Stress Corrosion Cracking of Ring Type Joint of Reactor Pipeline of a Hydrocracker Unit
A ring-type joint in a reactor pipeline for a hydrocracker unit had failed. Cracks were observed on the flange and the associated ring gasket during an inspection following a periodic shutdown of the unit. The components were manufactured from stabilized grades of austenitic stainless steel; the flange from type 321, and the ring gasket from 347. Examination revealed that the failure occurred by transgranular stress-corrosion cracking, initiated by the presence of polythionic acid. Detailed metallurgical investigation was subsequently conducted to identify what may have caused the formation of polythionic acid in the process gas.
Poorwa Gore, M. Sujata, S.K. Bhaumik, Stress Corrosion Cracking of Ring Type Joint of Reactor Pipeline of a Hydrocracker Unit, Handbook of Case Histories in Failure Analysis, Vol 3, Edited By Larry Berardinis, ASM International, 2019, p 158–164, https://doi.org/10.31399/asm.fach.v03.c9001774
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