Production of Cold-Weather Electric-Welded 1020-1220-mm-Diam. Pipes Made of Promising New Steels

• Published in: Metallurgist (New York) Vol. 46; no. 9-10; pp. 305 - 308
• Main Authors: Romantsov, I A, Plyasunov, V A, Zhuchaev, V A, Tanchuk, A K
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01-09-2002
• ISSN: 0026-0894; 1573-8892
• DOI: 10.1023/A:1021914418536

Important changes have recently taken place in the production of pipes for major pipelines. In addition to pipes made of the traditional grades of steel, manufacturers have begun to make pipes of promising new steels with low contents of carbon, sulfur, and phosphorus. These steels weld easily and do not become brittle at temperatures down to -60 deg C. Also, their production does not pose any problems in regard to obtaining the required values of low-temperature toughness. One of these steels is steel 06GFBAA. Skelp made of this steel has been produced at the Chelyabinsk Pipe Plant (ChTPZ) and the plant of the company Severstal' to make cold-resistant 1020-mm-diam. pipes with wall thicknesses of 12.0 and 12.2 mm and 1220-mmdiam. pipes with wall thicknesses of 12.4, 14.3, 15.2, and 15.4 mm. The skelp was shipped in accordance with technical standard TS-105-123-2001 (with appendix 1) and was certified as having met the corresponding requirements. Its adherence to the standard was corroborated by delivery tests involving determinations of chemical composition and mechanical properties. The difficulty in producing pipes in the diameter range 1020-1220 mm lies in ensuring that the impact toughness of specimens with a notch at the center of the internal weld satisfies the requirements of TU-3r-28-99 at temperatures of -20 and -60 deg C (KCV-20 and KCU-60). To do this, a considerable amount of work was done to select the proper welding materials and determine the correct welding regimes, and a large volume of metallographic study was completed. As a result, we chose 4.0-mm-diam. welding wire SV- 08GNM and flux AN-67B to internally and externally weld commercial batches of 1020-1220-mm-diam. pipes of steel 06GFBAA with walls 12.0-15.4 mm thick. The flux was calcined to a residual moisture content no greater than 0.005%.