Prediction of Sulfide Stress Cracking in High-Strength Tubulars

It is important to systematically assess the severity of a sour environment for susceptibility to sulfide stress cracking (SSC). A prediction system was established based upon SSC as a phenomenon of hydrogen embrittlement (HE). The content of H entering into steel (HFe) could be predicted from the hydrogen sulfide (H2S) concentration and hydrogen ion (H+) concentration by the equation: HFe (in ppm) = 13 x (H+ x H2S)0.26. SSC failure stress decreased with increases in HFe for any combination of pH and H2S. A critical hydrogen content (Hc) below which no SSC occurred decreased with increases in yield strength (YS) of a steel and could be formulated as a function of YS.