German SMSMEER (formerly internationally renowned mannesmann) Company, Japanese NKK Company, Japanese O.T.K (Osaka Special Steel Pipe Factory), Indian WELSPVN Pipe Manufacturing Company, Korean Hyundai Heavy Industry Company and Shiya Company all have their own unique pipe manufacturing technologies, and they are all elites in the international pipe manufacturing industry.
International pipe-making technology and characteristics, the forming methods of large-diameter longitudinal submerged arc welded steel pipes abroad include UOE method, CFE roll bending method, RBE roll bending method, JCOE forming method, C forming method, PFP step-by-step bending forming method and so on. A brief introduction is as follows:
1.UOE method is to press the pre-bent steel plate into a U-shape in the forming die of a U-shaped press, then press it into an O-shape in the forming die of an O-shaped press and weld it into a pipe, and then expand the diameter as a whole. UOE method is one of the most advanced forming methods in the world. So far, there are nearly 30 sets of such welded pipe units in the world. UOE method is famous for its high production efficiency and good product quality, but the equipment is expensive and the investment scale is large.
2.2 Row Roll Forming Machine. CFE method consists of preforming stand, flat roll stand, edge bending roll and small row roll stand. Because of the arrangement of several rows of identical rollers, the trajectory of the edge of the steel plate is almost straight in the forming process, thus avoiding the phenomenon of "edge drawing". The forming quality of CFE method is good, and the product quality is the same as that of UOF method. The raw material used in this method is hot-rolled strip coil, which is different from other forming methods. It is mainly suitable for the production of large quantities and single varieties of steel pipes, but it is difficult to produce high-strength thick-walled steel pipes and large-diameter steel pipes.
3.RBE roll bending method is used to roll steel plates between three or four rolls for many times. The welded pipe produced by this method is close to UOE welded pipe in performance and reliability. RBE method has the advantages of less investment, quick plant construction, moderate output, great flexibility and strong market adaptability. This method has been applied in some developing countries in recent years. However, due to the lack of support in the middle of the upper roller formed by this forming method, the diameter of the formed steel pipe cannot be less than 508mm(20in) because of its rigidity, which reduces the market share. Many pipelines in China are below 508 mm in diameter.
4.JCOE forming method: firstly, press the steel plate into J shape on a hydraulic press, then press it into C shape on both sides, and finally press it into O shape with semi-O shape. The product quality of JCOE method is close to UOE welded pipe, and the price of production line is much lower than that of UOE unit, but the production efficiency is low.
5.C forming method replaces U press and O press in UOE unit with two C forming machines. The forming process is as follows: the pre-bent steel plate first forms half of the steel plate on the first press, and then forms the other half of the steel plate on another press to obtain the O-shaped round tube. The welded pipe produced by C forming method has the advantages of appropriate size, moderate output and low production line price.
6.PFP step-by-step bending forming method is to gradually bend the steel plate with pre-bent end in a press with a smaller step size and more times, and finally form it into a circular tube by a steel pipe seam welder. PFP method has small investment because of small reduction and small tonnage of press. By this method, welded pipes with different pipe diameters and wall thicknesses can be formed, and the processing diameter can be less than 406 mm, and the produced welded pipes have good quality and moderate output.