A Time-Dependent Corrosion Wastage Model for the Structures of Single-and Double-Hull Tankers and FSOs and FPSOs

This paper presents a mathematical model for predicting time-variant corrosion wastage of the structures of single-and double-hull tankers; floating, storage, and off-loading units (FSOs); and floating, production, storage, and off-loading units (FPSOs). The measurement data of corrosion depth (thickness loss) for single-skin oil tanker structures of various ages are collected, and the statistical characteristics (mean, variance, distribution) of measured corrosion data are quantified in terms of ship age. A set of timedependent corrosion wastage models for 34 different structural member groups by type and location, considering plating, and webs and flanges of stiffening, are then developed by the statistical analysis of the corrosion measurements. The nominal design corrosion values for primary member locations/categories are also proposed. The results of this study can be updated as additional experience is accumulated. The procedures and insights developed in the present work will be useful for predicting the depth of corrosion in oil tanker structures. They will also be useful for establishing requirements and guidelines for the relevant corrosion protection measures and for designing corrosion-tolerant tanker structures in general.