How corrosion under insulation occurs?

Corrosion under insulation is a form of external corrosion that is caused by trapped water on insulated surfaces. It is an industry problem affecting equipment in the oil and gas, petrochemical, specialty chemical, fertilizer, and related industries.

How to prevent corrosion under insulation?

Wrapping equipment with aluminum foil before applying insulation will reduce the risk of corrosion, since the foil provides a physical barrier that prevents the saturated chloride solution from reaching the metal surface.

What is the mechanism of galvanic corrosion?

Mechanism of Galvanic Corrosion When two metals come in contact in the presence of an electrolyte, the more reactive metal acts as an anode whereas the less reactive metal acts as a cathode. The electrolyte offers a channel for the movement of particles, which in turn leads to the rapid eroding of the anodic metal.

What is the mechanism of corrosion under insulation?

The article “CUI: An In-Depth Analysis,” which appeared in the November 2006 issue of Insulation Outlook, 1 described the mechanism of corrosion under insulation (CUI) for carbon steel and stainless steel, as well as prevention tools and techniques available to minimize CUI’s effects.

What does corrosion under insulation ( CUI ) mean?

Executive Summary. Corrosion under insulation (CUI) is a major safety threat to chemical processes with pipes and pressure vessels for moving and storing fluids where anions and cations are transported via water to pipe surfaces to corrode away pipe surfaces.

What is the API for corrosion under insulation?

API RP 583 is a standard that covers the design, maintenance, inspection, and mitigation practices involving CUI. And finally, I’d recommend that you download a copy of The 101 Essential Elements in a Pressure Equipment Integrity Management Program by John Reynolds.

Is there any insulation that is exempt from corrosion?

After a number of years investigating corrosion failures under insulation, it’s apparent that no insulation or insulation system is exempt from external corrosion to the substrate. Fireproofing materials must be included as a contributor to a wet environment that promotes corrosion.