Accepted Manuscripts

Nima Mohajer Rahbari, Mengying Xia, Xiaoben Liu, J.J. Roger Cheng, Millan Sen and Samer Adeeb
J. Pressure Vessel Technol   doi: 10.1115/1.4041198
In service pipelines exhibit bending loads in a variety of in-field situation. These bending loads can induce large longitudinal strains, which may trigger local buckling on pipe's compressive side and/or lead to rupture of the pipe's tensile side. In this article, the post-buckling failure modes of pressurized X65 steel pipelines under monotonic bending loading conditions are studied via both experimental and numerical investigations. Through the performed full-scale bending test, it is shown that that the post-buckling rupture is only plausible to occur in the pipe wall on the tensile side of the wrinkled cross-section under the increased bending, no fracture failure appears for the investigated specimens. Based on the experimental results, a finite element based numerical model with a calibrated cumulative fracture criterion was proposed to conduct a parametric analysis on the effects of the internal pressure on pipe's failure modes. The results show that, the internal pressure is the most crucial variable that controls the ultimate failure mode of a wrinkled pipeline under monotonic bending load. And the post-buckling rupture of tensile wall can only be reached in highly pressurized pipes (hoop stress no less than 70% SMYS for the investigated X65 pipe). That is, no post-wrinkling rupture is likely to happen below a certain critical internal pressure even after an abrupt distortion of the wrinkled wall on the compressive side of the cross-section.
TOPICS: Steel, Failure mechanisms, Pipes, Buckling, Rupture, Pipelines, Pressure, Stress, Fracture (Materials), Fracture (Process), Finite element analysis, Computer simulation, Hoop stress, Failure
Ashley D Elizondo and Robert Iacovone, III
J. Pressure Vessel Technol   doi: 10.1115/1.4041056
Protective suits are worn by personnel working in contaminated environments at the Savannah River Site (SRS) in Aiken, South Carolina. These suits require that cooling be applied to keep the interior temperature within safe and comfortable limits. A vortex tube, also known as the Ranque-Hilsch vortex tube, can provide the necessary cooling. As mechanical devices void of moving components, vortex tubes separate a compressed gas into hot and cold streams; the air emerging from the "hot" end reaching a temperature of 433.2 K, and the air emerging from the "cold" end reaching a temperature of 241.5 K [1]. Routing the cold stream of the vortex tube to the user's protective suit facilitates the required cooling. Vortex tubes currently in use at SRS are pre-set, through sole modification by and within the SRS Respiratory Equipment Facility (REF), to provide a temperature reduction between 22.2 and 25.0 K. When a new model of vortex tube capable of user adjustment during operation recently became available, prototype testing was conducted for product comparison. Similar cooling performance between the old and new models is achievable. Implementing the use of the new model of vortex tube at SRS will result in significant cost savings because the product could be shipped directly to the end user, circumventing adjustment by the REF. Production units were acquired to be subjected to complete product analysis at SRS utilizing a statistical test plan. The statistical test plan, data, thermodynamic calculations, and conclusions were reviewed.
TOPICS: Cooling, Vortices, Performance evaluation, Respirators, Temperature, Rivers, Engineering prototypes, Testing
Junya Miura, Terutaka Fujioka and Yasuhiro Shindo
J. Pressure Vessel Technol   doi: 10.1115/1.4041057
This paper proposes simplified methods to evaluate fatigue damage in a component subjected to cyclic thermal loads to visualize damage distribution by using typical CAE systems. The objective is to perform the evaluations on a standard desktop PC within a reasonably short computation time. Three simplified methods for defining elastic stress ranges are proposed in place of the method in the ASME Subsection NH procedures. A thermal fatigue test that was previously performed using a type-304 stainless steel (304SS) cylinder is simulated to validate the proposed methods. Heat transfer and elastic analyses are conducted. Simultaneously with the analyses, fatigue usage factors are calculated using user subroutines formulated in this study, including the three simplified methods and the ASME NH-based method. The calculated values of the fatigue usage factor are visualized using a graphical user interface (GUI) incorporated into a commercial finite-element analysis (FEA) code. The fatigue usage factor distribution obtained using the simplified methods could be calculated without requiring large amounts of memory and long computation time. In addition, the distribution of the fatigue usage factor was consistent with the distribution of cracks observed in the test.
