Hydrogen induced cracking (HIC) testing of low alloy steel in sour environment: Impact of time of exposure on the extent of damage

Hydrogen induced cracking (HIC) of line pipe steel was investigated through immersion testing and hydrogen permeation measurements. At constant pH and hydrogen sulphide partial pressure (pH2S), the extent of HIC was found to depend on exposure time until a stable level was reached. The time to reach this stable value is affected by pH and pH2S. Results of permeation experiments confirmed that HIC is linked with the increase of hydrogen concentration in the steel. It is also shown that low severity requires longer exposures to reach equilibrium. This must be taken into account for HIC testing in mildly sour environment.