Stress-Oriented Hydrogen Induced Cracking (SOHIC) is a common, insidious form of wet H2S cracking. SOHIC is a type of cracking that can easily lead to failure and needs to be mitigated. It is made up of a series of HIC (hydrogen induced cracking) cracks that are stacked perpendicularly in the direction of through wall cracks and driven by high residual or applied stresses. It's fairly well known that above 50 ppm of H2S content, below 180F temperature in aqueous sour waters, that our pressure equipment is susceptible to wet H2S cracking. It's also fairly well known that cyanides in overhead systems of cat crackers and cokers can significantly increase susceptibility.

All susceptible systems should be inspected and maintained according to the latest edition of NACE RP0296. Equipment that is susceptible to SOHIC needs to be post weld heat treated (PWHT) or alloyed up. HIC resistant steels and polymeric coatings have been successfully applied, as well as stainless steel clad materials in more aggressive environments.

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Related Topics

• Amine Stress Corrosion Cracking (SCC)
• Ammonia Stress Corrosion Cracking
• Brittle Fracture
• Carburization
• Caustic Stress Corrosion Cracking (Caustic Embrittlement)
• Cavitation
• Chloride Stress Corrosion Cracking
• Cooling Water Corrosion
• Corrosion Fatigue
• Corrosion Under Insulation (CUI)
• Cracking
• Decarburization
• Embrittlement
• Erosion Corrosion
• Fatigue (Material)
• Graphitization
• High Temperature Hydrogen Attack (HTHA)
• Hydrochloric (HCl) Acid Corrosion
• Hydrofluoric (HF) Acid Corrosion
• Hydrogen Blistering
• Hydrogen Embrittlement
• Hydrogen Induced Cracking (HIC)
• Hydrogen Stress Cracking
• Liquid Metal Embrittlement (LME)
• Metal Dusting
• Microbiologically Induced Corrosion (MIC)
• Naphthenic Acid Corrosion (NAC)
• Phosphoric Acid Corrosion
• Polythionic Acid Stress Corrosion Cracking (PASCC)
• Spheroidization (Softening)
• Stress Assisted Corrosion
• Sulfidation Corrosion
• Sulfuric Acid Corrosion
• Thermal Fatigue
• Vibration-Induced Fatigue
• Wet H2S Damage

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