Manufacturing technology of large diameter straight seam submerged arc welded steel pipes
Large diameter straight seam submerged arc welded (LSAW) steel pipes are primarily used for the transportation of various media, including oil, gas, coal, and slurry, both offshore and onshore. The international manufacturing techniques for these pipes vary in method and characteristics. Currently, the main forming methods for large diameter LSAW pipes include UOE, CFE, RBE, JCOE, C, and PFP forming processes. Below is a brief introduction to these methods:
1.UOE Method
In the UOE process, pre-curved steel plates are first shaped into a U-shape using a U-shaped press. They are then further shaped into an O-shape using an O-shaped press before being welded into pipes and expanded to the required diameter. The UOE method is recognized as an advanced international forming technique, with nearly 30 sets of such pipe welding units worldwide. Known for its high production efficiency and excellent product quality, the UOE method requires substantial investment, making it relatively costly.
2.CFE Method
The CFE method utilizes a forming machine composed of a pre-forming frame, flat rollers, edge bending rollers, and several small rows of rollers. The numerous small rollers create a nearly linear trajectory at the edges of the steel plate during the forming process, thereby avoiding the “edge stretching” phenomenon. The quality of the products produced via the CFE method is comparable to that of UOE pipes. This method uses hot-rolled steel coils as raw materials, which differentiates it from other forming methods. It is mainly suitable for high-volume production of single-type steel pipes but is not well-suited for producing high-strength, thick-walled, or large-diameter pipes.
3.RBE Roll Bending Method
The RBE method involves multiple roll bending of the steel plate between three or four rollers. Pipes produced with this method exhibit performance and reliability similar to UOE pipes. RBE has low investment costs, quick plant setup, moderate output, and high flexibility, making it suitable for various markets. However, due to the absence of support in the upper rollers, the diameter of the formed steel pipes cannot be less than 508 mm (20 inches), limiting its market share in China for pipes with diameters smaller than this.
4.JCOE Method
In the JCOE method, steel plates are first pressed into a J-shape using a hydraulic press. After both edges are pressed, the plate is formed into a C-shape through multiple stamping processes, eventually achieving an O-shape with a semi-O-shaped upper die. The product quality of JCOE pipes is close to that of UOE pipes, but the operating line costs are significantly lower, although the production efficiency is also lower.
5.C Forming Method
This method employs two C forming machines to replace the U-shaped and O-shaped presses in the UOE setup. The process involves first forming the pre-curved steel plate into a semi-plate on one press and then completing the other half on another press to achieve an O-shaped pipe. The pipes produced through this method have suitable dimensions and moderate output, with lower production line costs.
6.PFP Step Bending Method
The PFP method involves gradually bending pre-curved steel plates in small increments on a press, ultimately forming round pipes through a pipe welding machine. The small pressing increments require less tonnage for the press, resulting in lower investment costs. This method can produce welded pipes of various diameters and wall thicknesses, with processing diameters as small as 406 mm, and achieves high quality and moderate output in the produced welded pipes.
Large diameter straight seam submerged arc welded steel pipes are manufactured through various advanced techniques, each with its unique advantages and applications.As an expert in the field of pipeline systems, Haihao Group can produce large-diameter straight seam steel pipes that meet customer needs.