TOPICS: Stress, Fatigue damage, Visualization, Fatigue, Computation, Graphical user interfaces, Finite element analysis, Damage, Cylinders, Heat transfer, Computer-aided engineering, Stress analysis (Engineering), Fracture (Materials), Fatigue testing, Stainless steel, Elastic analysis
Hongsong Zhu and Jinguo Zhai
J. Pressure Vessel Technol   doi: 10.1115/1.4041059
Based on the unified and refined analytical (URA)method of stress analysis for fixed tubesheet (TS) heat exchangers (HEXs), floating head and U-tube HEXs presented in Part I and Part II, the applicable configuration of HEX which depends on the combination of the TS edge conditions is discussed in this paper as Part III. Comparison shows that the unified method covers a wide range of HEX configurations well beyond established ASME methods.
TOPICS: Stress analysis (Engineering), Heat exchangers
Weiya Jin, Yuebing Li, Mingjue Zhou and Zengliang Gao
J. Pressure Vessel Technol   doi: 10.1115/1.4041060
A new integrity pressure relief device in a non-refillable steel gas cylinder is proposed and tested. Instead of a rupture disc welded on the opening of the head, the new integrity pressure relief device is machined by stamping a circular groove on the vessel head, which not only avoids an additional penetration on the head but also reduces the manufacture cost. To ensure the safety and reliability of the device, its performance is evaluated using a reliability method based on material properties and burst pressure. The effect of stamping pressure on the groove depth is investigated, and then, the material properties taken from different locations are tested. Tensile properties taken along the circumferential direction of the cylinder are suggested to be used to predict burst pressure of the new integrity pressure relief device. The tolerance of the burst pressure in a percentage is analyzed, and a probabilistic model is built. The reliability analysis shows the batch of cylinders with the integrity pressure relief device has a very high qualified probability.
TOPICS: Steel, Reliability, Gas cylinders, Pressure relief devices, Pressure, Materials properties, Cylinders, Metal stamping, Probability, Rupture, Tensile strength, Vessels, Event history analysis, Safety, Disks
Review Article  
Reza Adibi-Asl and R. Seshadri
J. Pressure Vessel Technol   doi: 10.1115/1.4041058
This paper reviews the literature on variational method in limit load analysis, both analytical and numerical approaches are presented. One of the most successful application of variational method in theory of plasticity is limit load analysis. The main objective of the limit load analysis is to estimate the load at the impending plastic limit state of a body. However, for complicated problems it may very difficult to find the exact limit load. Therefore, based on the extremum principles of limit load analysis, the lower bound theorem or the upper bound theorem is employed to estimate the limit load directly without considering the entire loading history. In general, limit load analysis plays an important role in design and fitness-for-service assessment of pressurized vessels and piping.
TOPICS: Stress, Variational techniques, Theorems (Mathematics), Plasticity, Vessels, Fitness-for-service, Variational principles, Design, Pipes
Duncan Camilleri and Brian Ellul
J. Pressure Vessel Technol   doi: 10.1115/1.4040994
Composite pipes are currently being used in a multitude of applications varying from civil to oil and gas applications. Pipes are generally connected together by means of pipe elbows that in turn are subjected to bending moment and pressure loading. This study looks into the effect of combined loading on the first ply and ultimate failure load of pipe elbows. The influence of pressure loading followed by a bending moment versus firstly applying bending moment followed by subsequent pressure loading, on the ultimate catastrophic failure load, is investigated through numerical models. The combined bending moment and pressure load ramping, is also studied. Design by analysis finite element damage mechanics numerical methods are applied to investigate post first ply failure and stress redistribution. The study shows that different loading combinations can give rise to different damage mechanisms and ultimately failure loads. A safe design load envelope for different fiber-reinforced pipe elbows based on first ply failure and ultimate catastrophic load is identified and discussed.
