Numerical modelling of pipe internal stresses induced during the coating process – Influence of pipe geometric characteristics on stress state

The presence of internal stresses in organic coatings is a well-known phenomenon that can generate loss of adhesion. In the case of external coatings used to achieve long-term protection against corrosion, three-layer coatings are widely employed. They are composed by a thick polyolefin topcoat, a modified polyolefin adhesive and a fusion bonded epoxy. Several observations corroborate the existence of internal stresses in the coating. Furthermore, pipes of various diameters and thicknesses are found on the market depending on the in-service technical requirements. The aim of this finite element study is to show the influence of the steel pipe geometry on the internal stresses calculated in three-layer systems after the cooling process. Then the study is focused on a standard coated pipe in order to determine the optimal thicknesses of the different layers. For these purposes, a nonlinear thermo-mechanical approach by finite element modelling with Abaqus™ is used.