Effect of local wall thinning on limit loads for piping branch junctions. Part 1: Internal pressure

This paper presents plastic limit pressures of piping branch junctions with local wall thinning, based on systematic three-dimensional finite element (FE) limit analyses using elastic-perfectly plastic materials. An ideal branch junction is considered, where no weld or reinforcement around the intersection is considered. Two locations of wall thinning are considered: one is in the run pipe (opposite to the intersection) and the other is in the branch pipe (next to the intersection). Based on the assumption of possible plastic collapse modes, approximate plastic limit pressure solutions for piping branch junctions with local wall thinning are proposed using two limit pressure solutions: plastic limit loads for straight pipes with local wall thinning and those for branch junctions without wall thinning. Comparison with FE results shows overall good agreement.