Verifying Structural Integrity of Repaired Cylindrical Pressure Vessels by Partitioning Method

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Husain J. Al-Gahtani ◽  
Mahmoud Naffa'a
Keyword(s):  
Pressure Vessel ◽  
Structural Integrity ◽  
Welded Joint ◽  
Test Validity ◽  
Pressure Vessels ◽  
Testing Method ◽  
State Of Stress ◽  
Cylindrical Pressure Vessel ◽  
Pressure Test ◽  
Alternative Test

Pressure vessels that undergo repairs are normally pressure tested to verify their structural integrity before returning into service. Conventionally, the entire vessel is pressure tested, according to the relevant construction code. In this paper, partitioning the pressure vessel is suggested as an equivalent alternative test arrangement, where pressure testing is limited to the zone where a repair has been performed. Use of such an arrangement would alleviate potential concerns associated with the conventional testing method. Procedures are provided to specify the position of the partition relative to the repair location, in order to maintain the state-of-stress to that achieved in a conventional pressure test. Validity of this approach has been demonstrated for a repaired full-circumferential welded joint in the wall of a cylindrical pressure vessel.

Constraint-Dependent J-R Curves of a Dissimilar Metal Welded Joint for Connecting Pipe-Nozzle of Nuclear Pressure Vessel

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
J. Wang ◽  
G. Z. Wang ◽  
F. Z. Xuan ◽  
S. T. Tu
Keyword(s):  
Pressure Vessel ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Welded Joint ◽  
Pressure Vessels ◽  
Stress Constraint ◽  
Dissimilar Metal ◽  
Local Strength ◽  
T Stress

In this paper, the J-R curves of two cracks (A508 HAZ crack 2 and A508/Alloy52Mb interface crack 3) located at the weakest region in an Alloy52M dissimilar metal welded joint (DMWJ) for connecting pipe-nozzle of nuclear pressure vessel have been measured by using single edge-notched bend (SENB) specimens with different crack depths a/W (different constraint). Based on the modified T-stress constraint parameter τ*, the equations of constraint-dependent J-R curves for the crack 2 and crack 3 were obtained. The predicted J-R curves using different constraint equations derived from the three pairs of crack growth amount all agree with the experimental J-R curves. The results show that the modified T-stress approach for obtaining constraint-dependent J-R curves of homogeneous materials can also be used for the DMWJs with highly heterogeneous mechanical properties (local strength mismatches) in nuclear power plants. The use of the constraint-dependent J-R curves may increase the accuracy of structural integrity design and assessment for the DMWJs of nuclear pressure vessels.

To Analyze the Effects of Geometric Misalignment in a Cylindrical Pressure Vessel

2012 ◽  
Vol 152-154 ◽  
pp. 964-969 ◽  
Author(s):  
Musharaf Abbas ◽  
Asif Israr ◽  
Atiq Ur Rehman
Keyword(s):  
Finite Element ◽  
Alloy Steel ◽  
Pressure Vessel ◽  
Structural Integrity ◽  
High Strength ◽  
Fe Analysis ◽  
Low Alloy Steel ◽  
Affected Area ◽  
Cylindrical Pressure Vessel ◽  
Geometrical Effects

This particular work consider a pressurized vessel typically made of high strength low alloy steel and containing the geometric misalignment at the cylinder-to-cylinder junction. This misalignment produce in the vessel’s structure is because of girth weld that is evident in most of the fabrication of such type of structures apart from other factors which is beyond the scope of this study. This study evaluates the geometrical effects of mismatch on the structural integrity of the pressure vessel and prediction of stresses at the affected area of the cylinder. Analytical and Finite Element (FE) approaches are employed to analyze the configuration. FE analysis is performed by the use of ANSYS on one quarter of the structure due to symmetry. FE results are also compared with the analytical results of different authors. In addition, maximum allowable mismatch is also determined and is a part of this study.

