Underwater Inspection Planning Based on Reliability and Decision-Making Techniques: An FPSO Platform Case Study

Ensuring the integrity and safety of Floating Production Storage and Offloading (FPSO) platforms is crucial for the oil and gas industry, particularly in offshore environments. A critical component of this is the underwater inspection process, commonly referred to as Underwater Inspection in Lieu of Drydocking (UWILD). Despite its importance, planning such inspections is not trivial and requires a systematic approach that balances risk, reliability, and resource optimization. In this context, this paper proposes a method for planning underwater inspections based on reliability and decision-making techniques. It complies with three main processes: identification of what needs to be inspected, determination of when to inspect, and selection of which inspection method to apply. Each process integrates specific techniques to support the application of the proposed method. First, to prioritize inspection items, potential failure modes are identified, and their effects and criticality are assessed. For determining recommended inspection intervals, life data analysis and degradation analysis are applied to derive reliability functions and data-supported decisions. Finally, for the selection of inspection methods, a Multicriteria Decision-Making (MCDM) approach is used to prioritize inspection techniques based on the specific requirements of each maintenance scope. The proposed method is demonstrated through a case study based on an operational context of a Brazilian FPSO platform. The results obtained show the proposed method can support maintenance planning as it provides structured guidance to systematically define and review the scope of underwater inspections, contributing to the reliability and integrity ensuring. Accordingly, this study is expected to contribute the integration of reliability and decision-making techniques in the field of physical asset management research and the oil and gas industry.

Keywords: Underwater inspection, UWILD, Maintenance planning, Reliability techniques, FPSO.