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Category: Corrosion
Question: What steps can be taken to avoid stress corrosion cracking (SCC) in steel vessels used for storing anhydrous ammonia?
Keywords: v1i5,stress,corrosion,cracking,ammonia,anhydrous,tanks
Answer: The U.S. National Board of Pressure Vessel Inspectors recommends the following in one of their classic articles:1. Pressure vessels should be either fully stress relieved or fabricated with heads that are hot-formed or stress relieved. 2. Extreme care should be used to eliminate air from the ammonia systems; new vessels must be thoroughly purged to eliminate air contamination. 3. Ammonia should contain at least 0.2 percent water to inhibit SCC. Source: National Board of Pressure Vessel Inspectors
Links: National Board Classic Article Series