WJS London branch

Orbital Welding and Self-Tuning Power Sources

Report of meeting held on 14th February 2008 at Newham College, Stratford Complex, London

The February meeting of the London Branch of the Welding and Joining Society was held on the 14th February 2008 at Newham College, Stratford Complex, London. This was a presentation on 'Orbital Welding and Self-Tuning Power Sources', by Steve Powell of ESAB Group (UK) Ltd. who was introduced to the meeting by Bert Buckingham, the London Branch Programme Secretary.

Mr Powell started by describing the orbital TIG (Tungsten Inert Gas) process used for welding tubes in which the electrode rotates around the workpiece as opposed to the rotary process where the workpiece revolves. Pulsed current is usually used with the electrode negative to direct two thirds of the heat into the workpiece.

All the welding parameters are calculated from the diameter and wall thickness of the tubes. The weld heads are available either enclosed or open, the enclosed type being fully automatic and suitable for up to 4 mm2 whilst for greater sizes the open head is more suitable with multi pass operation.

Mr Powell then discussed problems which can occur with orbital TIG including the importance of good tube facing which should be carried out if the tube has been cut with a hacksaw or tube cutter. The misalignment should be less than 10% of wall thickness and the sulphur content of the tube should be controlled to prevent lack of penetration and misalignment of the weld.

The vote of thanks for the presentation was proposed by Charlie Barraclough, the London Branch Chairman and followed by an excellent buffet thanks to Newham College after which some of the London branch committee toured the welding facilities of the college which appeared comprehensive and capable of providing excellent practical training.