TOPICS: Pipes, Failure, Composite materials, Fibers, Stress, Pressure, Design, Finite element analysis, Numerical analysis, Damage mechanics, Damage, Computer simulation
He Xu, Haihang Wang, Mingyu Hu, Liye Jiao and Chang Li
J. Pressure Vessel Technol   doi: 10.1115/1.4040893
Water hydraulics relief valves are essential components of hydraulic systems. These valves maintain the desired pressure and thereby prevent other components from being damaged. During operation of the relief valve, the water flow often cavitates in the valve port owing to the rapid decline in pressure, affecting the stability and safety of the hydraulic system. To improve relief valve performance, an optimal design of the valve was determined. Using a CFD approach, the effects of the valve core design and the non-smooth groove structure of the valve seat on the jet flow structure were modeled and tested. The anti-cavitation structure was optimized parametrically, and the ideal valve port structure was determined. Tests were conducted to compare cavitation in the water hydraulics relief valve with and without the anti-cavitation structures. Results of these tests showed evident enhancement of cavitation performance.
TOPICS: Cavitation, Design, Water, Relief valves, Valves, Hydraulic drive systems, Pressure, Hydraulics, Safety, Stability, Flow (Dynamics), Jets, Computational fluid dynamics
Caputo Antonio C., Paolacci Fabrizio, Bursi Oreste S. and Giannini Renato
J. Pressure Vessel Technol   doi: 10.1115/1.4040804
Earthquakes represent a class of natural-technical (NaTech) hazards which in the past have been responsible of major accidents and significant losses in many industrial sites. However, while codes and standards are issued to design specific structures and equipment in the civil and industrial domain, established procedures for seismic quantitative risk assessment (QRA) of process plants are not yet available. In this paper, a critical review of seismic QRA methods applicable to process plants is carried out. Their limitations are highlighted and areas where further research is needed are identified.
TOPICS: Engineering standards, Accidents, Design, Decision making, Earthquakes, Risk assessment, Hazards, Chemical processes
Xiaoyong Ruan, Toshiki Nakasuji and Kazunori Morishita
J. Pressure Vessel Technol   doi: 10.1115/1.4040698
The structural integrity of a reactor pressure vessel (RPV) is important for the safety of a nuclear power plant. When the emergency core cooling system (ECCS) is operated and the coolant water is injected into the RPV due to a loss-of-coolant accident (LOCA), the pressurized thermal shock (PTS) loading takes place. With the neutron irradiation, PTS loading may lead a RPV to fracture. Therefore, it is necessary to evaluate the performance of RPV during PTS loading to keep the reactor safety. In the present study, optimization of RPV maintenance is considered, where two different attempts are made to investigate the RPV integrity during PTS loading by employing the deterministic and probabilistic methodologies. For the deterministic integrity evaluation, 3D-CFD and finite element method (FEM) simulations are performed, and stress intensity factors (SIFs) are obtained as a function of crack position inside the RPV. As to the probabilistic integrity evaluation, on the other hand, a practically more useful spatial distribution of SIF on the RPV is calculated. By comparing the distribution thus obtained with the fracture toughness included as a part of the master curve, the dependence of conditional failure probabilities on the position inside the RPV is obtained. Using the spatial distribution of conditional failure probabilities in RPV, the priority of the inspection and maintenance is finally discussed.
TOPICS: Maintenance, Finite element methods, Computational fluid dynamics, Thermal shock, Reactor vessels, Emergency core cooling systems, Coolants, Probability, Failure, Fracture (Materials), Safety, Irradiation (Radiation exposure), Simulation, Stress, Accidents, Neutrons, Inspection, Fracture toughness, Nuclear power stations, Engineering simulation, Optimization, Water
Hyunjun Kim, Sanghyun Kim, Youngman Kim and Jonhwhan Kim
J. Pressure Vessel Technol   doi: 10.1115/1.4040361
The Direct Spring Loaded Pressure Relief Valve(DSLPRV) is an efficient hydraulic structure to control the waterhammer in pipeline systems. The optimization of DSLPRV was explored to consider the chattering issue of the valve disk and the surge control for the pipeline system. A surge analysis scheme, the method of characteristics, was implemented into the multiple-objective genetic algorithm to determine adjustable factors in the operation of DSLPRV. Forward transient analysis and multi-objective optimization of the adjustable factors such as the spring constant, the degree of pre-compression and the disk mass showed substantial relaxation both the surge pressure and the oscillation of valve disk in a hypothetical pipeline system. Regression analysis between surge and parameters was compared with optimization to demonstrate the potential of the developed method as a solution for computational cost issue.
