Stress analysis of welded steel catenary risers

Steel catenary risers (SCRs) have become a necessary cost saving alternative to flexible risers for economically viable deep-water oil and gas exploration and production. One of the primary challenges in SCR design is the need... [ view full abstract ]

Steel catenary risers (SCRs) have become a necessary cost saving alternative to flexible risers for economically viable deep-water oil and gas exploration and production. One of the primary challenges in SCR design is the need for weight reduction by reducing wall thickness. Reducing wall thickness results in significant savings by minimising the buoyant support required from floating production facilities, and increasing pipe laying productivity via reduced welding times for thinner sections.
To safely design the required next generation SCR systems, a greater understanding of the loading conditions experienced at failure locations such as welded connections must be achieved. Commercial finite element software packages such as Wood Group Kenny’s Flexcom provide invaluable global analysis to such SCR systems. However to allow detailed assessment of the resulting stresses at a girth welded joint of a large scale system, a coupled global-local modelling approach is required. This approach allows for the assignment of a representative weldment geometry, incorporating varying material properties in the three primary weldment regions, namely the base metal, heat affected zone and weld metal. Results will be presented in terms of this global-local approach.