With insulated metallic piping, the phenomenon known as corrosion under insulation (CUI) is a problem that is hard to quantify. The presence of moisture between insulation and pipe is hidden from view unless a facility adopts a fairly radical approach to detection. If moisture is present between the steel surface and insulation, then corrosion is practically a certainty. CUI can lead to prolonged downtime due to equipment failure, severe catastrophic leaks or explosions, and general safety and environmental concerns. The problem is common to insulated carbon steel, low alloy steel, galvanized, and stainless steel piping operating in all different temperature conditions.