ADHESIVE INFLUENCE ON THE LINER DETACHMENT OF MECHANICALLY LINED PIPES SUBJECTED TO BENDING AND INTERNAL PRESSURE

Mechanically lined pipes (MLPs) employ a thin-walled corrosion resistant alloy (CRA) liner to avoid corrosion in offshore pipelines. During reeling installation, the liner may wrinkle in the compression side due to reverse elasto-plastic bending cycles. This problem can be avoided by either increasing the liner thickness or applying internal pressure during the installation but both solutions lead to a cost increase. A proposed alternative is to manufacture the pipe with an adhesive layer between the carrier pipe and the liner to avoid wrinkle formation and potentially reduce the laying costs. Its effectiveness depends on a number of factors, including the adhesive properties and the resulting residual contact pressure from the manufacture process. In this work, a uniform ovalization finite element model is employed to assess the bending behaviour of tight-fit and snug-fit lined pipes, respectively denoted TFP and SFP, with three different types of adhesives. Three dimensional solid elements are employed for both the carrier pipe and the liner with elasto-plastic response and the adhesive is represented by a contact surface. The uniform ovalization model, while unable to capture wrinkling effects, reveals the adhesive's significant influence on liner detachment and stress distribution.