Influence of 3D defect geometry on burst pressure and repair efficiency of composite-repaired steel pipelines

Abstract

Steel pipelines affected by corrosion defects may experience a significant reduction in burst resistance, even after composite repair. This study investigates the effect of three-dimensional defect geometry on the burst pressure and repair performance of API 5L Grade B steel pipelines reinforced with a glass/epoxy composite patch and epoxy putty. A three-dimensional finite element model was developed in Abaqus/Standard and validated against analytical, numerical, and experimental results reported in the literature. Five defect geometries were considered, namely reference, axial, circumferential, mixed, and superficial. The results demonstrate that defect geometry strongly influences the residual strength of unrepaired pipelines. Compared to an intact pipe, the maximum reduction in burst pressure reaches 41.02% for defect D3, highlighting the critical role of defect morphology even at comparable defect depths. For repaired pipelines, the influence of geometry remains significant, with the highest performance observed for D5 and the lowest for D3. These findings indicate that reliable assessment of composite repairs cannot rely solely on defect depth, but must also account for axial extent, circumferential width, and overall defect morphology.