TOPICS: Optimization, Pipeline systems, Springs, Relief valves, Surges, Disks, Valves, Transient analysis, Compression, Elastic constants, Genetic algorithms, Pareto optimization, Regression analysis, Oscillations, Pressure, Hydraulic structures, Relaxation (Physics)
Valerio De Biagi, Bernardino Chiaia, Luca Fiorentini and Cristina Zannini-Quirini
J. Pressure Vessel Technol   doi: 10.1115/1.4040313
Seismic hazard represents one of the possible triggering causes for NaTech accidents in refineries and production plants. The vulnerability of steel storage tanks was evaluated within the framework of a rapid risk assessment. This paper reports the results of the investigation. The outputs of the analysis are plotted on normalized axes and trends among the results are observed. Finally, a comparison between the criticalities and the fragility curves found in the literature is proposed
TOPICS: Steel, Accidents, Risk assessment, Storage tanks, Risk, Earthquake risk
Mohamed Fersi and Ali Triki
J. Pressure Vessel Technol   doi: 10.1115/1.4040136
This paper explored and compared the effectiveness of the inline and the branching re-design strategies used to control water-hammer surges initiated into an existing steel piping systems. The piping system is handled, at its transient sensitive regions, by replacing an inline, or adding a branching, short-section made of high- or low-density polyethylene pipe-wall materials. The Ramos model was used to describe the transient flow, along with the Method of Characteristics implemented for numerical computations. The comparison of the numerical solution with experimental data available from the literature and alternative numerical solution evidenced that the proposed model could reproduce satisfactorily the magnitude and the phase shift of pressure head evolution. Further, the robustness of the proposed protection procedures was tested with regard to water-hammer up- and down-surge mechanisms, taken separately. Results demonstrated that both utilized techniques provided a useful tool to soften both water-hammer up- and down-surges. Additionally, the amortization of pressure-head -rise and -drop was sensitive to the short-section material and size. Moreover, the branching strategy illustrated several enhancements to the inline one in terms of period spread-out limitation, while providing acceptable pressure-head damping.
TOPICS: Water hammer, Design, Pipes, Pressure, Surges, Piping systems, Robustness, Unsteady flow, Steel, Low density polyethylene, Phase shift, Transients (Dynamics), Computation, Damping
Marta D'Amico and Nicola Buratti
J. Pressure Vessel Technol   doi: 10.1115/1.4040137
The evaluation of seismic vulnerability of atmospheric on-grade steel storage tanks is a fundamental topic in the context of industrial safety. Depending on the shell portion affected, on the extent of damage and on toxicity, flammability and reactivity of stored substances, liquid leakages can trigger hazardous chains of events whose consequences affect not only the plant but also the surrounding environment. In light of that, the study proposed herein provides an analysis of the seismic fragility of cylindrical on-grade storage tanks, based on observational damage data. The first phase of this work has consisted in collecting a large empirical dataset of information on failures of atmospheric tanks during past earthquakes. Two sets of Damage States have then been used in order to characterize the severity of damage and the intensity of liquid releases. Empirical fragility curves has been fitted by using Bayesian regression. The advantage of this approach is that it is well suited to treat direct and indirect information obtained from field observations and to incorporate subjective engineering judgement. Different models have been employed in order to investigate the effects of tank aspect ratio, filling level and base anchorage. Moreover, the effects of interaction between these critical aspects is included in fragility analysis. The hazard parameter used is the Peak Ground Acceleration. Seismic Fragility curves obtained from the described procedure are compared to those available in the technical literature.
