Corrosion models for steel plates in ship structure based on statistical data

To have a proper maintenance policy for ships and offshore structures, it is necessary to predict corrosion wastage accurately. It is the main aim of the present work to propose corrosion models for plates in ship structures. In total 66,480 data were collected from thickness measurements carried out by different classification societies. The data were sorted out based on the position of the plate, the age of the ship, the country where the ship was built, and the type of ship. Using regression analysis, some models were proposed as a function of the ship's age and position of plate. Based on this study, the proposed models are checked against existing corrosion models in the literature and it is found that other corrosion models underestimate the corrosion rate in the inner bottom plates, and deck plates. However, they overestimate the amount of corrosion in the side plates of ships. The existing corrosion models are justified for the prediction of corrosion wastage in hatch-coaming plates. For corrosion of outer bottom plates, the existing corrosion models are applicable for ships under 20 years old. They overestimate corrosion wastage for ships older than 20 years. Also, existing corrosion models overestimate corrosion wastage of plates at the side structure of ships above the water line at the early age of ships and underestimate in older ships.