Extreme pressure of oil/gas pipeline with internal/external wall defects

Pipeline defect is one of the most common factors causing pipeline failure, and the plastic extreme pressure is an important parameter of pipeline structure design which is closely related to material performance. Comparative study is conducted on pipelines with internal or external wall defects. Finite element modeling method is used to simulate the sphere defect and groove defect of pipe wall, and the pipeline with defects is compared with integrated pipeline for extreme pressures, suggesting that the defects on the internal or external wall will have different influences on the extreme pressure. Considering such influences, the impacts of different distribution positions of defects on extreme pressures are analyzed. The result shows that the groove defect distributed on the internal or external wall has impact on the pipeline extreme pressure to the extent related to the length of defect.