Extreme and Fatigue Analysis of a Dynamic Subsea Power Umbilical

This paper presents an analysis procedure and results of extreme loading effect and fatigue damage of a dynamic subsea power umbilical. The umbilical was proposed by Hengtong submarine power cable Co., Ltd intended for a FPSO in south China sea at a water depth of 400 m. The umbilical cross section consists of three copper conductor strands and two layers of steel amour wires. A pliant wave configuration is used to accommodate large offset of the FPSO in the harsh environmental condition. Orcaflex is used to verify the tension and curvature of the umbilical in extreme condition against the umbilical capacity curve. UFLEX is used to estimate the mechanical properties and local stress of the umbilical. Fatigue damage is estimated by using results from the global analysis and local stress analysis. The results show that the umbilical cross section design satisfices the acceptance criteria for both extreme and fatigue damage.