Classification process square tube divided by the production process: hot-rolled seamless pipe, cold drawn seamless pipe, extruded seamless pipe, welded square tube. Welded square tube which is divided into: (a) according to process sub - arc welding pipe, ERW square tube (high frequency, low frequency), welding pipe, square tube furnace brazed (b) by weld points - straight seam welded pipe, spiral welded square tube square tube material classification Material: carbon steel square tube, low-alloy square tube. Carbon steel is divided into: Q195, Q215, Q235, SS400,20 # steel, 45 # steel; low-alloy steel into Q345,16Mn, Q390, ST52-3 like. Pipes in steel building applications with good prospects. Meanwhile, the square and rectangular steel pipe and have their own characteristics, flanges, each with the most reasonable range, the use of square and rectangular steel tube column as building a better performance than the tube. For example, in the corner of the location, use the pipe to get the maximum floor area can make effective use. Therefore, in the steel housing and high-rise steel buildings, square and rectangular steel pipe more promising. Flange steel prices _ Chun (certified) _ flange provided by the Tianjin Steel Co., Ltd. Chun Branch. Chun Branch Tianjin Iron and Steel Co. (www.tjsjkgt.com) (www.tjsjkgt.com) is Jinghai County of Tianjin, steel leaders, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, the maximum meet customer needs. Chun Branch pipe in leadership with the staff warmly welcome all inquiries negotiations to create Chun steel better future.