Arc Applications, Inc.

Explore: Dual Torch Narrow Groove GTAW

One of the more amusing nuances of the welding industry are the acronyms used to refer to the welding processes. What is known as stick welding by most people is officially titled Shielded Metal Arc Welding, SMAW. Well today we would like to share with you one of our favorite processes, and with it, its amusingly long, unofficial, acronym:

Dual torch, horizontal, rotating tungsten, narrow groove, hot wire, gas tungsten arc welding, or GTAW-DTHRTNGHW for short.

Although it’s a little unwieldy to say, these modifications transform the everyday manual GTAW torch, well known for its slow tedious operation, into a very precise high productivity welding process well suited to thick welds for critical applications:

  • The rotating tungsten allows directing of the arc within the narrow groove. This allows a balance between limiting arc energy into the sidewall (reduced heat affected zone) and arc energy to the underlying weld bead (grain refinement).
  • Allows for reduced groove angles, including zero degree included angle straight side walls, which reduces the total fusion zone size.
  • Commonly used for weld grooves in the 5 to 8 inch (125 to 200 mm) range, but advertised capability up to 12 inches (300 mm) thick.
  • Can be set up to support hot wire welding, which can increase deposition rate in flat and horizontal weld grooves.
  • Full penetration root welding in all positions.
  • High quality deposit with low distortion.
  • Proven performance with steel, stainless steel, nickel based, titanium, and zirconium.

While this process is often used to join piping in land based, Naval, and the oil and gas power generation industries, the setup pictured is a mock-up used to demonstrate the welding practices used to join solid forgings for the electric power generation industry.

The system consists of a turn table which rotates the part while two independent welding systems deposit material into the weld groove. Manipulation of the welding system is performed via a touch screen or pendant interface while observation of the weld is provided by direct view cameras which display the leading and trailing views of the weld on two monitors above the welding power supplies. With this approach, two welding operators can perform continuous welding with near hands free operation of the system during welding.

So there you have it, GTAW-DTHRTNGHW, a welding process variant that transforms the tame GTAW process into a specialized tool for important jobs.

Narrow groove rotating tungsten station welding operators Narrow Groove Horizontally opposed dual torch hotwire set-up