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research-article  
Mohammed Alziadeh and Atef Mohany
J. Pressure Vessel Technol   doi: 10.1115/1.4040549
This paper presents an experimental investigation of the near-wake flow characteristics for isolated crimped spirally finned cylinders in cross-flow, and its influence on the generated sound pressure during flow-excited acoustic resonance. Four crimped spirally finned cylinders are investigated, which have pitch-to-root diameter ratio (p/Dr) ranging between 0.384 = p/Dr = 1. The addition of crimped spiral fins weakens and reduces the coherence of the vortex shedding process as compared to that of a bare cylinder. It has also been shown that the addition of crimped spiral fins elongated the vortex formation length. A larger velocity deficit was also observed in the near-wake of the crimped spirally finned cylinders. Reduction in the pitch-to-diameter ratio (p/Dr) led to a progressive increase in the strength and coherence of the vortex shedding process. It also caused a gradual reduction in the vortex formation length and velocity deficit. The near-wake flow characteristics of the crimped spirally finned cylinders has shown to inherently affect the generated sound pressure during flow-excited acoustic resonance. Furthermore, it has been observed that the helical fins impose an asymmetrical inclination in the acoustic particle velocity. This resulted in weaker flow-acoustic coupling, which hindered the energy transfer between the flow field and the sound field. The findings of this investigation provide better understanding of the complex flow-sound interaction mechanism from crimped spirally finned cylinders in heat exchanger tube bundle.
TOPICS: Resonance, Acoustics, Wakes, Cylinders, Cross-flow, Excitation, Flow (Dynamics), Fins, Vortex shedding, Vortices, Sound pressure, Heat exchangers, Energy transformation, Particulate matter
research-article  
Bingjun Gao, Zongxun Yin, Fuhai Zhao and Chengwen Shang
J. Pressure Vessel Technol   doi: 10.1115/1.4040496
Although the inner container of cryogenic liquid semitrailer works under inner pressure, it needs to be vacuumed during the helium leak detection. Although equipped with stiffening structure such as supporting rings for baffles inside the container, the inner container usually cannot meet the stability requirements during the evacuation. So a kind of temporary local rigid clamping structure was proposed to improve the anti-buckling ability of the inner container during the helium leak detection. "Lulu" can was taken as thin-walled cylindrical shell specimen under external pressure, and is clamped with the temporary local rigid ring outside. The critical pressure were experimentally and numerically studied for specimen with local clamping rings of different sizes, in which eigenvalue buckling analysis and nonlinear analysis were employed with the aid of ANSYS. It indicates that the critical pressure of specimen with local clamping ring is higher than that without clamping ring. Finally, the optimal clamping scheme including size and location of clamping rings for the inner container of DC18 type cryogenic liquid semitrailer was studied with finite element method, which aimed to improve the anti-buckling capacity of the inner container during the helium leak detection.
TOPICS: Buckling, Cylinders, External pressure, Containers, Pressure, Helium, Leakage, Stability, Eigenvalues, Finite element methods, Evacuations, Pipes
research-article  
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)
research-article  
Jeong Nyeon Kim, Richard L. Tutwiler and Judith Todd
J. Pressure Vessel Technol   doi: 10.1115/1.4040316
In pressure vessel and pipe inspection, ultrasonic nondestructive evaluation (NDE) plays a pivotal role in both in-situ and laboratory examinations. Scanning acoustic microscopy (SAM) has been a well-recognized laboratory tool for both visualization and quantitative evaluation of pressure vessel and piping materials at the microscale since its invention in 1974. While there have been multiple advances in SAM over the past four decades, some issues still remain to be addressed. First, the measurement speed is limited by the mechanical movement of the acoustic lens and the sample stage. Second, a single element transducer with an acoustic lens forms a predetermined beam pattern for a fixed focal length and incident angle, thereby limiting control of the inspection beam. Here, we propose to develop a phased-array probe as an alternative to overcome these issues. Preliminary studies to design a practical high frequency phased-array acoustic microscope probe were explored. A linear phased-array, comprising 32 elements and operating at 5 MHz, was modeled using PZFlex, a finite-element method software. This phased-array system was characterized in terms of electrical input impedance response, pulse-echo and impulse response, surface displacement profiles, mode shapes, and beam profiles. Details of the construction of the model and the results are presented in this paper. Development of a phased-array acoustic microscope probe will significantly enhance scanning acoustic microscopy techniques for detecting surface and subsurface defects and microstructural changes in laboratory samples of pressure vessel and piping materials.
