Large-diameter straight-slit
submerged arc steel pipes are mainly responsible for the pipeline transportation of marine and onshore oil and gas, petroleum and natural gas, coal and mineral pulp, and other media. They are especially suitable for the "West-East Gas Transmission" project currently under construction in my country, and can also be used for export and import substitution. International pipe-making technology methods and characteristics. The forming methods for producing large-diameter straight seam submerged arc welded steel pipes abroad include the UOE method, CFE roller forming method, RBE roll bending forming method, JCOE forming method, C forming method, and PFP stepwise bending. Forming method, etc. A brief introduction is as follows:
1. The UOE method first presses the pre-bent steel plate into a U shape in the forming die of a U press, then presses it into an O shape in the forming die of an O press, and then welds it into a pipe and then expands the overall diameter. The UOE method is an internationally advanced forming method. So far, there are nearly 30 sets of this forming welded pipe unit in the world. The UOE method is famous for its high production efficiency and good product quality, but it is not expensive and has a large investment scale.
2. The roller forming machine of the CFE method consists of a performing frame, a flat roller frame, an edge bending roller, and a small row of rollers. Due to the installation of many identical small rows of rollers, the trajectory of the edge of the steel plate during the forming process is almost It is straight and avoids the "edge stretching" phenomenon. The CFE method has good forming quality, and its product quality is no different from that of the UOF method. This method uses hot rolled steel coils as raw materials, which is different from other forming methods. It is mainly suitable for the production of large batches and single varieties of steel pipes, but it is difficult to produce high-strength thick-walled steel pipes and large-diameter steel pipes.
3. The RBE roll bending forming method rolls the steel plate multiple times between three or four rollers. The welded pipe produced by this method is close to the UOE welded pipe in terms of performance and reliability. The RBE method has low investment, fast factory construction, moderate output, greater flexibility, and strong market adaptability. In recent years, this method has been applied in some developing countries. However, since this forming method has no support in the middle of the upper roller, and is limited by its stiffness, the diameter of the formed steel pipe cannot be less than 508mm (20in), which reduces the market share. The diameter of many pipes in my country is below 508mm.
4. JCOE forming method, first press the steel plate into a J shape on a hydraulic press. After pressing the edges on both sides, it is formed into a C shape through multiple stampings. Finally, it is pressed into an O shape through a semi-O-shaped upper mold. The product quality of the JCOE method is close to that of the UOE welded pipe, and the price of the operation line is much lower than that of the UOE unit, but its production efficiency is low.
5. The C forming method uses two C forming machines to replace the U press and O press in the UOE unit. The forming process is: the pre-bent steel plate is first formed into half of the steel plate on one press, and then on another press. The other half of the steel plate is formed on the machine to obtain an O-shaped circular tube. The welded pipe produced by the C forming method has a suitable size, moderate output, and low production line price.
6. The PFP progressive bending forming method is to gradually bend the steel plate with the end pre-bent on the press in smaller steps and more times, and finally form it into a round pipe by a steel pipe seam welding machine. The PFP method has a small pressing amount each time, so the press tonnage is not large, and the investment is also small. This method can form welded pipes with different pipe diameters and different wall thicknesses. The processed diameter can be less than 406mm, and the quality of the produced welded pipes is relatively high. Good, moderate yield.
