observed in the ASRT exceeded initial estimates by one to two orders of magnitude, the Space Shuttle Program deemed there was significant conservatism in the model and accepted continued operation with existing flight hardware. Given the variability in tank-to-tank original prooftest response, a non-destructive evaluation (NDE) technique utilizing Raman Spectroscopy was developed to directly measure COPV residual stress state. Preliminary results showed that patterns of low fiber elastic strains over the outside vessel surface, together with measured permanent volume growth during proof, could be directly correlated to increased fiber stress ratios on the inside fibers adjacent to the liner, and thus reduced reliability.

Kezirian, Michael T.; Johnson, Kevin L.; Phoenix, Stuart L.

2011-01-01

244

Filament wound pressure vessels with load sharing liners for Space Shuttle Orbiter applications  

NASA Technical Reports Server (NTRS)

It is recognized that the use of overwrapped pressure vessels with load sharing liners may provide significant weight savings for high pressure gas containment in Space Shuttle Orbiter systems. The technology readiness to produce Kevlar wound vessels with load sharing liners of titanium 6Al-4V, Inconel 718 or cryoformed 301 steel has been demonstrated. It has been estimated that about 400 lbs can be saved in the Orbiter by using overwrapped vessels with load sharing liners instead of monolithic metal designs. Total weight of the composite vessels would be about 1350 lbs as opposed to about 1750 lbs for all-metal vessels.

Ecord, G. M.

1976-01-01

245

Design of Semi-composite Pressure Vessel using Fuzzy and FEM  

Microsoft Academic Search

The present study attempts to present a new method to design a semi-composite pressure vessel (known as hoop-wrapped composite\\u000a cylinder) using fuzzy decision making and finite element method. A metal-composite vessel was designed based on ISO criteria\\u000a and then the weight of the vessel was optimized for various fibers of carbon, glass and Kevlar in the cylindrical vessel.\\u000a Failure criteria

Mohammad H. Sabour; Mohammad F. Foghani

2010-01-01

246

Design of Semi-composite Pressure Vessel using Fuzzy and FEM  

Microsoft Academic Search

The present study attempts to present a new method to design a semi-composite pressure vessel (known as hoop-wrapped composite cylinder) using fuzzy decision making and finite element method. A metal-composite vessel was designed based on ISO criteria and then the weight of the vessel was optimized for various fibers of carbon, glass and Kevlar in the cylindrical vessel. Failure criteria

Mohammad H. Sabour; Mohammad F. Foghani

2010-01-01

247

Numerical Simulation of Impact Damage Induced by Orbital Debris on Shielded Wall of Composite Overwrapped Pressure Vessel  

NASA Astrophysics Data System (ADS)

This paper presents a methodology for numerical simulation of the formation of the front wall damage in composite overwrapped pressure vessels under hypervelocity impact. Both SPH particles and Lagrangian finite elements were employed in combination for numerical simulations. Detailed numerical models implementing two filament winding patterns with different degree of interweaving were developed and used to simulate 2.5 km/s and 5.0 km/s impacts of 5 mm-diameter spherical aluminum-alloy projectile. Obtained results indicate that winding pattern may have a pronounced effect on vessel damage in case of orbital debris impact, influencing propagation of the stress waves in composite material.

Cherniaev, Aleksandr; Telichev, Igor

2014-12-01

248

Reactor pressure vessel neutron fluence surveillance dosimetry using solid-state track recorders  

Microsoft Academic Search

Many neutron dosimetry issues arose in the context of life assurance\\/extension programs for nuclear power plants. The most important of these relates to determining the extent of reactor pressure vessel steel embrittlement caused by fast neutron leakage from the reactor core, since a key factor in reactor plant life is the service lifetime of the reactor pressure vessel. In the

F. H. Ruddy; J. G. Seidel; E. D. McGarry

1991-01-01

249

46 CFR 54.01-2 - Adoption of division 1 of section VIII of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2014 CFR

...of section VIII of the ASME Boiler and Pressure Vessel Code. 54.01-2 Section...CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54...of section VIII of the ASME Boiler and Pressure Vessel Code. (a) Pressure...

2014-10-01

250

46 CFR 54.01-2 - Adoption of division 1 of section VIII of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2012 CFR

...of section VIII of the ASME Boiler and Pressure Vessel Code. 54.01-2 Section...CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54...of section VIII of the ASME Boiler and Pressure Vessel Code. (a) Pressure...

2012-10-01

251

46 CFR 54.01-2 - Adoption of division 1 of section VIII of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2013 CFR

...of section VIII of the ASME Boiler and Pressure Vessel Code. 54.01-2 Section...CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54...of section VIII of the ASME Boiler and Pressure Vessel Code. (a) Pressure...

2013-10-01

252

46 CFR 54.01-2 - Adoption of division 1 of section VIII of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2010 CFR

...of section VIII of the ASME Boiler and Pressure Vessel Code. 54.01-2 Section...CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54...of section VIII of the ASME Boiler and Pressure Vessel Code. (a) Pressure...

2010-10-01

253

46 CFR 54.01-2 - Adoption of division 1 of section VIII of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2011 CFR

...of section VIII of the ASME Boiler and Pressure Vessel Code. 54.01-2 Section...CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54...of section VIII of the ASME Boiler and Pressure Vessel Code. (a) Pressure...

2011-10-01

254

Probabilistic prediction of the crack resistance of nuclear pressure vessel steels on the basis of a local approach. Part 1  

Microsoft Academic Search

We analyze the stochastic nature of various critical parameters responsible for the brittle fracture of nuclear pressure vessel\\u000a steels. It is shown that the critical stress of brittle fracture Sc governing the process of propagation of shear microcracks can be regarded (with sufficient accuracy) as a deterministic parameter.\\u000a At the same time, the critical parameter controlling the process of initiation

B. Z. Margolin; A. G. Gulenko; V. A. Shvetsova

1999-01-01

255

Characterizing the effects of cladding on semi-elliptical longitudinal surface flaws in cylindrical vessels subjected to internal pressure  

SciTech Connect

Flaws on the inside surface of cladded reactor vessels are often analyzed by modelling the carbon steel base metal without consideration of a layer of stainless steel cladding material, thus ignoring the effects of this bimetallic discontinuity. Adding cladding material to the inside surface of a finite element model of a vessel raises concerns regarding adequate mesh refinement in the vicinity of the base metal/cladding interface. This paper presents results of three-dimensional linear stress analysis that has been performed to obtain stress intensity factors for clad and unclad reactor vessels subjected to internal pressure loading. The study concentrates on semi-elliptical longitudinal surface flaws with a 6 to 1 length-to-depth ratio and flaw depths of 1/8 and 1/4 of the base metal thickness. Various meshing schemes are evaluated for modelling the crack front profile, with particular emphasis on the region near the inside surface and at the base metal/cladding interface. The shape of the crack front profile through the cladding layer and the number of finite elements used to discretize the cladding thickness are found to have a significant influence on typical fracture mechanic measures of the crack tip stress fields. Results suggest that the stress intensity factor at the inner surface of a cladded vessel may be affected as much by the finite element mesh near the surface as by the material discontinuity between the two parts of the structure.

Killian, D.E.; Yoon, K.K. [Framatome Technologies, Lynchburg, VA (United States)

1996-12-01

256

Advances in crack-arrest technology for reactor pressure vessels  

SciTech Connect

The Heavy-Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory (ORNL) under the sponsorship of the US Nuclear Regulatory Commission is continuing to improve the understanding of conditions that govern the initiation, rapid propagation, arrest, and ductile tearing of cracks in reactor pressure vessel (RPV) steels. This paper describes recent advances in a coordinated effort being conducted under the HSST Program by ORNL and several subcontracting groups to develop the crack-arrest data base and the analytical tools required to construct inelastic dynamic fracture models for RPV steels. Large-scale tests are being carried out to generate crack-arrest toughness data at temperatures approaching and above the onset of Charpy upper-shelf behavior. Small- and intermediate-size specimens subjected to static and dynamic loading are being developed and tested to provide additional fracture data for RPV steels. Viscoplastic effects are being included in dynamic fracture models and computer programs and their utility validated through analyses of data from carefully controlled experiments. Recent studies are described that examine convergence problems associated with energy-based fracture parameters in viscoplastic-dynamic fracture applications. Alternative techniques that have potential for achieving convergent solutions for fracture parameters in the context of viscoplastic-dynamic models are discussed. 46 refs., 15 figs., 3 tabs.

Bass, B.R.; Pugh, C.E.

1988-01-01

257

Swim Pressure: Stress Generation in Active Matter  

NASA Astrophysics Data System (ADS)

We discover a new contribution to the pressure (or stress) exerted by a suspension of self-propelled bodies. Through their self-motion, all active matter systems generate a unique swim pressure that is entirely athermal in origin. The origin of the swim pressure is based upon the notion that an active body would swim away in space unless confined by boundaries—this confinement pressure is precisely the swim pressure. Here we give the micromechanical basis for the swim stress and use this new perspective to study self-assembly and phase separation in active soft matter. The swim pressure gives rise to a nonequilibrium equation of state for active matter with pressure-volume phase diagrams that resemble a van der Waals loop from equilibrium gas-liquid coexistence. Theoretical predictions are corroborated by Brownian dynamics simulations. Our new swim stress perspective can help analyze and exploit a wide class of active soft matter, from swimming bacteria to catalytic nanobots to molecular motors that activate the cellular cytoskeleton.

Takatori, S. C.; Yan, W.; Brady, J. F.

2014-07-01

258

Composite Overwrapped Pressure Vessels (COPV): Developing Flight Rationale for the Space Shuttle Program  

NASA Technical Reports Server (NTRS)

Introducing composite vessels into the Space Shuttle Program represented a significant technical achievement. Each Orbiter vehicle contains 24 (nominally) Kevlar tanks for storage of pressurized helium (for propulsion) and nitrogen (for life support). The use of composite cylinders saved 752 pounds per Orbiter vehicle compared with all-metal tanks. The weight savings is significant considering each Shuttle flight can deliver 54,000 pounds of payload to the International Space Station. In the wake of the Columbia accident and the ensuing Return to Flight activities, the Space Shuttle Program, in 2005, re-examined COPV hardware certification. Incorporating COPV data that had been generated over the last 30 years and recognizing differences between initial Shuttle Program requirements and current operation, a new failure mode was identified, as composite stress rupture was deemed credible. The Orbiter Project undertook a comprehensive investigation to quantify and mitigate this risk. First, the engineering team considered and later deemed as unfeasible the option to replace existing all flight tanks. Second, operational improvements to flight procedures were instituted to reduce the flight risk and the danger to personnel. Third, an Orbiter reliability model was developed to quantify flight risk. Laser profilometry inspection of several flight COPVs identified deep (up to 20 mil) depressions on the tank interior. A comprehensive analysis was performed and it confirmed that these observed depressions were far less than the criterion which was established as necessary to lead to liner buckling. Existing fleet vessels were exonerated from this failure mechanism. Because full validation of the Orbiter Reliability Model was not possible given limited hardware resources, an Accelerated Stress Rupture Test of a flown flight vessel was performed to provide increased confidence. A Bayesian statistical approach was developed to evaluate possible test results with respect to the model credibility and thus flight rationale for continued operation of the Space Shuttle with existing flight hardware. A non-destructive evaluation (NDE) technique utilizing Raman Spectroscopy was developed to directly measure the overwrap residual stress state. Preliminary results provide optimistic results that patterns of fluctuation in fiber elastic strains over the outside vessel surface could be directly correlated with increased fiber stress ratios and thus reduced reliability.

Kezirian, Michael T.

2010-01-01

259

Design of a standalone-type beryllium vessel for high-pressure protein crystallography  

NASA Astrophysics Data System (ADS)

A standalone-type beryllium (Be) high-pressure crystallography vessel has been developed. Using a coupler-joint unit and a pressure valve, we could keep the pressure in the vessel constant at 100±1 MPa for more than 24 h without connecting to a pressure-generating apparatus. Diffraction spots of a glucose isomerase (GI) crystal under 100 MPa were collected using the vessel and a rotating copper-anode in-house x-ray generator (0.8 kW). We successfully collected a 2.0 Å resolution data set of a 0.5 mm size GI crystal in an aqueous solution at 100 MPa.

Suzuki, Yoshihisa; Tsukamoto, Masayuki; Sakuraba, Haruhiko; Matsumoto, Masamitsu; Nagasawa, Makoto; Tamura, Katsuhiro

2010-08-01

260

Fatigue performance of metal-lined graphite/epoxy pressure vessels  

NASA Technical Reports Server (NTRS)

Using an ultrahigh-strength graphite fiber, a program was started to develop a thin metal-lined fiber/epoxy pressure vessel that would have a fatigue life of over 1000 cycles. First, the performance factor of the fiber/epoxy composite was found to be 351 kN m/kg from the average of 18 rubber-lined pressure vessels. Then, both aluminum- and titanium-lined vessels were filament wound with the graphite fiber in an epoxy matrix. Several of these metal-lined vessels were subjected to hydraulic fatigue testing to about 50% of their expected burst pressures. The average fatigue life of the aluminum-lined vessels was 462 cycles; the average for the titanium-lined vessels was 2190 cycles.

Hamstad, M. A.; Chiao, T. T.; Patterson, R. G.

1975-01-01

261

A survey of pressure vessel code compliance methods for superconducting radio frequency cryomodules  

NASA Astrophysics Data System (ADS)

Superconducting radio frequency (SRF) cavities made from niobium and cooled with liquid helium are becoming key components of many particle accelerators. The helium vessels surrounding the RF cavities, portions of the niobium cavities themselves, and also possibly the vacuum vessels containing these assemblies, generally fall under the scope of local and national pressure vessel codes. In the U.S., Department of Energy rules require national laboratories to follow national consensus pressure vessel standards or to show "a level of safety greater than or equal to" that of the applicable standard. Thus, while used for its superconducting properties, niobium ends up being treated as a low-temperature pressure vessel material. Niobium material is not a code listed material and therefore requires the designer to understand the mechanical properties for material used in each pressure vessel fabrication; compliance with pressure vessel codes therefore becomes a problem. This report summarizes the approaches that various institutions have taken in order to bring superconducting RF cryomodules into compliance with pressure vessel codes.

Peterson, Thomas J.; Hayano, Hitoshi; Jensch, Kay; Kako, Eiji; Klebaner, Arkadiy; Mammosser, John; Matheisen, Axel; Nakai, Hirotaka; Nicol, Thomas H.; Theilacker, Jay; Yamamoto, Akira

2012-06-01

262

Pressure vessel fracture, fatigue, and life management: PVP-Volume 233  

SciTech Connect

This volume contains papers relating to the structural integrity assessment of pressure vessels and piping, with special emphasis on the effects of aging. The papers are organized in the following five areas: (1) pressure vessel life management; (2) fracture characterization using local and dual-parameter approaches; (3) stratification and thermal fatigue; (4) creep, fatigue, and fracture; and (5) integrated approach to integrity assessment of pressure components. Separate abstracts were prepared for 39 papers in this conference.

Bhandari, S.; Milella, P.P.; Pennell, W.E. (eds.)

1992-01-01

263

ANSI/AIAA S-081A, Pressure Vessel Standards Implementation Guidelines  

NASA Technical Reports Server (NTRS)

The stress rupture specification for Composite Overwrapped Pressure Vessels (COPV) is discussed. The composite shell of the COPV shall be designed to meet the design life considering the time it is under sustained load. A Mechcanical Damage Control Plan (MDCP) shall be created and implemented that assures the COPV will not fail due to mechanical damage due to manufacturing, testing, shipping, installation, or flight. Proven processes and procedures for fabrication and repair shall be used to preclude damage or material degradation during material processing, manufacturing operations, and refurbushment.Selected NDI techniques for the liner and/or boss(es) shall be performed before overwrapping with composite. When visual inspection reveals mechanical damage or defects exceeding manufacturing specification levels (and standard repair procedures), the damaged COPV shall be submitted to a material review board (MRB) for disposition. Every COPV shall be subjected to visual and other non-destructive inspection (NDI), per the inspection plan.

Greene, Nathanael J.

2009-01-01

264

Non-invasive method and apparatus for measuring pressure within a pliable vessel  

NASA Technical Reports Server (NTRS)

A non-invasive method and apparatus is disclosed for measuring pressure within a pliable vessel such as a blood vessel. The blood vessel is clamped by means of a clamping structure having a first portion housing a pressure sensor and a second portion extending over the remote side of the blood vessel for pressing the blood vessel into engagement with the pressure sensing device. The pressure sensing device includes a flat deflectable diaphragm portion arranged to engage a portion of the blood vessel flattened against the diaphragm by means of the clamp structure. In one embodiment, the clamp structure includes first and second semicylindrical members held together by retaining rings. In a second embodiment the clamp structure is of one piece construction having a solid semicylindrical portion and a hollow semicylindrical portion with a longitudinal slot in the follow semicylindrical portion through which a slip the blood vessel. In a third embodiment, an elastic strap is employed for clamping the blood vessel against the pressure sensing device.

Shimizu, M. (inventor)

1983-01-01

265

Evaluation of Progressive Failure Analysis and Modeling of Impact Damage in Composite Pressure Vessels  

NASA Technical Reports Server (NTRS)

NASA White Sands Test Facility (WSTF) is leading an evaluation effort in advanced destructive and nondestructive testing of composite pressure vessels and structures. WSTF is using progressive finite element analysis methods for test design and for confirmation of composite pressure vessel performance. Using composite finite element analysis models and failure theories tested in the World-Wide Failure Exercise, WSTF is able to estimate the static strength of composite pressure vessels. Additionally, test and evaluation on composites that have been impact damaged is in progress so that models can be developed to estimate damage tolerance and the degradation in static strength.

Sanchez, Christopher M.

2011-01-01

266

46 CFR 53.01-3 - Adoption of section IV of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2014 CFR

...IV of the ASME Boiler and Pressure Vessel Code. 53.01-3 Section 53.01-3...IV of the ASME Boiler and Pressure Vessel Code. (a) Heating boilers shall be designed...IV of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see...

2014-10-01

267

46 CFR 52.01-2 - Adoption of section I of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2014 CFR

...I of the ASME Boiler and Pressure Vessel Code. 52.01-2 Section 52.01-2...I of the ASME Boiler and Pressure Vessel Code. (a) Main power boilers and auxiliary...I of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see...

2014-10-01

268

46 CFR 53.01-3 - Adoption of section IV of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2013 CFR

...Adoption of section IV of the ASME Boiler and Pressure Vessel Code. 53.01-3 Section...Adoption of section IV of the ASME Boiler and Pressure Vessel Code. (a) Heating boilers...with section IV of the ASME Boiler and Pressure Vessel Code (incorporated by...

2013-10-01

269

46 CFR 53.01-3 - Adoption of section IV of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2011 CFR

...Adoption of section IV of the ASME Boiler and Pressure Vessel Code. 53.01-3 Section...Adoption of section IV of the ASME Boiler and Pressure Vessel Code. (a) Heating boilers...with section IV of the ASME Boiler and Pressure Vessel Code (incorporated by...

2011-10-01

270

46 CFR 53.01-3 - Adoption of section IV of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2010 CFR

...Adoption of section IV of the ASME Boiler and Pressure Vessel Code. 53.01-3 Section...Adoption of section IV of the ASME Boiler and Pressure Vessel Code. (a) Heating boilers...with section IV of the ASME Boiler and Pressure Vessel Code (incorporated by...

2010-10-01

271

46 CFR 53.01-3 - Adoption of section IV of the ASME Boiler and Pressure Vessel Code.  

Code of Federal Regulations, 2012 CFR

...Adoption of section IV of the ASME Boiler and Pressure Vessel Code. 53.01-3 Section...Adoption of section IV of the ASME Boiler and Pressure Vessel Code. (a) Heating boilers...with section IV of the ASME Boiler and Pressure Vessel Code (incorporated by...

2012-10-01

272

Recent advances in lightweight, filament-wound composite pressure vessel technology  

NASA Technical Reports Server (NTRS)

A review of recent advances is presented for lightweight, high-performance composite pressure vessel technology that covers the areas of design concepts, fabrication procedures, applications, and performance of vessels subjected to single-cycle burst and cyclic fatigue loading. Filament-wound fiber/epoxy composite vessels were made from S-glass, graphite, and Kevlar 49 fibers and were equipped with both structural and nonstructural liners. Pressure vessel structural efficiencies were attained which represented weight savings, using different liners, of 40 to 60 percent over all-titanium pressure vessels. Significant findings in each area are summarized including data from current NASA-Lewis Research Center contractual and in-house programs.

Lark, R. F.

1977-01-01

273

DEVELOPMENT OF ASME SECTION X CODE RULES FOR HIGH PRESSURE COMPOSITE HYDROGEN PRESSURE VESSELS WITH NON-LOAD SHARING LINERS  

SciTech Connect

The Boiler and Pressure Vessel Project Team on Hydrogen Tanks was formed in 2004 to develop Code rules to address the various needs that had been identified for the design and construction of up to 15000 psi hydrogen storage vessel. One of these needs was the development of Code rules for high pressure composite vessels with non-load sharing liners for stationary applications. In 2009, ASME approved new Appendix 8, for Section X Code which contains the rules for these vessels. These vessels are designated as Class III vessels with design pressure ranging from 20.7 MPa (3,000 ps)i to 103.4 MPa (15,000 psi) and maximum allowable outside liner diameter of 2.54 m (100 inches). The maximum design life of these vessels is limited to 20 years. Design, fabrication, and examination requirements have been specified, included Acoustic Emission testing at time of manufacture. The Code rules include the design qualification testing of prototype vessels. Qualification includes proof, expansion, burst, cyclic fatigue, creep, flaw, permeability, torque, penetration, and environmental testing.

Rawls, G.; Newhouse, N.; Rana, M.; Shelley, B.; Gorman, M.

2010-04-13

274

Photoacoustic sample vessel and method of elevated pressure operation  

DOEpatents

An improved photoacoustic vessel and method of photoacoustic analysis. The photoacoustic sample vessel comprises an acoustic detector, an acoustic couplant, and an acoustic coupler having a chamber for holding the acoustic couplant and a sample. The acoustic couplant is selected from the group consisting of liquid, solid, and combinations thereof. Passing electromagnetic energy through the sample generates an acoustic signal within the sample, whereby the acoustic signal propagates through the sample to and through the acoustic couplant to the acoustic detector.

Autrey, Tom; Yonker, Clement R.

