Pressure vessels fatigue analysis

Pipe stress and pressure vessel analysis Pressure, dead-weight, thermal expansion, vibration modal analysis of fatigue. Analysis to ensure that the piping and pressure vessels conform to the codes of ASME, API or WRC as the case may be... 

The most common pressure vessel codes that include the evaluation of fatigue are the North-American "ASME Section VIII Division 2" [1] and the German "AD-Merkblatt S2" [2], the latter being the most detailed fatigue analysis currently available in pressure vessel codes. 

Moulin, D., and Roche, R.L., Correction of Poisson effect in the elastic analysis of low-cycle fatigue, Int. J. Pressure Vessels Piping, 19, 213-233, 1985. 

Langer, B.F., Design stress basis for pressure vessels, Exp. Mech., 1-12,1971. Petrequin, P., Roche, R., and Tortel, J., Life prediction in low cycle fatigue using elastic analysis. Proceedings of an ASME Conference on Advances in Life Prediction Methods, Albany, New York, 1983, pp. 151-156. 

Cisilino, A.P., Aliabadi, M.H. Three-dimensional BEM analysis for fatigue crack growth in welded components. Int. J. for Pressure Vessel and Piping 70, 135-144 (1997)... 

When a fatigue evaluation is required, it is necessary to determine the peak stresses around the openings. The current methods are the stress index method, experimental tests and measurements, or a theoretical analysis procedure such as a finite element analysis. The stress index method is the easiest method and is allowed by the ASME Code, III-l and VIII-2. The stress index method was developed from reviewing a large amount of experimental and analytical data determined in a program conducted by the Pressure Vessel Research Committee. 

Example 11.14. A cylindrical shell that is 36-in. ID by 2.5-in. thick contains a perpendicular nozzle th is 4-in. ID by 0.75-in. thick. The design pressure is 1900 psi at a design temperature of 450°F. The vessel is subjected to cyclic operation and a fatigue analysis is required. Peak stresses and stress concentration factors are not known for the specific geometry to be used. What method can be used to evaluate the peak stresses for a fatigue analysis ... 

For the fatigue analysis a cyclic pressure (Pmax=3 MPa, Pmin=0 MPa, f=0.25Hz) during two cycles, was applied. In order to prevent rigid body motion of the vessel during the analysis a encastre boundary condition was applied to the vessel valve. For the steel liner non-linear analysis symmetry boundary conditions were also applied. 

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