Corrosion under Insulation (CUI)

Corrosion under Insulation (CUI) is a severe form of localized external corrosion that occurs in carbon and low alloy steel equipment that has been insulated.  This form of corrosion occurs when water is absorbed by or collected under insulation.  The equipment begins to corrode as it is exposed to water and oxygen.  CUI is common in refineries and process plants that typically operate equipment at high temperatures.