Perpustakaan Digital ITB

Pipelines are susceptible to dent and corrosion during its operation, where the interaction of both damages can synergistically weaken the pipeline structural integrity. The research presented a Finite Element Method (FEM) simulation study to evaluate the interaction between dent and corrosion affects 24-inch API 5L X52 pipeline burst pressure and structural integrity under internal pressure loading. The FEM simulations were carried out in Abaqus software to model various corrosion scenarios, including external, internal, and combined external-internal corrosions. Denting was applied using spherical and sharp indenters to simulate realistic scenario such as those caused by excavation. The corrosion was modeled as uniform rectangular wall-thinning defect, positioned at the center of the pipe where the denting takes place. Three failure criteria were used to predict failure: von Mises stress, equivalent plastic strain (PEEQ), and fracture criterion based on Oyane ductile damage model. The spherical denting scenario results showed that interacting dent-corrosion was proven to synergistically reduce the burst pressure up to 22.68%, with the combined-corrosion pipe being the most critical. In sharp denting using excavator tooth, the longitudinal orientation of the tooth created the most severe scenario due to the engagement with longer portion of the corrosion length. The ANOVA analysis indicates that the three choice of failure criterion did not significantly affect the predicted burst pressure in spherical denting scenarios, while the corrosion location variation had significant influence. However, in the sharp denting scenarios, the predicted failure using damage model was less conservative by taking account of stress triaxiality effect. The research findings highlight the importance of using damage model in assessing pipeline integrity under complex damage modes.