Pneumatic Test of Pressurised Equipment: Its Hazards and Alternatives

2018 ◽  
Author(s):  
Kaveh Ebrahimi ◽  
Saeid Rahimi Mofrad
Keyword(s):  
Shock Waves ◽  
Liquid Medium ◽  
Pressure Vessel ◽  
Alternative Methods ◽  
Design Codes ◽  
Pressure Testing ◽  
Cylindrical Pressure Vessel ◽  
Pressure Test ◽  
Extreme Hazards ◽  
Methodological Assessment

Pressure testing of pressurised equipment is crucial in establishing confidence that it is capable of performing the duty for which it has been designed and fabricated. A pressure test is usually mandated by pressurised equipment design codes for newly fabricated equipment. Also many regulations or industry codes for the design and fabrication of pressurised equipment require that a pressure test is performed on any modified in-service pressurized equipment to verify that the integrity of the equipment has not been compromised after such modifications. Although the usual and normally the preferred method of pressure testing is conducting a full hydrostatic test on the entire equipment (i.e. using a liquid medium, typically water), there may be occasions that a hydrostatic test is simply not practical. As an alternative to a full hydrostatic test, the designer may consider performing a localized pressure test or sometimes a full pneumatic test on modified equipment. It must be emphasized that a full pneumatic test can create extreme hazards to a facility and nearby personnel and therefore needs a careful and methodological assessment prior to being attempted on any equipment. This article is structured primarily as an attempt to assist the organizations in charge of design and inspection of newly fabricated or in-service equipment to identify general hazards associated with pneumatic test of pressurised equipment in a structured manner. An analysis of a simple cylindrical pressure vessel is presented to provide a better understanding of hazards associated with pneumatic test. Two tables in the paper provide the recommended exclusion zones from the equipment being pneumatically tested in order to reduce hazards associated with shock waves and/or projectile fragments. The paper also briefly explains alternative methods of testing in lieu of a full hydrostatic or pneumatic test. [1, 2]

Kendall Analysis of Cannon Pressure Vessels

2012 ◽  
Author(s):  
John H. Underwood
Keyword(s):  
Fatigue Life ◽  
Yield Strength ◽  
Pressure Vessel ◽  
Structural Integrity ◽  
Pressure Vessels ◽  
Full Scale ◽  
Compressive Yield Strength ◽  
Us Army ◽  
Post Test ◽  
Engineering Mechanics

Engineering mechanics analysis of cannon pressure vessels is described with special emphasis on the work of the late US Army Benet Laboratories engineer David P. Kendall. His work encompassed a broad range of design and analysis of high pressure vessels for use as cannons, including analysis of the limiting yield pressure for vessels, the autofrettage process applied to thick vessels, and the fatigue life of autofrettaged cannon vessels. Mr. Kendall’s work has become the standard approach used to analyze the structural integrity of cannon pressure vessels at the US Army Benet Laboratories. The methods used by Kendall in analysis of pressure vessels were simple and direct. He used classic results from research in engineering mechanics to develop descriptive expressions for limiting pressure, autofrettage residual stresses and fatigue life of cannon pressure vessels. Then he checked the expressions against the results of full-scale cannon pressure vessel tests in the proving grounds and the laboratory. Three types of analysis are described: [i] Yield pressure tests of cannon sections compared with a yield pressure expression, including in the comparison post-test yield strength measurements from appropriate locations of the cannon sections; [ii] Autofrettage hoop residual stress measurements by neutron diffraction in cannon sections compared with expressions, including Bauschinger corrections in the expressions to account for the reduction in compressive yield strength near the bore of an autofrettaged vessel; [iii] Fatigue life tests of cannons following proving ground firing and subsequent laboratory simulated firing compared with Paris-based fatigue life expressions that include post-test metallographic determination of the initial crack size due to firing. Procedures are proposed for Paris life calculations for bore-initiated fatigue affected by crack-face pressure and notch-initiated cracking in which notch tip stresses are significantly above the material yield strength. The expressions developed by Kendall and compared with full-scale cannon pressure vessel tests provide useful first-order design and safety checks for pressure vessels, to be followed by further engineering analysis and service simulation testing as appropriate for the application. Expressions are summarized that are intended for initial design calculations of yield pressure, autofrettage stresses and fatigue life for pressure vessels. Example calculations with these expressions are described for a hypothetical pressure vessel.

