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research-article  
Masanori Ando, Hiroki Yada, Kazuyuki Tsukimori, Masakazu Ichimiya and Yoshinari Anoda
J. Pressure Vessel Technol   doi: 10.1115/1.4037564
Bellows structure is used to absorb the thermal expansion maintaining the boundary of the inside to outside, and it is applied to constitute the containment vessel boundary of the nuclear power plant. In this study, in order to develop the evaluation method of the ultimate pressure of the bellows structure subject to the internal pressure beyond the specified, the failure test and finite element analysis (FEA) of the bellows structure were performed. The failure modes were demonstrated through the test of five and six specimens with six and five convolutions, respectively. Water leakage was caused by contact of the expanded convolution and the neighbor structure in the specimens with the shipping rod mounts. On the other hand, local failure and ductile failure were observed in the specimen without shipping rod mounts. The maximum pressures in the test observed local and ductile failure were over 10 times larger than the estimated values of the limited design pressure for in-plane instability by the EJMA standard. To simulate the buckling and deformation behavior during the test, the implicit and explicit analyses were performed. Because the inversion of the convolution accompanied convolution contact observed in the test was too difficult problem for implicit analysis, the maximum pressures in the step of solution converged were compared to the maximum pressures in the tests. On the other hand, explicit analysis enabled to simulate the complex deformation during the test and the results were evaluated considering ductile failure to compare the test results.
research-article  
Weijie Shi, Shuping Cao, Xiaohui Luo, Zuti Zhang and Yuquan Zhu
J. Pressure Vessel Technol   doi: 10.1115/1.4037443
A water hydraulic throttle valve is often used to control the water flow in piping systems. When the water flows through the valve port, cavitation occurs frequently because of the high pressure drop across the valve. The cavitation can lead to wear, vibration and noise. To solve the problem, a modified throttle valve with a drainage device is proposed to suppress the cavitation. A contrasting test was conducted to analyze the effect of drainage device on the cavitation suppression. For evaluating the influence of inlet pressure and outlet pressure on the ability of the drainage device to suppress cavitation, the power spectrum density (PSD), normalized intensity, and cavitation suppression coefficient (CSC) of dynamic pressure are introduced. The results indicate that adopting the drainage device is a feasible method to suppress cavitation. In addition, the inlet pressure and outlet pressure have a great influence on the capacity for cavitation suppression of the drainage device (CCSDD) by changing the intensity of cavitation. When the inlet pressure is at 4.0MPa, the cavitation is generated and the CCSDD is weak. With increasing inlet pressure, the intensity of cavitation and CCSDD is gradually enhanced. But when the inlet pressure increases to 7.0 MPa, the cavitation is saturated and the cavitation suppression by the drainage device begins to decrease. On the other hand, the effect of cavitation suppression decreases significantly when the outlet pressure increases from 1.4MPa to 3.8 MPa.
TOPICS: Cavitation, Valves, Water, Pressure, Drainage, Flow (Dynamics), Wear, Density, Vibration, Piping systems, High pressure (Physics), Noise (Sound)
research-article  
Mohsen Jabbari, Seyedeh Matin Mousavi and Mohammad Amin Kiani
J. Pressure Vessel Technol   doi: 10.1115/1.4037444
In this paper, an analytical method is developed to obtain the solution for the two-dimensional (? ,?( transient thermal and mechanical stresses in a hollow sphere made of functionally graded material and piezoelectric layers. The functionally graded material properties vary continuously across the thickness, according to the power functions of radial direction. The temperature distribution as function of radial and circumferential directions and time, is obtained solving the energy equation, using the method of separation of variables and Legendre series. The Navier equations are solved analytically using the Legendre polynomials and the system of Euler differential equations.
TOPICS: Stress, Transients (Dynamics), Thermomechanics, Functionally graded materials, Polynomials, Temperature distribution, Differential equations, Separation (Technology)
research-article  
M. Clyde Zondi, Andrew Venter, Deon Marais and Clinton Bemont
J. Pressure Vessel Technol   doi: 10.1115/1.4037445
Pressure vessels comprise critical plant equipment within industrial operations. The fact that the vessel operates under pressure, and may carry toxic, dangerous or hazardous contents, necessitates that care is taken to ensure safety of humans operating it and the environment within which it operates. Residual stress developed during welding of pressure vessel structures adversely affects fatigue life of such structure by reducing fracture toughness. The present study applies the Neutron Diffraction technique to formulate the stress field distribution of a nozzle-to-shell weld joint of a pressure vessel. A number of experiments are conducted using the Submerged Arc Welding (SAW) process at various parametric combinations to develop a number of specimens with different stress profiles. It is shown that the hoop stresses close to the weld centre line (WCL) are highly tensile and have values close to the yield strength of the material. The ideal parametric combination is also determined based on the results with lowest stresses. The results obtained in this study are congruent to the results of similar studies in literature.
