Improving Mooring Reliability Through Risk Based Monitoring and Inspection

Over the last decades, a number of mooring incidents have been reported in the public domain by conference papers and safety alerts. Mooring chain corrosion and fatigue have been reported as dominant incident triggers for these mooring incidents. Corrosion development is closely related to the locations of the mooring site. Fatigue is related toenvironmental conditions as well as mooring configuration for the mooring line load. This paper provides a review of the environmental conditions and water quality at offshore mooring sites. Important factors affecting mooring line load and load bearing capacity (mooring line degradation) are investigated. The ship-shaped FPSOs,as a dominant type of floating installationsand with more than two hundred of them currently in service,are the focus of this paper. The performance and uncertainties associated with the mooring system of the ship-shaped FPSO are evaluated.The paper provides recent industry advances onmooring performance simulations, monitoring and mooring incident identification techniques. It is recommended that risk-basedmonitoring and inspectionof mooring system can play an important role in improving mooring reliability and operational efficiency. The key elements includeidentifying critical directions of environmental loads, most loaded mooring lines, and the segments of the mooring line thatsubject to heavy corrosions. Systematical data collection, data sorting,data sharing and optimization of algorithm for anomalyidentification play important roles in effective monitoring.