Buckling collapse is one of the important failure modes of pressure vessel. But, in the past protection against collapse from bulking has not been implemented as required by codes, especially local buckling. The situation is attributed to two reasons. The first one is that pressure vessel code usually only provided design method by rules to protect against global bulking of shell under conventional loads, such as external pressure or axial compression load. However, local bulking may occur in some local discontinuity regions rather than global region and has to be evaluated using design method by analysis. The second one is that bulking analysis based on numerical method (e.g. FEA) is more sophisticated to implement compared to typical strength analysis due to non-uniqueness of result, initial imperfection, mesh generation and other reasons.
The case studied in this paper is that a heavy attaching equipment was closely connected the main equipment by triangular steel structure instead of typical shirt support for the purpose of space saving. The key point of this project case is that the 240-ton attaching equipment causes significant compress stress in the local regions such as the bottom of nozzle, shirt support of main equipment and triangular steel structure. Regarding the loads, not only weight but also wind, seismic load etc. and their load cases combinations should be considered in the bulking analysis. With this case, the paper introduced the basic principles, implementation procedures and software applications of local buckling analysis of pressure vessel.
At the end, this paper proposed some suggestion for the Chinese code of bulking analysis through this typical case study.
Keywords:buckling analysis; finite element method; non-linear; pressure vessel