Corrosion under insulation(CUI) is the corrosion on the surface of pipeline or equipment with insulating materials. The corrosion mainly occurs in the carbon steel material and manifests pitting corrosion and corrosion thinning.
The insulating layer will make a closed environment with high temperature and high moisture, which will cause the aggravation of corrosion. The crucial factor of corrosion is the moisture which is mainly from the moisture permeation and condensation.
Besides, the insulation materials will also contribute to corrosion. The insulation material is composed of much inorganic salt such as chloride, fluoride, sulfide. These corrosive impurities and insulation materials make strong electrolyte solution. When metal device contact the solution, corrosion will happen.