Welded pipe refers to a steel pipe or steel plate that is bent and deformed into a round, square or other shape and then welded into a seam on the surface. The blanks for welded pipes are steel sheets or strips. How to weld steel strips or steel plates together, and what are the welding skills? ‎

‎1) According to the application, the welded pipe has general purpose and special purpose of high temperature and high pressure. The latter pipe is usually made of special alloy steel, which needs to consider and solve the problem of shrinkage cracks during welding and the mechanical properties of the pipe in the heat-affected zone, which will not change too much due to the influence of welding operations. ‎

‎2) According to the thickness of the pipe wall, pipes made of thinner materials such as steel strips can be welded by high frequency; some thin-walled pipes can be welded by the shielding gas method; pipes with a wall thickness greater than 2mm can be welded by manual arc welding. ‎

‎3) According to the diameter of the pipe, the small diameter can only be welded on one side, and the technician can drill into the pipe for welding on both sides; single-sided welding requires two welders to weld. Through the steel ball test, it is ensured that the cross-sectional area meets the design requirements through welding and welding seam forming. ‎

‎4) As long as the pipes are high-strength alloy steels, including high-temperature, pressure-resistant, wear-resistant, and low-temperature-resistant alloy steel pipes, the welding process must be emphasized to prevent martensitic structures and cracks caused by high-temperature welding operations. The general requirement in the process is that the electrodes are selected and should be baked and sent to the welder as required. Before welding, both sides of the weld should be free of oil, water, rust and debris. During the welding process, the smaller the current, the smaller the swing, and the arrangement of the subsequent weld should produce an annealing effect on the heat-affected zone as much as possible. Cool slowly after welding, cover with asbestos cloth, etc.

‎5) To ensure the welding quality of pipes, welders must be trained and tested and qualified for the job. Welders must weld steel pipes well. In addition to basic theory, he also had to think about operational skills. The welding process of the pipe may include several positions of down welding, vertical welding and top welding (in the case where the pipe cannot be rotated). In the forming of welding and overhead welding (some tubes are not very large, the current cannot be adjusted in the middle of one forming), the stability and forming of the arc can be controlled during the process, and it can be properly oscillated. The molding is combined with the necessary wobble. ‎