What are the factors that cause transverse cracks in spiral steel pipes in industrial projects

Firstly, it may be due to the stress on the spiral submerged arc welded steel pipe, including residual stress after pipe forming and welding stress.

Secondly, it may be due to the presence of hydrogen. This could be caused by insufficient flux drying, inadequate preheating temperature, or lack of preheating, or insufficient interpass temperature in multi-layer welding.

Another factor is the metallurgical factors of the spiral welded steel pipe. Low-melting-point impurities, such as copper and copper alloys, may enter during the welding process. The copper mainly comes from the copper plating on the welding wire surface used to prevent corrosion. These copper shavings enter the flux through the inner hole of the contact nozzle and come into contact with the weld pool during welding, leading to transverse cracks.

Furthermore, an unreasonable welding process for spiral submerged arc welded steel pipes is another factor. This could be due to an excessively small weld bead forming coefficient, insufficient preheating temperature or lack of preheating, excessive welding heat input, improper post-weld heat treatment, or insufficient holding time.

When joining spiral submerged arc welded steel pipes, if weld slag appears, you can use argon arc welding or wait for the stainless steel welded pipe to cool and then tap it with a hammer to remove it. Both methods are relatively simple, but they may not clean it completely. Weld slag is relatively easy to clean, but the splattered slag is difficult to remove. When cleaning weld slag, use an electric grinder if possible; otherwise, the weld slag is very difficult to remove.

As for some defects that occur when cutting spiral welded steel pipes, we can also remove them, but to remove these defects, we need to find a reasonable method. Only the correct method can compensate for the defects of the welded pipe. There are corresponding solutions for these defects, but if the method is incorrect, it will make the use more troublesome. Another method for cleaning weld slag from welded pipes is to use a file, which can also clean the weld slag very cleanly. Another simpler and less labor-intensive method is to take a saw blade or half a saw, insert it into the spiral steel pipe, hold the spiral steel pipe with your left hand, and hold the saw blade with your right hand, pulling it clockwise or counterclockwise towards your body. This method allows for very thorough cleaning of the welding slag inside the spiral steel pipe without wasting too much time; it's simple and convenient.