Thermomechanical Creep Analysis of FGM Thick Cylindrical Pressure Vessels with Variable Thickness

2018 ◽  
Vol 10 (01) ◽  
pp. 1850008 ◽  
Author(s):  
Mosayeb Davoudi Kashkoli ◽  
Khosro Naderan Tahan ◽  
Mohammad Zamani Nejad
Keyword(s):  
Temperature Gradient ◽  
Differential Equations ◽  
Variable Thickness ◽  
Pressure Vessel ◽  
Shear Deformation Theory ◽  
Pressure Vessels ◽  
Mechanical And Thermal Properties ◽  
Creep Response ◽  
Cylindrical Pressure Vessel ◽  
Creep Analysis

In the present study, a theoretical solution for thermomechanical creep analysis of functionally graded (FG) thick cylindrical pressure vessel with variable thickness based on the first-order shear deformation theory (FSDT) and multilayer method (MLM) is presented. To the best of the researchers’ knowledge, in the literature, there is no study carried out into FSDT and MLM for creep response of cylindrical pressure vessels with variable thickness under thermal and mechanical loadings. The vessel is subjected to a temperature gradient and nonuniform internal pressure. All mechanical and thermal properties except Poisson’s ratio are assumed to vary along the thickness direction based on a power-law function. The thermomechanical creep response of the material is described by Norton’s law. The virtual work principle is applied to extract the nonhomogeneous differential equations system with variable coefficients. Using the MLM, this differential equations system is converted into a system of differential equations with constant coefficients. These set of differential equations are solved analytically by applying boundary and continuity conditions between the layers. In order to verify the results of this study, the finite element method (FEM) has been used and according to the results, good agreement has been achieved. It can be concluded that the temperature gradient has significant influence on the creep responses of FG thick cylindrical pressure vessel.

Probabilistic Structural Integrity Evaluation on a Pressurized Water Reactor Pressure Vessel Under Pressure–Temperature Limit Operations

2015 ◽  
Author(s):  
Hsoung-Wei Chou ◽  
Chin-Cheng Huang
Keyword(s):  
Fracture Toughness ◽  
Pressure Vessel ◽  
Structural Integrity ◽  
Temperature Limit ◽  
Pressure Vessels ◽  
Pressurized Water Reactor ◽  
Operational Flexibility ◽  
Pressurized Water ◽  
Water Reactor ◽  
Reactor Pressure

The normal reactor startup (heat-up) and shut-down (cool-down) operation limits are defined by the ASME Code Section XI-Appendix G, to ensure the structural integrity of the embrittled nuclear reactor pressure vessels (RPVs). In the paper, the failure risks of a Taiwan domestic pressurized water reactor (PWR) pressure vessel under various pressure-temperature limit operations are analyzed. Three types of pressure-temperature limit curves established by different methodologies, which are the current operation limits of the domestic RPV based on the KIa fracture toughness curve in 1998 or earlier editions of ASME Section XI-Appendix G, the recently proposed limits according to the KIC fracture toughness curve after the 2001 edition of ASME Section XI-Appendix G, and the risk-informed revision method proposed in MRP-250 report that provides more operational flexibility, are considered. The ORNL’s probabilistic fracture mechanics code, FAVOR, is employed to perform a series of fracture probability analyses for the RPV at multiple levels of embrittlement under such pressure-temperature limit transients. The analysis results indicate that the pressure-temperature operation limits associated with more operational flexibility will result in higher failure risks to the RPV. The shallow inner surface breaking flaw due to the clad fabrication defect is the most critical factor and dominates the failure risk of the RPV under pressure-temperature limit operations. Present work can provide a risk-informed reference for the safe operation and regulation of PWRs in Taiwan.

Comparison of Pressure-Temperature Limits for a Pressurized Water Reactor Pressure Vessel Considering Beltline and Extended Beltline Regions

2018 ◽  
Author(s):  
Hsoung-Wei Chou ◽  
Yu-Yu Shen ◽  
Chin-Cheng Huang
Keyword(s):  
Pressure Vessel ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Reference Temperature ◽  
Regulatory Body ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Reactor Pressure

