Offline-Process

In the offline process, the pipe is tack welded during forming in the spiral pipe welding system with a MAG tack welding machine in MAG tack welding and afterwards shortened to the appropriate length (plasma arc welding).

Continuous MAG tack welding is carried out in the 6 o’clock position where the edge of the incoming steel strip and the edge of the first formed turn of the steel strip merge.

After that, submerged arc welding (SAW) is carried out on separate internal and external welding stands (rewelding stands, two-run welding).

Before submerged arc welding is carried out, start and end tabs are welded to the pipe ends in order to position the craters, which are produced in the beginning and end of the submerged arc welding process, outside the pipe.

In the offline welding process, the pipe length is determined by the design of the rewelding stands. However, efficiency in the offline welding process is considerably higher.

Apart from that, process parameters can be optimised through the separate submerged arc welding process.