Floating production facilities are widely used in the exploitation of offshore oil and gas. Mooring system is the key structure component anchoring the floating system to sea bed. The structural reliability approach may be used for the structural analysis and design taking to account uncertainties related to both applied loading and material strength and time dependent degradation mechanisms. By the consideration of corrosion as the main cause of resistance deterioration, a time-dependent reliability analysis method can be used to investigate the ultimate strength of mooring system under wind, wave and current conditions that is presented in this paper. The paper also reviews a case study of the mooring system of "Huajiachi" test facility that a reliability model was developed to analyze the probability of declining resistance with time. The probability distribution function of the total loads was created by Matlab software using the metocean data. The comparison between time-dependent and time-invariant reliability assessment methods shows that the analysis results without considering time variation are lack of security. During design life, it's necessary to regularly assess integrity of mooring system and if any deficiency or risk is identified, a mooring line replacement program should be developed. Finally, based on the formulated model, the mooring system reliability analysis is subsequently performed which can provide a better understanding of potential risks.


With the exploitation of offshore oil and gas going to deeper water, the floating production has been widely used. Mooring system is the key structure component anchoring the floating structure to sea bed. The reliability assessment of mooring system is very well established and advanced within industry.

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