Spiral submerged arc welded steel pipe, also known as spiral welded pipe, spiral pipe, submerged arc welded steel pipe, etc., is a kind of welded steel pipe in which the weld seam is spiral-shaped, made from strip steel or coiled plate through multiple complex cold working processes.
Why do spiral submerged arc welded steel pipes have pores?
The pores in large-diameter spiral welded pipes not only affect the accuracy of the pipe weld and cause pipeline leakage, but also become corrosion induction points, seriously reducing the strength and resistance of the weld. Most of the bubbles in spiral steel pipes appear in the center of the weld bead. The main reason is that hydrogen is still hidden inside the weld metal in the form of bubbles. At the same time, the moisture, dirt, oxide scale and iron filings in the flux, the welding components and covering layer thickness, the surface quality of the steel plate and the treatment of the steel plate side plates, the welding process and the steel pipe forming technology may all induce the occurrence of pores in the spiral steel pipe.
Therefore, in order to eliminate this defect, it is necessary to remove rust, oil, moisture, and moisture from the welding wire and welding seam, and dry the flux to remove the moisture. In addition, increasing the current, reducing the welding speed, and slowing down the solidification speed of the molten metal are also effective.
