PREDICTION OF CORROSION IN BALLAST TANKS OF NAVAL SHIPS USING OPERATIONAL CHARACTERISTICS

摘要

Corrosion in ships is of major concern for ship managers. Presently, empirical corrosion loss models are applied to predict the future expected corrosion thickness reduction of various steel plating in ships. This is an improvement on past practices in which an in-built corrosion allowance, depending on the structural detail, was either too conservative or not high enough to account for corrosion rates experienced. The empirical models however are based on corrosion loss data collected from many ships for many and varied operational environments. Hence, the empirical corrosion models exhibit a high degree of variability and cannot be used to accurately predict the structural life of a particular ship for a particular environment. In this paper a more refined model is presented together with input based on Australian naval ship operational conditions. The model can help predict corrosion loss and subsequent cost of maintenance as a function of the operational characteristics of the ship. The focus for the modelling is the most critical part of the ship for corrosion repairs - the seawater ballast tanks. The operational characteristics used for input are the geographical location and the ballast condition. Previously developed corrosion loss models for seawater immersion and enclosed atmospheric spaces are applied in the modelling simulations. Validation of the corrosion loss modelling and the operational variables was performed through a shipboard experimental trial.