TOPICS: Welding, Stress, Neutron diffraction, Pressure vessels, Pressure, Safety, Arc welding, Nozzles, Fatigue life, Fracture toughness, Shells, Vessels, Yield strength, Hoop stress
research-article  
Kouichi Maruyama, Nobuaki Sekido and Kyosuke Yoshimi
J. Pressure Vessel Technol   doi: 10.1115/1.4037446
Predictions as to 105 hrs creep rupture strength of grade 91 steel have been made recently. The predicted values are examined with long-term creep rupture data of the steel. Three creep rupture databases were used in the predictions: data of tube products of grade 91 steel reported in NIMS Creep Data Sheet (NIMS T91 database), data of T91 steel collected in Japan, and data of grade 91 steel collected by an ASME code committee. Short-term creep rupture data points were discarded by the following criteria for minimizing overestimation of the strength: selecting long-term data points with low activation energy (multiregion analysis), selecting data points crept at stresses lower than a half of proof stress (?0.2/2 criterion), and selecting data points longer than 1000 hrs (cut-off time of 1000 hrs). In the case of NIMS T91 database, a time-temperature parameter (TTP) analysis of a dataset selected by multiregion analysis can properly describe the long-term data points and gives the creep rupture strength of 68 MPa at 600 oC. However, TTP analyses of datasets selected by ?0.2/2 criterion and cut-off time of 1000 hrs from the same database overestimate the data points and predict the strength over 80 MPa. Datasets selected by the same criterion from the three databases provide similar values of the strength. The different criteria for data selection have more substantial effects on predicted values of the strength of the steel than difference of the databases.
TOPICS: Creep, Steel, Rupture, Databases, Stress, Temperature, ASME Standards
Technology Review  
Kyle Gough and Daniel Peters
J. Pressure Vessel Technol   doi: 10.1115/1.4037197
Layered vessels have been in-service for many years which use layered construction. This construction technique has been employed since the 1930's. This generally involved either concentric plates or spirally wrapped plates to manufacture vessels with thick walls that otherwise would require very thick and heavy forgings. Long term asset management of these vessels, including non-destructive evaluation of the vessels welds and life assessment of the vessels due to operational cycling the vessels experience can be challenging. This paper is meant to address some of the challenges in managing these critical assets and provide a discussion on the application of state of the art techniques which are being applied today.
TOPICS: Design, Vessels, Fitness-for-service, Plates (structures), Construction, Nondestructive evaluation, Forgings (Products), Welded joints
research-article  
Majid Khayat, Davood Poorveis and Shapour Moradi
J. Pressure Vessel Technol   doi: 10.1115/1.4037042
Linearized buckling analysis of functionally graded shells of revolution subjected to displacement dependent pressure which remain normal to the shell middle surface throughout the deformation process is described in this work. Material properties are assumed to be temperature dependent, and varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The governing equations are derived based on first-order shear deformation theory which accounts for through thickness shear flexibility with Sanders-type of kinematic nonlinearity. Displacements and rotations in the shell middle surface are approximated by combining polynomial functions in the meridional direction and truncated Fourier series with an appropriate number of harmonic terms in the circumferential direction. The load stiffness matrix which accounts for variation of load direction derived for each strip and after assembling global load stiffness matrix of the shell which may be un-symmetric is formed. The un-symmetric parts which are due to load non-uniformity and unconstrained boundaries have been separated. The results indicate that considering pressure stiffness causes buckling pressure reduction. A detailed numerical study is carried out to bring out the effects of power-law index of functional graded material and geometry of the shell on the effect of follower action of lateral pressure on buckling load diminishes.
