It is not unusual to hear many engineers lay claim that by using stainless steel piping, that they are fully eliminating the risk of corrosion under insulation (CUI) within their piping circuits. But could stainless steel piping be susceptible to CUI much like it’s cousin in the piping family… carbon steel?
The short answer is YES, even stainless steel can fall prey to corrosion in certain conditions. Here is how…
Stainless steel’s Kryptonite is “chlorides” and when we have the two together, either from the water source or the insulation selected we have aligned the planets such that we can in fact have a piping failure caused by corrosion under insulation (CUI) on our stainless steel piping circuit. I first learned about this while working for a paper company and was working a turn around in the Charleston, SC region and we found corrosion on a SS vessel during a vessel inspection. The source was the salt water humidity and fog, which was such an issue with this plant that a nearby bridge had a fog warning system installed on it to help with traffic at certain times of the year.