Seam Treatment of Spiral Welded Pipes

The spiral steel pipe feeds the strip into the welded pipe unit. After being rolled by multiple rollers, the strip is gradually rolled up to form a circular tube blank with an opening gap. Adjust the reduction amount of the extrusion roller to control the weld gap between 1~ 3mm, and make both ends of the welding joint flush.
                                   
1. If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the inter-crystal bonding of the weld will be poor, resulting in a lack of fusion or cracking.
                                   
2. If the gap is too small, the proximity effect will increase and the welding heat will be too high, causing the weld to burn out; or the weld will form a deep pit after being extruded and rolled, affecting the surface quality of the weld.
                                   
After the two edges of the tube blank are heated to the welding temperature, under the squeeze of the extrusion roller, common metal grains are formed to penetrate and crystallize with each other and finally form a strong weld. If the extrusion force of the spiral steel pipe is too small, the number of common crystals formed will be small, the strength of the weld metal will decrease, and cracking will occur after stress; if the extrusion force is too large, the molten metal will be squeezed out of the weld, It not only reduces the strength of the weld, but also produces a large number of internal and external burrs, and even causes defects such as welding laps.