FPSO risk assessment and acceptance criteria with application to FPSO mooring systems

Risk based design code safety format calibration for FPSO installations is addressed based on the results of a recent industrial project performed for IMP by the authors. Generic risk models for general engineering systems are introduced taking basis in recent work by the Joint Committee on Structural Safety (JCSS). Thereafter, the scenarios considered for the risk based calibration of a design code safety format for the design of FPSO facilities in the Gulf of Mexico are outlined in some detail. Furthermore, it is shown how these scenarios may be represented in a generic risk assessment model greatly enhanced by the utilization of hierarchical risk modeling procedures such as Bayesian Probabilistic Nets (BPN's). A short outline of the Life Quality Index (LQI) principle is then introduced as a practically applicable means to determine how much should be invested into life saving activities. Finally, an example is given where the introduced concepts are used for the purpose of determining the target reliability index for individual mooring lines taking into account the direct and indirect consequences of failure of the mooring system for a considered generic FPSO installation.