Corrosion under insulation refers to any type of corrosion that occurs due to moisture buildup on the external surface of insulated steel, piping and vessels.
Introduction to Corrosion Under Insulation (CUI)
Corrosion under insulation refers to any type of corrosion that occurs due to moisture buildup on the external surface of insulated steel, piping and vessels. The most type of CUI is galvanic, chloride, acidic, or alkaline corrosion. According to API 570, for the carbon and steel piping system, the susceptible temperature ranges under which CUI may occur is 25 and 250°F where operating temperature cause frequent or continuous condensation of atmospheric moisture.

Why does Corrosion Under Insulation (CUI) Occur:
As we all aware corrosion under insulation has become a serious concern and more critical for the Industry for the number of reasons. So many Industries like Chemical, petrochemical, oil & gas, and food processing facilities, require more smart instrumentation and sophisticated equipment.
According to Inspection techniques for detecting corrosion under insulation, the deterioration of material components is caused due by adverse interactions with their environments, and excessive/sudden changes in the amount of pH value in water.

The rate at which corrosion occurs on carbon steel when the relative humidity of the air is 70% to 80% and the air temperature is above 32F.

One of the leading factors of corrosion is “Temperature”. For example, Pipe’s material normal operating temperature is elevated above `ambient temperature, condensation could occur during shutdown when the pipe’s temperature is reduced to the ambient temperature range.

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Corrosion under insulation refers to any type of corrosion that occurs due to moisture buildup on the external surface of insulated steel, piping and vessels.