Offshore Structures And Platform

The risk assessment, in this paper, includes the platform’s global risk level and the local risk levels of the platform’s structural components (e.g. tubular joints). The global risk assessment allows risk-based inspection intervals and general inspection requirements to be defined. It proposes a gradual risk evaluation in terms of available platform’s data from a semi-quantitative assessment based on key platform’s data (e.g. robustness, last inspection findings, manning status, and functionality) to a quantitative assessment based on structural analysis results or involving structural reliability method. The local risk assessment performs local risk ranking of the tubular joint of the jacket structure to identify local inspections scope if required. A semi-quantitative assessment is proposed to select the tubular joints or members where close visual survey (CVI) or alternatively flooded member detection survey (FMD) should be applied. A fatigue-based probabilistic method is also implemented to determine optimal inspection plans for selected tubular joints, the fatigue failure of which is critical for the overall structural integrity, and which joints require crack monitoring by non-destructive technique(NDT).