Using Coating Roughness to Control Pipe-Soil Friction and Influence Pipeline Global Buckling Behaviour-Paper

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The study investigates whether engineered coating roughness can control pipe–soil friction and thereby influence global buckling in high-pressure, high-temperature (HPHT) subsea pipelines. Thermal expansion in these pipelines generates axial stress, while seabed friction affects stress build-up, pipe walking, and buckle formation. Conventional buckling-control methods often require additional infrastructure; tailoring coating texture could offer an alternative.<br /><br />Laboratory tests on polypropylene coatings showed that friction depends on surface roughness and soil grain size. Typical coating specimens had ultimate friction coefficients of approximately 0.15–0.35, while enhanced textures achieved values up to 0.62. Using this experimental basis, the authors modelled an approximately 4.9 km unburied pipeline in Abaqus under operational temperature and pressure loads. Friction coefficients of 0.25, 0.50, and 0.75 were applied uniformly and in different patterns along the pipeline.<br /><br />Uniform-friction analyses showed expected trends: higher friction increased axial-force build-up and reduced end expansion, while lower friction generally produced larger lateral buckle displacements. In the model with an initially imperfect straight pipeline, non-uniform friction had a pronounced effect on buckle location and number. A low-friction central region tended to produce one central buckle; configurations with higher friction at the midpoint could instead produce two buckles positioned away from it. Differential-friction cases generally had end expansions comparable to or lower than those in uniform-friction cases.<br /><br />The results suggest that deliberately varying coating roughness along a pipeline could help designers influence buckle distribution and pipeline stability without installing additional seabed structures. However, this is a preliminary numerical study based on simplified assumptions, including a flat, rigid seabed and prescribed soil-response models. Further work is needed to assess performance under realistic seabed variability and field conditions.

Keywords

HPHT pipelines

global buckling

pipe-soil friction

engineered coating roughness

subsea pipelines

polypropylene coating

Abaqus modeling

thermal expansion

buckle distribution

coating texture