What are the factors that cause horizontal lines in spiral seam submerged arc welded steel pipes

What are the factors that cause horizontal lines in spiral seam submerged arc welded steel pipes?

First of all, it 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 insufficient or the preheating before welding is not carried out, and the interlayer temperature of multi-layer welding is not enough.

There are also the metallurgical factors of spiral welded steel pipes. There are low melting point impurities in the welding process, such as copper and copper alloys. The main source of copper is copper plated on the surface of the welding wire to prevent corrosion of the welding wire. These copper shavings enter the flux from the inner hole of the contact tip and contact the weld pool during the welding process to cause lateral cracks.

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 preheating before welding is not carried out, the welding heat input is too large, the heat treatment after welding is improper, and the holding time is too short.

If welding slag appears when the spiral seam submerged arc welded steel pipe is joined, use argon arc welding, or wait for the stainless steel welded pipe to cool and knock it off with a hammer. Both methods are relatively simple, but they may not be cleaned up. Welding slag is better to clean up. The splashed 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 will be difficult to clean up.

As for some of the defects in the spiral welded steel pipe cutting, we can also remove them, but if we want to remove these defects, we need to find a reasonable method. Only the correct method can make the defects of the welded pipe compensated. Corresponding solutions can be found for these defects, but if the method is not found correctly, it will be more troublesome to use. For the welded pipe, another way to clean the welding slag is to use a file, which can also clean the welding slag very cleanly. Another simpler and labor-saving method is to take a saw blade or half a heel, stretch it into the tube, hold the tube in your left hand, and the saw blade in your right hand, and pull it clockwise or counterclockwise into your arms. In this way, the welding slag in the welded pipe can be cleaned very cleanly without wasting too much time, which is simple and convenient.