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This paper investigates the corrosion factor to the global strength of aging offshore jacket platforms in different marine zones. The time-dependent corrosion wastage model from Melchers, an active corrosion expert, by considering different marine zones, i.e., atmospheric, splash, and immersion. In addition, three aged jacket platform models of the originally installed platform were selected to investigate the effect of corrosion wastage on global strength. The jacket platform's global strength is calculated by the Reserve Strength Ratio (RSR) value. RSR is obtained via nonlinear static pushover analysis and is always used to estimate overall structure strength reserves. Safety assessment is evaluated by the PETRONAS Technical Standard (PTS). According to this study, immersion zone corrosion is the most influential zone after splash zone corrosion. Furthermore, the study also predicts the lifetime of each jacket platform, and it is useful for structural engineers to estimate corrosion allowance at the early design stage.

This study compares the Residual ultimate longitudinal strength – grounding Damage index (R-D) diagrams produced by two analysis methods: the ALPS/HULL Intelligent Supersize Finite Element Method (ISFEM) and the design formula (modified Paik and Mansour) method – used to assess the safety of damaged ships. The comparison includes four types of double-hull oil tankers: Panamax, Aframax, Suezmax and VLCC. The R-D diagrams were calculated for a series of 50 grounding scenarios. The diagrams were efficiently sampled using the Latin Hypercube Sampling (LHS) technique and comprehensively analysed based on ship size. Finally, the two methods were compared by statistically analysing the differences between their grounding damage indices and ultimate longitudinal strength predictions. The findings provide a useful example of how to apply the ultimate longitudinal strength analysis method to grounded ships.