2004-05-04

275

Nondestructive Methods and Special Test Instrumentation Supporting NASA Composite Overwrapped Pressure Vessel Assessments  

NASA Technical Reports Server (NTRS)

Many aging composite overwrapped pressure vessels (COPVs), being used by the National Aeronautics and Space Administration (NASA) are currently under evaluation to better quantify their reliability and clarify their likelihood of failure due to stress rupture and age-dependent issues. As a result, some test and analysis programs have been successfully accomplished and other related programs are still in progress at the NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) and other NASA centers, with assistance from the commercial sector. To support this effort, a group of Nondestructive Evaluation (NDE) experts was assembled to provide NDE competence for pretest evaluation of test articles and for application of NDE technology to real-time testing. Techniques were required to provide assurance that the test article had adequate structural integrity and manufacturing consistency to be considered acceptable for testing and these techniques were successfully applied. Destructive testing is also being accomplished to better understand the physical and chemical property changes associated with progression toward "stress rupture" (SR) failure, and it is being associated with NDE response, so it can potentially be used to help with life prediction. Destructive work also includes the evaluation of residual stresses during dissection of the overwrap, laboratory evaluation of specimens extracted from the overwrap to evaluate physical property changes, and quantitative microscopy to inform the theoretical micromechanics.

Saulsberry, Regor; Greene, Nathanael; Cameron, Ken; Madaras, Eric; Grimes-Ledesma, Lorie; Thesken, John; Phoenix, Leigh; Murthy, Pappu; Revilock, Duane

2007-01-01

276

REACTOR PRESSURE VESSEL TEMPERATURE ANALYSIS OF CANDIDATE VERY HIGH TEMPERATURE REACTOR DESIGNS  

Microsoft Academic Search

Analyses were performed to determine maximum temperatures in the reactor pressure vessel for two potential Very-High Temperature Reactor (VHTR) designs during normal operation and during a depressurized conduction cooldown accident. The purpose of the analyses was to aid in the determination of appropriate reactor vessel materials for the VHTR. The designs evaluated utilized both prismatic and pebble-bed cores that generated

Hans D. Gougar; Cliff B. Davis; George Hayner; Kevan Weaver

277

Heavy-Section Steel Technology Program intermediate-scale pressure vessel tests  

Microsoft Academic Search

The tests of intermediate-size vessels with sharp flaws permitted the comparison of experimentally observed behavior with analytical predictions of the behavior of flawed pressure vessels. Fracture strains estimated by linear elastic fracture mechanics (LEFM) were accurate in the cases in which the flaws resided in regions of high transverse restraint and the fracture toughness was sufficiently low for unstable fracture

R. H. Bryan; J. G. Merkle; G. C. Smith; G. D. Whitman

1977-01-01

278

Study of tearing behaviour of a PWR reactor pressure vessel lower head under severe accident loadings  

Microsoft Academic Search

In PWR severe accident scenarios, involving a relocation of corium (core melt) into the lower head, the possible failure mode of the reactor pressure vessel (RPV), the failure time, the failure location and the final size of the breach are regarded as key elements, since they play an important part in the ex-vessel phase of the accident.Both the LHF and

Vincent Koundy; Cataldo Caroli; Laetitia Nicolas; Philippe Matheron; Jean-Marie Gentzbittel; Michel Coret

2008-01-01

279

Evaluation of polyimide/glass fiber composites for construction of light weight pressure vessels for cryogenic propellants  

NASA Technical Reports Server (NTRS)

The application of polyimide resin as a matrix for glass filament-wound thin metal-lined pressure vessels was studied over a temperature range of (minus) 320 to 600 F. Keramid 601 polyimide was found to perform quite well over the entire range of temperature. Hoop stress values of 425 ksi were determined at 75 F which is equivalent to epoxy resin in similar structures. At -320 and 600 F, 125 and 80% of this strength was retained. Thermal ageing at 500 F for up to 50 hours was studied with severe reduction in strength, but there is evidence that this reduction could be improved. Another polyimide resin studied was P10PA which was found to have processing characteristics inappropriate for filament-winding. NOL ring tensile and shear data was determined from both resins with S-glass. Pressure vessel design, fabrication and test procedures are described in detail.

Petker, I.; Segimoto, M.

1973-01-01

280

Filament-reinforced metal composite pressure vessel evaluation and performance demonstration  

NASA Technical Reports Server (NTRS)

Two different Kevlar-49 filament-reinforced metal sphere designs were developed, and six vessels of each type were fabricated and subjected to fatigue cycling, sustained loading, and hydrostatic burst. The 61 cm (24 inch) diameter Kevlar-49/cryoformed 301 stainless steel pressure vessels demonstrated the required pressure cycle capability, burst factor of safety, and a maximum pressure times volume divided by weight (pV/W) performance of 210 J/g (834 000 in-lb/lbm) at burst; this represented a 25 to 30% weight saving over the lightest weight comparable, 6A1-4V Ti, homogeneous pressure vessel. Both the Kevlar/stainless steel design and the 97 cm (38 inch) diameter Kevlar-49/2219-T62 aluminum sphere design demonstrated nonfragmentation and controlled failure mode features when pressure cycled to failure at operating pressure. When failure occurred during pressure cycling, the mode was localized leakage and not catastrophic. Kevlar/stainless steel vessels utilized a unique conical boss design, and Kevlar/aluminum vessels incorporated a tie-rod to carry port loads; both styles of polar fittings performed as designed during operational testing of the vessels.

Landes, R. E.

1976-01-01

281

High Pressure Composite Overwrapped Pressure Vessel (COPV) Development Tests at Cryogenic Temperatures  

NASA Technical Reports Server (NTRS)

Development tests were conducted to evaluate the performance of 2 COPV designs at cryogenic temperatures. This allows for risk reductions for critical components for a Gaseous Helium (GHe) Pressurization Subsystem for an Advanced Propulsion System (APS) which is being proposed for NASA s Constellation project and future exploration missions. It is considered an advanced system since it uses Liquid Methane (LCH4) as the fuel and Liquid Oxygen (LO2) as the oxidizer for the propellant combination mixture. To avoid heating of the propellants to prevent boil-off, the GHe will be stored at subcooled temperatures equivalent to the LO2 temperature. Another advantage of storing GHe at cryogenic temperatures is that more mass of the pressurized GHe can be charged in to a vessel with a smaller volume, hence a smaller COPV, and this creates a significant weight savings versus gases at ambient temperatures. The major challenge of this test plan is to verify that a COPV can safely be used for spacecraft applications to store GHe at a Maximum Operating Pressure (MOP) of 4,500 psig at 140R to 160R (-320 F to -300 F). The COPVs for these tests were provided by ARDE , Inc. who developed a resin system to use at cryogenic conditions and has the capabilities to perform high pressure testing with LN2.

Ray, David M.; Greene, Nathanael J.; Revilock, Duane; Sneddon, Kirk; Anselmo, Estelle

2008-01-01

282

Hydrogen degradation and microstructural effects of the near-threshold fatigue resistance of pressure vessel steels  

E-print Network

Safety of pressure vessels for applications such as coal conversion reactors requires understanding of the mechanism of environmentally-induced crack propagation and the mechanism by which process-induced microstructures ...

Fuquen-Molano, Rosendo

1982-01-01

283

Workbook for predicting pressure wave and fragment effects of exploding propellant tanks and gas storage vessels  

NASA Technical Reports Server (NTRS)

Technology needed to predict damage and hazards from explosions of propellant tanks and bursts of pressure vessels, both near and far from these explosions is introduced. Data are summarized in graphs, tables, and nomographs.

Baker, W. E.; Kulesz, J. J.; Ricker, R. E.; Bessey, R. L.; Westine, P. S.; Parr, V. B.; Oldham, G. A.

1975-01-01

284

30 CFR 56.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2010 CFR

...and may be obtained from the publisher, the National Board of Boiler and Pressure Vessel Inspector, 1055 Crupper Avenue, Columbus, Ohio 43229. (b) Records of inspections shall be kept in accordance with requirements of the National Board...

2010-07-01

285

Adaptation of mesenteric lymphatic vessels to prolonged changes in transmural pressure  

PubMed Central

In vitro studies have revealed that acute increases in transmural pressure increase lymphatic vessel contractile function. However, adaptive responses to prolonged changes in transmural pressure in vivo have not been reported. Therefore, we developed a novel bovine mesenteric lymphatic partial constriction model to test the hypothesis that lymphatic vessels exposed to higher transmural pressures adapt functionally to become stronger pumps than vessels exposed to lower transmural pressures. Postnodal mesenteric lymphatic vessels were partially constricted for 3 days. On postoperative day 3, constricted vessels were isolated, and divided into upstream (UP) and downstream (DN) segment groups, and instrumented in an isolated bath. Although there were no differences between the passive diameters of the two groups, both diastolic diameter and systolic diameter were significantly larger in the UP group than in the DN group. The pump index of the UP group was also higher than that in the DN group. In conclusion, this is the first work to report how lymphatic vessels adapt to prolonged changes in transmural pressure in vivo. Our results suggest that vessel segments upstream of the constriction adapt to become both better fluid conduits and lymphatic pumps than downstream segments. PMID:23666672

Dongaonkar, R. M.; Nguyen, T. L.; Hardy, J.; Laine, G. A.; Wilson, E.; Stewart, R. H.

2013-01-01

286

‘Sausage-string’ deformations of blood vessels at high blood pressures  

NASA Astrophysics Data System (ADS)

A new instability is proposed to explain the ‘sausage-string’ patterns of alternating constrictions and dilatations formed in blood vessels at high blood pressure conditions. Our theory provides predictions for the conditions under which the cylindrical geometry of a blood vessel becomes unstable. The theory is related to experimental observations in rats, where high blood pressure is induced by intravenous infusion of angiotensin II.

Alstrøm, P.; Mikkelsen, R.; Gustafsson, F.; Holstein-Rathlou, N.-H.

1999-12-01

287

Multilayer Pressure Vessel Materials Testing and Analysis Phase 2  

NASA Technical Reports Server (NTRS)

To provide NASA with a suite of materials strength, fracture toughness and crack growth rate test results for use in remaining life calculations for the vessels described above, Southwest Research Institute® (SwRI®) was contracted in two phases to obtain relevant material property data from a representative vessel. An initial characterization of the strength, fracture and fatigue crack growth properties was performed in Phase 1. Based on the results and recommendations of Phase 1, a more extensive material property characterization effort was developed in this Phase 2 effort. This Phase 2 characterization included additional strength, fracture and fatigue crack growth of the multilayer vessel and head materials. In addition, some more limited characterization of the welds and heat affected zones (HAZs) were performed. This report

Popelar, Carl F.; Cardinal, Joseph W.

2014-01-01

288

Pressure vessel with impact and fire resistant coating and method of making same  

NASA Technical Reports Server (NTRS)

An impact and fire resistant coating laminate is provided which serves as an outer protective coating for a pressure vessel such as a composite overwrapped vessel with a metal lining. The laminate comprises a plurality of fibers (e.g., jute twine or other, stronger fibers) which are wound around the pressure vessel and an epoxy matrix resin for the fibers. The epoxy matrix resin including a plurality of microspheres containing a temperature responsive phase change material which changes phase in response to exposure thereof to a predetermined temperature increase so as to afford increased insulation and heat absorption.

DeLay, Thomas K. (Inventor)

2005-01-01

289

Pressure Vessel with Impact and Fire Resistant Coating and Method of Making Same  

NASA Technical Reports Server (NTRS)

An impact and fire resistant coating laminate is provided which serves as an outer protective coating for a pressure vessel such as a composite overwrapped vessel with a metal lining. The laminate comprises a plurality of fibers (e.g., jute twine or other, stronger fibers) which are wound around the pressure vessel and an epoxy matrix resin for the fibers. The epoxy matrix resin including a plurality of microspheres containing a temperature responsive phase change material which changes phase in response to exposure thereof to a predetermined temperature increase so as to afford increased insulation and hear absorption.

DeLay, Thomas K. (Inventor)

2005-01-01

290

Effects of neutron irradiation and temperature on high strain rate behavior of reactor pressure vessel steel  

SciTech Connect

This paper describes the results f an investigation of the influence of neutron irradiation on mechanical properties of a reactor pressure vessel steel at high strain rates epsilon approx. = (10/sup 3/ to 10/sup 4/)s/sup -1/ produced by means of the Hopkinson split pressure bar technique (HSPBT). Our steel with chemical composition 0.18% C, 1.22% Mn, 0.012% P, 0.016% S, 0.17% Cr, 0.33% Ni, 0.055% Al, 0.028% Ti was irradiated by fast neutrons to an exposure of 1.35.10/sup 23/ (n)m/sup -2/. The extensive dynamic measurements performed in the temperature range of (90 + 573)/sup 0/K are analyzed in terms of state equation for viscoplastic flow. It is shown that neutron irradiation shifts the transition between thermally activated and viscous dislocation damping mechanism of plastic deformation to the higher strain rates. Particular attention is paid to the comparison of the influence of neutron irradiation and strain aging. The experimental data obtained indicate that plastic strain rate epsilon is a linear function of dynamic over stress sigma/sub fl//sigma/sub 2/ - 1, epsilon = ..gamma.. (sigma/sub fl//sigma/sub 2/ - 1) + epsilon/sub 2/ where ..gamma.. is viscosity coefficient, sigma/sub fl/ denotes flow stress and sigma/sub 2/, epsilon/sub 2/ are stress and strain rate respectively which control the transition between termally activated process and viscous damping mechanism. It appears that sigma/sub 2/ and epsilon/sub 2/ are strongly influenced by neutron irradiation and strain aging although ..gamma.. is nearly independent of both.

Buchar, J.; Bilek, Z.; Dusek, F.

1982-01-01

291

Creep failure of a reactor pressure vessel lower head under severe accident conditions  

SciTech Connect

A severe accident in a nuclear power plant could result in the relocation of large quantities of molten core material onto the lower head of he reactor pressure vessel (RPV). In the absence of inherent cooling mechanisms, failure of the RPV ultimately becomes possible under the combined effects of system pressure and the thermal heat-up of the lower head. Sandia National Laboratories has performed seven experiments at 1:5th scale simulating creep failure of a RPV lower head. This paper describes a modeling program that complements the experimental program. Analyses have been performed using the general-purpose finite-element code ABAQUS-5.6. In order to make ABAQUS solve the specific problem at hand, a material constitutive model that utilizes temperature dependent properties has been developed and attached to ABAQUS-executable through its UMAT utility. Analyses of the LHF-1 experiment predict instability-type failure. Predicted strains are delayed relative to the observed strain histories. Parametric variations on either the yield stress, creep rate, or both (within the range of material property data) can bring predictions into agreement with experiment. The analysis indicates that it is necessary to conduct material property tests on the actual material used in the experimental program. The constitutive model employed in the present analyses is the subject of a separate publication.

Pilch, M.M.; Ludwigsen, J.S.; Chu, T.Y. [Sandia National Labs., Albuquerque, NM (United States); Rashid, Y.R. [Anatech, San Diego, CA (United States)

1998-08-01

292

Prediction of failure behavior of a welded pressure vessel containing flaws during a hydrogen-charged burst test  

SciTech Connect

An industry-government collaborative program was carried out with an aim to promoting the acceptance of fracture mechanics based fitness-for-service assessment methodology for a service-damaged pressure vessel. A collaborative round robin exercise was carried out to predict the fracture behavior of a vessel containing hydrogen damage, fabrication related lack-of-fusion defects, an artificially induced fatigue crack and a localized thinned area. The fracture assessment procedures used include the US ASME Material Property Council`s PREFIS Program based on the British Standard (BS) Published Document (PD) 6493, ASME Section XI and The Central Electricity Generating Board (CEGB) R6 approach; The welding Institute (TWI) CRACKWISE program (based on BS PD6493 Level 2 approach), a variant of the R6 approach, J-tearing instability approaches, various J-estimation schemes, LEFM approach and simplified stress analysis. Assessments were compared with the results obtained from a hydrogen charged burst test of the vessel. Predictions, based on the J-tearing approach, compared well with the actual burst test results. Actual burst pressure was about five times the operating pressure.

Bhuyan, G.S. [Powertech Labs. Inc., Surrey, British Columbia (Canada); Sperling, E.J. [Amoco Corp., Naperville, IL (United States); Shen, G. [CANMET, Ottawa, Ontario (Canada). Metals Technology Labs.; Yin, H. [Mobil Research and Development Corp., Farmers Branch, TX (United States); Rana, M.D. [Praxair, Inc., Tonawanda, NY (United States)

1996-12-01

293

Method and apparatus for treating natural gas from gas wells for safe transportation in pressure vessels  

Microsoft Academic Search

A system for treating natural gas from a gas source, such as a gas well, to make it suitable for safe transport in high tensile strength pressure vessels at pressures in excess of 2000 psi. The system comprises suitable pipes and valves for taking gas from a gas well. A separator is provided for removing free liquids from the gas

R. Pronovost; P. Innis; L. M. ORouke

1985-01-01

294

Bobbin-Tool Friction-Stir Welding of Thick-Walled Aluminum Alloy Pressure Vessels  

SciTech Connect

It was desired to assemble thick-walled Al alloy 2219 pressure vessels by bobbin-tool friction-stir welding. To develop the welding-process, mechanical-property, and fitness-for-service information to support this effort, extensive friction-stir welding-parameter studies were conducted on 2.5 cm. and 3.8 cm. thick 2219 Al alloy plate. Starting conditions of the plate were the fully-heat-treated (-T62) and in the annealed (-O) conditions. The former condition was chosen with the intent of using the welds in either the 'as welded' condition or after a simple low-temperature aging treatment. Since preliminary stress-analyses showed that stresses in and near the welds would probably exceed the yield-strength of both 'as welded' and welded and aged weld-joints, a post-weld solution-treatment, quenching, and aging treatment was also examined. Once a suitable set of welding and post-weld heat-treatment parameters was established, the project divided into two parts. The first part concentrated on developing the necessary process information to be able to make defect-free friction-stir welds in 3.8 cm. thick Al alloy 2219 in the form of circumferential welds that would join two hemispherical forgings with a 102 cm. inside diameter. This necessitated going to a bobbin-tool welding-technique to simplify the tooling needed to react the large forces generated in friction-stir welding. The bobbin-tool technique was demonstrated on both flat-plates and plates that were bent to the curvature of the actual vessel. An additional issue was termination of the weld, i.e. closing out the hole left at the end of the weld by withdrawal of the friction-stir welding tool. This was accomplished by friction-plug welding a slightly-oversized Al alloy 2219 plug into the termination-hole, followed by machining the plug flush with both the inside and outside surfaces of the vessel. The second part of the project involved demonstrating that the welds were fit for the intended service. This involved determining the room-temperature tensile and elastic-plastic fracture-toughness properties of the bobbin-tool friction-stir welds after a post-weld solution-treatment, quenching, and aging heat-treatment. These mechanical properties were used to conduct fracture-mechanics analyses to determine critical flaw sizes. Phased-array and conventional ultrasonic non-destructive examination was used to demonstrate that no flaws that match or exceed the calculated critical flaw-sizes exist in or near the friction-stir welds.

Dalder, E C; Pastrnak, J W; Engel, J; Forrest, R S; Kokko, E; Ternan, K M; Waldron, D

2007-06-06

295

Design of a standalone-type beryllium vessel for high-pressure protein crystallography.  

PubMed

A standalone-type beryllium (Be) high-pressure crystallography vessel has been developed. Using a coupler-joint unit and a pressure valve, we could keep the pressure in the vessel constant at 100+/-1 MPa for more than 24 h without connecting to a pressure-generating apparatus. Diffraction spots of a glucose isomerase (GI) crystal under 100 MPa were collected using the vessel and a rotating copper-anode in-house x-ray generator (0.8 kW). We successfully collected a 2.0 A resolution data set of a 0.5 mm size GI crystal in an aqueous solution at 100 MPa. PMID:20815618

Suzuki, Yoshihisa; Tsukamoto, Masayuki; Sakuraba, Haruhiko; Matsumoto, Masamitsu; Nagasawa, Makoto; Tamura, Katsuhiro

2010-08-01

296

Distributed Sensing of Carbon-Epoxy Composites and Filament Wound Pressure Vessels Using Fiber-Bragg Gratings  

NASA Technical Reports Server (NTRS)

Multiple Fiber Bragg-gratings are embedded in carbon-epoxy laminates as well as in composite wound pressure vessel. Structural properties of such composites are investigated. The measurements include stress-strain relation in laminates and Poisson's ratio in several specimens with varying orientation of the optical fiber Bragg-sensor with respect to the carbon fiber in an epoxy matrix. Additionally, fiber Bragg gratings are bonded on the surface of these laminates and cylinders fabricated out of carbon-epoxy composites and multiple points are monitored and compared for strain measurements at several locations.

Grant, J.; Kaul, R.; Taylor, S.; Myer, G.; Jackson, K.; Osei, A.; Sharma, A.

2003-01-01

297

The effect of spacing and location of bolt holes of steel flanges for pressure vessels and piping  

E-print Network

of Materials"(5). In 1951 Holmberg and Axelson wrote a paper (4) in which they used the thin-plate theory in developing formulas for stresses in loose-ring flanges and in flanges made integral with the wall of a pressure vessel or pipe. Their analysis...), Jasper, Greger- sen, and Zoellner discussed further the formulas of Timo- shenko, an4 Holmberg and Azelson. They also made a oontr1- bution to the sub]ect by presenting the results of an ezten- sive series of tests on plaster of Paris models. Some oi...

Hall, Harris Harlan

1949-01-01

298

Feasibility for development of a nuclear reactor pressure vessel flaw distribution: Sensitivity analyses and NDE (nondestructive evaluation) capability  

SciTech Connect

Pressurized water reactor pressure vessels operate under US Nuclear Regulatory Commission (NRC) rules and regulatory guides that are intended to maintain a low probability of vessel failure. The NRC has also addressed neutron embrittlement of pressurized water reactor pressure vessels by imposing regulations on plant operation. Plants failing to meet the operating criteria specified by these rules and regulations are required, among other things, to analytically demonstrate fitness for service in order to continue safe operation. The initial flaw size or distribution of initial vessel flaws is a key input to the required vessel integrity analyses. A fracture mechanics sensitivity study was performed to quantify the effect of the assumed flaw distribution on the predicted vessel performance under a specified pressurized thermal shock transient and to determine the critical crack size. Results of the analysis indicate that vessel performance in terms of the estimated probability of failure is very sensitive to the assumed flaw distribution. 20 refs., 3 figs., 2 tabs.

