A Study on Piping Stress Analysis of Subsea Riser Base for HYSY111 FPSO in South China Sea

Subsea Dynamic Riser Base is an important equipment for floating production platform mooring system, one end connected to rigid pipeline, carrying a rigid pipeline thermal expansion load, the other end connected to flexible riser, carrying the dynamic load of flexible riser, so its function is a transition connection from flexible riser to rigid pipeline and fixed the flexible riser on the seabed. On the other hand, as a typical subsea product, the design shall be satisfied with requirements from the standards for subsea product. By studying the stress analysis philosophy of topside piping and subsea pipeline, physical model and procedure for piping stress analysis of SDRB have been established, the conditions of the adverse design load have been considered, combination of the static load from rigid pipeline and the dynamic load from flexible has also been optimized. And comparatively analysis with the AMSE, DNV and API standards for piping stress of checking rules has been done, for SDRB belongs to the subsea pipeline terminal product, the use of DNV standard to check its process piping stress is recommended. Finally, the process piping stress of SDRB has been calculated, and the results show that jacket pipe and carrier pipe stress of SDRB process piping is satisfied with DNV standard as a whole. As the bulkhead cannot be accurately simulated by AutoPIPE software which using the FEA software ANSYS in detailed analysis, and the checking results still meet the requirements of DNV standard.