The first may be due to the stress of the spiral seam submerged arc welded steel pipe. That is, the residual stress and welding stress after the steel pipe is formed. Secondly due to the presence of hydrogen. If the flux is not dried enough, the preheating temperature is not sufficient or the preheating before welding is not carried out, and the interlayer temperature of multi-layer welding is not enough.
There is also the metallurgical factor of the spiral welded steel pipe. There are low melting point impurities in the welding process, such as copper and copper alloys. The source of copper is mainly copper plated on the surface of the wire to prevent the wire from rusting. These copper shavings enter the flux from the inner hole of the contact tip and contact the weld puddle during the soldering process causing transverse cracks. Then one is: the welding process of spiral seam submerged arc welded steel pipe is unreasonable. For example, the welding seam forming coefficient is too small, the preheating temperature is not enough or the preheating before welding is not carried out, the welding line energy is too large, the heat treatment after welding is improper, and the holding time is too short.
If there is welding slag when the spiral seam submerged arc welded steel pipe is welded, use argon arc welding, or after the stainless steel welded pipe is cool, it will fall off with a hammer. These two methods are relatively simple, but they may not be cleaned up. Welding slag is easy to clean, but the spattered slag is not easy to clean. If you can use an electric grinder to clean the welding slag, use an electric grinder. Otherwise, the welding slag is difficult to be cleaned. As for the spiral welded steel pipe cutting We can also remove some defects, but to remove these defects, we must find a reasonable method. Only the correct method can make up for the defects of the welded pipe. Corresponding solutions can be found for these defects, but if the method is wrong, it will make the use more troublesome. Another method for cleaning the welding slag is to use a file, which can also be used to clean the welding slag very cleanly. A simpler and more labor-saving method is to take a saw blade or a half heel, reach into the pipe, hold the pipe in the left hand, and the saw blade in the right hand, and pull it clockwise or counterclockwise into the arms. In this way, the welding slag in the welded pipe can be cleaned very cleanly, and it will not waste too much time, which is simple and convenient.