In simplest terms, CUI (corrosion under insulation) is any type of corrosion that occurs due to a moisture buildup on the external surface of insulated equipment. It can be caused by multiple factors and can occur in equipment operating at ambient, low, and high temperatures, depending upon conditions. Moreover, CUI can occur in equipment that is in service, out of service, or in cyclic service.
Damaged insulation (as well as many other factors) provide a very easy route for water ingress into insulation. Once inside it can cause very serious damage to pipework and other susceptible steel elements.
Below are a couple of examples of damaged insulation that we recently identified during routine CUI Risk inspections for one of our clients.
Example 1: Insulation damage, visible water/moisture intrusion.
Example 2: Insulation damage caught early.
Example 3: Not so obvious, no visible sign of insulation damage.