Corrosion Under Insulation - Minimising the Risk

Unpredictable and often difficult to locate without major, costly and time-consuming exploratory work, Corrosion Under Insulation (CUI) is an ongoing and widespread problem across process industries such as those involved with oil and gas extraction and refinement. Making sure that the possibility of CUI is kept to its absolute minimum is essential and so all elements of an insulation system, particularly the fixings that hold the whole system together, must be of the highest quality and regularly checked and maintained.

The process of CUI begins with water gaining access to an insulation system, where it immediately begins to affect the metal's coating and, eventually, the metal substrdate beneath. The rate of corrosion, which is measured in units of Mils Penetration per Year (mpy), can vary greatly from just 1mpy to more than 40mpy, dependent on a wide range of circumstances that should be fully outlined in an RBI failure analysis assessment. CUI is more probable in certain places, including hot and humid, high-rainfall and marine environments and in systems operating at high temperatures and/or below atmospheric dew points.

A number of inspection techniques to locate CUI problems have been developed, including the use of ultrasonics, pulsed-eddy current (PEC), thermography and state-of-the-art digital radiography. The Piping Inspection Code API570 offers in-depth guidance and instruction on determining the most common types of systems susceptible to CUI as well as the locations where it most often occurs. If left unchecked, CUI will eventually lead to leakage in process systems and the oil and gas industries consequently invest hugely in the mitigation of the damaging, dangerous and costly process.

By using quality stainless steel insulation products with effective anti-corrosion coatings, the probability of CUI can be greatly reduced in process systems. BS Stainless are renowned across the globe for our stainless steel insulation jacketing products, which have been used in a large and diverse array of projects all over the world.