TOPICS: Pressure, Buckling, Displacement, Functionally graded materials, Shells, Stress, Stiffness, Strips, Kinematics, Geometry, Polynomials, Shear deformation, Shear (Mechanics), Materials properties, Fourier series, Deformation, Temperature, Metals, Ceramics
research-article  
Maria Vathi, Spyros A. Karamanos, Ioannis A. Kapogiannis and Konstantinos V. Spiliopoulos
J. Pressure Vessel Technol   doi: 10.1115/1.4036916
In the present paper, performance criteria for the seismic design of industrial liquid storage tanks and piping systems are proposed, aimed at defining a performance-based design framework, to be used for reliable development of fragility curves and assessment of seismic risk. Considering “loss of containment” as the ultimate damage state, the proposed performance limits are quantified in terms of local quantities obtained from a simple and efficient earthquake analysis. Liquid storage tanks and the corresponding principal failure modes (elephant’s foot buckling, roof damage, base plate failure, anchorage failure and nozzle damage) are examined first. Subsequently, performance limits for piping systems are presented in terms of local strain at specific piping components (elbows, Tees and nozzles), against ultimate strain capacity (tensile and compressive) and low-cycle fatigue. Modeling issues for liquid storage tanks and piping systems are also discussed, for simple and efficient analysis that provides reliable estimates of local strain demand. These models are compared successfully with available experimental data. Using the above reliable numerical models, the proposed performance limits are applied in two case studies: (a) a liquid storage tank and (b) a piping system, both located in areas of high seismicity.
TOPICS: Piping systems, Storage tanks, Damage, Failure, Nozzles, Pipes, Buckling, Earthquakes, Computer simulation, Earthquake resistant design, Anchorage, Design, Failure mechanisms, Modeling, Low cycle fatigue, Roofs, Containment, Earthquake risk
research-article  
DEEPESH V, Krishnan Balasubramaniam and Prabhu Rajagopal
J. Pressure Vessel Technol   doi: 10.1115/1.4036852
Interaction of fundamental torsional ultrasonic pipe guided mode T (0, 1) from defects caused by Induction Pressure Welding (IPW) process is studied using 3-D Finite Element (FE) analysis validated by experiments. Defects are assumed as cross-sectional notches along the weld bond-line, and both surface-breaking and embedded features are considered. Results show that T (0, 1) mode reflection from weld defects is strongly influenced by features of the weld itself. However, with supplementary results such as the mode-converted flexural F (1, 3) and F (1, 2) modes and circumferential variation of T (0, 1) reflection, there is potential for an effective screening solution.
TOPICS: Pressure, Electromagnetic induction, Welding, Bonding, Reflection, Waves, Finite element analysis, Pipes
Review Article  
Omesh K. Chopra, Gary L. Stevens, Robert Tregoning and A. S. Rao
J. Pressure Vessel Technol   doi: 10.1115/1.4035885
The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) provides rules for the design of Class 1 components of nuclear power plants. However, the Code design curves do not address the effects of light water reactor (LWR) water environments. Existing fatigue strain-vs.-life (e-N) data illustrate significant effects of LWR water environments on the fatigue resistance of pressure vessel and piping steels. Extensive studies have been conducted at Argonne National Laboratory and elsewhere to investigate the effects of LWR environments on the fatigue life. This article summarizes the results of these studies. Existing fatigue e-N data were evaluated to identify the various material, environmental, and loading conditions that influence fatigue crack initiation; a methodology for estimating fatigue lives as a function of these parameters was developed. The effects were incorporated into the ASME Code Section III fatigue evaluations in terms of an environmental correction factor, Fen, which is the ratio of fatigue life in air at room temperature to the life in the LWR water environment at reactor operating temperatures. Available fatigue data were used to develop fatigue design curves for carbon and low-alloy steels, austenitic stainless steels, and nickel-chromium-iron (Ni-Cr-Fe) alloys and their weld metals. A review of the Code Section III fatigue adjustment factors of 2 and 20 is also presented and the possible conservatism inherent in the choice is evaluated. A brief description of potential effects of neutron irradiation on fatigue crack initiation is presented.
TOPICS: Fatigue life, Water, Light water reactors, Fatigue, Alloys, Steel, Design, Fatigue cracks, Fatigue design, Pipes, ASME Boiler and Pressure Vessel Code, Iron, Nuclear power stations, Stainless steel, Pressure vessels, Irradiation (Radiation exposure), ASME, Carbon, Temperature, Neutrons, Metals, Nickel, ASME Standards, Operating temperature

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