To ensure the structural integrity of the embrittled reactor pressure vessels (RPVs) during startup or shutdown operation, the pressure-temperature (P-T) limits are mainly determined by the fracture toughness of beltline region material with the highest level of neutron embrittlement. However, other vessel parts such as nozzles with structural discontinuities may affect the limits due to the higher stress concentration, even though the neutron embrittlement is insignificant. Therefore, not only beltline material with the highest reference temperature, but also other components with structural discontinuities have to be considered for the development of P-T limits of RPV. In the paper, the pressure-temperature operational limits of a Taiwan domestic pressurized water reactor (PWR) pressure vessel considering beltline and extended beltline regions are established per the procedure of ASME Code Section XI-Appendix G. The three-dimensional finite element models of PWR inlet and outlet nozzles above the beltline region are also built to analyze the pressure and thermal stress distributions for P-T limits calculation. The analysis results indicate that the cool-down P-T limit of the domestic PWR vessel is still dominated by the beltline region, but the heat-up limit is partially controlled by the extended beltline region. On the other hand, the relations of reference temperature between nozzles and beltline region on the P-T limits are also discussed. Present work could be a reference for the regulatory body and is also helpful for safe operation of PWRs in Taiwan.

scholarly journals Numerical Analysis of Filament Wound Cylindrical Composite Pressure Vessels Accounting for Variable Dome Contour

2021 ◽  
Vol 5 (2) ◽  
pp. 56
Author(s):  
Kumar C. Jois ◽  
Marcus Welsh ◽  
Thomas Gries ◽  
Johannes Sackmann
Keyword(s):  
Stress Distribution ◽  
Pressure Vessel ◽  
Single Layer ◽  
Pressure Vessels ◽  
Filament Wound ◽  
Cylindrical Pressure Vessel ◽  
Composite Pressure Vessel ◽  
Polymer Liner ◽  
Specific Distance ◽  
Composite Pressure Vessels

In this work, the stress distribution along cylindrical composite pressure vessels with different dome geometries is investigated. The dome contours are generated through an integral method based on shell stresses. Here, the influence of each dome contour on the stress distribution at the interface of the dome-cylinder is evaluated. At first, the integral formulation for dome curve generation is presented and solved for the different dome contours. An analytical approach for the calculation of the secondary stresses in a cylindrical pressure vessel is introduced. For the analysis, three different cases were investigated: (i) a polymer liner; (ii) a single layer of carbon-epoxy composite wrapped on a polymer liner; and (iii) multilayer carbon-epoxy pressure vessel. Accounting for nonlinear geometry is seen to have an effect on the stress distribution on the pressure vessel, also on the isotropic liner. Significant secondary stresses were observed at the dome-cylinder interface and they reach a maximum at a specific distance from the interface. A discussion on the trend in these stresses is presented. The numerical results are compared with the experimental results of the multilayer pressure vessel. It is observed that the secondary stresses present in the vicinity of the dome-cylinder interface has a significant effect on the failure mechanism, especially for thick walled cylindrical composite pressure vessel. It is critical that these secondary stresses are directly accounted for in the initial design phase.

Stress Analysis and Optimization Design of Pressure Vessel of Underwater Gamma Spectrometer

2014 ◽  
Vol 518 ◽  
pp. 275-278
Author(s):  
Feng Gao ◽  
Jian Guo Zhang ◽  
Fang Fang Yang
Keyword(s):  
Photon Energy ◽  
Pressure Vessel ◽  
Optimization Design ◽  
Detection Efficiency ◽  
Side Wall ◽  
Pressure Vessels ◽  
Monte Carlo Code ◽  
Gamma Spectrometer ◽  
Cylindrical Pressure Vessel ◽  
The Impact

Pressure vessel makes the underwater gamma spectrometer can operation in underwater environment. In this paper, a kind of cylindrical pressure vessel has been simulated and analyzed using CAD software named Solidworks. Analysis results show the end covers are much thicker than the side wall to satisfy the same design safety factor and the centers of the end covers are the stress concentration areas. Further more, a 2× 2 LaBr3: Ce scintillation detector and a series of pressure vessels with various design safety factors and same inner space have been simulated by Monte Carlo code MCNP. Calculation indicates that the thicker the shell, the lower the detection efficiency. Further more, calculation shows the impact of the pressure vessel on detection efficiency of underwater gamma spectrometer varies with the photon energy. The law is that the higher the photon energy, the lower the influence on the detection efficiency.

Sign in / Sign up

Export Citation Format

Share Document