Effects of AC interference on the optimum cathodic protection potential of X70 steel in soil solution

Abstract

Purpose

The presence of alternating current (AC) causes serious damage on buried pipelines even when the off potential matches the −0.85 V/CSE criterion. The optimum cathodic protection potential (OCPP) is more accurate for cathodic protection. The paper aims to study how to get the optimum cathodic protection by electrochemical impedance spectroscopy (EIS) and the effects of AC on the OCPP.

Design/methodology/approach

This paper describes the application of EIS to investigate the OCPP of X70 steel in a soil simulating solution with different AC interferences.

Findings

The experimental results indicate that AC interference makes the OCPP decrease and the −0.85 V/CSE criterion is not reasonable when there is AC interference. When the AC voltage is less than 6 V, the OCPP is approximately −900 mV/SCE, and when AC voltage is more than 7 V, the OCPP is roughly −1,000 mV/SCE.

Originality/value

There have been some researches on the OCPP, and the paper is the first one to study the AC effects on the OCPP and found that the OCPP changed when there was AC interference.

Citation

Ding, Q., Li, Z. and Hao, H. (2013), "Effects of AC interference on the optimum cathodic protection potential of X70 steel in soil solution", Anti-Corrosion Methods and Materials, Vol. 60 No. 6, pp. 283-287. https://doi.org/10.1108/ACMM-02-2011-1089