The common limitations of spiral welded pipe in welding zone are porosity, hot crack and bottom cutting.
1. Bubbles. Bubbles mainly occur in the center of weld seam of welded steel pipe.  The main reason is that hydrogen is still hidden in the weld metal in the form of bubbles. Therefore, the first way to eliminate this defect is to remove the rust, oil and water from the wire and weld it. There are also water and other substances. Secondly, flux must be dried to remove water. In addition, it is also effective to increase the current, reduce the welding speed and slow down the solidification speed of molten metal. In addition to defects, the rust, oil, moisture and moisture of the wire and weld must be removed first, and secondly, the rust, oil, moisture and moisture of the weld must be removed. Fully dry the flux to remove moisture. In addition, it is also effective to increase the current, reduce the welding speed and slow down the solidification speed of molten metal.


2. Sulfur pyrolysis (cracks caused by sulfur). When sulphur is separated from the strong plate (especially the soft boiling steel), the cracks in the sulphur segregation zone are introduced into the welded metal. The reason is that hydrogen sulfide exists in the sulfur segregation zone containing low melting point iron sulfide and steel. Therefore, in order to prevent this from happening, it is also effective to use semi-killed steel or killed steel with less sulfur separation zone. Secondly, clean and dry steel pipe surface and flux are also needed.


3. Hot cracks. In submerged arc welding, hot cracks may occur in welds, especially in arcs and arc quenching pits. In order to eliminate this kind of crack, the cushion plate is usually set at the arc and arc extinguishing arc, and the spiral welded pipe can be reversed to weld into the laminate at the end of the coil to the welding end. When the welding stress is high or the silicon content in the weld metal is high, hot cracks are easy to occur.


4. Relevant to welding slag. A part of the welding slag is left in the weld metal.


5. Poor permeability. Metal overlap between internal and external welds is not enough, sometimes not welded. This situation is called insufficient penetration