Cathodic protection condition in the presence of AC interference

To assess cathodic protection criteria in the presence of alternating current (AC) interference, weight loss testson cathodically protected carbon steel specimens were performed in soil-simulated conditions in the presenceof AC densities ranging from 10 to about 500 A/m2. Tests last for four months. Carbon steel potential wasperiodically monitored by means of a Luggin capillary in order to eliminate the ohmic drop contribution and torecord the true polarization level of the polarised carbon steel samples. At the end of the test weight loss wasevaluated. On the basis of the results, a corrosion risk map is proposed. Main conclusion is that overprotectionis the most dangerous condition in the presence of AC interference.