Structural Repair at a Production Platform by Means of a Composite Material Patch

Abstract

Abstract This paper shows work performed through a Joint Industry Project (JIP), aimed to enable repairs made from composite materials to be applied to metallic structural components of offshore platforms in general and FPSOs in particular. The basic motivation was to provide a repair methodology that would cause a reduced impact to platform operations, particularly in classified areas. The focus on FPSOs derived from the fact that most of them are converted tankers, originally designed for overhauling in suitable docks from time to time. That is no longer possible once they are deployed as floating platforms, intended to stay in place for twenty years or more. An important prerequisite was that the repair procedure had necessarily to have the approval of the Classification Society of the platform. The project was conducted in three phases. The objective of the first phase was to develop a qualification procedure for the repair of relevant defects with adhesive patches and to demonstrate its feasibility with simple examples. Along phase two a Project Recommended Practice for Patch Repair was issued and more qualification tests were performed. Phase three consisted of a practical application of the Recommended Practice, accomplished within Petrobras by a repair at a ballast tank of the production semisubmersible platform P-20, in operation at Campos basin. The repair was accomplished by means of carbon fiber reinforcements within a vinylester matrix. This paper describes the P-20 repair case and the design of the bonded repair. A brief overview is presented of the installation of the repair, quality assurance issues and needs for future follow-up. The experimental and theoretical studies performed in support of the repair trial are briefly described. The successful repair trial demonstrates the utility of bonded repairs in managing the integrity of offshore steel structure assets. Introduction This paper shows the result of several years of research aimed to develop a cold repair technology for marine structures based on bonding of composite materials. The main objective was to minimize impact on the operational routine of a floating production platform, even if the repair takes place in a classified area. The work was done by means of a Joint Industrial Project (JIP) coordinated by Det Norske Veritas (DNV). The sponsors of the JIP were Petrobras, Petronas, Statoil, Norsk Hydro, Shell and ConocoPhillips. The role DNV plays on the usage of composite materials in offshore is well known, through the documentation it already produced on the subject. DNV is also the Classification Society of some production platforms in Brazil, making it easier to have the necesssary approval for a field trial of the technology.