Corrosion Under Insulation (CUI): How to Detect It Before It Becomes a Major Failure
In industrial facilities, some of the most expensive equipment failures begin where nobody can see them. Corrosion Under Insulation (CUI) is one of the most persistent hidden threats in industries such as oil & gas, petrochemicals, power generation, marine operations, food processing, and manufacturing. Because insulation covers the surface, deterioration often progresses unnoticed until leaks, shutdowns, or structural failures occur. Understanding how CUI develops—and detecting it early—can significantly reduce maintenance costs, improve reliability, and extend asset life. What Is Corrosion Under Insulation (CUI)? Corrosion Under Insulation refers to external corrosion that occurs on metal surfaces hidden beneath thermal insulation or fireproofing materials. Although insulation is designed to protect systems and improve energy efficiency, it can also trap moisture against equipment surfaces. Once water penetrates the insulation layer, conditions become ideal for corrosion to ...