Integrity assessment of API X70 pipe with corroded girth and seam welds via numerical simulation and burst test experiments

Welded pipes containing corrosion may lead to catastrophic situations during transportation of gas. Appropriate methods are needed to assess defective pipelines for integrity assessment. Corroded girth and seam welds were studied for the effect of corrosion length and depth on the burst pressure of API X70 pipe. Full-scale hydrostatic burst pressure tests and finite element analysis (FEA) were performed to investigate the burst pressure resulting from the corroded girth and seam welds. The experimental results were used to validate the finite element model, which considered the 3D elastic-plastic behavior. The FEA predicted burst pressures were compared with the ASME B31G, Modified ASME B31G, DNV RP-F101, and PCORRC standards in order to derive a proper equation for evaluation of corroded seam and girth welds.