A unique riser interface comprised of a riser porch and riser adaptor combination is presented in this paper. The unique riser interface structures were designed to be used on semi-submersible floating production systems (FPS) for both flexible and steel catenary risers (SCR's). The riser porch structures are integrated into the pontoon ring frames, which provide efficient local structural supports to carry the riser loads. The riser adaptor design is adjusted to the departure angle and azimuth angle for each specific riser. The design enables a safe and easy "drop in" installation of the riser adaptor into the riser porches so that the adaptor can either be installed in the shipyard or offshore at operating draft. One of the advantages of the riser porch and riser adaptor combination concept is the ease of installing future risers, with no underwater welding needed. It also offers schedule advantages to the hull design and fabrication since the riser design can now be finalized independently of the FPS hull construction. The strength capacities of the riser porch and riser adaptor structures were analyzed and verified using Finite Element (FE) analysis. A nonlinear FE contact analysis was carried out to simulate the load transfer between the Tapered Stress Joint (TSJ) and riser adaptor bushing. A special modeling approach for the riser adaptor FE model has been presented in the paper, with the methodologies of applying contact boundary conditions and environmental loads from the riser analysis. A time domain dynamic FE analysis was also performed to simulate the structural response during the riser installation. Results from a sample riser adaptor analysis for strength, fatigue and an installation simulation has been presented.

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