Influence of Internal Corrosive Defect on the Burn-Through of In-Service Welding on Pipelines

Abstract

In the course of the service of long-distance oil/gas pipelines, due to corrosion, abrasion, and other reasons, the possibility of pipeline leakage is growing. In-service welding is an advanced technique employed in the repair of pipelines, and it has wide application in guaranteeing the safe transmission of petroleum or gas. The present studies on in-service welding, including experiments and numerical simulations, all assumed that the inner wall of the pipeline was in good condition without considering the influence of defects. This paper started from internal corrosive defects, through the finite element simulation method, investigated how the pressure of inner medium and defect size influence the burn-through of in-service welding. The results show that, compared with the intact pipe, pipeline with internal corrosive defect is more prone to burn-through. With the increase of medium pressure, the maximum radial deformation, the von Mises stress, and hoop stress at the defect area increase. The radial deformation has a certain time effect. The depth of defect has an evident impact on the radial deformation and the stresses. The radial deformation, the von Mises stress, and hoop stress increase with the deepening of the defect, while the impacts of the defect's length and width are less obvious.