A large number of offshore platform are currently located in our seas, however many of these are destined to have a shorter useful life than they were designed for. This is due to the high rate of deterioration to which they are subject in the marine environment. In particular, corrosion is a major contributor to the degradation of marine and offshore structures. Therefore it is necessary to understand what kind of corrosion occurs on these structures and what are the environmental factors that determine it. Finally, the aim of this thesis is to predict long-term corrosion in order to calculate the loss of resistance of aging structures and thus avoid ultimate failure.