A non-linear finite-element analysis of buckle propagation in subsea corroded pipelines

A non-linear finite-element analysis for the steady-state buckle propagation phenomenon in subsea corroded pipelines subjected to external hydrostatic pressure is presented. The corroded pipeline is modeled as an infinitely long, cylindrical shell with a non-uniform thickness region. Using Maxwell's theory of two coexisting phases and principle of virtual work, the buckle propagation pressures for the corroded pipeline are calculated from pressure–volume change relations obtained from ABAQUS. The corresponding collapse modes of the corroded pipeline are generated from ABAQUS post-analysis. Symmetric and anti-symmetric collapse modes are found to occur, depending on the depth and angular extent of the corrosion. In addition, snap-through and global collapses are also identified. A parametric study shows how the buckle propagation pressures decrease when either the ratio of corrosion depth to the normal thickness or the angular extent of the corrosion increases. The finite-element model is validated using Timoshenko's classical solutions.