Spiral welding

ESAB offers welding equipment for 

Offline spiral pipe mills:

  • Strip joining (coil to coil welding)
  • Tack welding (MAG)
  • Internal SAW welding
  • External SAW welding

Online spiral pipe mills:

  • Internal SAW welding
  • External SAW welding

Offline Spiral Welding of pipes

In an off-line pipe mill, the forming station which is equipped with tack welding, feeds three separate offline welding stations, each with internal and external SAW welding heads.

Strip joining

The strip joining station consists of a beam-running carriage holding a plasma cutting torch, MIG/MAG tack welding torch and a tandem SAW welding head. The procedure is that after cutting the edges clean, the edges will be joint prepared by milling. The strips are then brought together, tack welded and completed by tandem SAW welding.

Tack welding station

Tack welding is done with the MIG/MAG process and with welding speeds up to 8 m/min. The tack welding torch is mounted on a slide (for joint tracking) along the forming arm in the forming station. The purpose of tack welding is just to hold the pipe together prior to the ID and OD SAW welding.

Internal welding station

The ID Welding station consists of a 16-18 m long boom with a 3-wire welding head at the end. The angle of the welding head is adjustable to match the helix angle of the weld seam of the pipe. The welding head is mounted on a slide with movement in the axial direction for joint tracking.

Prior to welding the welding boom is inserted by its full length into the pipe. Welding is done while rolling/screwing the pipe out from the ID boom. This is mainly to avoid the ID boom with all its cabling being affected by the heated pipe.

Internal and external spiral pipe welding 

External welding station

The OD welding station is built on a semi-stationary column and boom holding a 4-wire welding head. As the space for the welding head on the OD station is not so limited the wire feeders are mounted in a "rainbow" configuration enabling the wire liners between the contact nozzles and wire feed motors being straight.

External welding station

The whole "rainbow arrangement with wire feed motors is mounted on a ring enabling the welding head assembly to be rotated into correct helix angle of the spiral pipe.

Earthing system

ESAB offers different types of earthing systems for pipe production. Most common is to have a set of brushes mounted on a rack, one in front and one behind the external welding head. The internal welding head uses the same type of brushes.

Internal welding station and earthing system

ESAB also offers return current systems where the brushes are travelling on a carriage next to the pipe.

External welding and earthing system

The carriage with brushes first starts in a position by the internal welding head. When welding, the pipe moves towards the external welding head and the carriage with return brushes follows the pipe to the position of the external welding head where it stops. The advantage of this system is that the contact point for return current doesn't change from one point to another - it remains the same point but only changes position.

Online Welding of pipes

The online pipe mill welds SAW direct without tacking in the forming station, limiting the production to the welding speed in the forming station. In the forming station a SAW welding head is mounted at the same place as the tack welding head in an off-line station. Normally 2-3 SAW torches are used.

On the upper end of the forming station a 2-torch welding head is mounted in the same configuration as the OD welding station for off-line spiral welding.

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