PROPOSAL OF CP CRITERION IN THE PRESENCE OF AC-INTERFERENCE

Laboratory tests were conducted on cathodically protected carbon steel specimens in the presence of AC interference. Tests were carried out in soil simulated conditions, with a CP current density in the range of 0.2 to 10 A/m², and an AC density in the range of 1 to 500 A/m². CP criteria have been defined as a function of AC density, true protection potential and the ratio between AC density and CP current density. In 2008, field test started on thirty carbon steel coupon subjected to AC interference. Both cathodic protection and free corrosion conditions were considered. Collected data are discussed on the basis of proposed criteria.