VALIDATION FOR FINITE ELEMENT ANALYSIS OF FREE-SPANNING SUBSEA PIPELINE USING THEORETICAL FORMULA

Hydrocarbon products from offshore sources are primarily transported to onshore facilities using subsea pipelines, which typically rest on the seabed. To ensure safe operation and prevent failure, engineers must assess the reliability of these free-spanning pipelines, which are prone to structural risks due to uneven seabed conditions. The finite element method (FEM) is widely used for structural analysis due to its flexibility in modelling complex structures. Validation of FEM is essential for verifying its accuracy, typically against physical experiments or reliable theoretical data. This study validates a finite element (FE) model for the static analysis of free-spanning subsea pipelines by comparing FEM predictions with Euler-Bernoulli and Timoshenko beam theories. The pipeline model, developed in Abaqus, was evaluated across various length-to-diameter (L/D) ratios. Results show that for L/D < 140, FEM predictions align with beam theory, exhibiting errors below 2%. However, for L/D > 160, FEM deviations exceed 30%, indicating nonlinear effects beyond the range of beam models. These findings refine the applicability of DNV-RP-F105 guidelines, enhancing pipeline integrity assessment methodologies in offshore engineering. The validated FEM model offers confidence for further evaluation of pipeline integrity under combined loading or defects.