Welding seam treatment and process characteristics of spiral steel pipe

The spiral steel pipe sends the strip steel into the welded pipe unit, and the strip steel is rolled up gradually after rolling by multiple rollers to form a circular tube billet with an opening gap. Adjust the reduction of the extrusion roller to control the weld gap at 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, the welding heat will be too large, and the weld seam will be burned; or the weld seam will form deep pits after extrusion and rolling, which will affect the surface quality of the weld seam.

After the two edges of the tube blank are heated to the welding temperature, under the extrusion of the extrusion roller, the common metal grains are formed to penetrate and crystallize each other and finally form a firm 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 cracks will occur after being stressed; 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.

Process characteristics
a. During the forming process, the steel plate deforms evenly, has small residual stress, and does not produce scratches on the surface. The processed spiral steel pipe has greater flexibility in the size range of diameter and wall thickness, especially in the production of high-grade thick-walled pipes, especially small and medium-diameter thick-walled pipes. It has advantages that other processes cannot match, and can satisfy users' requirements in terms of spiral steel pipe specifications.
b. Using the advanced double-sided submerged arc welding process, welding can be achieved at the right position, and defects such as wrong edges, welding deviations, and incomplete penetration are less likely to occur, and the welding quality is easy to control.
c. Conduct 100% quality inspection on steel pipes so that the entire process of steel pipe production is under effective detection and monitoring, effectively ensuring product quality.
d. All equipment in the entire production line has the function of networking with the computer data collection system to realize real-time transmission of data, and the central control room monitors the technical parameters in the production process.