FPSO Hull Brackets Repair by Cold Bonded Reinforcements - Project Lessons Learnt from a World First Offshore West Africa

Abstract

An increasing number of Brazilian floating platform units are currently entering a mature age inducing numerous asset integrity issues. As corrosion damages FPSOs’ hull structures, costly structural maintenance operations in extreme marine conditions are sometimes necessary. Crop and renew are very labor-intensive operations and usually require dry docking vessels. The nature of an FPSO operation practically demands it stays offshore, which raises several operational, safety and financial challenges. Indeed, dealing with flammable substances means that the use of conventional hot works techniques, such as welding or grinding, involves many critical safety assessments and/or production shutdowns. Thus, the challenge would be to carry out these repairs offshore while guaranteeing high safety standards and avoiding production shutdowns. FPSO operators, like SBM Offshore, have therefore been looking for a while for "cold work" in-situ solutions that guarantee safe and economical hull repair. This paper will describe how SBM Offshore streamlined a world first implementation of a disruptive innovation (from TRL 5 to TRL 7 as per API) within less than a year through a partnership with COLD PAD, an industrial start-up of only 3 people at the time it was first proposed. It covers risk assessments, expert analysis, and overall qualification process. It will also detail how Classification society was involved as well as typical lessons learnt from the project execution with a focus on the offshore campaign which took less than two weeks. Finally, the paper will provide indications on the advantages such a solution generates for FPSO hull asset integrity in terms of safety, planning, economics (reduced total cost of ownership) and how it can be extrapolated to lower OPEX for deepwater ageing FPSOs. The business case considers an FPSO located in deepwater West Africa where, in 2016, SBM Offshore identified a set of corroded brackets in a void tank located close to two crude oil tanks. Classification Society imposed steel renewal for 4 of these brackets. After engineering assessment, it was concluded that conventional hot works would yield to a highly detrimental production disruption. At the same time, COLD PAD was finalizing the co-development with TOTAL and IFP Energies Nouvelles of an innovative alternative to "crop and renew" for structural reinforcement. ColdShield™ is specifically dedicated for the on-site maintenance of FPSO hulls without the need for hot works, thus avoiding production disruption for several scenarios. This original repair technique obtained a class approval with an anticipated service life of more than 10 years based on an established methodology of bonded composite reinforcement, used in other industries such as aerospace.