Risk based inspection for offshore structures

Floating Production Storage and Offloading Units (FPSOs) are specific installations regarding their operating conditions and functions in comparison with classic ships. One of these particularities is the lack of opportunity to dry-dock. Operating continuously whilst at the same time safely presents therefore a particular challenge which ultimately led to the development of new Inspection, Maintenance and Repair (IMR) procedures to be applied to FPSOs. This has encouraged major companies and class societies to adopt Risk Based Inspection (RBI) as one of the most appropriate procedures for IMR planning of FPSOs. As a consequence, the challenge for both parties is to develop and implement RBI methodologies which guarantee profitability and competitiveness of FPSOs whilst ensuring the required structural integrity throughout the service life. Objective of this paper is not to present a state-of-the-art review of RBI but rather to give some strong insights about all ingredients which have to be used to support the development of relevant RBI practices. Emphasis is put on quantitative fatigue RBI which is a good basis to highlight these ingredients. The model example, the RBI theoretical framework and the state-of-the-practice dealing with component quantitative RBI form a whole for which the objective is to open the door to other RBI issues which are briefly mentioned in the conclusion.