TOPICS: Acoustics, Nondestructive evaluation, Pressure vessels, Design, Pipes, Probes, Microscopes, Microscopy, Lenses (Optics), Inspection, Inventions, Finite element methods, Echoes, Impulse (Physics), Computer software, Displacement, Transducers, Visualization, Microscale devices, Construction, Mode shapes, Response surface methodology
research-article  
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
research-article  
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
research-article  
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
research-article  
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
Review Article  
Olawale Ifayefunmi and Jan Blachut
J. Pressure Vessel Technol   doi: 10.1115/1.4039695
It is generally accepted that the presence of imperfections in pressure vessel components can significantly reduce their buckling strength. In fact, the discrepancies between theoretical predictions and experimental results have been attributed to various kinds of existing and unavoidable imperfections. This is not a new problem but despite of substantial research effort in this area over the recent decades, it is far from being satisfactorily resolved. This review provides insight into the past findings and current activities related to the role of different types of imperfections on the buckling strength. It aims to contribute to a better understanding of the influence of imperfections on the structural stability of cones, cylinders and domes when these are subjected to external loading conditions. The review concentrates not only on the prominent role of initial geometric imperfections of the shell's generator but also on less known defects. This includes uneven axial length of cylinders, eccentricities and non-uniformities of applied load, inaccurately modelled boundary conditions, corrosion of the wall, influence of material discontinuity or crack and effect of pre-buckling deformation. The study examines: (i) how the data were obtained (analytically, experimentally and/or numerically), (ii) the type of material from which the shell structures were made, and (iii) the importance of findings of the previous works. Metallic and composite components are considered.
TOPICS: Domes (Structural elements), Buckling, Cylinders, Generators, Shells, Pressure vessels, Stress, Structural stability, Fracture (Materials), Corrosion, Boundary-value problems, Deformation, Composite materials
research-article  
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
research-article  
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
research-article  
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
Review Article  
Rajkumar Shufen and Uday S. Dixit
J. Pressure Vessel Technol   doi: 10.1115/1.4039206
Autofrettage is a metal forming technique widely incorporated for strengthening the thick-walled cylindrical and spherical pressure vessels. The technique is based on the principle of initially subjecting the cylindrical or spherical vessel to partial plastic deformation and then unloading it; as a result of which compressive residual stresses are set up. On the basis of the type of the forming load, autofrettage can be classified into hydraulic, swage, explosive, thermal and rotational. Considerable research studies have been carried out on autofrettage with a variety of theoretical models and experimental methods. This paper presents an extensive review of various types of autofrettage processes. A wide range of theoretical models and experimental studies are described. Optimization of an autofrettage process is also discussed. Based on the review, some challenging issues and key areas for future research are identified.
TOPICS: Autofrettage, Deformation, Metalworking, Pressure vessels, Residual stresses, Stress, Experimental methods, Optimization, Vessels, Explosives
Review Article  
Sasan Faghih, Hamid Jahed and Seyed Behzad Behravesh
J. Pressure Vessel Technol   doi: 10.1115/1.4039068
This paper provides a critical review of the advancements made in the application of the Variable Material Properties (VMP) method over the past two decades. The VMP method was originally proposed in 1997 (Jahed and Dubey, J. Press. Vessel Technol., vol. 119, no. 3, pp. 264-273, 1997; Jahed, Sethuraman, and Dubey, Int. J. Press. Vessel. Pip., vol. 71, no. 3, pp. 285-291, 1997) and further developed in 2001 (Parker, J. Press. Vessel Technol., vol. 123, no. 3, p. 271, 2001) as an elastoplastic method for the analysis of axisymmetric problems. The model was originally developed as a boundary value problem to predict the spatial distribution of stress. However, since 1997 it has been extended to include thermal effects to solve thermomechanical residual stresses; time domain to solve creep of discs and cylinders; finite deformation to solve cylinders under large strains; numerical solutions to make them more efficient; and asymmetric hardening behavior to accommodate non-slip deformation modes. These advancements, made over the past 20 years, are reviewed in this paper, and future trends and frontiers are discussed.
TOPICS: Materials properties, Vessels, Deformation, Cylinders, Creep, Residual stresses, Stress, Hardening, Temperature effects, Thermomechanics, Disks, Boundary-value problems
research-article  
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
research-article  
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
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

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