Development of coiled steels for electric-welded (HFC) oil and gas line pipe, casing, and pump-compressor tubing with high strength and good resistance to cold and corrosion

New steels 06GB (strength classes K48–K52) and 07GFB (strength class K55) have been developed for oil and gas line pipe welded with high-frequency current (HFC), while steels 18GFB (strength group K_c, σ_y ≥ 491 MPa) and 15KhGMF (strength group E_c, σ_y ≥ 552 MPa) have been created to make pumpcompressor tubing and casing welded with HFC. A technology developed for the converter production and out-of-furnace treatment of these steels ensures that they are clean with respect to harmful impurities, gases, and nonmetallic inclusions, and another technology developed for obtaining rolled coiled skelp under controlled conditions and heat-treating tubes made from the skelp produces the requisite set of mechanical and special properties (cold resistance down to −100°C, resistance to hydrogen sulfide at the stress level 0.8 σ_y, absence of hydrogen-induced cracks).