Collapse of Deepwater Pipelines

Abstract

The paper describes a series of full-scale collapse experiments using X-42 and X-65 grade steel tubes. The initial geometric imperfections of the tubes were measured using a specially designed scanning facility prior to collapsing them under external pressure. Geometric deviations from a circular shape were recorded at 90 points around the circumference. The wall thickness was also recorded at the same points. At least 31 circumferential scans were made over lengths of 9 diameters. The stress-strain characteristics in the axial and circumferential directions were measured for each tube. The measured parameters were used to calculate numerically the collapse pressures of the tubes. The biggest deviation between the experimental and calculated values was less than 8 percent. These are compared with the results obtained from the same analysis using various idealized imperfection measures.