Reliability-based management of inspection, maintenance and repair of offshore structures

TLDR

Reliability‑based management of inspection, monitoring, maintenance, and repair (IMMR) for offshore structures focuses on hull damage from crack growth and corrosion, integrating design criteria with operational experience. The approach uses robustness design against accidental collapse and leak‑before‑break monitoring to detect damage. Implementing robustness design, appropriate inspection methods, scheduling, and repair strategies achieves acceptable risk, and reliability‑based reassessment can extend service life. Keywords: Reliability, Inspection, Repair, Offshore structures, Cost benefit, and acknowledgements to ABS, Statoil, and collaborators.

Abstract

Abstract Development of reliability-based management of inspection, monitoring, maintenance and repair (IMMR) of various types of offshore structures is described, with a focus on management of hull damage due to crack growth and corrosion. Operational experiences with respect to degradation of various types of offshore structures are summarized. The interrelation between design criteria and IMMR is emphasized. Explicit design for robustness in terms of an accidental collapse limit state and monitoring by the use of the leak before break principle to identify damage are highlighted. It is shown how design for robustness, choice of inspection method and scheduling as well as repair strategy, need to be implemented to obtain an acceptable risk for various types of offshore structures. Finally, the particular features of reliability based structural reassessment for extension of the service life, are briefly outlined and exemplified. Keywords: ReliabilityInspectionRepairOffshore structuresCost benefit Acknowledgements The examples presented herein were partly based on methodology developed in the project “Reliability-based assessment of FPSOs for service life extension” for the American Bureau of Shipping (ABS) and “Reassessment of floating platforms for Statoil”. The author gratefully acknowledges the support received from ABS and Statoil as well as the cooperation with Ole Tom Vårdal and others at Aker Technology over many years. I also wish to thank my PhD students and postdoctors — especially E. Ayala-Uraga, G.O.Hovde , G. Jiao and R.Song — for many discussions and for running many of the analyses.