Risk-Based Approach in Composite Repair Integrity Assessment

Abstract

Abstract This paper presents the methodology in addressing composite repair integrity management through a qualitative risk-based approach based on Petronas Technical Guidelines, best practices, lessons learned, manufacturing data, design, application, and presence of defects. Recommendations for monitoring intervals and techniques are generated as the outcome of the assessment. The overall approach of this assessment consists of 5 major steps which include post-application inspection of composite repair, inspection report analysis and evaluation, the risk-based assessment, determination of risk profile, and the development of an Integrity Management Plan. Risk is typically defined as a factor of the probability of failure and the consequence of failure. In this risk-based approach, the probability of failure takes into consideration four hazard categories which are, Manufacturing, Design & Engineering, Application, and In-Service Factor. The consequence of failure on the other hand takes into consideration the effect on four categories namely people, environment, assets, and reputation. The final risk is represented in a 5x5 risk matrix whereby risk can be categorized into four major groups which are LOW, MEDIUM, HIGH, and VERY HIGH. As an outcome of the RBI analysis, Integrity Management Plan (IMP) prescribes an inspection method for a composite repair at a specific interval based on its risk profile. Distinctions are made between application locations to promote optimization and comprehensiveness of the integrity management plan deployed. For the above-ground piping section and vessel, for LOW, MEDIUM, HIGH, and VERY-HIGH risk categories, inspection intervals of 2 years, 1 year, 6 months, and 3 months are recommended respectively. It involves inspection methods like visual inspection, coin tap test, hardness test and NDT with prescription depending on risk profile. For buried external corrosion with Low and medium risk, pipe to soil potential measures are recommended at an aligned interval with OPU IMP or 2 years whichever comes first. Meanwhile, for High and very high, CIPS, DCVG, and defect verification are advised depending on the risk level. In offshore topsides and risers applications, is also recommended to conduct a visual inspection, coin tap test, hardness test, and NDT, with prescription based on respective risk profiles. Through this approach, a comprehensive integrity management plan can be established to monitor the performance of the composite repair while providing an evidential and qualifiable basis for composite repair design life extension. This will be a platform for the digitalization of composite repair databases which can be an accelerator towards automation in integrity management, especially in composite repair applications.