engleski

Stress and Strain Analysis of the Spherical Pressure Vessel: Analytical and Numerical Approach

Pressure vessels are employed as the vital parts of many power plants or built as equipment of oil refineries. They are often subjected to high pressure, temperature transition or corrosive media. EU norms committed designers, producers and users to calculate continuously the stresses and strains and keep them in safe margins in order to ensure safe in-service operation. This is particularly important by analysis of some critical parts of the vessel, where the cracks can occur. Such places are usually stressed or unrelieved welded joints of vessel body with nozzles or legs. It seems that thermal stress relief (postweld heat treatment, PWHT) could reduce sometimes the sensitivity to and the severity of cracking. However, it is not possible to generalize assessment guidelines, because they are depending on the type of construction, design code, maximum allowable pressure and temperature, vessel material, sensitivity to cracks etc. Therefore, it is not easy to make decision is it PWHT needed for some conditions or not. It is very influenced by the stress distribution and its magnitude in the critical part. In this paper stresses and strains analysis of the spherical pressure vessel was performed by using of finite element method. Special attention has been devoted to the detail of vessel support on the legs. Knowing of stress and strain fields could make the decision about the needs of PWHT easier. This data could be also of some help by structural integrity assessment.

spherical pressure vessel; finite element analysis; stress and strain fields; PWHT; in-service operation

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