A gray cast iron (ASTM 247 type A) gate valve in an oleum and sulfuric acid piping loop at a chemical process plant fractured catastrophically after approximately 10 years of service. The valve was a 150 mm (6 in.) bolted flange type rated to conform to ANSI B16.1 for service at 1034 kPa (150 psi) and 120 deg C (250 deg F) maximum in 93 to 99% sulfuric acid. The fracture originated at stress-corrosion cracks that occurred in a high-stress transition region at the valve body-to-flange juncture. The mechanical properties of the failed valve were below those of the...
Samuel J. Brown, Brittle Fracture of a Cast Iron Valve in Oleum and Sulfuric Acid Service, Handbook of Case Histories in Failure Analysis, Vol 1, Edited By Khlefa A. Esaklul, ASM International, 1992, p 202–209, https://doi.org/10.31399/asm.fach.v01.c9001071
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