Rosinski, S.T. (Sandia National Labs., Albuquerque, NM (USA)); Kennedy, E.L.; Foulds, J.R. (Failure Analysis Associates, Inc., Menlo Park, CA (USA))

1990-01-01

299

J-integral patch for finite element analysis of dynamic fracture due to impact of pressure vessels  

NASA Technical Reports Server (NTRS)

Prediction of whether a pressurized cylinder will fail catastrophically when impacted by a projectile has important applications ranging from perforation of an airplane's skin by a failed turbine blade to meteorite impact of a space station habitation module. This report summarizes the accomplishment of one task for a project whose aim is to simulate numerically the outcome of a high velocity impact of pressure vessels. A finite element patch covering the vicinity of a growing crack has been constructed to estimate the J-integral (crack driving force) during the impact. Explicit expressions for the J-integral through the nodal values of displacement, strain, and stress have been written. The patch is to be used repeatedly to estimate the amount of crack growth during the time of the impact. The resulting crack size is to be compared to an estimated critical crack size for the pressurized cylinder.

Kunin, Boris I.

1993-01-01

300

A novel high pressure, high temperature vessel used to conduct long-term stability measurements of silicon MEMS pressure transducers  

NASA Astrophysics Data System (ADS)

The need to quantify and to improve long-term stability of pressure transducers is a persistent requirement from the aerospace sector. Specifically, the incorporation of real-time pressure monitoring in aircraft landing gear, as exemplified in Tire Pressure Monitoring Systems (TPMS), has placed greater demand on the pressure transducer for improved performance and increased reliability which is manifested in low lifecycle cost and minimal maintenance downtime through fuel savings and increased life of the tire. Piezoresistive (PR) silicon MEMS pressure transducers are the primary choice as a transduction method for this measurement owing to their ability to be designed for the harsh environment seen in aircraft landing gear. However, these pressure transducers are only as valuable as the long-term stability they possess to ensure reliable, real-time monitoring over tens of years. The "heart" of the pressure transducer is the silicon MEMS element, and it is at this basic level where the long-term stability is established and needs to be quantified. A novel High Pressure, High Temperature (HPHT) vessel has been designed and constructed to facilitate this critical measurement of the silicon MEMS element directly through a process of mechanically "floating" the silicon MEMS element while being subjected to the extreme environments of pressure and temperature, simultaneously. Furthermore, the HPHT vessel is scalable to permit up to fifty specimens to be tested at one time to provide a statistically significant data population on which to draw reasonable conclusions on long-term stability. With the knowledge gained on the silicon MEMS element, higher level assembly to the pressure transducer envelope package can also be quantified as to the build-effects contribution to long-term stability in the same HPHT vessel due to its accommodating size. Accordingly, a HPHT vessel offering multiple levels of configurability and robustness in data measurement is presented, along with 10 year long-term stability results.

Wisniewiski, David

2014-03-01

301

Variabilities detected by acoustic emission from filament-wound Aramid fiber/epoxy composite pressure vessels  

NASA Technical Reports Server (NTRS)

Two hundred and fifty Aramid fiber/epoxy pressure vessels were filament-wound over spherical aluminum mandrels under controlled conditions typical for advanced filament-winding. A random set of 30 vessels was proof-tested to 74% of the expected burst pressure; acoustic emission data were obtained during the proof test. A specially designed fixture was used to permit in situ calibration of the acoustic emission system for each vessel by the fracture of a 4-mm length of pencil lead (0.3 mm in diameter) which was in contact with the vessel. Acoustic emission signatures obtained during testing showed larger than expected variabilities in the mechanical damage done during the proof tests. To date, identification of the cause of these variabilities has not been determined.

Hamstad, M. A.

1978-01-01

302

Effect of gravitation stress and hypokinesia on blood vessels of the testicle  

NASA Technical Reports Server (NTRS)

Rabbits were exposed to single maximum endurable stresses of cranio-caudal direction, hypokinesia for periods of one to eight weeks, and hypokinesia followed by gravitation stresses. The stresses caused dilatation of vessels, greater sinuosity, and occasional ruptures of the walls and extravasation. The greater part of the capillaries were dilated; the greatest part constricted. In hypokinesia there was an increasing atrophy of the testes. Significant results are reported.

Palazhchenko, E. F.

1979-01-01

303

Relationships between Age, Blood Pressure, and Retinal Vessel Diameters in an Older Population  

Microsoft Academic Search

PURPOSE. To describe the cross-sectional relationships between age, blood pressure (BP), and quantitative measures of retinal vessel diameters in an older Australian population. METHODS. Retinal photographs from right eyes of partici- pants (n 3654, aged 49 years) in the Blue Mountains Eye study taken during baseline examinations (1992-1994) were digitized. The width of all retinal vessels located 0.5 to 1.0

Harry Leung; Jie Jin Wang; Elena Rochtchina; Ava G. Tan; Tien Y. Wong; Ronald Klein; Larry D. Hubbard; Paul Mitchell

304

Reactor pressure vessel head vents and methods of using the same  

DOEpatents

Internal head vents are usable in nuclear reactors and include piping inside of the reactor pressure vessel with a vent in the reactor upper head. Piping extends downward from the upper head and passes outside of the reactor to permit the gas to escape or be forcibly vented outside of the reactor without external piping on the upper head. The piping may include upper and lowers section that removably mate where the upper head joins to the reactor pressure vessel. The removable mating may include a compressible bellows and corresponding funnel. The piping is fabricated of nuclear-reactor-safe materials, including carbon steel, stainless steel, and/or a Ni--Cr--Fe alloy. Methods install an internal head vent in a nuclear reactor by securing piping to an internal surface of an upper head of the nuclear reactor and/or securing piping to an internal surface of a reactor pressure vessel.

Gels, John L; Keck, David J; Deaver, Gerald A

2014-10-28

305

Pressure vessel with improved impact resistance and method of making the same  

NASA Technical Reports Server (NTRS)

A composite overwrapped pressure vessel is provided which includes a composite overwrapping material including fibers disposed in a resin matrix. At least first and second kinds of fibers are used. These fibers typically have characteristics of high strength and high toughness to provide impact resistance with increased pressure handling capability and low weight. The fibers are applied to form a pressure vessel using wrapping or winding techniques with winding angles varied for specific performance characteristics. The fibers of different kinds are dispersed in a single layer of winding or wound in distinct separate layers. Layers of fabric comprised of such fibers are interspersed between windings for added strength or impact resistance. The weight percentages of the high toughness and high strength materials are varied to provide specified impact resistance characteristics. The resin matrix is formed with prepregnated fibers or through wet winding. The vessels are formed with or without liners.

DeLay, Thomas K. (Inventor); Patterson, James E. (Inventor); Olson, Michael A. (Inventor)

2010-01-01

306

Considerations for acoustic emission monitoring of spherical Kevlar/epoxy composite pressure vessels  

NASA Technical Reports Server (NTRS)

We are continuing to research the applications of acoustic emission testing for predicting burst pressure of filament-wound Kevlar 49/epoxy pressure vessels. This study has focused on three specific areas. The first area involves development of an experimental technique and the proper instrumentation to measure the energy given off by the acoustic emission transducer per acoustic emission burst. The second area concerns the design of a test fixture in which to mount the composite vessel so that the acoustic emission transducers are held against the outer surface of the composite. Included in this study area is the calibration of the entire test setup including couplant, transducer, electronics, and the instrument measuring the energy per burst. In the third and final area of this study, we consider the number, location, and sensitivity of the acoustic emission transducers used for proof testing composite pressure vessels.

Hamstad, M. A.; Patterson, R. G.

1977-01-01

307

Aging results for PRD 49 III/epoxy and Kevlar 49/epoxy composite pressure vessels  

NASA Technical Reports Server (NTRS)

Kevlar 49/epoxy composite is growing in use as a structural material because of its high strength-to-weight ratio. Currently, it is used for the Trident rocket motor case and for various pressure vessels on the Space Shuttle. In 1979, the initial results for aging of filament-wound cylindrical pressure vessels which were manufactured with preproduction Kevlar 49 (Hamstad, 1979) were published. This preproduction fiber was called PRD 49 III. This report updates the continuing study to 10-year data and also presents 7.5-year data for spherical pressure vessels wound with production Kevlar 49. For completeness, this report will again describe the specimens of the original study with PRD 49 as well as specimens for the new study with Kevlar 49.

Hamstad, M. A.

1983-01-01

308

Reactor pressure vessel structural integrity research in the US Nuclear Regulatory Commission HSST and HSSI Programs  

SciTech Connect

This report discusses development on the technology used to assess the safety of irradiation-embrittled nuclear reactor pressure vessels containing flaws. Fracture mechanics tests on reactor pressure vessel steel have shown that local brittle zones do not significantly degrade the material fracture toughness, constraint relaxation at the crack tip of shallow surface flaws results in increased fracture toughness, and biaxial loading reduces but does not eliminate the shallow-flaw fracture toughness elevation. Experimental irradiation investigations have shown that the irradiation-induced shift in Charpy V-notch versus temperature behavior may not be adequate to conservatively assess fracture toughness shifts due to embrittlement and the wide global variations of initial chemistry and fracture properties of a nominally uniform material within a pressure vessel may confound accurate integrity assessments that require baseline properties.

Pennell, W.E.; Corwin, W.R.

1994-02-01

309

Teaching evolutionary biology: Pressures, stress, and coping  

NASA Astrophysics Data System (ADS)

Understanding what teachers need to be more comfortable and confident in their profession is crucial to the future of effective teachers and scientific literacy in public schools. This study focuses on the experiences of Arizona biology teachers in teaching evolution, using a clinical model of stress to identify sources of pressure, the resulting stresses, and coping strategies they employ to alleviate these stresses. We conducted focus groups, one-on-one interviews, and written surveys with 15 biology teachers from the Phoenix area. On the basis of their responses, teachers were clustered into three categories: Conflicted, who struggle with their own beliefs and the possible impact of their teaching, Selective, who carefully avoid difficult topics and situations, and Scientists, who see no place for controversial social issues in their science classroom. Teachers from each group felt that they could be more effective in teaching evolution if they possessed the most up-to-date information about evolution and genomics, a safe space in which to reflect on the possible social and personal implications with their peers, and access to richer lesson plans for teaching evolution that include not only science but personal stories regarding how the lessons arose, and what problems and opportunities they created.

Griffith, Joyce A.; Brem, Sarah K.

2004-10-01

310

Reliability-based design of externally pressurized vessels  

SciTech Connect

A reliability based Level 1 design procedure is proposed for ring-stiffened cylindrical shells under external pressure. The main collapse modes and the present safety factor approach are reviewed. The major aspects involved in code development, such as the statistical properties of the basic variables, reliability methods, sensitivity studies, code format, target reliability, partial safety factor optimization and comparison with the present practice are described. Safety margins for design are proposed which depend on the design pressure, maximum expected overdive and shell slenderness. Some suggestions for future work are also given.

Morandi, A.C.; Das, P.K.; Faulkner, D. [Univ. of Glasgow (United Kingdom). Dept. of Naval Architecture and Ocean Engineering

1995-12-31

311

New Developments in Nickel-Hydrogen Dependent Pressure Vessel (DPV) Cell and Battery Design  

NASA Technical Reports Server (NTRS)

THe Dependent Pressure Vessel (DPV) Nickel-Hydrogen (NiH2) design is being developed as an advanced battery for military and commercial, aerospace and terrestrial applications. The DPV cell design offers high specific energy and energy density as well as reduced cost, while retaining the established Individual Pressure Vessel (IPV) technology flight heritage and database. This advanced DPV design also offers a more efficient mechanical, electrical and thermal cell and battery configuration and a reduced part count. The DPV battery design promotes compact, minimum volume packaging and weight efficiency, and delivers cost and weight savings with minimal design risk.

Caldwell, Dwight B.; Fox, Chris L.; Miller, Lee E.

1997-01-01

312

Advanced developments in NiH{sub 2} dependent pressure vessel (DPV) cell and battery technology  

SciTech Connect

The Dependent Pressure Vessel (DPV) Nickel-Hydrogen (NiH{sub 2}) design is being developed by Eagle-Picher Industries, Inc. (EPI) as an advanced battery for military and commercial, aerospace and terrestrial applications. The DPV cell design offers high specific energy and energy density as well as reduced cost, while retaining the established Individual Pressure Vessel (IPV) technology flight heritage and database. This advanced DPV design also offers a more efficient mechanical, electrical and thermal cell and battery configuration and a reduced parts count. The DPV battery design promotes compact, minimum volume packaging and weight efficiency, and delivers cost and weight savings with minimal design risks.

Caldwell, D.B.; Fox, C.L. [Eagle-Picher Industries, Inc., Joplin, MO (United States). Technologies Div.

1997-12-01

313

Advanced nickel/hydrogen dependent pressure vessel (DPV) cell and battery concepts  

NASA Astrophysics Data System (ADS)

The dependent pressure vessel (DPV) nickel/hydrogen (NiH 2) design is being developed by Eagle-Picher Industries, Inc. (EPI) as an advanced battery for military and commercial aerospace and terrestrial applications. The DPV cell design offers high specific energy and energy density as well as reduced cost, while retaining the established individual pressure vessel (IPV) technology, flight heritage and database. This advanced DPV design also offers a more efficient mechanical, electrical and thermal cell and battery configuration and a reduced parts count. The DPV battery design promotes compact, minimum volume packaging and weight efficiency, and delivers cost and weight savings with minimal design risks.

Caldwell, Dwight B.; Fox, C. L.; Miller, L. E.

314

Evaluation of Agency Non-Code Layered Pressure Vessels (LPVs) . Volume 2; Appendices  

NASA Technical Reports Server (NTRS)

In coordination with the Office of Safety and Mission Assurance and the respective Center Pressure System Managers (PSMs), the NASA Engineering and Safety Center (NESC) was requested to formulate a consensus draft proposal for the development of additional testing and analysis methods to establish the technical validity, and any limitation thereof, for the continued safe operation of facility non-code layered pressure vessels. The PSMs from each NASA Center were asked to participate as part of the assessment team by providing, collecting, and reviewing data regarding current operations of these vessels. This document contains the appendices to the main report.

Prosser, William H.

2014-01-01

315

Simple method for forming thin-wall pressure vessels  

NASA Technical Reports Server (NTRS)

Application of internal hydrostatic pressure to seam-welded circular cylindrical tanks having corner-welded, flat, circular ends forms large thin-walled high quality tanks. Form limits expansion of cylindrical portion of final tank while hemispherical ends develop freely; no external form or restraint is required to fabricate spherical tanks.

Erickson, A. L.; Guist, L. R.

1972-01-01

316

Analysis of the Effect of Partial Vitrification on Stress Development in Cryopreserved Blood Vessels  

PubMed Central

Thermal stress development in blood vessels, during processes associated with vitrification (vitreous means glassy in Latin), is studied. This paper addresses the limiting case where the specimen completely crystallizes, while the cryoprotectant medium (CPA) completely vitrifies. This case is expected to provide upper boundary estimates for stresses for the more common problem of a partially vitrified sample. The CPA is modeled as a linear viscoelastic medium, with viscosity increasing exponentially with decreasing temperature; given the assumption of complete crystallization, the blood vessel is modeled as linear elastic below the freezing temperature. Consistent with previous observations, the CPA is found to behave linear elastically below a set-temperature, at which point the viscosity rises sufficiently quickly with further cooling. This observation reduces computational efforts and allows for parametric studies based on suitably chosen wholly elastic models. Both 2D concentric cylinder models of the blood vessel in a straight configuration and a 3D model of the vessel curled in a vial of CPA are studied; 2D models are shown to bound the results of the more general 3D problem. It is found that stress in the CPA decreases with increase in CPA volume, at least under conditions where the temperature can be viewed as uniform. Planar cracks are predicted to form transverse to the vessel axis, and to propagate right up to the blood vessel wall. Should such cracks propagate into the vessel, even over only a few ?m, the mechanical damage to the lumen, or to endothelial cells, may cause the blood vessel to completely loose its functionality at the end of the cryopreservation protocol. PMID:16996295

Steif, Paul S.; Palastro, Matthew C.; Rabin, Yoed

2007-01-01

317

Ten year environmental test of glass fiber/epoxy pressure vessels  

NASA Technical Reports Server (NTRS)

By the beginning of the 1970's composite pressure vessels had received a significant amount of development effort, and applications were beginning to be investigated. One of the first applications grew out of NASA Johnson Space Center efforts to develop a superior emergency breathing system for firemen. While the new breathing system provided improved wearer comfort and an improved mask and regulator, the primary feature was low weight which was achieved by using a glass fiber reinforced aluminum pressure vessel. Part of the development effort was to evaluate the long term performance of the pressure vessel and as a consequence, some 30 bottles for a test program were procured. These bottles were then provided to NASA Lewis Research Center where they were maintained in an outdoor environment in a pressurized condition for a period of up to 10 yr. During this period, bottles were periodically subjected to cyclic and burst testing. There was no protective coating applied to the fiberglass/epoxy composite, and significant loss in strength did occur as a result of the environment. Similar bottles stored indoors showed little, if any, degradation. This report contains a description of the pressure vessels, a discussion of the test program, data for each bottle, and appropriate plots, comparisons, and conclusions.

Faddoul, J. R.

1985-01-01

318

Under Pressure: Sensing Stress of Computer Users Javier Hernandez1  

E-print Network

when computer users are stressed can help reduce their frustration and prevent a large varietyUnder Pressure: Sensing Stress of Computer Users Javier Hernandez1 Pablo Paredes2 Asta Roseway3 of negative health conditions associated with chronic stress. However, measuring stress non

319

Ocean Pressurization, Stress Evolution, and Tensile Fracture Within Icy Moons  

Microsoft Academic Search

Thickening of an ice shell overlying an ocean pressurizes the ocean and tangential stresses of several MPa are produced in the overlying ice shell. These stresses drive tensile fractures which may facilitate cryovolcanism.

M. L. Rudolph; M. Manga

2009-01-01

320

Fast neutron fluence of yonggwang nuclear unit 1 reactor pressure vessel  

SciTech Connect

The Code of Federal Regulations, Title 10, Part 50, Appendix H, requires that the neutron dosimetry be present to monitor the reactor vessel throughout plant life. The Ex-Vessel Neutron Dosimetry System has been installed for Yonggwang Nuclear Unit 1 after complete withdrawal of all six in-vessel surveillance capsules. This system has been installed in the reactor cavity annulus in order to measure the fast neutron spectrum coming out through the reactor pressure vessel. Cycle specific neutron transport calculations were performed to obtain the energy dependent neutron flux throughout the reactor geometry including dosimetry positions. Comparisons between calculations and measurements were performed for the reaction rates of each dosimetry sensors and results show good agreements. (authors)

Yoo, C.; Km, B.; Chang, K.; Leeand, S. [Korea Atomic Energy Research Inst., 150 Dukjin-dong, Yuseung-gu, Daejeon 305-353 (Korea, Republic of); Park, J. [Chungnam National Univ., 220 Gung-dong, Yuseung-gu, Daejeon 305-764 (Korea, Republic of)

2006-07-01

321

Multi-scale finite element analyses for stress and strain evaluations of braid fibril artificial blood vessel and smooth muscle cell.  

PubMed

In this study, we developed a multi-scale finite element (FE) analysis code to obtain the stress and strain that occurred in the smooth muscle cell (SMC) at micro-scale, which was seeded in the real fabricated braid fibril artificial blood vessel. This FE code can predict the dynamic response of stress under the blood pressure loading. We try to establish a computer-aided engineering (CAE)-driven scaffold design technique for the blood vessel regeneration. Until now, there occurred the great progresses for the endothelial cell activation and intima layer regeneration in the blood vessel regeneration study. However, there remains the difficulty of the SMC activation and media layer regeneration. Therefore, many researchers are now studying to elucidate the fundamental mechanism of SMC activation and media layer regeneration by using the biomechanical technique. As the numerical tool, we used the dynamic-explicit FE code PAM-CRASH, ESI Ltd. For the material models, the nonlinear viscoelastic constitutive law was adapted for the human blood vessel, SMC and the extra-cellular matrix, and the elastic law for the polyglycolic acid (PGA) fiber. Through macro-FE and micro-FE analyses of fabricated braid fibril tubes by using PGA fiber under the combined conditions of the orientation angle and the pitch of fiber, we searched an appropriate structure for the stress stimulation for SMC functionalization. Objectives of this study are indicated as follows: 1. to analyze the stress and strain of the human blood vessel and SMC, and 2. to calculate stress and strain of the real fabricated braid fibril artificial blood vessel and SMC to search an appropriate PGA fiber structure under combined conditions of PGA fiber numbers, 12 and 24, and the helical orientation angles of fiber, 15, 30, 45, 60, and 75 degrees. Finally, we found a braid fibril tube, which has an angle of 15 degree and 12 PGA fibers, as a most appropriate artificial blood vessel for SMC functionalization. PMID:24599892

Nakamachi, Eiji; Uchida, Takahiro; Kuramae, Hiroyuki; Morita, Yusuke

2014-08-01

322

Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.  

SciTech Connect

Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

Nibur, Kevin A.

2010-11-01

323

Subcritical crack growth of selected aerospace pressure vessel materials  

NASA Technical Reports Server (NTRS)

This experimental program was undertaken to determine the effects of combined cyclic/sustained loads, stress level, and crack shape on the fatigue crack growth rate behavior of cracks subjected to plane strain conditions. Material/environment combinations tested included: 2219-T87 aluminum plate in gaseous helium, room air, and 3.5% NaCl solution at room temperature, liquid nitrogen, and liquid hydrogen; 5Al-2.5 Sn (ELI) titanium plate in liquid nitrogen and liquid hydrogen and 6AL-4V (ELI) STA titanium plate in gaseous helium and methanol at room temperature. Most testing was accomplished using surface flawed specimens instrumented with a clip gage to continuously monitor crack opening displacements at the specimen surface. Tapered double cantilever beam specimens were also tested. Static fracture and ten hour sustained load tests were conducted to determine fracture toughness and apparent threshold stress intensity values. Cyclic tests were performed using sinusoidal loading profiles at 333 MHz (20 cpm) and trapezoidal loading profiles at both 8.3 MHz (0.5 cpm) and 3.3 MHz (0.2 cpm). Data were evaluated using modified linear elastic fracture mechanics parameters.

Hall, L. R.; Bixler, W. D.

