How to Weld for Large-diameter Welded Steel Pipe at Low Temperatures

Under cold conditions a low-carbon steel welding, the cooling rate of the welded joint, which has made cracking tendency to increase, especially in the first weld Heavy structures susceptible to cracking, it is necessary to take the following process steps:

1) Do not possible under conditions of low temperature bending, correction and assembly weldments.

2) Preheat, 16Mn seamless steel pipe welding process strictly maintained interlayer temperature should not fall below the preheating temperature.

3) Hydrogen or ultra-low hydrogen welding.

4) The whole seam continuous welding should be completed to avoid interruption.

5) When positioning welding to increase the welding current, welding speed slows down, due to increase tack welds cross-sectional area and length, preheated if necessary.

6) Not be performed on a base material arc groove surface other than the need to fill the crater when extinction.