1. If the gap is too large, the neighboring effect will be reduced, the temperature of the vortex is insufficient, and the welding seam crystals are indirectly combined with the molten or cracking.
2. If the gap is too small, the neighboring effect will increase, the welding heat is too large, causing welding seams to be damaged; or the welding seams are squeezed and rolled to form a deep pit, which affects the surface quality of the weld.
After heating the two edges of the tube billet to the welding temperature, under the squeeze of the squeezing roller, the common metal grains penetrate and crystallize, and finally form a firm welding seam. If the pressure of the spiral steel pipe is too small, the number of common crystals will be small, the intensity of the metal metal of the weld is reduced, and it will crack after the force; if the pressure is too large, the metal of the melting state will be squeezed out of the weld. Not only reduces the intensity of welds, but it will also produce a large amount of internal and external burrs, and even cause defects such as welding seams.
Not only does it not need to be welded, but also the internal and external welds are 1-3mm. The spiral angle of the spiral tube weld is usually 50-75 degrees, so the synthetic stress of the spiral weld is 60-85 % of the primary stress that is directly welded. Under the same working pressure, the spiral tube with the same tube is reduced by straight welding of the wall thickness.
In the process of forming, the steel pipe is uniformly deformed, the residual stress is small, and the surface does not produce scratches. The processing spiral steel pipes have greater flexibility within the size and specification range of the diameter and wall thickness.
Spiral steel pipes can be used for liquid transportation: water drainage. Can be used for natural gas transportation: gas, steam, liquefied petroleum gas. It can be used for the structure: pile tube, beams, docks, roads and architectural structures.
