Stress corrosion cracking (SCC) is the “Achilles heel” of austenitic stainless steels. Because of this weakness, these excellent corrosion resistant alloys are avoided whenever possible in unit construction. Failure occurs quickly and is often disastrous. Failures due to SCC seldom occur during normal operation because this possibility is screened in the initial design. Most problems are generated in unit shutdowns when a hot unit containing chloride deposits must be cooled and opened to the atmosphere. If moisture contacts these deposits before the vessel reaches about 150 F (66 C), SCC is possible. In an attempt to solve this problem, various downtime techniques1  have been tried which involve changing the unit environment (purging, washing) prior to opening to the atmosphere. The NACE is currently considering a recommended practice2  aimed at reducing SCC failures during shutdown.

Subject
Steel surfaces, Stainless alloys, Magnesium chloride, Metal surfaces, Nickel based alloys, Nitrates, Corrosion inhibitors, Steel, Stainless steel, Nickel, Cracks, Stress corrosion cracking, Chloride stress corrosion cracking
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1970
Association for Materials Protection and Performance (AMPP)
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