ntroduction to submerged arc welding of straight seam steel pipe:
1. Bubbles occur in the middle of the weld. The main reason is that hydrogen is still hidden in the weld metal in the form of bubbles. Therefore, the first step to eliminate this defect is to remove the rust, oil, water and moisture of the wire and weld, followed by the need to dry flux to remove moisture. In addition, increasing current, reducing welding speed and slowing down the melting speed of molten metal are also very effective.


2. Sulfur cracks (sulphur caused by cracks). Cracks in sulphur segregation zone of weld seam, especially in molten steel. The reason is that hydrogen exists in the sulfur segregation zone containing low melting point iron and steel. Therefore, in order to prevent this situation, the use of less semi-killed steel or sedative steel for sulfur separation is also effective. Secondly, it is necessary to clean and dry the welding surface and flux.