1972-01-01

324

Reactor Pressure Vessel Temperature Analysis for Prismatic and Pebble-Bed VHTR Designs  

SciTech Connect

Analyses were performed to determine maximum temperatures in the reactor pressure vessel for two potential Very-High Temperature Reactor (VHTR) designs during normal operation and during a depressurized conduction cooldown accident. The purpose of the analyses was to aid in the determination of appropriate reactor vessel materials for the VHTR. The designs evaluated utilized both prismatic and pebble-bed cores that generated 600 MW of thermal power. Calculations were performed for fluid outlet temperatures of 900 and 950 °C, corresponding to the expected range for the VHTR. The analyses were performed using the RELAP5-3D and PEBBED-THERMIX computer codes. Results of the calculations were compared with preliminary temperature limits derived from the ASME pressure vessel code.

H. D. Gougar; C. B. Davis

2006-04-01

325

Review of reactor pressure vessel evaluation report for Yankee Rowe Nuclear Power Station (YAEC No. 1735)  

Microsoft Academic Search

The Yankee Atomic Electric Company has performed an Integrated Pressurized Thermal Shock (IPTS)-type evaluation of the Yankee Rowe reactor pressure vessel in accordance with the PTS Rule (10 CFR 50. 61) and a US Regulatory Guide 1.154. The Oak Ridge National Laboratory (ORNL) reviewed the YAEC document and performed an independent probabilistic fracture-mechnics analysis. The review included a comparison of

R. D. Cheverton; T. L. Dickson; J. G. Merkle; R. K. Nanstad

1992-01-01

326

EQUATIONS FOR GAS RELEASING PROCESS FROM PRESSURIZED VESSELS IN ODH EVALUATION.  

SciTech Connect

IN THE EVALUATION OF ODH, THE CALCULATION OF THE SPILL RATE FROM THE PRESSURIZED VESSEL IS THE CENTRAL TASK. THE ACCURACY OF THE ENGINEERING ESTIMATION BECOMES ONE OF THE SAFETY DESIGN ISSUES. THIS PAPER SUMMARIZES THE EQUATIONS FOR THE OXYGEN CONCENTRATION CALCULATION IN DIFFERENT CASES, AND DISCUSSES THE EQUATIONS FOR THE GAS RELEASE PROCESS CALCULATION BOTH FOR THE HIGH-PRESSURE GAS TANK AND THE LOW-TEMPERATURE LIQUID CONTAINER.

JIA,L.X.; WANG,L.

2001-07-16

327

An observational pressure vessel for studying the behaviour of planktonic animals  

Microsoft Academic Search

A design for a pressure vessel, suitable for continuous observation of small planktonic animals at moderate hydrostatic pressures is presented. The long side windows are 3\\/4 inch (ca. 19 mm) armourplate glass, and smaller windows are provided at each end. The dimensions of the inner working chamber are approximately 16 × 2 × 1 3\\/4 inches (ca. 0.41×0.05×0.045 m). Internal

R. J. Lincoln; I. Gilchrist

1970-01-01

328

Catalase activity measured with a micro oxygen electrode in a pressurized reaction vessel. [Mice, rats  

Microsoft Academic Search

The assembly and the use of a simple airtight pressurized reaction vessel are described for the measurement of catalase activity with a micro oxygen electrode in an optically heterogenous medium. The oxygen concentration is expressed as the ratio of observed current to the current in an air-saturated solution. Thus, an individual standard can be obtained for each measurement and the

Halbach

1977-01-01

329

FATIGUE ANALYSIS METHODS: THEIR PERFORMANCE EVALUATION FOR A CLASS OF PRESSURE VESSELS WITH WELDED JOINTS  

Microsoft Academic Search

This paper provides a basis for evaluating the performance of a fatigue analysis method for a selected class of welded pressure vessels. After the allowable number of cycles that the method permits for a member of the class is calculated, the question is addressed whether that number of cycles can be regarded as conservative or unconservative. To answer that question,

Arturs Kalnins

2009-01-01

330

1 Copyright 2012 by ASME Proceedings of the ASME 2012 Pressure Vessels & Piping Division Conference  

E-print Network

1 Copyright © 2012 by ASME Proceedings of the ASME 2012 Pressure Vessels & Piping Division - DOUBLE PIPE - ORIFICE SYSTEM Arris S. TIJSSELING Department of Mathematics and Computer Science Eindhoven Acoustic resonance in a two-pipe system is simulated with four different models for the periodic excitation

Tijsseling, A.S.

331

Proceedings of PVP2006-ICPVT-11 2006 ASME Pressure Vessels and Piping Division Conference  

E-print Network

Proceedings of PVP2006-ICPVT-11 2006 ASME Pressure Vessels and Piping Division Conference July 23-27, 2006, Vancouver BC, CANADA PVP2006-ICPVT11-93670 STRUCTURAL RESPONSE OF PIPING TO INTERNAL GAS, CA 91125 Email: jeshep@galcit.caltech.edu ABSTRACT Detonation waves in gas-filled piping or tubing

Barr, Al

332

Exploratory Study of Irradiation, Annealing, and Reirradiation Effects on American and Russian Reactor Pressure Vessel Steels  

Microsoft Academic Search

One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVS) is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. even though a postirradiation anneal may be deemed successful, a critical aspect of continued RPV operation is the rate of embrittlement upon reirradiation. There are insufficient data available

Chernobaeva; Kryukov; Nikolaev

1997-01-01

333

Development of a mechanistic understanding of radiation embrittlement in reactor pressure vessel steels: Final report  

Microsoft Academic Search

The microstructures of a series of reactor pressure vessel (RPV) steels and model iron alloys with various Cu, Ni, and P contents were examined in unirradiated and neutron-irradiated conditions using high resolution analytical microscopy. Fractography techniques were also applied. Objectives were to isolate and identify the mechanisms by which these elements affect steel radiation embrittlement sensitivity as evidenced by notch

F. Ebrahimi; D. T. Hoelzer; D. Venables; V. Krishnamoorthy

1988-01-01

334

Determination of toughness and embrittlement for reactor pressure vessel steels using ultrasonic measurements  

Microsoft Academic Search

Neutron irradiation embrittlement of nuclear reactor pressure vessel (RPV) steels results in a loss of fracture toughness (e.g., reduction in load carrying capacity of the steel). For the setting of operational limits and assuring the continued safe operation of the plant, current procedures estimate the effects of neutron embrittlement using empirical relations or the results of small samples irradiated in

Allen Lee Hiser Jr.

2003-01-01

335

Analysis of warm prestressing effect on fracture toughness of reactor pressure vessel steels  

Microsoft Academic Search

We have performed finite element calculation of precracked Charpy-like three-point bending specimen, in order to analyze the\\u000a effect of warm prestressing on fracture toughness value of reactor pressure vessel steels. Two different hardening laws were\\u000a applied in the calculation. J-integral was determined in both cases and comparative analysis was made.

R. Beleznai; Sz. Szávai

2010-01-01

336

A comparison of Western and Eastern nuclear reactor pressure vessel steels  

Microsoft Academic Search

The task was essentially to compare the irradiation response of `East' and `West' steels. Since the plates and forgings of pressure vessels must be welded together, it is obvious that the strength requirements of the welds and heat affected zones (HAZ) can be no less demanding than those of the plates and the forgings themselves, particularly as experience has shown

L. M Davies

1999-01-01

337

Irradiation, Annealing, and Reirradiation Effects on American and Russian Reactor Pressure Vessel Steels  

Microsoft Academic Search

One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVs) is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. Even though a postirradiation anneal may be deemed successful, a critical aspect of continued RPV operation is the rate of embrittlement upon reirradiation. There are insufficient data available

A. A. Chernobaeva; Y. N. Korolev; R. K. Nanstad; Y. A. Nikolaev; M. A. Sokolov

1998-01-01

338

Magnetic measurements to evaluate irradiation effects on Reactor Pressure Vessel high nickel steel  

Microsoft Academic Search

With the aim to characterise material changes due to irradiation exposure, the possibility of using magnetic measurements have been continuously studied. In this work, a further study is described dealing with a reactor pressure vessel (RPV) shell of a Russian WWER-1000 nuclear power plant type. The shell has been cut into blocks and finally several sets of Charpy specimens were

Luigi Debarberis; Soraia Pirfo; Ferenc Gillemot

339

Walking and Climbing Service Robots for Safety Inspection of Nuclear Reactor Pressure Vessels  

E-print Network

Walking and Climbing Service Robots for Safety Inspection of Nuclear Reactor Pressure Vessels B of Electronics and Computer Science, University of Southampton, Southampton, UK Abstract: Nuclear reactor and the usefulness of these robots for improving safety inspection of nuclear reactors in general are discussed

Chen, Sheng

340

Test calculations of the neutron flux on VVER-1000 reactor pressure vessel  

SciTech Connect

A three dimensional test for calculation of the neutron fluence onto the VVER-1000 reactor pressure vessel (RPV) is presented. The test is based on the commercial VVER-1000 reactor design data. The flux results obtained by different authors are in good agreement.

Ilieva, K.D.; Belousov, S.I.; Antonov, S.Y. [Inst. for Nuclear Research and Nuclear Energy, Sofia (Bulgaria). Neutron and Reactor Physics Dept.; Zaritsky, S.M.; Brodkin, E.B. [Kurchatov Inst., Moscow (Russian Federation). Russian Research Center

1994-12-31

341

Radiation embrittlement modelling for reactor pressure vessel steels: I. Brittle fracture toughness prediction  

Microsoft Academic Search

Modelling for the irradiation effect on brittle fracture toughness of reactor pressure vessel (RPV) steel is performed on the basis of the probabilistic model for fracture toughness prediction proposed by the authors earlier. The irradiation effect on parameters controlling plastic deformation and brittle fracture of RPV steels is analyzed. The physical mechanisms are considered which control the cleavage microcrack nucleation

B. Z. Margolin; V. A. Shvetsova; A. G. Gulenko

1999-01-01

342

New TACIS regional projects on radiation embrittlement and integrity assessment of WWER reactor pressure vessels  

Microsoft Academic Search

Neutron embrittlement of the reactor pressure vessel (RPV) core weld of the VVER 440 type of NPP was recognised as a serious problem in the early 1980s, when the first surveillance specimens were tested. A lot of measures were taken in order to ensure the integrity and acceptable safety margins of the RPV in possible pressurised thermal shock transients. In

M Bieth; C Rieg; R Ahlstrand

2004-01-01

343

Neutron embrittlement of VVER reactor pressure vessels—recent results, open issues and new developments  

Microsoft Academic Search

Decisions regarding the verification of design plant lifetime involve a determination of the component and circuit condition. Neutron embrittlement of reactor pressure vessels (RPV) becomes a crucial consideration for continued safe plant operation. Since 1991, the European Commission (EC) has financed a significant number of projects in this area, in particular through the TACIS and PHARE programmes. In Nuclear Safety

Ralf Ahlstrand; Michel Bièth; Claude Rieg

2004-01-01

344

Basis of the tubesheet heat exchanger design rules used in the French pressure vessel code  

Microsoft Academic Search

For about 40 years most tubessheet exchangers have been designed according to the standards of TEMA. Partly due to their simplicity, these rules do not assure a safe heat-exchanger design in all cases. This is the main reason why new tubesheet design rules were developed in 1981 in France for the French pressure vessel code CODAP. For fixed tubesheet heat

F. Osweiller

1992-01-01

345

1 Copyright 2012 by ASME Proceedings of the ASME 2012 Pressure Vessels & Piping Division Conference  

E-print Network

.Mendez-Torres@srnl.doe.gov ABSTRACT The increasing number, size, and complexity of nuclear facilities deployed worldwide are increasing the need to maintain readiness and develop innovative sensing materials to monitor important to safety structures (ITS) such as pressure vessels and piping (PVP) in a nuclear reactor. Technologies

Giurgiutiu, Victor

346

BWR In-Core Monitor Housing Replacement Under Dry Condition of Reactor Pressure Vessel  

Microsoft Academic Search

A new method of In-Core Monitor Housing replacement has been successfully applied to Tokai Unit 2 (BWR with 1100 MWe) in April of 2001. It was designed to replace a housing under dry condition of reactor pressure vessel (RPV): this enabled the elimination of water filled-up and drained processes during the replacement procedure resulting in the reduction of implementation schedule.

Tatsuo Ishida; Shoji Yamamoto; Fujitoshi Eguchi; Motomasa Fuse; Kouichi Kurosawa; Sadato Shimizu; Minoru Masuda; Shinya Fujii; Junji Tanaka; Bryce A. Jacobson

2002-01-01

347

An improved correlation of the pressure drop in stenotic vessels using Lorentz's reciprocal theorem  

NASA Astrophysics Data System (ADS)

A mathematical model of the human cardiovascular system in conjunction with an accurate lumped model for a stenosis can provide better insights into the pressure wave propagation at pathological conditions. In this study, a theoretical relation between pressure drop and flow rate based on Lorentz's reciprocal theorem is derived, which offers an identity to describe the relevance of the geometry and the convective momentum transport to the drag force. A voxel-based simulator V-FLOW VOF3D, where the vessel geometry is expressed by using volume of fluid (VOF) functions, is employed to find the flow distribution in an idealized stenosis vessel and the identity was validated numerically. It is revealed from the correlation that the pressure drop of NS flow in a stenosis vessel can be decomposed into a linear term caused by Stokes flow with the same boundary conditions, and two nonlinear terms. Furthermore, the linear term for the pressure drop of Stokes flow can be summarized as a correlation by using a modified equation of lubrication theory, which gives favorable results compared to the numerical ones. The contribution of the nonlinear terms to the pressure drop was analyzed numerically, and it is found that geometric shape and momentum transport are the primary factors for the enhancement of drag force. This work paves a way to simulate the blood flow and pressure propagation under different stenosis conditions by using 1D mathematical model.

Ji, Chang-Jin; Sugiyama, Kazuyasu; Noda, Shigeho; He, Ying; Himeno, Ryutaro

2015-02-01

348

Shear stress effects on plant cell suspension cultures in a rotating wall vessel bioreactor  

Microsoft Academic Search

  A rotating wall vessel, designed for growth of mammalian cells under microgravity, was used to study shear effects on Taxus cuspidata plant suspension cell cultures. Shear stress, as quantified by defined shear fields of Couette viscometers, improved specific\\u000a cell growth rates and was detrimental to volumetric product formation rates.

X Sun; J C Linden

1999-01-01

349

Optimization of Composite Material System and Lay-up to Achieve Minimum Weight Pressure Vessel  

NASA Astrophysics Data System (ADS)

The use of composite pressure vessels particularly in the aerospace industry is escalating rapidly because of their superiority in directional strength and colossal weight advantage. The present work elucidates the procedure to optimize the lay-up for composite pressure vessel using finite element analysis and calculate the relative weight saving compared with the reference metallic pressure vessel. The determination of proper fiber orientation and laminate thickness is very important to decrease manufacturing difficulties and increase structural efficiency. In the present work different lay-up sequences for laminates including, cross-ply [ 0 m /90 n ] s , angle-ply [ ±?] ns , [ 90/±?] ns and [ 0/±?] ns , are analyzed. The lay-up sequence, orientation and laminate thickness (number of layers) are optimized for three candidate composite materials S-glass/epoxy, Kevlar/epoxy and Carbon/epoxy. Finite element analysis of composite pressure vessel is performed by using commercial finite element code ANSYS and utilizing the capabilities of ANSYS Parametric Design Language and Design Optimization module to automate the process of optimization. For verification, a code is developed in MATLAB based on classical lamination theory; incorporating Tsai-Wu failure criterion for first-ply failure (FPF). The results of the MATLAB code shows its effectiveness in theoretical prediction of first-ply failure strengths of laminated composite pressure vessels and close agreement with the FEA results. The optimization results shows that for all the composite material systems considered, the angle-ply [ ±?] ns is the optimum lay-up. For given fixed ply thickness the total thickness of laminate is obtained resulting in factor of safety slightly higher than two. Both Carbon/epoxy and Kevlar/Epoxy resulted in approximately same laminate thickness and considerable percentage of weight saving, but S-glass/epoxy resulted in weight increment.

Mian, Haris Hameed; Wang, Gang; Dar, Uzair Ahmed; Zhang, Weihong

2013-10-01

350

Comparison of Irradiation Conditions of VVER-1000 Reactor Pressure Vessel and Surveillance Specimens for Various Core Loadings  

Microsoft Academic Search

The comparative analysis of irradiation conditions of surveillance specimens and pressure vessel of VVER-1000 reactor has been carried out for various configurations of the core. It is proved the fluences onto specimens and a pressure vessel don't correlate with each other but only the spectral indexes do. It is revealed that in the case of the specimen reconstitution technique application

V. N. Bukanov; V. L. Diemokhin; O. V. Grytsenko; O. G. Vasylieva; S. M. Pugach

2009-01-01

351

Probabilistic prediction of the crack resistance of nuclear pressure-vessel steels on the basis of a local approach. Part 2  

Microsoft Academic Search

On the basis of a new local probabilistic criterion of brittle fracture, a local criterion of ductile fracture proposed by\\u000a the authors earlier, and the obtained approximate solution of the problem of stress-strain state near the crack tip, we develop\\u000a a probabilistic model for the prediction of the crack resistance of pressure-vessel steels. The model enables one to predict\\u000a the

B. Z. Margolin; A. G. Gulenko; V. A. Shvetsova

1999-01-01

352

Time pressure and stress as a factor during emergency egress  

Microsoft Academic Search

While human beings, as information processing entities, use environmental cues during route selection in fire emergencies, time pressure, i.e. the limited time available to people, and the stress created by the physical threat of fire, can affect how they process environmental information. This study focuses on theories on decision making under time pressure and stress, and applies them to the

F Ozel

2001-01-01

353

Use of multidimensional fiber grating strain sensors for damage detection in composite pressure vessels  

NASA Astrophysics Data System (ADS)

Arrays of multi-axis fiber grating strain sensors have been integrated into a composite pressure vessel test article, and are used to monitor changes in the transverse and axial strain fields during curing and pressure cycling near cut tow and Teflon tape defects. These changes in the multi-axis strain due to four pressure cycles and repeated impacts are measured and compared to ultrasonic and eddy current scans. Examples of the remote detection of damage using transverse strain and transverse strain gradients is given as well as data showing the ability of the system to distinguish broken tow and delamination defects.

Kunzler, Marley; Udd, Eric; Johnson, Mont; Mildenhall, Kurt

2005-05-01

354

A new hybrid pressure-coring system for the drilling vessel Chikyu  

NASA Astrophysics Data System (ADS)

Retrieving core samples without releasing the in situ hydrostatic pressure during core recovery is one of the many technical challenges in scientific drilling. We report here a newly developed hybrid pressure-coring system for the use on the drilling vessel Chikyu and its successful use during expeditions 906 and 802 in the Nankai Trough of Japan. The system is gas-tight and hence enables researchers to study in situ geophysical and geochemical characteristics of sediments containing gaseous components, such as methane hydrates that cannot be reliably recovered with nonpressure coring systems. In addition, pressure coring is a powerful tool, not only for scientific but also for hydrocarbon resources research.

Kubo, Y.; Mizuguchi, Y.; Inagaki, F.; Yamamoto, K.

2014-04-01

355

Next Generation Nuclear Plant Reactor Pressure Vessel Materials Research and Development Plan (PLN-2803)  

SciTech Connect

The U.S. Department of Energy has selected the High Temperature Gas-cooled Reactor design for the Next Generation Nuclear Plant (NGNP) Project. The NGNP will demonstrate the use of nuclear power for electricity and hydrogen production. It will have an outlet gas temperature in the range of 900°C and a plant design service life of 60 years. The reactor design will be a graphite moderated, helium-cooled, prismatic, or pebble-bed reactor and use low-enriched uranium, Tri-Isotopic-coated fuel. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during accidents. The NGNP Materials Research and Development Program is responsible for performing research and development on likely NGNP materials in support of the NGNP design, licensing, and construction activities. Selection of the technology and design configuration for the NGNP must consider both the cost and risk profiles to ensure that the demonstration plant establishes a sound foundation for future commercial deployments. The NGNP challenge is to achieve a significant advancement in nuclear technology while setting the stage for an economically viable deployment of the new technology in the commercial sector soon after 2020. Studies of potential Reactor Pressure Vessel (RPV) steels have been carried out as part of the pre-conceptual design studies. These design studies generally focus on American Society of Mechanical Engineers (ASME) Code status of the steels, temperature limits, and allowable stresses. Three realistic candidate materials have been identified by this process: conventional light water reactor RPV steels A508/533, 2¼Cr-1Mo in the annealed condition, and modified 9Cr 1Mo ferritic martenistic steel. Based on superior strength and higher temperature limits, the modified 9Cr-1Mo steel has been identified by the majority of design engineers as the preferred choice for the RPV. All of the vendors have concluded, however, that with adequate engineered cooling of the vessel, the A508/533 steels are also acceptable.

J. K. Wright; R. N. Wright

2008-04-01

356

Develop Critical Profilometers to Meet Current and Future Composite Overwrapped Pressure Vessel (COPV) Interior Inspection Needs  

NASA Technical Reports Server (NTRS)

The objective of this project is to develop laser profilometer technology that can efficiently inspect and map the inside of composite pressure vessels for flaws such as liner buckling, pitting, or other surface imperfections. The project will also provide profilometers that can directly support inspections of flight vessels during development and qualification programs and subsequently be implemented into manufacturing inspections to screen out vessels with "out of family" liner defects. An example interior scan of a carbon overwrapped bottle is shown in comparison to an external view of the same bottle (Fig. 1). The internal scan is primarily of the cylindrical portion, but extends about 0.15 in. into the end cap area.

Saulsberry, Regor L.

2010-01-01

357

A Multiscale Modeling Approach to Analyze Filament-Wound Composite Pressure Vessels  

SciTech Connect

A multiscale modeling approach to analyze filament-wound composite pressure vessels is developed in this article. The approach, which extends the Nguyen et al. model [J. Comp. Mater. 43 (2009) 217] developed for discontinuous fiber composites to continuous fiber ones, spans three modeling scales. The microscale considers the unidirectional elastic fibers embedded in an elastic-plastic matrix obeying the Ramberg-Osgood relation and J2 deformation theory of plasticity. The mesoscale behavior representing the composite lamina is obtained through an incremental Mori-Tanaka type model and the Eshelby equivalent inclusion method [Proc. Roy. Soc. Lond. A241 (1957) 376]. The implementation of the micro-meso constitutive relations in the ABAQUS® finite element package (via user subroutines) allows the analysis of a filament-wound composite pressure vessel (macroscale) to be performed. Failure of the composite lamina is predicted by a criterion that accounts for the strengths of the fibers and of the matrix as well as of their interface. The developed approach is demonstrated in the analysis of a filament-wound pressure vessel to study the effect of the lamina thickness on the burst pressure. The predictions are favorably compared to the numerical and experimental results by Lifshitz and Dayan [Comp. Struct. 32 (1995) 313].

