Numerical Study on Contact Pressure in Mechanically Lined Pipe Fabrication With Imperfection

Abstract Mechanically Lined Pipe (MLP) is a composite tubular structure consisting of a thin-walled Corrosion Resistant Alloy (CRA) liner mechanically bonded to the internal surface of an outer carbon steel carrier pipe. This design combines the corrosion resistance of the CRA material with the structural strength of the carrier pipe, making it a cost-effective solution for offshore applications. However, the integrity of the interface bonding is critical, particularly during offshore installation, where plastic bending and large deformations are repeated. The interlayer residual contact pressure, generated during the hydroforming process, plays a vital role in preventing liner detachment and maintaining structural integrity under such demanding situations. To provide a more practical and accurate analysis of this process, this study developed a two-dimensional axisymmetric elastoplastic Finite Element Model (FEM) using ABAQUS/Standard Implicit. The model incorporates geometric and thickness imperfections in the liner and carrier pipe, which are implemented through Python programming in the input file. The study records the distribution and magnitude of interlayer contact pressure for various defeat scenarios, capturing data both at the maximum hydraulic expansion pressure and after the completion of the manufacturing process. Additionally, the effects of various defect types and parameters in the liner and carrier pipe are analyzed in detail, highlighting their impact on the MLP product performance. This analysis reveals how single cylinder defects arising from respective manufacturing stages influence subsequent lined pipe hydroforming and offers valuable insights for optimizing the design and production of MLPs.