Study on residual strength of pipe with single hemisphere bottom defect using FEM analysis

The stress and strain condition of the corroded line pipe with single hemisphere bottom defect under deferent inner pressure were analyzed by the Finite Element Methods (FEM) in this paper; At the same time, the residual strength models for the corroded pipe were established based on both the Von Mises equivalent stress and the Von Mises equivalent strain of the finite unit on the defect local zone respectively, the residual strength was decreased with the defect size (d/t) linearly. This way, the residual strength for the corroded pipe with a given defect size (d/t) could be conducted by using the model properly, which could help the owner make a decision when happened to the same defect in the operation. The analysis results shown that the residual strength calculation should choose based on stress when the defect depth (d/t) was less than 0.5, or else choose based on the strain when defect depth (d/t) was exceeds 0.5.