Simplified electrochemical potential noise method to predict corrosion and corrosion rate

Abstract

Corrosion is a costly and dangerous issue in most industries causing breakdown of equipment, increased downtime and potential risk to personnel and environment. Corrosion under insulation (CUI) is a significant contributor to these issues. As CUI is difficult to detect, real time monitoring is an important part of identifying, controlling and preventing this serious issue. Electrochemical noise (EN) is a promising technique that can be applied to components under insulation. Issues with traditional EN techniques when applied to field conditions necessitate the need for simplified methods to incorporate the benefits of EN monitoring to in-situ application. By using three identical electrodes made of the same materials as the bulk materials in production to simulate the corrosion behaviour, this research introduces a simplified methodology using measured electrochemical potential noise (EPN) to predict the corrosion rate of individual electrodes and demonstrates its application through short term testing. A relationship between isolated electrode EPN, mass loss and corrosion rate was found for electrodes undergoing corrosion. The relatively high impact of retained corrosion product in short term tests for electrodes undergoing localized corrosion was found to contribute to the reduced correlation in the EPN-mass loss relationship. The relationship between EPN and corrosion rate was observed to be dependent on immersion times.