We, Hefei Zijin Steel Tube Manufacturing Co., Ltd. is established in the year 2004 and is specialized in the developing and manufacturing of the large-diameter thick-wall straight-seam longitudinally submerged arc welded carbon steel pipes including oil & gas line pipe, rolled steel pipes, joist frame structure pipes, machinery roller -making pipes, concrete filled steel tubular structure, fluids conveying pipe, structure building pipes. The dimension of our products covers such a scope as followings: For oil and gas pipes: Grade: X80 or/ and lower, Diameter: ¦ 406-1524mm, Wall thickness: 6-40mm, Unit length: 8-12m For structural pipes: Diameter: ¦ 350-1600mm, Wall thickness: 6-60mm Unit length: 6-12m For rolled pipes: Diameter: ¦ 1200-3800mm, Wall thickness: 12-120mm, Maximum unit length: 3.2m All our production and inspection abide by API certificate. If necessary, we can provide the copy of API certificate