Nguyen, Ba Nghiep; Simmons, Kevin L.

2013-07-22

358

Influence of pore pressure and production-induced changes in pore pressure on in situ stress  

SciTech Connect

Knowledge of in situ stress and how stress changes with reservoir depletion and pore pressure drawdown is important in a multi-disciplinary approach to reservoir characterization, reservoir management, and improved oil recovery projects. This report summarizes a compilation of in situ stress data from six fields showing the effects of pore pressure and production-induced changes in pore pressure on the minimum horizontal stress. The in situ stress data and corresponding pore pressure data were obtained from field records of the operating companies and published reports. Horizontal stress was determined from closure pressure data of hydraulic fractures and leak-off tests. The stress measurements clearly demonstrate that the total minimum-horizontal stress is dependent on pore pressure. A decrease in pore pressure either by geologic processes or production of a reservoir will result in a decrease in the total minimum-horizontal stress. The magnitude of changes in stress state with net changes in pore pressure is dependent on local field conditions and cannot be accurately predicted by the uniaxial strain model that is commonly used by the petroleum industry.

Teufel, L.W.

1996-02-01

359

Evaluation of Agency Non-Code Layered Pressure Vessels (LPVs). Corrected Copy, Aug. 25, 2014  

NASA Technical Reports Server (NTRS)

In coordination with the Office of Safety and Mission Assurance and the respective Center Pressure System Managers (PSMs), the NASA Engineering and Safety Center (NESC) was requested to formulate a consensus draft proposal for the development of additional testing and analysis methods to establish the technical validity, and any limitation thereof, for the continued safe operation of facility non-code layered pressure vessels. The PSMs from each NASA Center were asked to participate as part of the assessment team by providing, collecting, and reviewing data regarding current operations of these vessels. This report contains the outcome of the assessment and the findings, observations, and NESC recommendations to the Agency and individual NASA Centers.

Prosser, William H.

2014-01-01

360

Dosimetry assessments for the reactor pressure vessel and core barrel in UK PWR plant  

SciTech Connect

Specimens for the Sizewell B reactor pressure vessel (RPV) inservice steels surveillance program are irradiated inside eight capsules located within the reactor pressure vessel and loaded prior to commissioning. The periodic removal of these capsules and testing of their contents provides material properties data at intervals during the lifetime of the plant. Neutron activation measurements and radiation transport calculations play an essential role in assessing the neutron exposure of the specimens and RPV. Following the most recent withdrawal, seven capsules have now been removed covering nine cycles of reactor operation. This paper summarizes the dosimetry results of the Sizewell B surveillance program obtained to date. In addition to an overview of the calculational methodology it includes a review of the measurements. Finally, it describes an extension of the methodology to provide dosimetry recommendations for the core barrel and briefly discusses the results that were obtained. (authors)

Thornton, D.A.; Allen, D.A.; Huggon, A.P.; Picton, D.J.; Robinson, A.T.; Steadman, R.J. [Serco, Rutherford House, Quedgeley, Gloucester, Gl2 4NF (United Kingdom); Seren, T.; Lipponen, M.; Kekki, T. [VTT, Technical Research Centre of Finland, Otakaari 3 K, P.O. BOX 1000, Espoo, FI-02044 (Finland)

2011-07-01

361

Effect of long-term thermal aging on magnetic property in reactor pressure vessel steels  

NASA Astrophysics Data System (ADS)

Effect of long-term thermal aging at 290 and 500 °C on magnetic hysteresis property in reactor pressure vessel steels and simple model alloys have been investigated for times up to 8800 h. While Vickers hardness is insensitive to thermal aging at both temperatures, coercivity generally exhibits a slight decrease after aging at 290 °C. In particular, at a higher temperature of 500 °C a steady increase of coercivity was observed for reactor pressure vessel steels, whereas coercivity for simple model alloys exhibits an abrupt drop just after aging and the decrease was 20-30% of that before aging. The results were interpreted by the thermally-assisted formation of Cu-rich precipitates and recovery, but the latter has the dominant effect for simple model alloys because of their ferritic microstructure. The possible effect of relaxation of lattice strain created by dissolved interstitial atoms during neutron irradiation is proposed.

Kobayashi, S.; Sato, H.; Iwawaki, T.; Yamamoto, T.; Klingensmith, D.; Odette, G. R.; Kikuchi, H.; Kamada, Y.

2013-08-01

362

Comparison of cell encapsulation technologies for single pressure vessel nickel-hydrogen battery  

Microsoft Academic Search

Two single pressure vessel (SPV) batteries containing 22 series-connected nickel-hydrogen (Ni-H2) cells of 19-Ah capacity were designed and procured from Eagle-Picher Industries. The two batteries were similar in mechanical design, dimensions, and composition of the active core. However, they differed in cell encapsulation, location and structure of the gas diffusion membrane, and cell activation. Both batteries have been subjected to

Gopalakrishna Rao; Hari Vaidyanathan

1996-01-01

363

High-density automotive hydrogen storage with cryogenic capable pressure vessels  

Microsoft Academic Search

LLNL is developing cryogenic capable pressure vessels with thermal endurance 5–10 times greater than conventional liquid hydrogen (LH2) tanks that can eliminate evaporative losses in routine usage of (L)H2 automobiles. In a joint effort BMW is working on a proof of concept for a first automotive cryo-compressed hydrogen storage system that can fulfill automotive requirements on system performance, life cycle,

Salvador M. Aceves; Francisco Espinosa-Loza; Elias Ledesma-Orozco; Timothy O. Ross; Andrew H. Weisberg; Tobias C. Brunner; Oliver Kircher

2010-01-01

364

Methods for incorporating the effects of LWR coolant environments in pressure vessel and piping fatigue evaluations  

Microsoft Academic Search

This paper summarizes the work performed at Argonne National Laboratory on the fatigue of piping and pressure vessel steels in the coolant environments of light water reactors. The existing fatigue strain vs. life ({var_epsilon}-N) data were evaluated to establish the effects of various material and loading variables, such as steel type, strain range, strain rate, temperature, and dissolved-oxygen level in

O. K. Chopra; W. J. Shack

2002-01-01

365

Master Curve and Unified Curve applicability to highly neutron irradiated Western type reactor pressure vessel steels  

Microsoft Academic Search

While the Master Curve (MC) method is gradually entering brittle fracture safety assessment procedures world-wide, knowledge is still lacking about its limits of applicability to highly neutron irradiated material. In this paper two reactor pressure vessel (RPV) steels A533B Cl.1 (IAEA reference material code JRQ) and A508 Cl.3 (code JFL) were scrutinized for possible deviations of the postulated invariant MC

Conrad Zurbuchen; Hans-Werner Viehrig; Frank-Peter Weiss

2009-01-01

366

Hardening and microstructure evolution in proton-irradiated model and commercial pressure-vessel steels  

Microsoft Academic Search

In an effort to understand the mechanisms of irradiation embrittlement of reactor pressure-vessel steels, hardening and microstructure evolution in a number of simple ferritic model alloys and complex bainitic steels irradiated with 3.2?MeV protons over a range of doses, dose rates and temperatures were characterized. Irradiations were conducted on selected model alloys to 1?dpa, which is a much higher dose

M. Hash; R. G. Odette

2005-01-01

367

Low-temperature fracture mechanisms in a spheroidised reactor pressure vessel steel  

Microsoft Academic Search

The micromechanisms of fracture of a spheroidised A533B reactor pressure vessel steel over the temperature range of ?190°C\\u000a to + 60°C were investigated by performing uniaxial tensile tests on double-notched cylindrical specimens. Failure was by quasi-cleavage\\u000a at temperatures between ?190°C and ?145°C. Quasi-cleavage fracture surfaces are characterised by clusters of planar facets\\u000a that are separated from other facets either by large

A. Kumar; S. G. Roberts; A. J. Wilkinson

2007-01-01

368

Micromechanical Coupled Study of Crack Growth Initiation Criterion in Pressure Vessel Steel  

Microsoft Academic Search

We present results of the combined design-theoretical investigation of the mechanism of crack growth at the onset of ductile fracture of NPP reactor pressure vessels. Micromechanical approach to the prediction of ductile fracture has been applied, according to which the volume fraction of voids in the deformed material is determined by the finite-element method. On the basis of CT-specimen tests

M. Rakin; A. Sedmak; Z. Cvijovic; M. Zrilic; S. Sedmak

2004-01-01

369

Application of Master Curve fracture toughness for reactor pressure vessel integrity assessment in the USA  

Microsoft Academic Search

The Master Curve fracture toughness approach has been used in the USA for better defining the transition temperature fracture toughness of irradiated reactor pressure vessel (RPV) steels for end-of-life (EOL) and EOL extension (EOLE) time periods. The first application was for the Kewaunee plant in which the life-limiting material was a circumferential weld metal. Fracture toughness testing of this weld

William Server; Stan Rosinski; Randy Lott; Charles Kim; Dennis Weakland

2002-01-01

370

Irradiation effects on toughness behaviour and microstructure of VVER-type pressure vessel steels  

Microsoft Academic Search

The irradiation sensitivity and the annealing behaviour were studied on seven different heats from VVER 440 and VVER 1000-type reactor pressure vessel steels. The specimens were irradiated at the Rheinsberg prototype VVER 2 reactor to mean neutron fluences between 43 and 127.6×1018n\\/cm2[E>0.5MeV]. Toughness and strength properties were determined and the microstructure was analysed using the small angle neutron scattering (SANS)

J. Bohmert; H.-W. Viehrig; A. Ulbricht

2001-01-01

371

Brittle fracture local criterion and radiation embrittlement of reactor pressure vessel steels  

Microsoft Academic Search

The application of local criteria for predicting brittle fracture of reactor pressure vessel steels is discussed with an emphasis\\u000a on radiation embrittlement. An association of the radiation-induced damages and the processes of initiation and propagation\\u000a of cleavage microcracks is analyzed from the standpoint of the local criterion for fracture. Physical-mechanical models are\\u000a put forward to describe the influence of radiation

B. Z. Margolin; V. A. Shvetsova; A. G. Gulenko; E. V. Nesterova

2010-01-01

372

Ultrasonic NDE of Kevlar-epoxy filament wound spherical pressure vessels  

SciTech Connect

The nondestructive evaluation of Kevlar-epoxy filament wound spherical composite pressure vessels is performed through the use of a six axis rotatorially articulated robotic manipulator. Ultrasonic pulse-echo techniques are employed to form C-scan images based upon amplitude and attenuation data gathered by a 68000 based microcomputer system. The data are imaged in planar and three dimensional forms and are further enhanced and analyzed through image processing techniques specifically developed for the analysis of complex composite structures. 25 figs.

Blake, R.A.; Steiner, K.V.

1985-10-01

373

A Reactor Pressure Vessel Dosimetry Calculation Using ATTILA, An Unstructured Tetrahedral Mesh Discrete-Ordinates Code  

SciTech Connect

Recently, a new state-of-the-art discrete-ordinates code, ATTILA, was developed. ATTILA provides the capabilities to solve geometrically complex 3-D transport problems by using an unstructured tetrahedral mesh. In this paper we describe the application of ATTILA to a 3-D reactor pressure vessel dosimetry problem. We provide numerical results from ATTILA and the Monte Carlo code, MCNP. The results demonstrate the effectiveness and efficiency of ATTILA for such calculations.

Wareing, T.A.; Parsons, D.K. [Los Alamos National Lab., NM (United States); Pautz, S. [Texas A and M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

1997-12-31

374

Accuracy of ultrasonic flaw sizing techniques for reactor pressure vessels: Final report  

Microsoft Academic Search

The accuracy of several ultrasonic flaw sizing techniques was measured using thick-walled mock-ups simulating typical reactor pressure vessel weld and clad configurations. The evaluated techniques were: backward-scattering tip-diffraction, time-of-flight diffraction (TOFD), dB-drop (with three different amplitude thresholds), and large-diameter focused probes. For the amplitude-based dB-drop technique, amplitude thresholds of 6 dB below peak, 50 percent DAC, and 20 percent DAC

A. J. Willetts; F. V. Ammirato; E. K. Kietzman

1989-01-01

375

Investigation of black spots and other blemishes inside small stainless steel pressure vessels  

SciTech Connect

Black spots and other blemishes were found on the inside surface of small stainless steel pressure vessels by borescope inspection. Most of the black spots originated from pyrolysis of lint contaminating the interior surface of these parts prior to welding. The lint originated from cotton gloves used to handle parts and from cotton gauze used to clean the parts. Pyrolysis of other hydrocarbons can also create black spots. 34 figs.

Heiple, C.R.; Doyle, J.H.; Burgardt, P.

1990-08-14

376

Pressure vessel sliding support unit and system using the sliding support unit  

DOEpatents

Provided is a sliding support and a system using the sliding support unit. The sliding support unit may include a fulcrum capture configured to attach to a support flange, a fulcrum support configured to attach to the fulcrum capture, and a baseplate block configured to support the fulcrum support. The system using the sliding support unit may include a pressure vessel, a pedestal bracket, and a plurality of sliding support units.

Breach, Michael R.; Keck, David J.; Deaver, Gerald A.

2013-01-15

377

Improvements to the Pool Critical Assembly Pressure Vessel Benchmark with 3-D Parallel SN PENTRAN  

NASA Astrophysics Data System (ADS)

The internationally circulated Pool Critical Assembly (PCA) Pressure Vessel Benchmark was analyzed using the PENTRAN Parallel SN code system for the geometry, material, and source specifications as described in the PCA Benchmark documentation. Improvements to the benchmark are proposed here through the application of more representative flux and volume weighted homogenized cross sections for the PCA reactor core, which were obtained from a rigorous heterogeneous modeling of all fuel assembly types in the core. A new source term definition is also proposed based on calculated relative power in each core fuel assembly with a spectrum based on the Uranium-235 fission spectra. This research focused on utilizing the BUGLE-96 cross section library and accompanying reaction rates, while also examining PENTRAN's adaptive differencing implemented on a coarse mesh basis, as well as fixed use of Directional Theta-Weighted (DTW) SN differencing scheme in order to compare the calculated PENTRAN results to measured data. The results show good comparison with the measured benchmark data, which suggests PENTRAN is a viable, reliable code system for calculation of light water reactor neutron shielding and pressure vessel dosimetry calculations. Furthermore, the improvements to the benchmark methodology resulting from this work provide a 6 percent increase in accuracy of the calculation (based on the average of all calculation points), when compared with experimentally measured results at the same spatial locations in the PCA pressure vessel simulator.

Edgar, Christopher A.; Sjoden, Glenn E.; Yi, Ce

2014-06-01

378

High pressure deuterium-tritium gas target vessels for muon-catalyzed fusion experiments  

SciTech Connect

In experimental studies of muon-catalyzed fusion, the density of the hydrogen gas mixture is an important parameter. Catalysis of up to 150 fusions per muon has been observed in deuterium-tritium gas mixtures at liquid hydrogen density; at room temperature, such densities require a target gas pressure of the order of 1000 atmospheres (100 MPa, 15,000 psi). We report here the design considerations for hydrogen gas target vessels for muon-catalyzed fusion experiments that operate at 1000 and 10,000 atmospheres. The 1000 atmosphere high pressure target vessels are fabricated of Type A-286 stainless steel and lined with oxygen-free, high-conductivity (OFHC) copper to provide a barrier to hydrogen permeation of the stainless steel. The 10,000 atmosphere ultrahigh pressure target vessels are made from 18Ni (200 grade) maraging steel and are lined with OFHC copper, again to prevent hydrogen permeation of the steel. In addition to target design features, operating requirements, fabrication procedures, and secondary containment are discussed. 13 refs., 3 figs., 1 tab.

Caffrey, A.J.; Spaletta, H.W.; Ware, A.G.; Zabriskie, J.M.; Hardwick, D.A.; Maltrud, H.R.; Paciotti, M.A. (EG and G Idaho, Inc., Idaho Falls, ID (USA); Los Alamos National Lab., NM (USA))

1989-01-01

379

A creep-rupture model of filament-wound spherical pressure vessels  

NASA Technical Reports Server (NTRS)

The creep-rupture model is that of a quasi-isotropic filament-wound spherical pressure vessel, subjected to internal pressurization. The matrix material of the composite system is assumed to be linearly viscoelastic. Internal damage resulting from the relaxation of the matrix and the corresponding increase in microcracks is represented by a functional relationship between circumferential strain and transverse modulus. The numerical solution to this nonlinear problem is an iterative technique, whereby the elastic-viscoelastic correspondence principle is employed. In the Laplace domain, the associated elastic solution is obtained and this solution is inverted by the multidata method to yield the time-dependent solution.

Dozier, Jan D.; Hackett, Robert M.

1987-01-01

380

Environmental crack-growth behavior of high strength pressure vessel alloys  

NASA Technical Reports Server (NTRS)

Results of sustained-load environmental crack growth threshold tests performed on six spacecraft pressure vessel alloys are presented. The alloys were Inconel 718, 6Al-4V titanium, A-286 steel, AM-350 stainless steel, cryoformed AISI 301 stainless steel; and cryoformed AISI 304L steel. The test environments for the program were air, pressurized gases of hydrogen, oxygen, nitrogen, and carbon dioxide, and liquid environments of distilled water, sea water, nitrogen tetroxide, hydrazine, aerozine 50, monomethyl hydrazine, and hydrogen peroxide. Surface flaw type specimens were used with flaws located in both base metal and weld metal.

Forman, R. G.

1975-01-01

381

Comparison of Irradiation Conditions of VVER-1000 Reactor Pressure Vessel and Surveillance Specimens for Various Core Loadings  

NASA Astrophysics Data System (ADS)

The comparative analysis of irradiation conditions of surveillance specimens and pressure vessel of VVER-1000 reactor has been carried out for various configurations of the core. It is proved the fluences onto specimens and a pressure vessel don't correlate with each other but only the spectral indexes do. It is revealed that in the case of the specimen reconstitution technique application the data on the assembly orientation to the reactor core is sufficient to complete four representative groups from the samples of any container assembly. It is shown that the standard surveillance program of VVER-1000 allows obtaining reliable information on the reactor pressure vessel state.

Bukanov, V. N.; Diemokhin, V. L.; Grytsenko, O. V.; Vasylieva, O. G.; Pugach, S. M.

2009-08-01

382

REACTOR PRESSURE VESSEL TEMPERATURE ANALYSIS OF CANDIDATE VERY HIGH TEMPERATURE REACTOR DESIGNS  

SciTech Connect

Analyses were performed to determine maximum temperatures in the reactor pressure vessel for two potential Very-High Temperature Reactor (VHTR) designs during normal operation and during a depressurized conduction cooldown accident. The purpose of the analyses was to aid in the determination of appropriate reactor vessel materials for the VHTR. The designs evaluated utilized both prismatic and pebble-bed cores that generated 600 MW of thermal power. Calculations were performed for fluid outlet temperatures of 900 and 950 °C, corresponding to the expected range for the VHTR. The analyses were performed using the RELAP5-3D and PEBBED-THERMIX computer codes. Results of the calculations were compared with preliminary temperature limits derived from the ASME pressure vessel code. Because PEBBED-THERMIX has not been extensively validated, confirmatory calculations were also performed with RELAP5-3D for the pebble-bed design. During normal operation, the predicted axial profiles in reactor vessel temperature were similar with both codes and the predicted maximum values were within 2 °C. The trends of the calculated vessel temperatures were similar during the depressurized conduction cooldown accident. The maximum value predicted with RELAP5-3D during the depressurized conduction cooldown accident was about 40 °C higher than that predicted with PEBBED. This agreement is considered reasonable based on the expected uncertainty in either calculation. The differences between the PEBBED and RELAP5-3D calculations were not large enough to affect conclusions concerning comparisons between calculated and allowed maximum temperatures during normal operation and the depressurized conduction cooldown accident.

Hans D. Gougar; Cliff B. Davis; George Hayner; Kevan Weaver

2006-10-01

383

Fatigue crack growth behavior of pressure vessel steels and submerged arc weldments in a high-temperature pressurized water environment  

NASA Astrophysics Data System (ADS)

The fatigue crack growth rate (FCGR) properties of SA508 C1 2a and SA533 Gr A C1 2 pressure vessel steels and the corresponding automatic submerged are weldments were developed in a high-temperature pressurized water (HPW) environment at 288 °C (550°F) and 7.2 MPa (1044 psi) at load ratios of 0.02 and 0.50. The HPW enviromment FCGR properties of these pressure vessel steels and submerged arc weldments were generally conservative, compared with the approrpriate American Society of Mechanical Engineers (ASME) Section XI water environmental reference curve. The growth rate of fatigue cracks in the base materials, however, was considerably faster in the HPW environment than in a corresponding 288°C (550°F) base line air environment. The growth rate of fatigue cracks in the two submerged are weldments was also accelerated in the HPW environment but to a significantly lesser degree than that demonstrated by the corresponding base materials. In the air environment, fatigue striations were observed, independent of material and load ratio, while in the HPW environment, some intergranular facets were present. The greater environmental effect on crack growth rates displayed by the base materials, as compared with the weldments, was attributed to a different sulfide composition and morphology.

Liaw, P. K.; Logsdon, W. A.; Begley, J. A.

1989-10-01

384

Interrelationship of Nondestructive Evaluation Methodologies Applied to Testing of Composite Overwrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

Composite Overwrapped Pressure Vessels (COPVs) are commonly used in spacecraft for containment of pressurized gases and fluids, incorporating strength and weight savings. The energy stored is capable of extensive spacecraft damage and personal injury in the event of sudden failure. These apparently simple structures, composed of a metallic media impermeable liner and fiber/resin composite overwrap are really complex structures with numerous material and structural phenomena interacting during pressurized use which requires multiple, interrelated monitoring methodologies to monitor and understand subtle changes critical to safe use. Testing of COPVs at NASA Johnson Space Center White Sands T est Facility (WSTF) has employed multiple in-situ, real-time nondestructive evaluation (NDE) methodologies as well as pre- and post-test comparative techniques to monitor changes in material and structural parameters during advanced pressurized testing. The use of NDE methodologies and their relationship to monitoring changes is discussed based on testing of real-world spacecraft COPVs. Lessons learned are used to present recommendations for use in testing, as well as a discussion of potential applications to vessel health monitoring in future applications.

Leifeste, Mark R.

