Collapse resistance of mechanically lined pipes (MLP): A numerical and experimental study investigating the effects of friction coefficient

This study aims at investigating and quantifying the effect of corrosion-resistant alloy (CRA) liners on the resistance to collapse by external pressure of subsea mechanically lined pipes (MLP) through a comparison of experimental data provided by full-scale testing and finite element modelling (FEM) results. Collapse pressures and respective failure characteristics were identified for a wide range of pipe diameters and wall thicknesses, and the influence of parameters such as ovality and eccentricity was considered. Mechanical tests were performed on samples extracted from commercial pipes to measure the friction between the steel carrier pipe and the liner, and these results were included in the models. Both the experimental and numerical results demonstrate that the liner is critical in improving the collapse resistance of MLPs. They also suggest that existing subsea pipeline design standards may be overly conservative when the influence of the liner in the collapse resistance of MLP is not considered.