ASME limits and contradictions in the finite element analysis of pressure vessels

This paper is not one more guideline but an independent contribution focusing stress classification and failure mechanism in a FE framework. The authors examined a typical support skirt and showed interesting relations between the collapse load obtained by finite element analysis and the loads allowed from the ASME stress limits. Different skirt geometry configurations - with different angles of attachments between cylinder and cone parts - and a pressure vessel head are investigated. These configurations permitted to observe the influence of larger bending stress in the collapse load. They also showed the bending stress relationship to the allowable loads when calculated using the ASME limits. Using elastic and limit load FE analyses, the present paper determines the collapse loads of the skirts and pressure vessel head. It is also established the relationships between the calculated collapse loads and limits dictated by the ASME Code Subsection NB. Based on the NB rules, it will be possible to observe how different methods of stress assessment, classification, and limits may influence in the design of pressure vessel parts. (author). 6 refs., 1 fig., 4 tabs