Qualification of Reeled Mechanically Lined Pipes for Fatigue Service

To meet an increasing demand for conveying corrosive fluids in the subsea oil and gas sector, the authors have proposed a design of mechanically lined pipe (MLP) that enables reel-lay installation under atmospheric pressure without the risk of wrinkling of the corrosion resistant alloy (CRA) lining. The novel design was qualified for reeling and subsequent service life in accordance with DNV-RP-A203. To provide further evidence that a high fatigue performance can be achieved before a carbon steel backing pipe is exposed to corrosive constituents, a qualification programme, detailed in this paper, was undertaken. In addition, a 3D finite element (FE) study was performed on MLPs with interface flaws between the liner and clad overlay weld, and recommendations for the fatigue assessment of MLPs with interface flaws were made.