AC Corrosion – Part2: parameters influencing corrosion rate

Pipelines and AC power transmission lines frequently share corridors leading to AC interference corrosion problems, as documented by pipeline failures that have occurred in the USA, Canada and Europe, even when cathodic protection is applied. In order to investigate these phenomena, weight loss tests on carbon steel samples were performed in soil-simulating conditions (aerated and de-aerated sulphate solutions) at various AC current densities from 10 to about 900 A/m2. Tests on freely corroding samples showed that the corrosion rate increased as AC current density increased; the effect of AC on corrosion rate was also detected at current densities lower than 30 A/m2. The results obtained are analyzed and discussed together with polarization test results, which were presented in a previous paper by Goidanich et al. (submitted for publication) [1].