Stress Analysis of Non-Uniform Thickness Piping System with General Piping Analysis Software

摘要

Most general piping analysis software can only perform ASME design stage type code compliance analysis with uniform pipe wall thickness. However, non-uniform wall thickness, commonly on elbows or bends, can be found in many industrial applications. The non-uniform thickness caused by flow accelerated corrosion (FAC) or other similar factors could lead to thin region anywhere around the bends or elbows. In this paper, an analysis procedure is introduced to enable a general piping software to conduct ASME III class 1 piping analysis with non-uniform wall thickness. The demonstration is performed on CANDU (Canadian Deuterium Uranium) feeder pipes, which could be subject to FAC caused wall thinning on bends. The results are compared with both conventional uniform thickness piping analysis and non-uniform thickness solid finite element analysis. The comparison shows the validity of the proposed "average-minimum-average" approach which using the general piping analysis software. The approach remains conservative compared to the solid finite element results, yet it gives lower acceptable thickness than the conventional piping analysis. It is noted this approach is applicable to the thin region located anywhere at the bends.