Reliability Assessment of Fairleads in FPSO Units Based on Expert Elicitation

Fairleads are critical components of the mooring systems in Floating Production Storage and Offloading (FPSO) vessels, designed to guide anchor lines and withstand significant operational stresses. The reliability of these components is essential to ensure the safety and integrity of offshore operations, particularly given the harsh environments and extended service lives of FPSO units. However, the lack of historical failure data for fairleads poses significant challenges to reliability assessments, as their robust designs and high safety factors result in minimally recorded failures. Traditional inspection intervals, dictated by classification society rules, may not fully account for the specific operational conditions and reliability requirements of fairleads. Additionally, the application of rigorous theoretical models is often impractical due to the absence of sufficient data and the complexity of these offshore systems. In this context, expert elicitation emerges as a practical solution to address these limitations and to support reliability assessments and inspection planning. This paper presents a structured methodology for eliciting expert judgments, including the selection of experts, questionnaire design, and the integration of elicited data into reliability models. The proposed approach is demonstrated through its application to fairleads in a Brazilian FPSO fleet, showcasing its effectiveness in deriving probabilistic reliability estimates and determining optimal inspection intervals. The results highlight the potential of expert elicitation to enhance maintenance strategies, ensuring the long-term operational soundness of critical offshore equipment.

Keywords: Expert elicitation, Expert judgement, Fairlead, FPSO, Inspection interval selection, Reliability assessment.