First, it may be due to the stress of spiral submerged arc welded steel pipes. That is, the residual stress and welding stress after the steel pipe is formed.

Secondly, it is due to the presence of hydrogen. For example, the flux is not dried enough, the preheating temperature is not sufficient preheating is not performed before welding, and the interlayer temperature of multi-layer welding is not enough.

There are also metallurgical factors of spiral welded steel pipes. Low melting point impurities such as copper and copper alloys enter during welding. The main source of copper is the copper plated on the surface of the welding wire to prevent the welding wire from rusting. These copper chips enter the flux from the inner hole of the conductive nozzle and contact the welding pool during welding, causing transverse cracks.

Then one is: the welding process of spiral submerged arc welded steel pipes is unreasonable. For example, the weld formation coefficient is too small, the preheating temperature is not enough, or preheating is not performed before welding, the welding line energy is too large, the heat treatment after welding is improper, and the insulation time is too short.

When the spiral seam submerged arc welding steel pipe is connected, if welding slag appears, use argon arc welding, or wait for the stainless steel welded pipe to cool down, and then knock it with a hammer, it will fall off. Both methods are relatively simple, but they may not be cleaned cleanly. Welding slag is easier to clean, but the splashing 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 clean.

As for some defects that appear when cutting spiral welded steel pipes, we can also remove them, but if you want to remove these defects, you must find a reasonable method. Only the correct method can make up for the defects of the welded pipe. There are corresponding solutions for these defects, but if the method is not found correctly, it will make it more troublesome to use. For welded pipes, there is another way to clean welding slag, which is to use a file, and the file can also clean the welding slag very cleanly. Another simpler and more labor-saving method is to take a saw blade or a half heel, reach into the steel pipe, hold the steel pipe in your left hand, hold the saw blade in your right hand, and pull it clockwise or counterclockwise into your arms. This way, the welding slag in the welded pipe can be cleaned very cleanly without wasting too much time. It is simple and convenient.