2007-01-01

385

Fabrication Flaw Density and Distribution In Repairs to Reactor Pressure Vessel and Piping Welds  

SciTech Connect

The Pacific Northwest National Laboratory is developing a generalized fabrication flaw distribution for the population of nuclear reactor pressure vessels and for piping welds in U.S. operating reactors. The purpose of the generalized flaw distribution is to predict component-specific flaw densities. The estimates of fabrication flaws are intended for use in fracture mechanics structural integrity assessments. Structural integrity assessments, such as estimating the frequency of loss-of-coolant accidents, are performed by computer codes that require, as input, accurate estimates of flaw densities. Welds from four different reactor pressure vessels and a collection of archived pipes have been studied to develop empirical estimates of fabrication flaw densities. This report describes the fabrication flaw distribution and characterization in the repair weld metal of vessels and piping. This work indicates that large flaws occur in these repairs. These results show that repair flaws are complex in composition and sometimes include cracks on the ends of the repair cavities. Parametric analysis using an exponential fit is performed on the data. The relevance of construction records is established for describing fabrication processes and product forms. An analysis of these records shows there was a significant change in repair frequency over the years when these components were fabricated. A description of repair flaw morphology is provided with a discussion of fracture mechanics significance. Fabrication flaws in repairs are characterized using optimized-access, high-sensitivity nondestructive ultrasonic testing. Flaw characterizations are then validated by other nondestructive evaluation techniques and complemented by destructive testing.

GJ Schuster, FA Simonen, SR Doctor

2008-04-01

386

Development of automated ultrasonic device for in-service inspection of ABWR pressure vessel bottom head  

SciTech Connect

An automated device and its controller have been developed for the bottom head weld examination of pressure vessel of Advanced Boiling Water Reactor (ABWR). The internal pump casings and the housings of control rod prevent a conventional ultrasonic device from scanning the required inspection zone. With this reason, it is required to develop a new device to examine the bottom head area of ABWR. The developed device is characterized by the following features. (1) Composed of a mother vehicle and a compact inspection vehicle. They are connected only by an electric wire without using the conventional arm mechanism. (2) The mother vehicle travels on a track and lift up the inspection vehicle to the vessel. (3) The mother vehicle can automatically attach the inspection vehicle to the bottom head, and detach the inspection vehicle from it. (4) Collision avoidance control function with a touch sensor is installed at the front of the inspection vehicle. The device was successfully demonstrated using a mock-up of reactor pressure vessel.

Kojima, Y.; Matsuyama, A. [Ishikawajima-Harima Heavy Industries Co., Ltd., Yokohama (Japan)

1995-08-01

387

Monitoring Composite Material Pressure Vessels with a Fiber-Optic/Microelectronic Sensor System  

NASA Technical Reports Server (NTRS)

We discuss the concept of an integrated, fiber-optic/microelectronic distributed sensor system that can monitor composite material pressure vessels for Air Force space systems to provide assessments of the overall health and integrity of the vessel throughout its entire operating history from birth to end of life. The fiber optic component would include either a semiconductor light emitting diode or diode laser and a multiplexed fiber optic sensing network incorporating Bragg grating sensors capable of detecting internal temperature and strain. The microelectronic components include a power source, a pulsed laser driver, time domain data acquisition hardware, a microprocessor, a data storage device, and a communication interface. The sensing system would be incorporated within the composite during its manufacture. The microelectronic data acquisition and logging system would record the environmental conditions to which the vessel has been subjected to during its storage and transit, e.g., the history of thermal excursions, pressure loading data, the occurrence of mechanical impacts, the presence of changing internal strain due to aging, delamination, material decomposition, etc. Data would be maintained din non-volatile memory for subsequent readout through a microcomputer interface.

Klimcak, C.; Jaduszliwer, B.

1995-01-01

388

Blood Pressure Variability and Stress Management Training for Essential Hypertension  

ERIC Educational Resources Information Center

The purpose of this study was to determine whether stress management training reduces blood pressure (BP) variability in hypertensive patients. Previous literature suggests that cardiovascular risk is not only a function of BP levels, but also of BP variability, and this partially depends on changes induced by the stress of everyday life. The…

Garcia-Vera, Maria Paz; Sanz, Jesus; Labrador, Francisco J.

2004-01-01

389

The high pressure high shear stress rheology of liquid lubricants  

Microsoft Academic Search

A limiting shear stress model of liquid lubricant shear rheology is offered which accurately represents all available primary data. The model is of the nonlinear Maxwell type with shear modulus taken into the time derivative and broadening of the viscous-plastic transition with pressure. Property relations for viscosity, limiting stress and shear modulus are refined for a polyphenyl ether in particular.

S. Bair; W. O. Winer

1992-01-01

390

The pressure control technology of the active stressed lap  

NASA Astrophysics Data System (ADS)

The active stressed lap polishing technology is a kind of new polishing technology that can actively deform the lap surface to become an off-axis asphere according to different lap position on mirror surface and different angle of lap. The pressure of the lap on the mirror is an important factor affecting the grinding efficiency of the optics mirror. The active stressed lap technology using dynamic pressure control solution in the process of polishing astronomical Aspheric Mirror with faster asphericity will provide the advantage like high polishing speed and natural smooth, etc. This article puts emphases on the pressure control technology of the active stressed lap technology. It requires that the active stressed lap keeps symmetrical vertical compression on the mirrors in the process of grinding mirrors. With a background of an active stressed lap 450mm in diameter, this article gives an outline of the pressure control organization, analyzes the principle of pressure control and proposes the limitations of the present pressure control organization and the relevant solutions, designs a digital pressure controller with C32-bit RISC embedded and gives the relevant experimental test result finally.

Li, Ying; Wang, Daxing

2010-10-01

391

Model testing conducted to benchmark the Shippingport Reactor Pressure Vessel\\/Neutron Shield Tank package safety analysis  

Microsoft Academic Search

The decommissioned Shippingport Reactor Pressure Vessel (RPV) and its integral Neutron Shield Tank (NST) were transported from Shippingport, Pennsylvania, via barge to Hanford, Washington for burial in the Hanford Site Radioactive Waste Disposal Area. To ensure that the Reactor Pressure Vessel\\/Neutron Shield Tank (RPV\\/NST) assembly could be shipped safely, without undue risk to the public or the environment, the RPV\\/NST

D. L. Becker; D. M. Burgess; W. W. Bowen; B. V. Winkel

1989-01-01

392

Estimation of mechanical properties of irradiated nuclear pressure vessel steel by use of subsized CT specimen and small punch specimen  

Microsoft Academic Search

This paper reports on the 2-1\\/4 Cr-1Mâ steel that has been selected as the material for the reactor pressure vessel (RPV) of a multipurpose experimental high temperature gas cooled reactor designed by JAERI. The 2-1\\/4 Cr-1Mâ steel has successful records for high temperature pressure vessels in the petrochemical industries and the ASME Code Case authorizes the use of the steel

X. Mao; H. Takahashi; T. Kodaira

1991-01-01

393

Prediction of the Brittle Fracture Toughness of Neutron-Irradiated Reactor Pressure-Vessel Steels. Part 1  

Microsoft Academic Search

The irradiation effect on the temperature dependence of the brittle fracture toughness of reactor pressure-vessel steels is simulated using the probabilistic model for the fracture-toughness prediction, which was proposed by the authors earlier. The paper analyzes the irradiation effect on the parameters controlling the plastic deformation and brittle fracture of reactor pressure-vessel steels. We consider the mechanisms of microcrack nucleation

B. Z. Margolin; V. A. Shvetsova; A. G. Gulenko

2001-01-01

394

RADIATION DOSIMETRY OF THE PRESSURE VESSEL INTERNALS OF THE HIGH FLUX BEAM REACTOR.  

SciTech Connect

In preparation for the eventual decommissioning of the High Flux Beam Reactor after the permanent removal of its fuel elements from the Brookhaven National Laboratory, both measurements and calculations of the decay gamma-ray dose rate have been performed for the reactor pressure vessel and vessel internal structures which included the upper and lower thermal shields, the transition plate, and the control rod blades. The measurements were made using Red Perspex{trademark} polymethyl methacrylate high-level film dosimeters, a Radcal ''peanut'' ion chamber, and Eberline's high-range ion chamber. To compare with measured gamma-ray dose rate, the Monte Carlo MCNP code and geometric progressive Microshield code were used to model the gamma transport and dose buildup.

HOLDEN,N.E.; RECINIELLO,R.N.; HU,J.P.; RORER,D.C.

2002-08-18

395

Prestressed-concrete pressure vessels and their applicability to advanced-energy-system concepts  

SciTech Connect

Prestressed concrete pressure vessels (PCPVs) are, in essence, spaced steel structures since their strength is derived from a multitude of steel elements made up of deformed reinforcing bars and prestressing tendons which are present in sufficient quantities to carry tension loads imposed on the vessel. Other major components of a PCPV include the concrete, liner and cooling system, and insulation. PCPVs exhibit a number of advantages which make them ideally suited for application to advanced energy concepts: fabricability in virtually any size and shape using available technology, improved safety, reduced capital costs, and a history of proven performance. PCPVs have many applications to both nuclear- and non-nuclear-based energy systems concepts. Several of these concepts will be discussed as well as the research and development activities conducted at ORNL in support of PCPV development.

Naus, D.J

1983-01-01

396

Weld Repair of a Stamped Pressure Vessel in a Radiologically Controlled Zone  

SciTech Connect

In September 2012 an ASME B&PVC Section VIII stamped pressure vessel located at the DOE Hanford Site Effluent Treatment Facility (ETF) developed a through-wall leak. The vessel, a steam/brine heat exchanger, operated in a radiologically controlled zone (by the CH2MHill PRC or CHPRC), had been in service for approximately 17 years. The heat exchanger is part of a single train evaporator process and its failure caused the entire system to be shut down, significantly impacting facility operations. This paper describes the activities associated with failure characterization, technical decision making/planning for repair by welding, logistical challenges associated with performing work in a radiologically controlled zone, performing the repair, and administrative considerations related to ASME code requirements.

Cannell, Gary L. [Fluor Enterprises, Inc.; Huth, Ralph J. [CH2MHill Plateau Remediation Company; Hallum, Randall T. [Fluor Government Group

2013-08-26

397

Damage Control Plan for International Space Station Recharge Tank Assembly Composite Overwrapped Pressure Vessel  

NASA Technical Reports Server (NTRS)

As NASA has retired the Space Shuttle Program, a new method of transporting compressed gaseous nitrogen and oxygen needed to be created for delivery of these crucial life support resources to the International Space Station (ISS). One of the methods selected by NASA includes the use of highly pressurized, unprotected Recharge Tank Assemblies (RTAs) utilizing Composite Overwrapped Pressure Vessels (COPVs). A COPV consists of a thin liner wrapped with a fiber composite and resin or epoxy. It is typically lighter weight than an all metal pressure vessel of similar volume and therefore provides a higher-efficiency means for gas storage. However COPVs are known to be susceptible to damage resulting from handling, tool drop impacts, or impacts from other objects. As a result, a comprehensive Damage Control Plan has been established to mitigate damage to the RTA COPV throughout its life cycle. The DCP is intended to evaluate and mitigate defined threats during manufacturing, shipping and handling, test, assembly level integration, shipment while pressurized, launch vehicle integration and mission operations by defining credible threats and methods for preventing potential damage while still maintaining the primary goal of resupplying ISS gas resources. A comprehensive threat assessment is performed to identify all threats posed to the COPV during the different phases of its lifecycle. The threat assessment is then used as the basis for creating a series of general inspection, surveillance and reporting requirements which apply across all phases of the COPV's life, targeted requirements only applicable to specific work phases and a series of training courses for both ground personnel and crew aboard the ISS. A particularly important area of emphasis deals with creating DCP requirements for a highly pressurized, large and unprotected RTA COPV for use during Inter Vehicular Activities (IVA) operations in the micro gravity environment while supplying pressurized gas to the ISS for crew life support.

Cook, Anthony J.

2011-01-01

398

The effect of endogenous opioids on blood pressure during stress.  

PubMed

1. A series of experiments were conducted to investigate the effect of endogenous opioids on blood pressure of laboratory rats during stress. 2. Rats subjected to 120 min immobilization showed a significant drop in systolic pressure which could be prevented by pretreatment injections of naloxone. 3. Adrenalectomized rats subjected to the same kind of stress showed a drop in systolic pressure equivalent to only 30% of the systolic pressure drop in the intact animals. This decrease in systolic pressure could also be prevented by pretreatment injections of naloxone. 4. It was concluded that the decrease in systolic pressure in intact rats during immobilization was mostly due to endogenous opioids released from the adrenal glands, whereas opioids of other origins such as the pituitary gland, were also important. PMID:3665195

Nordin, M; Morat, P; Zainora, M

1987-04-01

399

Licensing and regulatory process for the shipment of the Shippingport RPV (Reactor Pressure Vessel) package: Extended summary  

SciTech Connect

At the Shippingport Station Decommissioning Project (SSDP) the irradiated hardware was essentially confined to those components that were a part of the reactor. The disposal of the irradiated reactor components was investigated by the Decommissioning Engineering Contractor. Due to the design of the reactor pressure vessel and its internals it was determined that the complete reactor vessel, its internal parts, and the neutron shield tank could be transported and disposed of as a single package. The technical feasibility of performing the one-piece shipment of the Reactor Pressure Vessel (RPV) package was reported in the Decommissioning Plan and the Environmental Impact Statement for the SSDP. 3 refs., 1 fig.

Van Sickle, G.E.

1988-01-01

400

The criteria of fracture in the case of the leak of pressure vessels  

SciTech Connect

In order to forecast the break of the high pressure vessels and the network of pipes in a nuclear reactor, according to the concept of leak before break of pressure vessels, it is necessary to analyze the conditions of project, production, and mounting quality as well as of exploitation. It is also necessary to evaluate the process of break by the help of the fracture criteria. In the Ignalina Nuclear Power Plant of, in Lithuania, the most important objects of investigation are: the highest pressure pipes, made of Japanese steel 19MN5 and having an anticorrosive austenitic: coal inside, the pipes of distribution, which arc made of 08X1810T steel. The steel of the network of pipes has a quality of plasticity: therefore the only criteria of fragile is impossible to apply to. The process of break would be best described by the universal criteria of elastic - plastic fracture. For this purpose the author offers the criterion of the double parameter.

Habil; Ziliukas, A.

1997-04-01

401

Standard practice for examination of seamless, Gas-Filled, pressure vessels using acoustic emission  

E-print Network

1.1 This practice provides guidelines for acoustic emission (AE) examinations of seamless pressure vessels (tubes) of the type used for distribution or storage of industrial gases. 1.2 This practice requires pressurization to a level greater than normal use. Pressurization medium may be gas or liquid. 1.3 This practice does not apply to vessels in cryogenic service. 1.4 The AE measurements are used to detect and locate emission sources. Other nondestructive test (NDT) methods must be used to evaluate the significance of AE sources. Procedures for other NDT techniques are beyond the scope of this practice. See Note 1. Note 1—Shear wave, angle beam ultrasonic examination is commonly used to establish circumferential position and dimensions of flaws that produce AE. Time of Flight Diffraction (TOFD), ultrasonic examination is also commonly used for flaw sizing. 1.5 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only. 1.6 Thi...

American Society for Testing and Materials. Philadelphia

2009-01-01

402

Strength and life of pressure vessels subjected to impacts and thermomechanical GFRP loading  

NASA Astrophysics Data System (ADS)

Non-insulated GRFP (Glass Fiber Reinforced Plastics) pipes were experimentally investigated. Particular consideration was given to the effects of short term thermal overloads and impact damage. It was shown that for a matrix with a long term specified service temperature of less than 140 C and starting from 140 C at 10 bar pressure up to 200 C and 30 bar pressure up to 170 C such thermalcycling up to some 100 cycles is acceptable when the hold time at the peak temperature is less than one hour. A prerequisite for this is the outer surface of the pipes remaining non-insulated and cooler (by about 30 C) than the content. No significant creep strain under static 10 bar pressure at 140 C was measured up to 350 hours of testing time. At 200 C and 30 bar, creep was fast enough to produce failure in a few hours. Clearly, the matrix material is not well suited to these high temperatures. Nevertheless, temporary surges in inside temperature to 170 C or even relatively long periods peaking at 140 C should not cause significant problems at normal service pressures near 10 bar, at least up to some 100 cycles. Impact testing and subsequent static pressure testing showed that for a given type of material, the leakage pressure of the vessel can be relatively easily predicted from the incident impact energy or from the ultrasonically determined size of the impact defect.

Pankakoski, Pekka H.; Uuttu, Tero; Kauppinen, Pentti; Sarkimo, Matti; Auerkari, Pertti

1992-10-01

403

Overview of NASA White Sands Test Facility Composite Overwrapped Pressure Vessel Testing  

NASA Technical Reports Server (NTRS)

This viewgraph presentation examines the White Sands Test Facility testing of Composite overwrapped pressure vessel (COPV). A COPV is typically a metallic liner overwrapped with a fiber epoxy matrix. There is a weight advantage over the traditional all metal design. The presentation shows pictures of the facilities at White Sands, and then examines some of the testing performed. The tests include fluids compatibility, and Kevlar COPV. Data for the Kevlar tests are given, and an analysis is reviewed. There is also a comparison between Carbon COPVs and the Kevlar COPVs.

Greene, Nathanael; Saulsberry, Regor; Thesken, John; Phoenix, Leigh

2006-01-01

404

Viscoelastic/damage modeling of filament-wound spherical pressure vessels  

NASA Technical Reports Server (NTRS)

A model of the viscoelastic/damage response of a filament-wound spherical vessel used for long-term pressure containment is developed. The matrix material of the composite system is assumed to be linearly viscoelastic. Internal accumulated damage based upon a quadratic relationship between transverse modulus and maximum circumferential strain is postulated. The resulting nonlinear problem is solved by an iterative routine. The elastic-viscoelastic correspondence is employed to produce, in the Laplace domain, the associated elastic solution for the maximum circumferential strain which is inverted by the method of collocation to yield the time-dependent solution. Results obtained with the model are compared to experimental observations.

Hackett, Robert M.; Dozier, Jan D.

1987-01-01

405

Review of the Palisades pressure vessel accumulated fluence estimate and of the least squares methodology employed  

SciTech Connect

This report provides a review of the Palisades submittal to the Nuclear Regulatory Commission requesting endorsement of their accumulated neutron fluence estimates based on a least squares adjustment methodology. This review highlights some minor issues in the applied methodology and provides some recommendations for future work. The overall conclusion is that the Palisades fluence estimation methodology provides a reasonable approach to a {open_quotes}best estimate{close_quotes} of the accumulated pressure vessel neutron fluence and is consistent with the state-of-the-art analysis as detailed in community consensus ASTM standards.

Griffin, P.J.

1998-05-01

406

Assessment of the master curve approach on three reactor pressure vessel steels  

Microsoft Academic Search

This study aims at assessing the applicability of the Master Curve procedure to the measurement of the reference temperature\\u000a for three well-characterised reactor pressure vessel steels (22NiMoCr37, JSPS, JRQ). The following aspects of the methodology\\u000a were investigated, using statistical tools such as the Generalised Maximum Likelihood (GML) and Monte Carlo methods: independence\\u000a ofT\\u000a o from test temperature and specimen type

Enrico Lucon; Marc Scibetta; Eric Van Walle

2003-01-01

407

Nondestructive evaluation of reactor pressure vessel steels using the giant magnetoimpedance sensor  

NASA Astrophysics Data System (ADS)

Recently, the giant magnetoimpedance (GMI) effect found in amorphous wires has been noticed as a method for sensing a magnetic field. The GMI sensor was applied to nondestructive evaluation of microstructural changes for reactor pressure vessel steels passing through the refining process. They were measured by using a GMI sensor and the measured GMI signals were strongly influenced by the microstructural features. The signals are closely related to the grain size, carbide morphology, lath width, and lath boundary that act as a barrier to irreversible domain wall motion.

Kim, D. J.; Park, D. G.; Hong, J. H.

2002-05-01

408

Fiber/epoxy filament-wound vessels. Final report  

SciTech Connect

The present investigation has provided a valuable insight into the design, fabrication and performance of filament-wound pressure vessels. The long-term stress rupture data generated under the contract is perhaps the only available lifetime data of its kind for Kevlar 49/epoxy pressure vessels. Now, it is clear that Kevlar 49/epoxy pressure vessels can be made to last at least 9 years at 50% of the static burst pressure.

Chiao, T.T.; Moore, R.L.

1986-08-14

409

Neural Network Burst Pressure Prediction in Graphite/Epoxy Pressure Vessels from Acoustic Emission Amplitude Data  

NASA Technical Reports Server (NTRS)

Acoustic emission (AE) data were taken during hydroproof for three sets of ASTM standard 5.75 inch diameter filament wound graphite/epoxy bottles. All three sets of bottles had the same design and were wound from the same graphite fiber; the only difference was in the epoxies used. Two of the epoxies had similar mechanical properties, and because the acoustic properties of materials are a function of their stiffnesses, it was thought that the AE data from the two sets might also be similar; however, this was not the case. Therefore, the three resin types were categorized using dummy variables, which allowed the prediction of burst pressures all three sets of bottles using a single neural network. Three bottles from each set were used to train the network. The resin category, the AE amplitude distribution data taken up to 25 % of the expected burst pressure, and the actual burst pressures were used as inputs. Architecturally, the network consisted of a forty-three neuron input layer (a single categorical variable defining the resin type plus forty-two continuous variables for the AE amplitude frequencies), a fifteen neuron hidden layer for mapping, and a single output neuron for burst pressure prediction. The network trained on all three bottle sets was able to predict burst pressures in the remaining bottles with a worst case error of + 6.59%, slightly greater than the desired goal of + 5%. This larger than desired error was due to poor resolution in the amplitude data for the third bottle set. When the third set of bottles was eliminated from consideration, only four hidden layer neurons were necessary to generate a worst case prediction error of - 3.43%, well within the desired goal.

Hill, Eric v. K.; Walker, James L., II; Rowell, Ginger H.

