Pipeline and pipeline connection (butt welding) is widely used in industries such as petrochemical industry, long-distance pipeline construction, municipal construction, and boiler power station construction. Especially in long-distance pipeline construction projects, the pipe circumferential seam butt welding technology has become a bottleneck restricting the progress of the project. The more advanced technologies currently used are self-insured household flux-cored wire semi-automatic welding, STT gas shielded semi-automatic welding, and molten electrode gas shielded automatic welding. First of all, in essence, these methods belong to the category of arc welding. Their common shortcoming is that the filler metal has to be transferred to the weld a little bit, so the welding speed is slow, the welding process control is complicated, and the factors that affect the welding quality More difficult to control. In large-scale projects such as the construction of more than 4,000 kilometers of West-East Gas Pipeline, the butt time of each circular seam will become a key factor affecting the construction period, and the quality of the weld seam is also the key to the quality of the entire project. Secondly, the existing pipe circumferential butt welding methods generally have the problem of single-sided welding and double-sided forming. The back forming of the weld is difficult to control, and the back forming is the key to the corrosion resistance and service life of the pipeline.
When the traditional arc welding method is used for butt welding, the groove forms are generally V-shaped and U-shaped grooves, while flash welding and foreign transition liquid diffusion welding (TLP) are used for welding. These bevel forms have disadvantages such as difficulty in alignment and strict requirements on the shape error of the tube.
