Reference Stress Values for Toroidal Vessels Subjected to Uniform Internal Pressure

Author(s):  
Khosrow Zarrabi ◽  
Abheek Basu

Using the finite element method, the paper presents an explicit expression for the reference stress of tube/pipe bends with various degrees of ovality that are subjected to uniform internal pressures. No such task has been accomplished before. The presented reference stress may be used in conjunction with the uniaxial creep rupture data to obtain the creep life of the bend.

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
AR. Veerappan ◽  
S. Shanmugam ◽  
S. Soundrapandian

Thinning and ovality are commonly observed irregularities in pipe bends, which induce higher stress than perfectly circular cross sections. In this work, the stresses introduced in pipe bends with different ovalities and thinning for a particular internal pressure are calculated using the finite element method. The constant allowable pressure ratio for different ovalities and thinning is presented at different bend radii. The allowable pressure ratio increases, attains a maximum, and then decreases as the values of ovality and thinning are increased. An empirical relationship to determine the allowable pressure in terms of bend ratio, pipe ratio, percent thinning, and percent ovality is presented. The pipe ratio has a strong effect on the allowable pressure.


1984 ◽  
Vol 106 (1) ◽  
pp. 130-136 ◽  
Author(s):  
W. T. Asbill ◽  
P. D. Pattillo ◽  
W. M. Rogers

The purpose of this investigation was to gain a better understanding into the mechanical behavior of the API 8 Round casing connection, when subjected to service loads of assembly interference, tension and internal pressure. The connection must provide both structural and sealing functions and these functions were evaluated by several methods. Part I discusses the methods of analysis, which include hand calculations using strength of materials, finite element method via unthreaded and threaded models, and experimental analysis using strain gages. Comparisons of all three methods are made for stresses and show that the finite element method accurately models connection behavior.


2013 ◽  
Vol 652-654 ◽  
pp. 1362-1366 ◽  
Author(s):  
Xian Yong Zhang ◽  
Jin Feng

Reliability of eccentric wear casing was studied by Monte-Carlo and finite element method. In different internal pressures, calculated reliability of P110 steel grade 9 5/8 inches casing with wear depth less than 0.5 times wall thickness. The influence of different cement ring circumferential missing amount and stratum pressures on wear casing reliability were presented. The results provide basis for casing safety evaluation and reasonable replacement.


Author(s):  
E. H. Perez ◽  
S. Diab ◽  
R. D. Dixon

Fatigue analyses of the inner and outer rings of hyper compressor retainers were performed to determine the optimum interference fit and interference fit diameter to maximize the fatigue life of both the inner and outer rings when subjected to cyclic operating internal pressures. The relationships between the optimum interference fit diameter, the amount of interference and cyclic pressures are derived using the fatigue analysis methodology of the ASME Code, Section VIII, Division 3. The effect of axial preload is evaluated, and the results are checked using the finite element method.


Author(s):  
I.E. Adeyanov ◽  
◽  
M.Y. Alexandrov ◽  

The article presents a numerical calculation of the corrugated wall of a transformer under pressure. The permissible degree of evacuation of the wavy transformer tank is determined. The statement of the problem is formulated as follows: to determine the limit of the maximum allowable pressure during the evacuation of the tank with different geometrical dimensions of the corrugation. In this case, the maximum equivalent stress should not exceed the yield point and the walls of the corrugation should not close. Numerical calculation is carried out by the finite element method. This approach to calculating the behavior of a corrugated wall under pressure can be used to determine the maximum allowable internal pressure of the tank.


2002 ◽  
Author(s):  
Masahide Katsuo ◽  
Toshiyuki Sawa

This study deals with the stress analysis and the estimation of the sealing performance of the pipe flange connections combining a metallic gasket with an adhesive subjected to an internal pressure and a temperature change. Stress distributions at the interface between the adherends and the adhesive in the connections are analyzed by using the finite element method (FEM). From the numerical calculations, the following results are obtained: (1) the stress distributes uniformly at the interface except near the edges, (2) the stress increases as Young’s modulus of an adhesive decreases, (3) the stress becomes singular at the edges of the interfaces. In the experiments, the pipe flange connections consisting of dissimilar circular gaskets with an adhesive were manufactured, and the leakage tests of the connections were carried out by applying an internal pressure and a temperature change to the connections. From the experimental results, the following results were obtained: (1) the sealing performance increased as the width of a gasket decreased and the initial clamping stress increased, and (2) the sealing performance of the pipe flange connections subjected to a temperature change increased under a moderately high temperature.


Author(s):  
Toshiyuki Sawa ◽  
Ryo Kurosawa ◽  
Wataru Maezaki

The contact gasket stress distributions of a non-circular flange connection with a compressed sheet gasket subjected to internal pressure were analyzed taking into account of the hysteresis behavior of the gasket by using the finite element method (FEM). Leakage tests were also conducted using an actual non-circular flange connection with a compressed sheet gasket under internal pressure. Using the contact gasket stress distributions and the results of the leakage tests, the new gasket constants were calculated. The difference in the new gasket constants between the values obtained from the present study and those by the PVRC procedure was substantial. In addition, a method to determine the initial clamping bolt force (bolt preload) for a given tightness parameter was demonstrated.


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