1995-01-01

410

Pressure pulse test results and qualification of the FLASH34 flexible structural member model with a surge tank attached to the test vessel (LWBR Development Program)  

Microsoft Academic Search

Pressure pulse tests were conducted with both solid and flexible test sections installed in a test vessel filled with room temperature water. A surge tank whose volume was approximately equal to that of the test vessel with the test section installed was connected to the test vessel by a 1\\/8 inch I.D., 8 inch long surge line. Pressure pulses of

R. E. Schwirian

1977-01-01

411

HTGR Base Technology Program. Task 2: concrete properties in nuclear environment. A review of concrete material systems for application to prestressed concrete pressure vessels  

Microsoft Academic Search

Prestressed concrete pressure vessels (PCPVs) are designed to serve as primary pressure containment structures. The safety of these structures depends on a correct assessment of the loadings and proper design of the vessels to accept these loadings. Proper vessel design requires a knowledge of the component (material) properties. Because concrete is one of the primary constituents of PCPVs, knowledge of

Naus

1981-01-01

412

Bayes Analysis and Reliability Implications of Stress-Rupture Testing a Kevlar/Epoxy COPV Using Temperature and Pressure Acceleration  

NASA Technical Reports Server (NTRS)

Composite Overwrapped Pressure Vessels (COPVs) that have survived a long service time under pressure generally must be recertified before service is extended. Flight certification is dependent on the reliability analysis to quantify the risk of stress rupture failure in existing flight vessels. Full certification of this reliability model would require a statistically significant number of lifetime tests to be performed and is impractical given the cost and limited flight hardware for certification testing purposes. One approach to confirm the reliability model is to perform a stress rupture test on a flight COPV. Currently, testing of such a Kevlar49 (Dupont)/epoxy COPV is nearing completion. The present paper focuses on a Bayesian statistical approach to analyze the possible failure time results of this test and to assess the implications in choosing between possible model parameter values that in the past have had significant uncertainty. The key uncertain parameters in this case are the actual fiber stress ratio at operating pressure, and the Weibull shape parameter for lifetime; the former has been uncertain due to ambiguities in interpreting the original and a duplicate burst test. The latter has been uncertain due to major differences between COPVs in the database and the actual COPVs in service. Any information obtained that clarifies and eliminates uncertainty in these parameters will have a major effect on the predicted reliability of the service COPVs going forward. The key result is that the longer the vessel survives, the more likely the more optimistic stress ratio model is correct. At the time of writing, the resulting effect on predicted future reliability is dramatic, increasing it by about one "nine," that is, reducing the predicted probability of failure by an order of magnitude. However, testing one vessel does not change the uncertainty on the Weibull shape parameter for lifetime since testing several vessels would be necessary.

Phoenix, S. Leigh; Kezirian, Michael T.; Murthy, Pappu L. N.

2009-01-01

413

Predictive Reactor Pressure Vessel Steel Irradiation Embrittlement Models: Issues and Opportunities  

SciTech Connect

Nuclear plant life extension to 80 years will require accurate predictions of neutron irradiation-induced increases in the ductile-brittle transition temperature ( T) of reactor pressure vessel (RPV) steels at high fluence conditions that are far outside the existing database. Remarkable progress in mechanistic understanding of irradiation embrittlement has led to physically motivated T correlation models that provide excellent statistical fi ts to the existing surveillance database. However, an important challenge is developing advanced embrittlement models for low fl ux-high fl uence conditions pertinent to extended life. These new models must also provide better treatment of key variables and variable combinations and account for possible delayed formation of late blooming phases in low copper steels. Other issues include uncertainties in the compositions of actual vessel steels, methods to predict T attenuation away from the reactor core, verifi cation of the master curve method to directly measure the fracture toughness with small specimens and predicting T for vessel annealing remediation and re-irradiation cycles.

Odette, George Robert [UCSB; Nanstad, Randy K [ORNL

2009-01-01

414

Computational experiments; Proceedings of the ASME/JSME Pressure Vessels and Piping Conference, Honolulu, HI, July 23-27, 1989  

NASA Astrophysics Data System (ADS)

Papers applying FEM to engineering problems are presented, covering topics such as a numerical approach to software development for thermoforming simulations, flow three-dimensional analysis of pressure responses in an enclosed launching system, comparing flow three-dimensional calculations with very large amplitude slosh data, and the computational analysis of stress concentrations in pressure vessel cascades. Other topics include FEM studies of flow past an array of plates, stochastic finite elements for automotive impact, numerical simulation in the deployment of space structures, axial buckling of a thin cylindrical shell, applying FEM to the prediction of vibrations of liquid propelled launch vehicles, analysis of a large bore piping system supported with viscodampers, stochastic simulation of lubricant depletion on a magnetic storage disk, and two-dimensional crak inclusion interaction effects. Additional topics include analyzing damage mechanisms using the energy release rate, the suspension of solid particles in an aerospace plane's slush hydrogen tanks, modal methods for the analysis of vibrations of structures coupled with fluids, the elastic-plastic behavior of fibrous metal matrix composites, and stochastic finite element analysis of nonlinear media.

Liu, W. K.; Smolinski, P.; Ohayon, R.; Navickas, J.; Gvildys, J.

1989-06-01

415

Characteristics of the turbulent boundary layer pressure spectra for high-speed vessels  

NASA Astrophysics Data System (ADS)

Recent studies demonstrate that the fluctuating pressure field generated by the turbulent boundary layer (TBL) is an important flow noise source for high-speed marine vehicles. In fact, wall-pressure fluctuations induce vibrations in the hull plates of the vessel that are responsible for undesirable noise on board. In this framework, the correct description of the pressure load acting on the hull needs a deep knowledge of its spectral features and, in this work, the problem of the power spectral density characterization is analysed. This quantity is usually obtained experimentally, because of limitations of the available computational resources at the high Reynolds numbers typical of engineering applications. However, the experimental evaluation of the power spectral density presents as well some problems because of the low frequency pollution due to the background noise of the facilities and because of the high frequency attenuation due to the finite size of the pressure sensors. Boundary-layer characteristics depend, for a body moving in an unbounded flow, on the Reynolds number, while, in the case of a surface ship, a Froude number dependency must be taken into account. In view of the evaluation of the noise level on board of civil high-speed vessels generated by flow-induced vibrations, an experimental campaign aimed at measuring the pressure fluctuations beneath the TBL attached to the hull of a ship model was performed in a towing tank. The use of this facility, new for this kind of experiments, provides ideal flow conditions because background noise and turbulence are absent. Pressure signals are acquired for a large range of Reynolds numbers by varying both the model velocity and the test-section along the hull length. With this experimental set-up it was possible to analyse the details of the pressure spectra in the different frequency regions. In this work, a detailed discussion on the pressure scaling laws is provided together with a critical comparison with the available results obtained for different facilities and experimental conditions.

Ciappi, E.; Magionesi, F.

2005-11-01

416

The effect of compression on individual pressure vessel nickel/hydrogen components  

NASA Technical Reports Server (NTRS)

Compression tests were performed on representative Individual Pressure Vessel (IPV) Nickel/Hydrogen cell components in an effort to better understand the effects of force on component compression and the interactions of components under compression. It appears that the separator is the most easily compressed of all of the stack components. It will typically partially compress before any of the other components begin to compress. The compression characteristics of the cell components in assembly differed considerably from what would be predicted based on individual compression characteristics. Component interactions played a significant role in the stack response to compression. The results of the compression tests were factored into the design and selection of Belleville washers added to the cell stack to accommodate nickel electrode expansion while keeping the pressure on the stack within a reasonable range of the original preset.

Manzo, Michelle A.; Perez-Davis, Marla E.

1988-01-01

417

Application of small specimens to fracture mechanics characterization of irradiated pressure vessel steels  

SciTech Connect

In this study, precracked Charpy V-notch (PCVN) specimens were used to characterize the fracture toughness of unirradiated and irradiated reactor pressure vessel steels in the transition region by means of three-point static bending. Fracture toughness at cleavage instability was calculated in terms of elastic-plastic K{sub Jc} values. A statistical size correction based upon weakest-link theory was performed. The concept of a master curve was applied to analyze fracture toughness properties. Initially, size-corrected PCVN data from A 533 grade B steel, designated HSST Plate O2, were used to position the master curve and a 5% tolerance bound for K{sub Jc} data. By converting PCVN data to IT compact specimen equivalent K{sub Jc} data, the same master curve and 5% tolerance bound curve were plotted against the Electric Power Research Institute valid linear-elastic K{sub Jc} database and the ASME lower bound K{sub Ic} curve. Comparison shows that the master curve positioned by testing several PCVN specimens describes very well the massive fracture toughness database of large specimens. These results give strong support to the validity of K{sub Jc} with respect to K{sub Ic} in general and to the applicability of PCVN specimens to measure fracture toughness of reactor vessel steels in particular. Finally, irradiated PCVN specimens of other materials were tested, and the results are compared to compact specimen data. The current results show that PCVNs demonstrate very good capacity for fracture toughness characterization of reactor pressure vessel steels. It provides an opportunity for direct measurement of fracture toughness of irradiated materials by means of precracking and testing Charpy specimens from surveillance capsules. However, size limits based on constraint theory restrict the operational test temperature range for K{sub Jc} data from PCVN specimens. 13 refs., 8 figs., 1 tab.

Sokolov, M.A.; Wallin, K.; McCabe, D.E.

1996-12-31

418

Advanced Dependent Pressure Vessel (DPV) Nickel-Hydrogen Spacecraft Cell and Battery Design  

NASA Technical Reports Server (NTRS)

The dependent pressure vessel (DPV) nickel-hydrogen (Ni-H2) battery is being developed as a potential spacecraft battery design for both military and commercial satellites. Individual pressure vessel (IPV) Ni-H2 batteries are currently flying on more than 70 Earth-orbiting satellites and have accumulated more that 140,000,000 cell-hours in actual spacecraft operation. The limitations of standard Ni-H2 IPV flight battery technology are primarily related to the internal cell design and the battery packaging issues associated with grouping multiple cylindrical cells. The DPV cell design offers higher specific energy and reduced cost, while retaining the established IPV Ni-H2 technology flight heritage and database. A design performance analysis is presented at both the cell and battery level. The DPV is capable of delivering up to 76 Watthours per kilogram (Wh/kg) at the cell level and 70 Wh/kg at the full battery level. This represents a 40 percent increase in specific energy at the cell level and a 60 percent increase in specific energy at the battery level compared to current IPV Ni-H2 technology.

Coates, Dwaine K.; Wright, R. Doug; Repplinger, Ron S.

1996-01-01

419

Assessment of Radiation Embrittlement in Nuclear Reactor Pressure Vessel Surrogate Materials  

NASA Astrophysics Data System (ADS)

The radiation-enhanced formation of small (1-2 nm) copper-rich precipitates (CRPs) is critical for the occurrence of embrittlement in nuclear-reactor pressure vessels. Small CRPs are coherent with the bcc matrix, which causes local matrix strain and interaction with the dislocation strain fields, thus impeding dislocation mobility. As CRPs grow, there is a critical size at which a phase transformation occurs, whereby the CRPs are no longer coherent with the matrix, and the strain is relieved. Diffraction-line-broadening analysis (DLBA) and small-angle neutron scattering (SANS) were used to characterize the precipitate formation in surrogate ferritic reactor-pressure vessel steels. The materials were aged for different times at elevated temperature to produce a series of specimens with different degrees of copper precipitation. SANS measurements showed that the precipitate size distribution broadens and shifts toward larger sizes as a function of ageing time. Mechanical hardness showed an increase with ageing time, followed by a decrease, which can be associated with the reduction in the number density as well as the loss of coherency at larger sizes. Inhomogeneous strain correlated with mechanical hardness.

Balzar, Davor

2010-10-01

420

Standard Master Matrix for Light-Water Reactor Pressure Vessel Surveillance Standards, E706(0)  

E-print Network

1.1 This master matrix standard describes a series of standard practices, guides, and methods for the prediction of neutron-induced changes in light-water reactor (LWR) pressure vessel (PV) and support structure steels throughout a pressure vessel's service life (Fig. 1). Some of these are existing ASTM standards, some are ASTM standards that have been modified, and some are proposed ASTM standards. General requirements of content and consistency are discussed in Section 6 . More detailed writers' and users' information, justification, and specific requirements for the nine practices, ten guides, and three methods are provided in Sections 3-5. Referenced documents are discussed in Section 2. The summary-type information that is provided in Sections 3 and 4 is essential for establishing proper understanding and communications between the writers and users of this set of matrix standards. It was extracted from the referenced documents, Section 2 and references (1-106) for use by individual writers and users. 1...

American Society for Testing and Materials. Philadelphia

2002-01-01

421

Helium leak testing of a radioactive contaminated vessel under high pressure in a contaminated environment  

SciTech Connect

At ANL-W, with the shutdown of EBR-II, R&D has evolved from advanced reactor design to the safe handling, processing, packaging, and transporting spent nuclear fuel and nuclear waste. New methods of processing spent fuel rods and transforming contaminated material into acceptable waste forms are now in development. Storage of nuclear waste is a high interest item. ANL-W is participating in research of safe storage of nuclear waste, with the WIPP (Waste Isolation Pilot Plant) site in New Mexico the repository. The vessel under test simulates gas generated by contaminated materials stored underground at the WIPP site. The test vessel is 90% filled with a mixture of contaminated material and salt brine (from WIPP site) and pressurized with N2-1% He at 2500 psia. Test acceptance criteria is leakage < 10{sup -7} cc/seconds at 2500 psia. The bell jar method is used to determine leakage rate using a mass spectrometer leak detector (MSLD). The efficient MSLD and an Al bell jar replaced a costly, time consuming pressure decay test setup. Misinterpretation of test criterion data caused lengthy delays, resulting in the development of a unique procedure. Reevaluation of the initial intent of the test criteria resulted in leak tolerances being corrected and test efficiency improved.

Winter, M.E.

1996-10-01

422

Improved mechanical properties of A 508 class 3 steel for nuclear pressure vessel through steelmaking  

SciTech Connect

The present work is concerned with the steelmaking practices which improve the mechanical properties of the A 508 class 3 steel for reactor pressure vessel. Three kinds of steelmaking practices were applied to manufacture the forged heavy wall shell for reactor pressure vessel, that is, the vacuum carbon deoxidation (VCD), modified VCD containing aluminum and silicon-killing. The segregation of the chemical elements through the thickness was quite small so that the variations of the tensile properties at room temperature were small and the anisotropy of the impact properties was hardly observed regardless of the steelmaking practices. The Charpy V-notch impact properties and the reference nil-ductile transition temperature by drop weight test were significantly improved by the modified VCD and silicon-killing as compared with those of the steel by VCD. Moreover, the plane strain fracture toughness values of the materials by modified VCD and silicon-killing practices was much higher than those of the steel by VCD. These were resulted from the fining of austenite grain size. It was observed that the grain size was below 20 {micro}m (ASTM No. 8.5) when using the modified VCD and silicon-killing, compared to 50 {micro}m (ASTM No. 7.0) when using VCD.

Kim, J.T.; Kwon, H.K.; Kim, K.C.; Kim, J.M. [Korea Heavy Industries and Construction Co., Ltd., Changwon (Korea, Republic of)

1997-12-31

423

Irradiation effects on toughness behaviour and microstructure of VVER-type pressure vessel steels  

NASA Astrophysics Data System (ADS)

The irradiation sensitivity and the annealing behaviour were studied on seven different heats from VVER 440 and VVER 1000-type reactor pressure vessel steels. The specimens were irradiated at the Rheinsberg prototype VVER 2 reactor to mean neutron fluences between 43 and 127.6×10 18 n/cm2[E>0.5 MeV] . Toughness and strength properties were determined and the microstructure was analysed using the small angle neutron scattering (SANS) technique. There is an obvious correlation between the irradiation-induced changes of transition temperature, hardness and volume fraction of microstructural features of radii up to 2 nm. The main parameters of influence are the neutron fluence and the nickel content. The nickel-containing VVER 1000-type pressure vessel steel is more sensitive to irradiation than the VVER 440-type steel which has a low nickel content. For the latter, the sensitivity to radiation embrittlement depends on the copper and phosphorus contents. Annealing at 475°C (100 h) reduces the irradiation effect but not completely in every case.

Böhmert, J.; Viehrig, H.-W.; Ulbricht, A.

2001-09-01

424

New developments in Nickel-Hydrogen Dependent Pressure Vessel (DPV) cell and battery design  

NASA Astrophysics Data System (ADS)

The Dependent Pressure Vessel (DPV) Nickel-Hydrogen (NiH2) design is being developed by Eagle-Picher Industries, Inc. (EPI) as an advanced battery for military and commercial, aerospace and terrestrial applications. The DPV cell design offers high specific energy, energy density and reduced cost, while retaining the established Individual Pressure Vessel (IPV) technology flight heritage and database. This advanced DPV design also offers a more efficient mechanical, electrical and thermal cell and battery configuration and a reduced parts count. The DPV battery design promotes compact, minimum volume packaging and weight efficiency, and delivers significant cost and weight savings while providing minimal design risks. This presentation will discuss new DPV design concepts and production features and present test data from existing development cells. The DPV combines the unique features and significant advantages of NiH2 electrochemistry with the simplicity and extensive design heritage of the NiCd battery system to create a power source ideal for military and commercial terrestrial projects as well as traditional aerospace applications.

Caldwell, Dwight B.; Fox, Chris L.; Miller, Lee E.

1997-01-01

425

Radiation damage characterization in reactor pressure vessel steels with nonlinear ultrasound  

SciTech Connect

Nuclear generation currently accounts for roughly 20% of the US baseload power generation. Yet, many US nuclear plants are entering their first period of life extension and older plants are currently undergoing assessment of technical basis to operate beyond 60 years. This means that critical components, such as the reactor pressure vessel (RPV), will be exposed to higher levels of radiation than they were originally intended to withstand. Radiation damage in reactor pressure vessel steels causes microstructural changes such as vacancy clusters, precipitates, dislocations, and interstitial loops that leave the material in an embrittled state. The development of a nondestructive evaluation technique to characterize the effect of radiation exposure on the properties of the RPV would allow estimation of the remaining integrity of the RPV with time. Recent research has shown that nonlinear ultrasound is sensitive to radiation damage. The physical effect monitored by nonlinear ultrasonic techniques is the generation of higher harmonic frequencies in an initially monochromatic ultrasonic wave, arising from the interaction of the ultrasonic wave with microstructural features such as dislocations, precipitates, and their combinations. Current findings relating the measured acoustic nonlinearity parameter to increasing levels of neutron fluence for different representative RPV materials are presented.

Matlack, K. H. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Kim, J.-Y. [School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Wall, J. J. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 and Nuclear Sector, The Electric Power Research Institute, Charlotte, NC 28262 (United States); Qu, J. [Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208 (United States); Jacobs, L. J. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

2014-02-18

426

Radiation damage characterization in reactor pressure vessel steels with nonlinear ultrasound  

NASA Astrophysics Data System (ADS)

Nuclear generation currently accounts for roughly 20% of the US baseload power generation. Yet, many US nuclear plants are entering their first period of life extension and older plants are currently undergoing assessment of technical basis to operate beyond 60 years. This means that critical components, such as the reactor pressure vessel (RPV), will be exposed to higher levels of radiation than they were originally intended to withstand. Radiation damage in reactor pressure vessel steels causes microstructural changes such as vacancy clusters, precipitates, dislocations, and interstitial loops that leave the material in an embrittled state. The development of a nondestructive evaluation technique to characterize the effect of radiation exposure on the properties of the RPV would allow estimation of the remaining integrity of the RPV with time. Recent research has shown that nonlinear ultrasound is sensitive to radiation damage. The physical effect monitored by nonlinear ultrasonic techniques is the generation of higher harmonic frequencies in an initially monochromatic ultrasonic wave, arising from the interaction of the ultrasonic wave with microstructural features such as dislocations, precipitates, and their combinations. Current findings relating the measured acoustic nonlinearity parameter to increasing levels of neutron fluence for different representative RPV materials are presented.

Matlack, K. H.; Kim, J.-Y.; Wall, J. J.; Qu, J.; Jacobs, L. J.

2014-02-01

427

Recovering strain readings from chirping fiber Bragg gratings in composite overwrapped pressure vessels  

NASA Astrophysics Data System (ADS)

This study reports on signal recovery of optical fiber Bragg gratings embedded in a carbon fiber composite overwrapped pressure vessel's (COPV) structure which have become chirped due to microcracks. COPVs are commonly used for the storage of high pressure liquids and gases. They utilize a thin metal liner to seal in contents, with a composite overwrap to strengthen the vessel with minimal additional mass. A COPV was instrumented with an array of surface mounted and embedded fiber Bragg gratings (FBGs) for structural health monitoring (SHM) via strain sensing of the material. FBGs have been studied as strain sensors for the last couple decades. Many of the embedded FBGs reflected a multi-peak, chirped response which was not able to be interpreted well by the current monitoring algorithm. Literature and this study found that the chirping correlated with microcracks. As loading increases, so does the number of chirped FBGs and microcracks. This study uses optical frequency domain reflectometry (OFDR) to demultiplex the array of FBGs, and then sub- divide individual FBGs. When a FBG is sub-divided using OFDR, the gratings' strain along its length is recovered. The sub-divided chirped FBGs have strain gradients along their length from microcracks. Applying this to all chirped gratings, nearly the entirety of the embedded sensors' readings can be recovered into a series of single peak responses, which show very large local strains throughout the structure. This study reports on this success in recovering embedded FBGs signal, and the strain gradient from microcracks.

Strutner, Scott M.; Pena, Frank; Piazza, Anthony; Parker, Allen R.; Richards, W. Lance; Carman, Gregory P.

2014-04-01

428

Balancing food and predator pressure induces chronic stress in songbirds.  

PubMed

The never-ending tension between finding food and avoiding predators may be the most universal natural stressor wild animals experience. The 'chronic stress' hypothesis predicts: (i) an animal's stress profile will be a simultaneous function of food and predator pressures given the aforesaid tension; and (ii) these inseparable effects on physiology will produce inseparable effects on demography because of the resulting adverse health effects. This hypothesis was originally proposed to explain synergistic (inseparable) food and predator effects on demography in snowshoe hares (Lepus americanus). We conducted a 2 x 2, manipulative food addition plus natural predator reduction experiment on song sparrows (Melospiza melodia) that was, to our knowledge, the first to demonstrate comparable synergistic effects in a bird: added food and lower predator pressure in combination produced an increase in annual reproductive success almost double that expected from an additive model. Here we report the predicted simultaneous food and predator effects on measures of chronic stress in the context of the same experiment: birds at unfed, high predator pressure (HPP) sites had the highest stress levels; those at either unfed or HPP sites showed intermediate levels; and fed birds at low predator pressure sites had the lowest stress levels. PMID:15590598

Clinchy, Michael; Zanette, Liana; Boonstra, Rudy; Wingfield, John C; Smith, James N M

2004-12-01

429

A dual output pressure, high reliability, long storage life gas delivery vessel assembly  

NASA Technical Reports Server (NTRS)

A Gas Vessel Assembly has been developed that delivers purified, very low moisture content gas at two different output pressures. High pressure gas is delivered at up to 6,700 psi, and low pressure gas regulated to 130 psi is also delivered via a second outlet over a wide range of flow rates. The device is extremely lightweight (less than 1 lb) and compact, affords maximum mechanical integrity, high reliability (0.9999 at 95 percent confidence level), and offers extremely long storage life. Specialized design and fabrication techniques are employed that guarantee gas purity and negligible leakage for more than 20 years, in widely varying conditions of storage temperature, humidity, altitude, and vibration environments. The technology offers unique advantages in fast, high pressure discharge applications. For example, when combined with a cryostat, cryogenic temperatures can be achieved such as those used in missile seeker technology. The technology has many additional applications such as: emergency power sources for safety devices such as those needed in nuclear power plants, refineries, collision cushioning devices, superconductor cooling devices, emergency egress systems, miniature mechanical devices that employ gas bearings, and other areas where long storage, extremely high reliability and/or high energy density sources are required.

