The Tandem Twin submerged arc welding process is designed to improve productivity by increasing metal deposition rate and decreasing arc time. The process is suited for circumferential welding of large cylindrical objects such as the “cans” used in production of wind towers.
 
The welding process uses two small-diameter wires with a single power source and a single contact tip. It can increase deposition rates versus single-wire DC SAW, the company says. Tandem welding uses two separate power supplies, two wire feeders and two large-diameter wires. Both wires feed into the same molten puddle, but each has a separate contact tip, power supply and control.
 
The welding process solution consists of two heads, each using twin wires, mounted on a column and boom. The heads are powered by one LAF DC power source and one TAF AC power source that deliver as much as 1,250 amps per head.
 
According to the company, the development of this process coincided with the development of a flux, OK Flux 10.72, which is designed for low-temperature toughness requirements while using a non-alloyed wire electrode, OK Autrod 12.22. The flux/wire combination provides slag detachability in narrow joints and is said to be suitable for virtually all SAW variants.