How long does a coating protect?
The steel structures, which make up a wind farm, need protection. Importantly, those offshore need a specific type, because without the correct coating corrosion occurs. This weakens and shortens the lifespan of the parts. Jo van Montfort, from Bjond, explains to PES why the choice of coating should be made by an expert, based on experience and not just lab tests.
Main function of a coating
The most important characteristic of an organic coating: paint is to form a barrier between the steel to be protected and the environment. Functional loss of the barrier effect leads to corrosion of the substrate depending on the circumstances. On average, it can be assumed that unprotected steel corrodes at a velocity of between 0.2 and 0.8mm per year and under specific marine conditions it can be even up to a few millimetres per year.
It is very important for an asset owner or maintenance manager to understand which parameters influence the lifetime of a coating system.
Next to organic coating systems also metallic coatings: e.g. Thermal Sprayed Aluminium/TSA are used. The costs for a TSA coating are significantly higher (>20%) than a conventional organic paint.
If a metallic, inorganic, coating is used, the covered steel has cathodic protection at the places where the coating no longer covers the steel, provided that: