There may be induced AC voltage on the buried pipeline of oil and gas by power line and electrified railway, resulting in "AC corrosion". Although the reseach on AC corrosion has lasted for 74 years, many important problems about this subject are, heretofore, not clear.
In this paper, a new way viz. to investigate the AC corrosion on the basis of the theory of electric field in combination with that of the electrochemistry was proposed. New concept is hereby introduced; that is the electric-field corrossion.
Under the effect of the field which varies swiftly and holds powerful intensity, the reactive process of internal electrochemistry changes essentially, and the intensity of electric field is an important physical quantity. Making measurement and analysis of the interfered voltage, the gradient of potential, the point density of current, the weight-loss and depth of corrosion, we discovered that the weight-loss increases according to average density of current, and the depth of cavity becomes deeper according to the interfered voltage. Based on the results of experiment, prematurely safety limits of voltage of AC corrosion are proposed.