Corrosion can occur if incompatible components of an insulation system are in contact with each other, if water intrudes into the insulation system, or if the insulation system is installed in a corrosive environment. Corrosion may attack the jacketing, the insulation hardware, or the underlying piping or equipment. Depending on other factors, chloride, and galvanic, acidic or alkaline corrosion may occur. Since system components are normally designed to be compatible with each other, the primary concern is either the interface between the insulation and the equipment being insulated (e.g. metal pipe or duct surface) or the insulation jacket that may be exposed to a corrosive atmosphere. ASTM C 665 governs suitability for insulation interfaces with steel, copper and aluminum. Galvanized steel can also be tested. Polyisocyanurate and expanded polystyrene insulation have been found to be compatible with virtually all metals used in pipe, ducts, and equipment. There excellent moisture resistance also contributes to minimizing corrosion. Click here for more on corrosion.