What is K-TIG

Overview

K-TIG is a single-pass, full-penetration keyhole welding technology which performs a 6 hour TIG weld in under 3 minutes - just 1% of the time normally required. The average cost saving of K-TIG customers is between 80 and 95 percent. K-TIG is intended as an automated welding process for 1G and 2G welding of ferrous and non-ferrous alloys.

K-TIG is a GTAW process which requires no edge bevelling, uses as little as 10% of the gas normally required and produces highly repeatable, x-ray quality welds with superb cap and root aesthetics.

K-TIG welds meet US, European & Australasian welding standardsincluding ASME IX, and have been subjected to exhaustive Lloyds-witnessed and certified testing.

K-TIG has been exported to 18 countries and is being used in production by many of the world’s most productive fabricators in numerous industries from pressure vessels and tanks to power generation and nuclear applications.

K-TIG performs single pass, full penetration welds in a wide range of materials, including:

  • Titanium up to 5/8 inch (16mm) thickness
  • Stainless steel up to 1/2 inch (13mm) thickness
  • Duplex & Super Duplex up to 1/2 inch (13mm) thickness
  • Nickel alloys & super alloys up to 1/2 inch (13mm) thickness
  • High quality carbon steel up to 1/4 inch (6mm) thickness

K-TIG’s incredibly fast welding times result in dramatic reductions in labor costs, welding cycle times, rework and repair costs, gas and power consumption. K-TIG's full-penetration welds significantly reduce or eliminate grinding, back-gouging & reworking. The K-TIG process eliminates the need for edge bevelling and dramatically reduces or eliminates the need for filler material. K-TIG requires only a simple square butt joint, and can also be utilised with all standard GTAW preparations. 

Typical examples K-TIG welding speeds include welding of:

  • 12 mm (15/32 inch) thick austenitic stainless steel at 250 mm/min (10 inch/min),
  • 8 mm (5/16 inch) thick C-Mn steel at 400 mm/min (15.5 inch/min),
  • 3 mm (1/8 inch) thick ferritic stainless steel at 1000 mm/min (39 inch/min).

All in a full penetration pass.

These speeds are in the middle of the operating window for the K-TIG process and can be increased (in some cases significantly) if the objective is to optimise for speed, such as may be desirable in a tube mill application.

 Learn about K-TIG in action with the GE Case Study, Bilfinger Case Study, Titan Case Study or check out and subscribe to our YouTube Channel.

Where it began

Keyhole TIG is a patented, high productivity GTAW variant which was originally developed by the Australian Government’s Commonwealth Scientific & Industrial Research Organisation (CSIRO), in conjunction with the Cooperative Research Centre for Welded Structures. 

K-TIG welding is a new productivity benchmark. It sets an entirely new bar for what can be achieved with an arc welding system. The speed, penetration, quality and overall savings generated by the process are extraordinary
Attila Szabo, Principal Joining Engineer, GE

The K-TIG process delivers advantages previously achievable with only high-cost laser, hybrid laser or electron beam welding.

This simple process makes automated, high quality, deep penetration welding accessible to any small-to-medium sized fabricator.

This patented technology is based on extensive, scientific study of the gas-tungsten-arc process, and is the result of many innovations relating to arc characteristics, weld pool stabilisation, heat removal and process efficiency. The K-TIG process is well suited to lower conductivity materials such as stainless steels, nickel alloys, titanium alloys and indeed most corrosion resistant and exotic materials.

 K-TIG welding technology combines the high-quality and cleanliness of GTAW with a depth of penetration that is unmatched by conventional gas-tungsten arc, gas metal arc or plasma welding processes.

How It Works

K-TIG uses self-induced effects to generate a plasma jet.

There is no orifice, making the process much simpler than plasma arc welding.

Just one welding gas is used, and its flow rate is not critical. The K-TIG keyhole has high inherent stability, and operates over a very wide range of welding currents. Setup is straightforward.

 

Through the Keyhole

The K-TIG variant of the GTAW process is the solution to the weld pool instabilities which are characteristic of higher current GTAW welding.

A fundamental characteristic of the keyhole process is the intentional increase in arc pressure to the point where it extends the crater to the bottom of the pool. At this point, the bottom of the crater breaks through the root face of the weldment, forming a keyhole and allowing the arc gases to escape. Most importantly, the openings in the front and root faces of the weldment act to anchor the liquid surface of the pool. In helping to understand what this looks like, it’s helpful to visualise the elastic properties of a soap film bubble, as illustrated in the image to the right.

The minimisation of the surface energy associated with the keyhole geometry and the relatively unrestricted egress of the arc gases combine to produce a very robust and tranquil weld pool. Added to this, the molten metal within the weld pool is prevented from falling from the root face by surface tension, as evidenced above.

The K-TIG keyhole is unique because it does not rely on the very high energy densities of other keyhole processes such as laser and plasma, resulting in a wider fusion zone at the front face. 

Soap film bubble analogy of a K-TIG keyhole, illustrating the stabilising effect of surface tension when the keyhole surface is anchored to both front and root faces.

The K-TIG Welding System

The K-TIG Welding System has been specifically engineered to deliver the Keyhole GTAW process in a robust, intelligent and extremely simple to operate system. K-TIG welding systems are produced in Adelaide, South Australia.

The complete K-TIG system is comprised of the following components:

K-TIG Comparison Study TIG MIG