Corrosion has a major influence on the technical lifespan and the operational costs of a ship and steel structures in a seawater environment. Extending the life of obsolete steel structures such as ship hulls requires knowledge about the reduction in wall thickness as a result of corrosion. Corrosion control systems such as coating and cathodic protection are often not sufficient to stop this aging process.
Most models for predicting corrosion rate and material degradation over time are conservative and do not take operational and environmental conditions into account. However, the influence of these conditions and factors is significant, so that predictions of material loss based on the outdated models are not very reliable.
The model that has been into a web application within the framework of the Port4Innovation project “Corrosion modeling” looks beyond standard prediction. The model takes into account both the non-linear behavior of the corrosion process itself, as well as the operational conditions and environmental factors during the use phase of a seagoing vessel.
The model is based on the weakest link that must ensure the integrity of a ship's hull in an aggressive seawater environment; the ballast tank. The ballast tank is generally the most susceptible to corrosion in the hull because the preservation system of a ballast tank is difficult to maintain. This due to the poor accessibility and positioning of parts to be preserved and the ineffectiveness of anodes in an empty ballast tank.
Based on literature research, experience and research results, the project partners have developed a model that can predict the corrosion rate and thus the material thickness at a future point in time. Special thanks are due to WEAPP and to Professor Rob Melchers of the University of Newcastle, Australia for their active contribution to the improved calculation model during the project and to the development of the application.
We invite ship owners and shipowners to use the model to accurately plan the measures that should lead to corrosion control. The results can thus contribute to maintenance and inspection planning, so that cost savings in maintenance can be achieved.
Because this is a model in which not all known factors influencing corrosion have been incorporated, it remains wise to regularly measure the wall thickness and the quality of preservation based on the Risk Based Inspection Strategy. The project partners Control Union, Endures and Vector Maintenance Management B.V. are happy to be of service to you in the field of corrosion control based on their own specialism.