Corrosion Under Insulation (CUI)

Corrosion Under Insulation (CUI) is a major risk factor in Oil&Gas producing facilities. The integrity of pipelines and process equipment carrying hydrocarbons under pressure is essential and a potential leak or breakage can have catastrophic results. Even the best surface coating system can be compromised due to mechanical damages of the surface coating and when the defect is hidden under the insulation covering the pipe or vessel, the potential corrosion can develop undetected.

The development of corrosion is quite predictable and is depending on several well-known factors. One key element is presence of water, which is why the first line of defence against CUI is to keep the water out (water proofing) of the insulation system. Various insulation systems depends on different methods of protecting the insulation system against water. The insulation system typically have some sort of stainless steel cladding, non-metallic cladding or an integrated weather proofing surface. The common problem with all is that the water proofing barrier may be compromised due to mechanical damages. Once water or water vapour get into the insulation system it might be trapped and not permitted to dry out. It’s a common saying that it’s water proof if the water can’t get out, it will always get in. The drainage and/or detection of water under the insulation is therefore essential to reduce the potential for corrosion and focus physical inspection to areas where water is detected.