The current demand for cathodic protection of coated steel samples have been measured for 5 years. Organic coatings of various thickness and type have been tested, representing different classes of coatings according to DNV RP 401 and NORSOK M501. The samples were exposed in natural seawater and polarised with zinc anodes. For samples with only a primer coating (50 lure thick) the current
demand started to increase immediately after immersion. However, after a few months the current demand stabilised and it has been stabile since. The current demand after five years was 10 - 20 % of the
value for bare steel. For samples with 150 lam thick coatings the current demand increased during the first two - three years of exposure, but was stabile since. The current demand for these coatings after five years was 3 - 6 % of the value for bare steel. For samples with 450...
Keywords: Cathodic protection, organic coating, coating quality, current demand, cathodic disbonding, coating breakdown