Do you know these little knowledge of submerged arc welding steel pipe?

Submerged arc welded steel pipe: it is a spiral welded pipe made of strip steel coil, which is often formed by warm extrusion and automatic double-line and double-sided submerged arc welding. The characteristics of submerged arc welded steel pipe are: straight seam welded steel pipe has simple production process, high production efficiency, low cost and fast development speed. The strength of spiral welded pipe is generally higher than that of straight seam welded pipe, and the welded pipe with large pipe diameter can be produced with narrow billet, Welded pipes with different diameters can produce billets with the same width.However, compared with the straight welded pipe with the same length, the weld length is increased by 30% and 100% respectively, and the production speed is low. Therefore, straight seam welding is mostly used for small-diameter welded pipes, while spiral welding is mostly used for large-diameter welded pipes.(1) The raw materials are coil, wire and flux, which must undergo strict physical and chemical tests before being put into use.(2) Single wire submerged arc welding or double wire submerged arc welding shall be adopted for the head and tail of strip steel. After coiling the steel pipe, the automatic submerged arc welding shall be adopted for repair welding.(3) Before forming, the strip shall be smoothed, cut and polished, the surface shall be cleaned and transported, and the curved edge shall be treated.(4) Use the electric contact pressure gauge to control the pressure of the oil cylinders on both sides of the conveyor to ensure the smooth transportation of the strip.(5) The roll shape is controlled externally or internally.(6) The weld gap control device shall be adopted to ensure that the weld gap meets the welding requirements, and the pipe diameter, staggered edge and weld gap shall be strictly controlled(7) The on-line continuous ultrasonic automatic damage instrument is used to detect the welding seam, which ensures the nondestructive testing coverage of 100% spiral weld. In case of defects, automatic alarm and spraying marks, the production personnel can adjust the work at any time