A form of hydrogen embrittlement in which H2S poisons the surface reaction that normally recombines hydrogen atoms into gas, so far more hydrogen enters the steel. Hard microstructures crack under applied or residual tension, often in weld heat-affected zones. Sour service rules such as NACE MR0175/ISO 15156 control it mainly through hardness limits, 22 HRC for carbon steel, and approved materials. Its cousin, hydrogen-induced cracking, blisters and steps through softer plate without any applied stress.
Weld cap hardness hit 28 HRC, that's a sulfide stress cracking risk, grind it and retest before it goes in sour.
Also heard as
- SSC
- sulfide cracking
Related terms
Sour service
Operating conditions with wet hydrogen sulfide, which call for cracking-resistant materials and controls.
Hydrogen embrittlement
Loss of ductility when atomic hydrogen gets into steel, leading to sudden cracking under stress.
SCC
Stress corrosion cracking: brittle cracking caused by tensile stress acting together with a specific corrosive environment.