The Development of X80 Steel Plate and Coil for the 2^nd West-East Pipeline Project

The growing economy of China has resulted in an increase in energy demands. This increased demand for energy has resulted in plans to expand the oil and gas transmission pipeline infrastructure throughout China. This transmission pipeline infrastructure expansion demands higher strength steels of API grade X70 and X80 for economical movement of the oil and gas. With most of the major natural gas supply in countries to the west of China and the major population centers of China in the east, long distant transmission pipelines from west to east have been built with additional capacity being designed. The first major natural gas transmission pipeline, 1^st West-East Pipeline was API X70. A parallel mainline of approximately 4950 km with 8 sub lines resulting in an overall total length of approximately 8800 km is being designed for construction in 2008. This line will be the 2^nd West-East Pipeline Project and will be built out of API X80. The major dimension of this line is 1219 mm OD × 18.4 mm wall thickness. Nanjing Iron and Steel Company (NISCO) in Nanjing, China commissioned a wide plate/coil Steckel mill in 2004 and has successfully developed API grades in plate and coil for the Chinese pipeline industry. Since 2004 NISCO has successfully ramped up production to where in 2007 anticipated delivery of API plate and coil will be approximately 350,000 mT. Over that time period NISCO has been developing API X80 plate and coil capabilities in anticipation of the 2^nd West-East Pipeline Project. The 2^nd West-East Pipeline specification major requirements for coil and plate mechanical properties include round bar tensile testing, YT maximum of 0.93 for round bar, ≥ 240 J @ −20 °C average TCVN and ≥ 85% DWTT shear average @ −15 °C. During the development process two alloy approaches have been identified for plate and coil to produce the ferrite/acicular ferrite microstructure required for API X80 pipe. This paper will describe Nanjing Iron and Steel Company’s development and results to produce API grade X80 plate and coil that successfully met the specification requirements of the 2^nd West-East Pipeline Project.