Between 1975 and 1995 roughly half a million kilometers of duplex stainless steel (DSS) pipe had been installed in the North Sea, subsea, with insulation coating and cathodic protection (CP) applied. In contrast to the previous 20 year of good experience, between 1996 and 2004 a cluster of subsea failures of new and relatively newly installed DSS assets occurred. These failures were attributed to HISC as a consequence of CP. The paper reviews the available literature detailing a number of case histories and presents some additional anecdotal information not previously reported. Some similarities between these failures and a cluster of HISC failures of martensitic stainless steel pipelines that occurred shortly after the first DSS failures are detailed. Current methods of mitigation such as those detailed in design codes, the use of hot iso-statically pressed production methods, surface treatments and modified alloys with improved HISC resistance are discussed. The paper considers issues surrounding analysis of the problem and changes in practice that may further reduce the risk of HISC failure in the future.

Subject
Materials, Piping, Secondary cracks, Microstructure, Nitrides, Manifolds, Stress cracking, Joints, Stress, Ferrite, Grain, Austenite, Hydrogen
Keywords:
HISC, Duplex Stainless Steels, Cathodic Protection, Hydrogen Embrittlement
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2022
Association for Materials Protection and Performance (AMPP)
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