TOPICS: Steel, Damage, Storage tanks, Hazards, Safety, Anchorage, Chain, Earthquakes, Failure, Shells, Leakage
Akira Maekawa and Tsuneo Takahashi
J. Pressure Vessel Technol   doi: 10.1115/1.4039697
This study describes inelastic seismic design of piping systems considering the damping effect caused by elastic-plastic property of a pipe support which is called an elastic-plastic support. Though the elastic-plastic support is proposed as inelastic seismic design framework in the Japan Electric Association code for the seismic design of nuclear power plants (JEAC4601), the seismic responses of the various piping systems with the support are unclear. In this study, the damping coefficient of a piping system is focused on, and the relation between seismic response of the piping system and elastic-plastic behavior of the elastic-plastic support was investigated using nonlinear time history analysis and complex eigenvalue analysis. The analysis results showed that the maximum seismic response acceleration of the piping system decreased largely in the area surrounded by pipe elbows including the elastic-plastic support which allowed plastic deformation. The modal damping coefficient increased a maximum of about seven-fold. Furthermore, the amount of the initial stiffness of the elastic-plastic support made a difference in the increasing tendency of the modal damping coefficient. From the viewpoint of the support model in the inelastic seismic design, the reduction behavior for the seismic response of the piping system was little affected by the 10% variation of the secondary stiffness. These results demonstrated the elastic-plastic support is a useful inelastic seismic design of piping systems on the conditions where the design seismic load is exceeded extremely.
TOPICS: Earthquake resistant design, Damping, Pipes, Piping systems, Stiffness, Eigenvalues, Nuclear power stations, Design, Stress, Deformation
Hoang Nam Phan, Fabrizio Paolacci and Silvia Alessandri
J. Pressure Vessel Technol   doi: 10.1115/1.4039635
Catastrophic failure of above ground storage tanks was observed during past earthquakes, which caused serious economic and environmental consequences. Many of the existing steel storage tanks were designed with outdated analysis methods and underestimated seismic loads. Therefore, the assessment of their seismic vulnerability is extremely important. Fragility functions are useful tools to quantify the seismic vulnerability of structures in the framework of probabilistic risk assessment. They give the probability that a seismic demand on a structural component exceeds its capacity. The objective of this study is to examine the seismic vulnerability of an unanchored steel storage tank based on the fragility analysis, considering both aleatoric and epistemic uncertainties. The significance of uncertain modeling parameters, attributed to the epistemic uncertainty, is first investigated with a screening study, which is based on nonlinear pushover analyses of the tank using the ABAQUS software. In this respect, a fractional factorial design and ANOVA technique have been adopted. The results indicated that the considered modeling parameters have a significant effect on the uplift behavior of the tank. The fragility curves are then developed based on a simplified model, where the uplift behavior is modeled based on static pushover analysis. Sources of uncertainty, associated with the significant parameters previously identified and the ground motion, are considered in the fragility analysis using a sampling procedure to generate statistically significant samples of the model. The relative importance of ground motion and modeling parameter uncertainties on the fragility curves of the tank is assessed and discussed in detail.
TOPICS: Steel, Modeling, Storage tanks, Accounting, Uncertainty, Probabilistic risk assessment, Computer software, Earthquakes, Failure, Probability, Structural elements (Construction), Stress, Design
Konstantinos Bakalis, Athanasia Kazantzi, Dimitrios Vamvatsikos and Michalis Fragiadakis
J. Pressure Vessel Technol   doi: 10.1115/1.4039634
A simplified approach is presented for the seismic performance assessment of liquid storage tanks. The proposed methodology relies on a nonlinear static analysis, in conjunction with suitable 'strength ratio-ductility-period' relationships, to derive the associated structural demand for the desired range of seismic intensities. In absence of available relationships that are deemed fit to represent the nonlinear-elastic response of liquid storage tanks, several Incremental Dynamic Analyses are performed for variable post-yield hardening ratios and periods in order to form a set of data that enables the fitting of the response. Following the identification of common modes of failure such as elephant's foot buckling, base plate plastic rotation and sloshing wave damage, the aforementioned relationships are employed to derive the 16%, 50% and 84% percentiles for each of the respective response parameters. Fragility curves are extracted for the considered failure modes, taking special care to appropriately quantify both the median and the dispersion of capacity and demand. A comparison with the corresponding results of Incremental Dynamic Analysis reveals that the pushover approach offers a reasonable agreement for the majority of failure modes and limit states considered.
