Integrity of Mechanically Lined Pipes Subjected to Multi-Cycle Plastic Bending

There is an increasing demand for submarine pipelines which can transport highly corrosive products. Due to the significant cost of solid stainless steel pipes, the interest in more economical mechanically lined pipes (i.e. carbon steel pipes lined with a thin stainless steel layer) is growing. There is further incentive to combine this technology with the highly efficient reel-lay method, which is an alternative to the S-lay and J-lay methods for installation of small to medium size steel submarine pipelines. Reeled pipelines, however, are subjected to at least two symmetrical plastic strain cycles during installation. The plastic straining associated with reeled installation may trigger wrinkling of the corrosion resistant liner. Technip have undertaken a development programme in accordance with DNV-RP-A203 to design and qualify mechanically lined pipes for reeling without the use of internal pressure. The proposed novel design enables a safe and reliable reeled installation and a subsequent lifetime operation of mechanically lined pipes by controlling the liner thickness.