Perpustakaan Digital ITB

Subsea pipelines are vulnerable to cracks and geometric imperfections like ovality. Standard Fitness-for-Service (FFS) assessments, specifically API 579-1, assume perfectly cylindrical geometries, risking dangerous underestimations of the Stress Intensity Factor . This study evaluates ovality's impact on fracture mechanics and develops a novel correction factor. Through 3D Extended Finite Element Method (XFEM) simulations, a parametric study varied D/t ratios (15-45), ovality (0 - 4%), relative crack depths, and aspect ratios under internal pressure. The baseline model achieved excellent validation against API 579-1 (3.09% deviation). Results reveal ovality significantly amplifies , particularly in thin-walled pipes (D/t = 45) due to secondary bending moments. Thick-walled pipes (D/t = 15) proved generally less sensitive, although specific shallow and elongated flaws exhibited anomalous stress behaviors requiring further numerical validation. Consequently, a new Ovality Correction Factor was systematically formulated by isolating the ovality effectvia multi-variable non-linear regression (2= 0.680), providing a more realisticstructural integrity assessment tool.