Absorption of hydrogen generated by corrosion of steel in a wet hydrogen sulfide (H 2S) environment can have several effects which depend on the properties of the steel, the characteristics of the environment, and other variables. One adverse effect observed in pipeline and pressure vessel steels is the development of cracks along the rolling direction of the steel. Cracks on one plane tend to link up with the cracks on adjacent planes to form steps across the thickness. The cracks can reduce the effective wall thickness until the pipe or pressure vessel becomes overstressed and ruptures. Cracking is sometimes accompanied by surface blistering. Several service failures attributed to such cracking have been reported.

The terms stepwise cracking (SWC), hydrogen pressure cracking, blister cracking, and

hydrogen-induced stepwise cracking have been used in the past to describe cracking of this type in pipeline and pressure vessel steels, but are now considered obsolete. The term hydrogen-induced cracking (HIC) has been widely used for describing cracking of this type, and has been adopted by NACE International. Therefore, it is used throughout this standard test method.

This standard establishes a test method for evaluating the resistance of pipeline and pressure vessel plate steels to HIC caused by hydrogen absorption from aqueous sulfide corrosion. Historical Document 1996