Fatigue life prediction method for fairlead of single point mooring system of FPSO

  Objectives  As an indispensable component of mooring system of ship or platform, fairlead is subjected to the alternating force of mooring cable, and its fatigue problem is especially troublesome.

  Methods  In this paper, an in-development rotary fairlead is used as the study object. First, the time domain hydrodynamic calculation method is used to study the load borne by the fairleads of single point mooring system of Floating Production Storage and Offloading (FPSO) in the S4 area in South China Sea. Then the Finite Element Analysis (FEA) method is used to carry out static analysis calculation and study the structural strength and this method is also used to calculate the Stress Concentrate Factor (SCF) of the fairlead. Finally, based on the wave load calculation and structural strength calculation, a forecast method is provided to predict the fatigue life of FSPO fairleads in various sea conditions.

  Results  The results show that the fatigue life of the fairleads is 16.21 years, and the fatigue damage is mainly concentrated in the sea conditions 51-64.

  Conclusions  The study in this paper can be used for reference in the design of fairleads and the calculation of the fatigue life.