Local buckling and compressive strain capacity of metallurgically clad pipes with dent defects at girth welds

Abstract

Metallurgically clad pipes (MCPs) have effectively addressed corrosion issues associated with deep-sea oil and gas transportation. However, MCPs frequently suffer dent damage resulting from third-party impacts during the installation and operational conditions. Such dent defects may precipitate local buckling failures under combined loading scenarios involving bending moments, axial forces, and internal pressure. In this study, a three-dimensional finite element model incorporating girth welds is developed to investigate the local buckling failure mechanism of MCPs induced by dents located in weld regions under combined loading conditions. Traditional strain-based assessment approaches are inherently limited and thus inadequate for evaluating MCPs with dent-induced damage in the girth weld area. To overcome this limitation, a novel calculation method utilizing the far-field average strain approach is proposed to predict local buckling failure accurately. Comprehensive analyses examine the influence of critical parameters, namely including bending moment, internal pressure, external pressure, dent depth, and the spatial proximity between dents and girth welds, on the MCP's buckling behavior and compressive strain capacity. The proposed method is validated through comparisons with established critical buckling failure loads. Results indicate that dents near girth weld regions significantly compromise the limited compressive strain capacity of MCPs, with dent depth, internal pressure, and external pressure notably influencing the local buckling failure modes. A predictive formula quantifies the limited compressive strain capacity, incorporating the effects of external pressure, internal pressure, dent depth, and dent-to-weld distance. The prediction errors are all within 10 %, satisfying the requirements of practical engineering applications. The proposed method provides a valuable reference for the integrity assessment of metallurgically clad pipes.