Corrosion protection of water injection Steel Catenary Risers (SCRs) has been identified as a multi discipline challenge facing the industry. Readily available solutions often lead to excessive riser weight and top tensions, expensive materials, complex welding solutions, and increased fabrication time and risk. Currently, a technology qualification program for an integrated liner system in dynamic riser service is aiming to address this and achieve formal Technology Readiness Level 5 (TRL5 from DNVGL-RP-A203) by Q3 2020.
Individual components of a liner system are often unique and proprietary requiring individual qualification. This multi discipline program utilizes an integrated liner system incorporating carbon steel host pipe (including girth welds), polymer liner (including butt fusion welds), electrofusion welded polymer connectors (EWPC), and mechanical corrosion resistant alloy terminations (MCRAT). Fatigue testing is the primary method of assessment in this case, a series of nine fatigue trials spread over three stress ranges; 200MPa, 150MPa and 100MPa, have been scoped.
Initial positive results have proven the concept of using the integrated liner system components in the dynamic riser application with successful completion of high stress range (200MPa) fatigue tests utilizing the full integrated liner system. To date, the conducted fatigue testing achieves performance equivalent to DNVGL-RP-C203 S-N curve D (in water with cathodic protection) after subjecting the pipe to pre-straining via reeling trials. Upon scope completion, it is expected to extend performance to meet the requirement for S-N curve C/2. Completion of testing with an intact corrosion barrier combined with assessment of vertical orientation on the system enables design of polymer lined pipelines suitable for dynamic riser service.
The integrated liner system offers a potential step change in SCR and SLWR design. The technology application is able to provide key benefits such as an optimized design over the life of the pipeline, improved flow assurance, minimized installation complexity, optimized host and operational needs, thus resulting in an efficient and optimized field life cycle.