Carbon steel and low alloy steel are the common, cost effective materials of choice for design of production risers in deep water. They are, however, often challenged by high stress and fatigue loadings. When production fluids are corrosive and or sour, steel risers may not be feasible without the protection from corrosive effects. To mitigate degradation, the only proven solution to date is the use of corrosion resistant alloys (CRA), either in homogeneous or clad/lined steel pipe product. However, corrosion resistant alloys are very expensive and market supply is limited due to the number of...
Carbon steel and low alloy steel are the common, cost effective materials of choice for design of production risers in deep water. They are, however, often challenged by high stress and fatigue loadings. When production fluids are corrosive and or sour, steel risers may not be feasible without the protection from corrosive effects. To mitigate degradation, the only proven solution to date is the use of corrosion resistant alloys (CRA), either in homogeneous or clad/lined steel pipe product. However, corrosion resistant alloys are very expensive and market supply is limited due to the number of developments worldwide requiring CRA solutions and the limited number mills capable of supplying the product. This study looks at the feasibility and current state of development of alternatives to clad steel in steel catenary risers (SCR). The study focuses on polymer liners and coatings as a way to prolong the life of the risers in corrosive hydrocarbon service. The study includes an industry survey of candidate liners and a risk assessment based on the threats and failure modes. FMECA is conducted on the more promising candidates. The gaps in the knowledge base are identified and a map of further qualification requirements is made. SCRs are currently fabricated with girth welds. However, there is significant amount of testing that indicates that mechanical connectors are a feasible alternative. The potential use of mechanical connectors in conjunction with a coating or liner solution to mitigate corrosion risks is also addressed.