Use of Aluminum Foil for Prevention of Stress Corrosion Cracking of Austenitic Stainless Steel Under Thermal Insulation
SourceFor many years, it has been preferred practice within Imperial Chemical Industries (ICI) to use aluminum foil on austenitic stainless steel surfaces operating at temperatures within the range 60 to 500°C. The foil protects in two ways. It presents a physical barrier to chloride-containing fluids migrating through lagging materials towards hot stainless steel surfaces. It also cathodically protects stainless steel in the event of flooding of the lagging system, thereby preventing initiation of pitting and stress corrosion cracking. ICI's experience with aluminum foil is summarized. Laboratory data are presented that confirm the galvanic protection afforded by the foil, and the efficiency of the foil in preventing chloride stress corrosion cracking relative to a number of coating systems specified for the same purpose.