Influence of the thickness of pipeline coating on internal stresses during the manufacturing process by finite element analysis

Internal stresses in organic coatings can generate loss of adhesion. This phenomenon must then take into account in order to achieve long-term protection. For corrosion protection of steel pipelines, the external coatings are usually three layered. They are composed of an epoxy primer, an adhesive and a thick layer of polyethylene. The presence of internal stresses has been suggested to explain the appearance of some spontaneous disbondments of these coatings after only few years in-service. This finite element study aims to calculate the internal stress generated during the application process for different thicknesses of coating and to compare these with measured values of adhesion. This comparison should allow concluding if this phenomenon is responsible for the loss of adhesion observed. Whatever the thickness of the coating, internal stresses at the interfaces have similar values. However, there in an edge effect at the end of the pipeline that affects values of these stresses. (C) 2012 Elsevier B. V. All rights reserved.