Performance of a volatile corrosion inhibitor for mitigating corrosion under insulation

Abstract

This study evaluated the efficacy of a commercial volatile corrosion inhibitor (VCI) in mitigating the corrosion of carbon steel insulated with mineral wool insulation, especially as a retrofitted solution to CUI management. When VCI was added in dry insulation before the test solution was introduced, severity of CUI was reduced after 14-day exposure. However, when the exposure time was extended to 90 days, no significant mitigation effect was observed. Furthermore, VCI was ineffective when added to pre-corroded insulated systems, indicating that it could not be used as a retrofitted solution to alleviate CUI problems. A separate set of tests with bare steel samples exposed to 10 mL VCI in closed jars showed that VCI was adsorbed on the corrosion products but could not effectively impede the propagation of localized corrosion. The possible influences of insulation jacketing, insulation properties, VCI dosages and dosing methods were also discussed, suggesting the need for further investigations.