Maya, Isaac; Mckee, Joe; Rajpurkar, Rajiv

1993-01-01

430

Measurement of Averaged Heat Transfer Coefficients in High-Pressure Vessel during Charging with Hydrogen, Nitrogen or Argon Gas  

NASA Astrophysics Data System (ADS)

Heat transfer to the wall of a small pressure vessel during filling with some different kinds of gas was investigated experimentally. The vessel was orientated vertically with the inlet at the top. The space-averaged Nusselt number for the curved wall was found to be a function of both the Reynolds and Rayleigh numbers indicating a mixed convection heat transfer situation. A correlation is proposed for the heat transfer coefficient during charging of the vessel. For the six positions where measurements were taken, the local heat transfer coefficient typically did not differ from the space-averaged value by more than about 30 percent. Measurements were also taken during discharging to atmospheric pressure. For discharging, some of the data was found to agree with a correlation for natural convection in cylindrical geometry. Local Nusselt numbers for discharging tended to be higher towards the bottom of the vessel.

Woodfield, Peter Lloyd; Monde, Masanori; Mitsutake, Yuichi

431

Identification of Pressure Measurement Systems based on Surface Stress Sensitive Films and Pressure Sensitive Paints  

Microsoft Academic Search

This paper describes the methodology for extracting applied surface loads from Surface Stress Sensitive Films (S3F). Experimentally measured 3D deformations of an S3F sensor in combination with Finite Element Analysis (FEA) modeled response functions are utilized to deconvolve the applied normal (pressure) and tangential (shear) loads. Comparisons with pressure sensitive paint (PSP) and pressure taps results obtained under the same

S. D. Fonov; L. P. Goss; E. G. Jones; J. W. Crafton; V. S. Fonov

2005-01-01

432

Plain bearing stresses due to forming and oil film pressure  

NASA Astrophysics Data System (ADS)

This paper describes a methodology for assessing critical stress ranges arising in automotive plain bearings during engine operations. An industry-produced and run simulation program provides information on oil film pressure and overall bearing deformation during accelerated performance tests. This code performs an elasto-hydrodynamic lubrication analysis accounting for the compliance of the housing and journal. Finite element analyses of a multilayer bearing are performed to assess the conditions responsible for possible fatigue damage over the bearing lining. The residual stresses arising from the forming and fitting process are first assessed. The stress analyses over the engine cycle show the intensity and distribution of cyclic tensile and compressive stresses in the bearing. The location of maximum stress range is found to be consistent with the damage observed in accelerated fatigue tests. Critical zones are identified in the lining for possible fatigue crack initiation and growth studies.

Burke-Veliz, A.; Wang, D.; Wahdy, N.; Reed, P. A. S.; Merritt, D.; Syngellakis, S.

2009-08-01

433

Survey of welding processes for field fabrication of 2 1/4 Cr-1 Mo steel pressure vessels. [128 references  

SciTech Connect

Any evaluation of fabrication methods for massive pressure vessels must consider several welding processes with potential for heavy-section applications. These include submerged-arc and shielded metal-arc, narrow-joint modifications of inert-gas metal-arc and inert-gas tungsten-arc processes, electroslag, and electron beam. The advantage and disadvantages of each are discussed. Electroslag welding can be dropped from consideration for joining of 2 1/4 Cr-1 Mo steel because welds made with this method do not provide the required mechanical properties in the welded and stress relieved condition. The extension of electron-beam welding to sections as thick as 4 or 8 inches (100 or 200 mm) is too recent a development to permit full evaluation. The manual shielded metal-arc and submerged-arc welding processes have both been employed, often together, for field fabrication of large vessels. They have the historical advantage of successful application but present other disadvantages that make them otherwise less attractive. The manual shielded metal-arc process can be used for all-position welding. It is however, a slow and expensive technique for joining heavy sections, requires large amounts of skilled labor that is in critically short supply, and introduces a high incidence of weld repairs. Automatic submerged-arc welding has been employed in many critical applications and for welding in the flat position is free of most of the criticism that can be leveled at the shielded metal-arc process. Specialized techniques have been developed for horizontal and vertical position welding but, used in this manner, the applications are limited and the cost advantage of the process is lost.

Grotke, G.E.

1980-04-01

434

Manufacturing Cost Analysis of Novel Steel/Concrete Composite Vessel for Stationary Storage of High-Pressure Hydrogen  

SciTech Connect

A novel, low-cost, high-pressure, steel/concrete composite vessel (SCCV) technology for stationary storage of compressed gaseous hydrogen (CGH2) is currently under development at Oak Ridge National Laboratory (ORNL) sponsored by DOE s Fuel Cell Technologies (FCT) Program. The SCCV technology uses commodity materials including structural steels and concretes for achieving cost, durability and safety requirements. In particular, the hydrogen embrittlement of high-strength low-alloy steels, a major safety and durability issue for current industry-standard pressure vessel technology, is mitigated through the use of a unique layered steel shell structure. This report presents the cost analysis results of the novel SCCV technology. A high-fidelity cost analysis tool is developed, based on a detailed, bottom-up approach which takes into account the material and labor costs involved in each of the vessel manufacturing steps. A thorough cost study is performed to understand the SCCV cost as a function of the key vessel design parameters, including hydrogen pressure, vessel dimensions, and load-carrying ratio. The major conclusions include: The SCCV technology can meet the technical/cost targets set forth by DOE s FCT Program for FY2015 and FY2020 for all three pressure levels (i.e., 160, 430 and 860 bar) relevant to the hydrogen production and delivery infrastructure. Further vessel cost reduction can benefit from the development of advanced vessel fabrication technologies such as the highly automated friction stir welding (FSW). The ORNL-patented multi-layer, multi-pass FSW can not only reduce the amount of labor needed for assembling and welding the layered steel vessel, but also make it possible to use even higher strength steels for further cost reductions and improvement of vessel structural integrity. It is noted the cost analysis results demonstrate the significant cost advantage attainable by the SCCV technology for different pressure levels when compared to the industry-standard pressure vessel technology. The real-world performance data of SCCV under actual operating conditions is imperative for this new technology to be adopted by the hydrogen industry for stationary storage of CGH2. Therefore, the key technology development effort in FY13 and subsequent years will be focused on the fabrication and testing of SCCV mock-ups. The static loading and fatigue data will be generated in rigorous testing of these mock-ups. Successful tests are crucial to enabling the near-term impact of the developed storage technology on the CGH2 storage market, a critical component of the hydrogen production and delivery infrastructure. In particular, the SCCV has high potential for widespread deployment in hydrogen fueling stations.

Feng, Zhili [ORNL; Zhang, Wei [ORNL; Wang, Jy-An John [ORNL; Ren, Fei [ORNL

2012-09-01

435

Advanced Dependent Pressure Vessel (DPV) nickel-hydrogen spacecraft cell and battery design  

NASA Technical Reports Server (NTRS)

The dependent pressure vessel (DPV) nickel-hydrogen (NiH2) battery is being developed as a potential spacecraft battery design for both military and commercial satellites. Individual pressure vessel (IPV) NiH2 batteries are currently flying on more than 70 Earth orbital satellites and have accumulated more than 140,000,000 cell-hours in actual spacecraft operation. The limitations of standard NiH2 IPV flight battery technology are primarily related to the internal cell design and the battery packaging issues associated with grouping multiple cylindrical cells. The DPV cell design offers higher specific energy and reduced cost, while retaining the established IPV NiH2 technology flight heritage and database. The advanced cell design offers a more efficient mechanical, electrical and thermal cell configuration and a reduced parts count. The internal electrode stack is a prismatic flat-plate arrangement. The flat individual cell pressure vessel provides a maximum direct thermal path for removing heat from the electrode stack. The cell geometry also minimizes multiple-cell battery packaging constraints by using an established end-plateltie-rod battery design. A major design advantage is that the battery support structure is efficiently required to restrain only the force applied to a portion of the end cell. As the cells are stacked in series to achieve the desired system voltage, this increment of the total battery weight becomes small. The geometry of the DPV cell promotes compact, minimum volume packaging and places all cell terminals along the length of the battery. The resulting ability to minimize intercell wiring offers additional design simplicity and significant weight savings. The DPV battery design offers significant cost and weight savings advantages while providing minimal design risks. Cell and battery level design issues will be addressed including mechanical, electrical and thermal design aspects. A design performance analysis will be presented at both the cell and battery level. The DPV is capable of delivering up to 76 Watt-hours per kilogram (Wh/kg) at the cell level and 70 Wh/kg at the full battery level. This represents a 40 percent increase in specific energy at the cell level and a 60 percent increase in specific energy at the battery level compared to current IPV NiH2 technology.

Coates, Dwaine; Wright, Doug; Repplinger, Ron

1995-01-01

436

Study, Examinations, and Stress: Blood Pressure Assessments in College Students  

ERIC Educational Resources Information Center

The issue of stress associated with higher education and its impact on markers of student health is explored in three experiments looking at blood pressure levels in college students. All participants were full-time undergraduate students of psychology. In Experiment 1, academic fear of failure, assessed using psychometric testing, was found to be…

Hughes, Brian M.

2005-01-01

437

Neural Network Prediction of Failure of Damaged Composite Pressure Vessels from Strain Field Data Acquired by a Computer Vision Method  

NASA Technical Reports Server (NTRS)

This effort used a new and novel method of acquiring strains called Sub-pixel Digital Video Image Correlation (SDVIC) on impact damaged Kevlar/epoxy filament wound pressure vessels during a proof test. To predict the burst pressure, the hoop strain field distribution around the impact location from three vessels was used to train a neural network. The network was then tested on additional pressure vessels. Several variations on the network were tried. The best results were obtained using a single hidden layer. SDVIC is a fill-field non-contact computer vision technique which provides in-plane deformation and strain data over a load differential. This method was used to determine hoop and axial displacements, hoop and axial linear strains, the in-plane shear strains and rotations in the regions surrounding impact sites in filament wound pressure vessels (FWPV) during proof loading by internal pressurization. The relationship between these deformation measurement values and the remaining life of the pressure vessels, however, requires a complex theoretical model or numerical simulation. Both of these techniques are time consuming and complicated. Previous results using neural network methods had been successful in predicting the burst pressure for graphite/epoxy pressure vessels based upon acoustic emission (AE) measurements in similar tests. The neural network associates the character of the AE amplitude distribution, which depends upon the extent of impact damage, with the burst pressure. Similarly, higher amounts of impact damage are theorized to cause a higher amount of strain concentration in the damage effected zone at a given pressure and result in lower burst pressures. This relationship suggests that a neural network might be able to find an empirical relationship between the SDVIC strain field data and the burst pressure, analogous to the AE method, with greater speed and simplicity than theoretical or finite element modeling. The process of testing SDVIC neural network analysis and some encouraging preliminary results are presented in this paper. Details are given concerning the processing of SDVIC output data such that it may be used as back propagation neural network (BPNN) input data. The software written to perform this processing and the BPNN algorithm are also discussed. It will be shown that, with limited training, test results indicate an average error in burst pressure prediction of approximately six percent,

Russell, Samuel S.; Lansing, Matthew D.

1997-01-01

438

Vibration-based damage detection for filament wound pressure vessel filled with fluid  

NASA Astrophysics Data System (ADS)

Filament wound pressure vessels have been extensively used in industry and engineering. The existing damage detection and health monitoring methods for these vessels, such as X-ray and ultrasonic scan, can not meet the requirement of online damage detection; moreover optical grating fibre can only sense the local damage, but not the damage far away from the location of sensors. Vibration-based damage detection methods have the potential to meet such requirements. There methods are based on the fact that damages in a structure results in a change in structural dynamic characteristics. A damage detection method based on a residual associated with output-only subspace-based modal identification and global or focused chi^2-tests built on that residual has been proposed and successfully experimented on a variety of test cases. The purpose of this work is to describe the damage detection method and apply this method to assess the composite structure filled with fluid. The results of identification and damage detection will be presented.

Zhou, W.; Wu, Z.; Li, H.

2008-03-01

439

Pump and pressure vessel considerations for nuclear-heated steam rockets  

SciTech Connect

The purpose of this work is to estimate the pump and nuclear reactor pressure vessel masses for a reactor-type decision, between a pressurized water reactor (PWR) and a boiling water reactor (BWR). The main objective is to estimate pump performance, given that its mass must be limited to under 300 kg. The Lunar Prospector spacecraft found water ice at permanently shadowed, 80 K regions inside crater basins at the North and South Poles of the moon. Either a PWR or a BWR would power a nuclear-heated steam rocket, using water from the moon as propellant. A nuclear-heated steam rocket offers an exceptionally simple and presumably inexpensive system to shuttle people and payloads to and from the moon`s surface. Previous work determined the specific power required to develop sufficient thrust for liftoff: Each ton of nuclear rocket engine must deliver at least 150 MW into 1,100 K, or hotter, steam. The scaled pump mass (3,850 kg) for a PWR exceeds budget (300 kg). This implies that the PWR cannot be used unless pump-specific mass can be lowered by an order of magnitude. The scaled pump mass for a BWR would provide acceptable pressure (1.7 MPa).

Zuppero, A.C.; Richins, W.D. [Lockheed Martin Idaho Technologies, Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.

1998-09-01

440

Assemblies and methods for mitigating effects of reactor pressure vessel expansion  

DOEpatents

Support assemblies for allowing RPV radial expansion while simultaneously limiting horizontal, vertical, and azimuthal movement of the RPV within a nuclear reactor are described. In one embodiment, the support assembly includes a support block and a guide block. The support block includes a first portion and a second portion, and the first portion is rigidly coupled to the RPV adjacent the first portion. The guide block is rigidly coupled to a reactor pressure vessel support structure and includes a channel sized to receive the second portion of the support block. The second portion of the support block is positioned in the guide block channel to movably couple the guide block to the support block.

Challberg, Roy C. (Livermore, CA); Gou, Perng-Fei (Saratoga, CA); Chu, Cherk Lam (San Jose, CA); Oliver, Robert P. (Topsham, ME)

1999-01-01

441

Assemblies and methods for mitigating effects of reactor pressure vessel expansion  

DOEpatents

Support assemblies for allowing RPV radial expansion while simultaneously limiting horizontal, vertical, and azimuthal movement of the RPV within a nuclear reactor are described. In one embodiment, the support assembly includes a support block and a guide block. The support block includes a first portion and a second portion, and the first portion is rigidly coupled to the RPV adjacent the first portion. The guide block is rigidly coupled to a reactor pressure vessel support structure and includes a channel sized to receive the second portion of the support block. The second portion of the support block is positioned in the guide block channel to movably couple the guide block to the support block. 6 figs.

Challberg, R.C.; Gou, P.F.; Chu, C.L.; Oliver, R.P.

1999-07-27

442

Research and Development Roadmaps for Nondestructive Evaluation of Cables, Concrete, Reactor Pressure Vessels, and Piping Fatique  

SciTech Connect

To address these research needs, the MAaD Pathway supported a series of workshops in the summer of 2012 for the purpose of developing R&D roadmaps for enhancing the use of Nondestructive Evaluation (NDE) technologies and methodologies for detecting aging and degradation of materials and predicting the remaining useful life. The workshops were conducted to assess requirements and technical gaps related to applications of NDE for cables, concrete, reactor pressure vessels (RPV), and piping fatigue for extended reactor life. An overview of the outcomes of the workshops is presented here. Details of the workshop outcomes and proposed R&D also are available in the R&D roadmap documents cited in the bibliography and are available on the LWRS Program website (http://www.inl.gov/lwrs).

Clayton, Dwight A [ORNL] [ORNL; Bakhtiari, Sasan [Argonne National Laboratory (ANL)] [Argonne National Laboratory (ANL); Smith, Cyrus M [ORNL] [ORNL; Simmons, Kevin [Pacific Northwest National Laboratory (PNNL)] [Pacific Northwest National Laboratory (PNNL); Ramuhalli, Pradeep [Pacific Northwest National Laboratory (PNNL)] [Pacific Northwest National Laboratory (PNNL); Coble, Jamie [Pacific Northwest National Laboratory (PNNL)] [Pacific Northwest National Laboratory (PNNL); Brenchley, David [Pacific Northwest National Laboratory (PNNL)] [Pacific Northwest National Laboratory (PNNL); Meyer, Ryan [Pacific Northwest National Laboratory (PNNL)] [Pacific Northwest National Laboratory (PNNL)

2013-01-01

443

Reactor pressure vessel integrity research at the Oak Ridge National Laboratory  

SciTech Connect

Maintaining the integrity of the reactor pressure vessel (RPV) in a light-water-cooled nuclear power plant is crucial in preventing and controlling severe accidents that have the potential for major contamination release. The RPV is the only key safety-related component of the plant for which a duplicate or redundant backup system does not exist. It is therefore imperative to understand and be able to predict the integrity inherent in the RPV. For this reason, the U.S. Nuclear Regulatory Commission has established the related research programs at ORNL described herein to provide for the development and confirmation of the methods used for: (1) establishing the irradiation exposure conditions within the RPV in the Embrittlement Data Base and Dosimetry Evaluation Program, (2) assessing the effects of irradiation on the RPV materials in the Heavy-Section Steel Irradiation Program, and (3) developing overall structural and fracture analyses of RPVs in the Heavy-Section Steel Technology Program.

Corwin, W.R.; Pennell, W.E.; Pace, J.V.

1995-12-31

444

A Unified Cohesive Zone Approach to Model Ductile Brittle Transition in Reactor Pressure Vessel Steels  

SciTech Connect

In this study, a unified cohesive zone model has been proposed to predict, Ductile to Brittle Transition, DBT, in Reactor Pressure Vessel, RPV, steels. A general procedure is described to obtain the Cohesive Zone Model, CZM, parameters for the different temperatures and fracture probabilities. In order to establish the full master-curve, the procedure requires three calibration points with one at the upper-shelf for ductile fracture and two for the fracture probabilities, Pf, of 5% and 95% at the lower-shelf. In the current study, these calibrations were carried out by utilizing the experimental fracture toughness values and flow curves. After the calibration procedure, the simulations of fracture behavior (ranging from completely unstable to stable crack extension behavior) in one inch thick compact tension specimens at different temperatures yielded values that were comparable to the experimental fracture toughness values, indicating the viability of such unified modeling approach.

Pritam Chakraborty; S. Bulent Biner

2014-08-01

445

Carbon Resistor Pressure Gauge Calibration at Low Stresses  

SciTech Connect

The 470 Ohm carbon resistor gauge has been used in the stress range up to approximately 4-5 GPa for highly heterogeneous materials and/or divergent flow experiments. The attractiveness of the gauge is due to its rugged nature, simple construction, low cost, reproducibility, and survivability in dynamic events. The associated drawbacks are a long time response to pressure equilibration and gauge resistance hysteresis. In the range below 0.4 GPa, the gauge calibration has been mainly extrapolated into this regime. Because of the need for calibration data within this low stress regime, calibration experiments were performed using a split-Hopkinson bar, drop tower apparatus, and a gas pressure chamber. Since the performance of the gauge at elevated temperatures is a concern, the change in resistance due to heating at atmospheric pressure was also investigated. Details of the various calibration arrangements and the results will be discussed and compared a calibration curve fit to previously published calibration data.

Cunningham, B; Vandersall, K S; Niles, A M; Greenwood, D W; Garcia, F; Forbes, J W

2001-06-22

446

Spin Forming Aluminum Crew Module (CM) Metallic Aft Pressure Vessel Bulkhead (APVBH) - Phase II  

NASA Technical Reports Server (NTRS)

The principal focus of this project was to assist the Multi-Purpose Crew Vehicle (MPCV) program in developing a spin forming fabrication process for manufacture of the Orion crew module (CM) aft pressure vessel bulkhead. The spin forming process will enable a single piece aluminum (Al) alloy 2219 aft bulkhead resulting in the elimination of the current multiple piece welded construction, simplify CM fabrication, and lead to an enhanced design. Phase I (NASA TM-2014-218163, (1)) of this assessment explored spin forming the single-piece CM forward pressure vessel bulkhead. The MPCV Program and Lockheed Martin (LM) recently made two critical decisions relative to the NESC Phase I work scope: (1) LM selected the spin forming process to manufacture a singlepiece aft bulkhead for the Orion CM, and (2) the aft bulkhead will be manufactured from Al 2219. Based on the Program's new emphasis related to the spin forming process, the NESC was asked to conduct a Phase II assessment to assist in the LM manufacture of the aft bulkhead and to conduct a feasibility study into spin forming the Orion CM cone. This activity was approved on June 19, 2013. Dr. Robert Piascik, NASA Technical Fellow for Materials at the Langley Research Center (LaRC), was selected to lead this assessment. The project plan was approved by the NASA Engineering and Safety Center (NESC) Review Board (NRB) on July 18, 2013. The primary stakeholders for this assessment are the NASA and LM MPCV Program offices. Additional benefactors are commercial launch providers developing CM concepts.

Hoffman, Eric K.; Domack, Marcia S.; Torres, Pablo D.; McGill, Preston B.; Tayon, Wesley A.; Bennett, Jay E.; Murphy, Joseph T.

2015-01-01

447

Integrated use of design aspects of new ASME pressure vessel code with requalification aspects of the ASME High Pressure Systems Standard  

SciTech Connect

This paper implements various procedures in the design articles of the proposed ASME BPV Section VIII, Division 3 to re-evaluate the compound shell of a 15 year old large hot isostatic high pressure vessel. The analysis then is subjected to the requalification procedures of the ASME High Pressure Systems Standard (HPS-1994) to create an updated periodic examination program. The purpose of the paper is to show how the two codes mesh for either new or existing vessels to provide rational guidance for obtaining optimum cyclic service performance.

Fryer, D.M. [High Pressure Engineering and Safety, Fairview, PA (United States); Aggarwal, M.C. [Gannon Univ., Erie, PA (United States). Mechanical Engineering Dept.