Page 35: of Offshore Engineer Magazine (Nov/Dec 2014)

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based on a combination of the existing conditions and remain- ing predicted design loads.

Determining whether life extension of an SCR system is pos- sible requires understanding and evaluation of the potential failure mechanisms. These could be overstress, fatigue, internal or external corrosion, erosion, elastomer failure in the fexjoint, blockage or something that gets dragged across the SCR such as a mooring line.

Evaluation of each failure mechanism requires past opera- tional data, direct assessment measurements, future expected operational data and system modeling. While the process is a straightforward one, in reality the information needed to com- plete each step is often interspersed with gaps and inconsisten- cies. For instance in the GOM, most of the infeld fowlines and risers are not designed for in-line inspection, and where this is possible, the inspection technology often has inadequate resolu- tion/accuracy to identify small but critical cracks or faws in the system. Finally, where direct assessments such as a cathodic protection surveys or ultrasonic tests are completed, the results can sometimes be inconclusive.

Top Steel

Single Line Flexible

Assumed

Tensioned Catenary

O