The continuing increase in oil and natural gas prices has made the utilization of sour gas reserves more and more economical. In addition, sweet gas may in time turn sour due to the action of bacteria carried in by injected seawater. Thus, future pipeline steels must be increasingly resistant to hydrogen sulfide and hydrogen-induced cracking (HIC). The present investigation on the susceptibility of steels to HIC covers pipe diameters from ∼50 to 142 cm (20 to 56 in.) and steel grades from X42 to X80. The influence of the alloying elements carbon, manganese, sulfur, chromium, molybdenum, copper, nickel, niobium, and the rare earth metals was investigated. Hydrogen effects were evaluated by means of sulfide stress corrosion (SSC) and British Petroleum (BP) tests on base metal and U-bend tests on welded joints. The effects of inclusion shape, control rolling practices and cold deformation on hydrogen susceptibility were also studied. A new welding method, able to produce joints fully resistant to HIC, was developed. Large diameter, cold expanded, submerged arc welded pipes not susceptible to hydrogen cracking have been produced.