TOPICS: Performance evaluation, Storage tanks, Dynamic analysis, Failure mechanisms, Buckling, Failure, Fittings, Rotation, Hardening, Waves, Ductility, Damage, Sloshing
Shuangmiao Zhai, Shaoping Zhou, Shaojie Chen, Bin Yang and Yong Li
J. Pressure Vessel Technol   doi: 10.1115/1.4039502
Pressure vessel plays an increasingly important role in process industries, in which its performance degradation, such as crack and corrosion, may lead to serious accidents and significant economic losses. Guided wave-based method is a cost-effective means for pressure vessel rapid interrogation. In this paper, direct-wave and fuzzy C-means clustering algorithm (FCM) are used to locate defect for pressure vessel. Finite element (FE) simulation is applied to analyze the propagation characteristics of guided waves. The experiment using the method based on direct-wave and FCM has been conducted on the barrel and head with different sensor arrays respectively. The variation rule of the direct-wave difference with different distance coefficients has been studied. By combination of the FCM, the defects on barrel and head can be detected accurately. The defect inspection experiment for pressure vessel using ellipse imaging algorithm is conducted as well. The experimental results show that the method based on direct-wave and FCM can locate the defects on barrel and head of pressure vessel effectively and accurately.
TOPICS: Pressure vessels, Waves, Algorithms, Corrosion, Finite element analysis, Process industries, Imaging, Simulation, Sensors, Inspection, Fracture (Materials), Accidents
Yonghee Ryu, Abhinav Gupta and Ju Bu Seog
J. Pressure Vessel Technol   doi: 10.1115/1.4039004
Many studies assessing the damage from 1971 San Fernando and 1994 North Ridge earthquakes reported that the failure of non-structural components like piping systems was one of the significant reasons for shutdown of hospitals immediately after the earthquakes. This paper is focused on evaluating seismic fragility of a large-scale piping system in representative high-rise, mid-rise, and low-rise buildings using nonlinear time history analyses. The emphasis is on evaluating piping's interaction with building and its effect on piping fragility. The building models include the effects of nonlinearity in the performance of beams and columns. In the 20-story building that is detuned with the piping system, critical locations are on the top two floors for the linear frame building model. For the nonlinear building model, critical locations are on the bottom two floors. In the 8-story building that is nearly tuned with the piping system, the critical locations for both the linear frame and nonlinear models are the 3rd and 4th floors. It is observed that building nonlinearity can reduce fragility due to reduction in the tuning between building and piping systems. In the 2-story building, the nonlinear building frequencies are closer to the critical piping system frequencies than the linear building frequency; the nonlinear building is more fragile than the linear building for this case. However, it is observed that the linear building models give excessively conservative estimates of fragility than the nonlinear building models.
TOPICS: Structures, Pipes, Piping systems, Earthquakes, Failure, Damage
Xu Liang, Zeng Cao, Hongyue Sun, Xing Zha and Jianxing Leng
J. Pressure Vessel Technol   doi: 10.1115/1.4038724
An analytical method and a semi-analytical method are proposed to analyze the dynamic thermo-elastic behavior of structures resting on a Pasternak foundation. The analytical method employs a finite Fourier integral transform and its inversion, as well as a Laplace transform and its numerical inversion. The semi-analytical method employs the state space method, the differential quadrature method (DQM) and the numerical inversion of the Laplace transform. To demonstrate the two methods, a simply-supported Euler-Bernoulli beam of variable length is considered. The governing equations of the beam are derived using Hamilton's principle. A comparison between the results of analytical method and the results of semi-analytical method is carried out, and it is shown that the results of the two methods generally agree with each other, sometimes almost perfectly. A comparison of natural frequencies between the semi-analytical method and the experimental data from relevant literature shows good agreements between the two kinds of results, and and the semi-analytical method is validated. Different numbers of sampling points along the axial direction are used to carry out convergence study. It is found that the semi-analytical method converges rapidly. The effects of different beam lengths and heights, thermal stress, and the spring and shear coefficients of the Pasternak medium are also investigated. The results obtained in this paper can serve as benchmark in further research.
TOPICS: Thermoelasticity, Laplace transforms, Springs, Shear (Mechanics), Thermal stresses, Hamilton's principle

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