Unexpected High-Energy Failure of Type 304L Stainless Steel Piping in the Tail Gas System in Nitric Acid Plant Due to Intergranular Stress Corrosion Cracking (IGSCC)
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An incident occurred at a Nitric Acid Plant when a failed 18-in. (457 mm)-diameter 304L stainless steel pipe connecting the Converter to the Tail Gas Catalytic Reactor ruptured. The rupture resulted in thrown fragments and some damage to equipment in the vicinity of the pipe. Normally, pipe operating conditions are about 80 psig (0.55 MPa) and 850–900 °F (454–482 °C), and the nominal thickness of the pipe was 0.180-in. (0.46 mm). This article summarizes the discovery of a very unusual condition of intergranular stress corrosion cracking due to sensitization of the low-carbon stainless steel used in manufacture of the pipe. The lessons learned from this failure investigation are vital to those who use stainless steel in Tail Gas systems.
KeywordsRupture Type 304L Sensitization IGSCC Nitric acid Explosion
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