Probabilistic Risk Assessment for FPSO Topside Structures Under Drop Impact: An Application to Pipeline Protections

In offshore structural design, it is necessary to evaluate probabilistic risk so that the topside structure has sufficient capacity to resist the effects of accidental loads such as drop impact, helicopter impact, vessel collision, fire, and explosion. Most engineers in the offshore industry, however, have difficulties in estimating a reliable risk value because there are still too many uncertainties in computing the probability of exceeding a target structural damage where the guideline for hazard analysis, which provides design load, is quite well described. Therefore, a framework to compute reasonable probability of structural failure is proposed in this paper. 88 impact scenarios were applied to a pipeline protection system on a topside module of Nexus genetic FPSO in order to perform regression analysis for structural damage. For risk calculation, the hazard analysis in this study is based on the detail engineering report worked by Ramboll Oil & Gas.