What Does Corrosion Under Supports (CUS) Mean?
Corrosion under supports (CUS), as its name suggests, is corrosion that occurs at the interface between a metal component and the object that supports it. Support locations, such as brackets and clamps, tend to act as entrapment areas for water and other liquids that can result in corrosion. This type of corrosion is highly localized and can result in the formation of pits and other forms of corrosion damage.
Corrosionpedia Explains Corrosion Under Supports (CUS)
Corrosion under supports (CUS) often occurs due to a lack of proper inspection and maintenance of the affected areas, which are more likely in areas with low visibility or are inaccessible directly below the supports. Usually, unless appropriate nondestructive tools are used, visually inspecting areas under pipe supports entails dismantling and lifting of the supported structure in question.
Water that remains trapped under supports remains stagnant, forming ideal conditions for localized crevice corrosion. As the paint/coating system fails, corrosion attacks the metal component leading to other types of corrosion such as pitting and mesa attack.