Studies on CUI of carbon steel in simulation environment containing chloride and sulfur at 80°C

Corrosion under insulation (CUI) is a localized corrosion occurring at the interface of a metal surface and the insulation on the metal surface. In order to explore the mechanism of CUI, some tests were conducted on 20 ^# carbon steel under insulation dripping different testing solution at 80°C in an experimental simulation device for CUI. Corrosion behaviors were analyzed by weight loss methods and other methods. The results showed that CUI rate of 20 ^# carbon steel increased with NaCl concentration. The addition of sulfur and the decrease of pH promoted corrosion. The pits and small cracks were found on the corroded metal and the bonding between products and matrix was strong.