FAILURE MECHANISM AND LIMIT LOAD CAPACITY OF SUBSEA PIPELINES WITH DENT DEFECTS

With the development of oil and gas resources extending to the deep sea, more and more submarine pipelines are applied, and the importance of the structural and functional integrity of submarine pipelines is becoming more and more prominent. Dent has long been considered one of the potential factors affecting the integrity of submarine pipelines, which can be formed when pipelines are impacted by fallings objects from the sea surface. Due to the seabed subsidence, pipeline suspension and earthquake, mudslide activity and other factors, submarine pipelines may be under bending moment, seriously affecting the safe operation of submarine pipelines. The study of failure and limit load capacity of submarine pipelines under external pressure and bending moment is of great significance. In this paper, the nonlinear finite element method is used to study the collapse failure and local buckling failure of subsea pipelines under external pressure and bending moment respectively. The process of the pipeline being dented by the impact of objects is simulated, spherical denter and wedge-shaped denter are considered. The influence of D/t and dent depth on collapse capacity and bending capacity are investigated. The results can be referred in engineering practice.