Corrossion Under Insulation (CUI)

Corrosion is a process of electro-chemistry which involves an electrolyte that reacts with a metal and water forming a depositing salt layer on the surface of the metal which we know as Rust. Corrosion can affect pipes, vessels,tanks and other equipment usually with a metallic surface which oxidizes it when it comes in-contact with the electrolyte. This electrolyte is usually water in the form of free or condensed liquid. Some good immersion grade coatings and proper weather barrier jacketing and insulation materials can help minimize the corrosion on the equipment. Other methods for corrosion inhibition include cathodic protection which involves using an easily corroded metal in contact with the metal you are trying to protect to act as a sacrificial metal. There is no permanent solution for corrosion, so the best solutions are the ones that lasts the longest whilst minimizing the corrosion rate.

Corrosion Under Insulation (CUI) is a more problematic form of corrosion which plagues most industries as the accumulation of water or humid air under the layer of insulation allows the electrolyte to maintain longer contact with the metal surface and remains largely undetected until which time the insulation is removed for inspection. Often times, the corrosion occurring under insulation systems are quite severe and can lead to accelerated and unexpected failures.