Linepipe steels intended for use in sour gas environments must combine high strength, superior toughness and excellent resistance to hydrogen induced cracking. Steel-making techniques for HIC resistant steel grades (from X52 to X65) have been developed, through selective chemistry, clean steel-making practices, nonmetallic inclusion control and hot strip mill process control. The typical chemical analysis is low Carbon (< 0.06 % wt), low Manganese (<1 % wt) and low Phosphorus
content (< 0.015 % wt). The level of Sulfur is restricted to 0.002 % wt with the careful addition of Calcium in order to avoid the formation of elongated MnS. Special conditions adopted in the steelshop and during continuous casting allow the production of very clean steels with limited and controlled centerline segregation. These conditions gave very satisfactory HIC results. Thermomechanical hot rolling leads to a very fine ferrite-perlite microstructure with good notch toughness and consistent mechanical properties throughout the coil length. Examples of results from HIC resistant X56 and X60 industrial production are shown,
Keywords: Hydrogen Induced Cracking, notch toughness, thermomechanical hot rolling, electric resistance welded pipe, double submerged arc welded pipe.