Modeling of damage-crack evolution for subsea pipelines subject to corrosion-fatigue

Subsea pipelines approaching design life demonstrate structural degradation as progressive corrosion and fatigue cracking. This deterioration elevates the potential leak while reducing operation integrity for the industrial safety and marine ecosystem protection. A damage-crack evolution model is developed to predict the degradation from the pit initiation to crack propagation. Three models of aging pipelines with distinct corrosion pit configurations are established. The influence of corrosion pits depth, width, and spacing for crack initiation locations and life is evaluated. It is observed that increased pit depth enhances crack nucleation susceptibility at pit shoulder regions. Axially symmetric pits reduce local stress concentration, whereas circumferentially aligned pits accelerate crack initiation. This modeling supports the development of optimized maintenance strategies for aging subsea pipelines.