Single-single 
                         Single + Single

Twin-single
                        Twin + Single


Tandem wire

In tandem SAW welding each of the two wires is connected to its own power source and fed simultaneously by its own feed unit. The lead arc, operating at high current (mostly DC+) and low voltage, ensures deep penetration, whilst the trailing arc uses lower current (mostly AC to avoid arc blow) to smooth and finish the weld bead.

The wires are normally large diameter (3.0-5.0 mm) and deposition rates are about twice that of single-wire welding.

Tandem SAW is widely used in shipbuilding, the offshore industry, beam production, wind tower production and at pipe mills.