Unlike single-carbon arc welding, in twin-carbon arc welding the arc is maintained between two carbon electrodes held in a special holder. Current is switched on and by operating the mechanism of arc length adjustment the two electrodes are brought closer. The two electrodes touch momentarily, then separate and thus an arc is established.
The size of the arc depends upon the distance between the electrode tips, electrode diameters and the welding current. The heat input to the job can be varied by changing the arc size or the distance between the arc and workpiece. After striking the arc, welding can be carried out in the same way as in TIG welding process.