Online-Process

Already while the steel strip is formed into a pipe in the spiral pipe welding system, in the online process, the final internal and external SAW process are carried out in submerged arc welding (two-run welding).

In this process, MAG tack welding is not required.

Internal submerged arc 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. Usually, external SAW is carried out with an offset of one turn with respect to internal SAW in the 12 o' clock position.

The great advantage of this process is the fact that the pipe length is not limited through the length of the steel strip. The flying parting-off device (torch cutting) can be adjusted to different pipe lengths.

However, productivity of spiral pipe welding systems is restricted by the welding speeds of submerged arc welding.

Thus, today, more and more spiral pipe mills are equipped for offline welding .