The spiral pipe is roll-by-roll machine, folding the spiral direction, and then double submerged arc welding through capacitors. In the production process of spirally welded steel pipe, leakage welding is easy to occur, and in many cases there will be wrong edges and other phenomena. However, in these cases, trachoma is the most difficult to master the butt weld of spiral steel pipe.
So-called trachoma: during the welding process, there are no particles or bubbles penetrating thoroughly on the weld or the surface of the weld, and the shape of sand pits on the surface of the weld. The causes of trachoma are as follows:
1. During torch power supply, the welding current is too small, the capacitor is too short, and when the welding surface has hardened, the capacitor is not fully welded, so there is no penetrating sand or bubbles.
2. There is no good docking when entering the bending strip of curved cutter. The docking strips are completely mismatched, and there is too much gap between the docking strips.
3. Both sides did not clean the edges of rust or scale in time when butt welding rod was used.
4. The production equipment is not maintained and cleaned in time. Dust or dirt on the worktable falls into the gap of butt welding rod by mistake.
5. The working temperature of the workshop is too low or too wet, which will affect the temperature and dryness of the solder joints.