Resistance of Line Pipe Steels to Wet Sour Gas

Hydrogen‐Induced Cracking and Sulfide Stress Cracking

“…Type II MnS inclusions occur in the core, and specimens taken from cores having average S contents as low as 0.001% can show HIC susceptibility [47,49]. Calcium is sometimes added for shape control of type II MnS inclusions, but excess Ca results in CaS clusters, so that there is a best Ca/S range that depends on the S concentration [50,51].…”

“…If the MnS inclusion content is sufficiently low, even the adverse effects of low-temperature controlled rolling are reduced [29]. Both Q and T treatments can reduce the susceptibility substantially [50]. FIGURE 15.11.…”

The effect of hydrogen induced cracking on the integrity of steel components

“…The formation of banded microstructures in pipeline steels is due to dendritic segregation of manganese and phosphorus. According to Taira et al (1984) restricting the segregation zone hardness to below 300 HV is needed to eliminate HIC, since hard "banded" structures of bainite or martensite are susceptible to hydrogen embrittlement as well as HIC. Thus homogenization of microstructures by quenching and tempering would also reduce SSC.…”

“…Moreover, rare earth sulphides tend to produce ionization effects which interfere with arc stability in automatic welding processes. Calcium treated steels were also found to have improved resistance to HIC (Brown & Jones 1984;Taira et al 1984). According to Taira et al (1984) calcium content must be delicately controlled so that neither manganese sulphide, nor calcium sulphide clusters are present.…”

“…Calcium treated steels were also found to have improved resistance to HIC (Brown & Jones 1984;Taira et al 1984). According to Taira et al (1984) calcium content must be delicately controlled so that neither manganese sulphide, nor calcium sulphide clusters are present. They believed that the HIC resistance of a calcium-treated steel depended on the ratio of the Ca content to the S content.…”