KTIG welding in progress

What is Keyhole TIG?

Joanne McIntyre - 7 March 2017

Guest blogger Ms Belinda Latz, Operations Manager at at K-TIG in Australia looks at Keyhole GTAW (known as K-TIG), a relatively new welding variant of the gas tungsten arc welding (GTAW) process.

About the author

Mrs Joanne McIntyre
Joanne McIntyre is the Editor in Chief of Stainless Steel World magazine, and Conference Coordinator for the Duplex Seminar & Summit.
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K-TIG is suited to single pass, full penetration welds on Corrosion Resistant Alloys (CRAs), pipe or plate up to 12 mm thickness. Little to no filler metal or edge preparation is required, and completed welds have particularly good aesthetics when welding stainless steels, as well as titanium, zirconium, and nickel.
The primary attraction of K-TIG is that it is a fast, single-pass process, providing full penetration of stainless steel plates from 3 mm to about 12 mm thick (and to about 16 mm for titanium alloys). 

Set-up
Joints are presented in closed square-butt configuration requiring minimal, if any, filler addition. Plus, impact toughness tests performed on austenitic stainless steel gave better results than multi-pass welds using filler metal.
K-TIG’s automation needs are low; consistent travel speed is the only requirement. The system is easy to use; training is easy and an experienced welder will be comfortable with the basic operation in a couple of hours. 

Performance
Keyhole GTAW provides fabricators with the type of full-penetration welding technology that is capable of increasing productivity. It slashes job times by completing a traditional six-hour TIG weld in just three minutes, while still offering superior welds. 
K-TIG’s penetration can be compared to plasma arc welding, however K-TIG boasts a simple set-up and operation, lower implementation cost and higher speeds.

Limitations
Like all systems K-TIG has some limitations. Here they are, plain and simple:
Positions - The K-TIG system welds effortlessly in 1G and 2G welding positions. It’s not intended for orbital (5G/6G) applications.
Materials - Copper and aluminium cannot be welded with K-TIG. Carbon steels are generally not suitable.
Pipe Diameters - K-TIG can readily weld pipe diameters down to 3 inches. The tie-in on pipes with diameters smaller than 3 inches become challenging as the weld is completed within seconds and the tie-in (joining the beginning and end of the weld) must be performed over very hot material. Essentially K-TIG is too fast for very small diameter pipes




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