September 27, 2011
Learning the facts about five common misconceptions about gas tungsten arc welding (GTAW) equipment can help you optimize this highly versatile process.
Even though gas tungsten arc welding (GTAW) is among the more difficult welding processes to master, it’s also one of the most versatile. Besides minimizing heat input so you can weld on thinner materials, the process also allows you to weld on almost any type of material, from carbon steel and aluminum to chrome-moly and more. The GTAW process also provides exceptionally clean, high-quality welds with no spatter, slag, or sparks, and you can use it to weld in all positions.
Achieving optimal welds with GTAW requires good operator skills and a solid knowledge about the equipment. Learning the truth behind five common misconceptions about GTAW torches and accessories can help.
As with any piece of welding equipment, water-cooled GTAW torches have their time and place. These torches allow you to weld at higher amperages and feature smaller torch heads and handles than most air-cooled GTAW torches, making them easier to maneuver. They also tend to be cooler to hold, which allows you to weld longer and minimize your downtime. As a rule, water-cooled GTAW torches are a good option when you have to weld for long periods of time. There is, however, the added cost for a separate water cooler with these torches.
Replacement parts — nozzles, collets, collet bodies — for water-cooled GTAW torches tend to cost about the same as similarly sized parts for lower-amperage, air-cooled torches. And because they often last longer than parts for air-cooled GTAW torches (due to the decreased temperatures in the torch head), you may be able to minimize downtime for changeover and costs of purchasing additional consumables.
The possibilities of leaks and the need for hose maintenance are factors to consider when using a water-cooled GTAW torch. But as long as you properly care for the equipment and install a cover to protect the hose and cable assemblies, you can easily extend the life of your torch, hoses/cables, and consumables.
Gas lenses are used most often for critical welds, such as alloys that are highly reactive to atmospheric contaminants or materials used in high-temperature applications. Still, any application can benefit from using a gas lens.
A gas lens allows you to extend the tungsten electrode farther out from the nozzle to gain better visibility of the joint and arc. This electrode extension also enables greater torch control and can help you achieve better weld quality, especially on hard-to-reach joints. Gas lenses help provide better, more even shielding gas flow around the tungsten and along the weld puddle, which helps protect against contaminants that could lead to weld defects and downtime for rework. A typical gas lens is composed of a copper and/or brass body with layered mesh screens of steel or stainless steel (stainless steel offers greater durability and resistance to rust and corrosion than steel) that help achieve this result.
Gas lenses can be used with all shielding gases and are available for both air- and water-cooled GTAW torches. They do add to the cost of consumables, but the gains in quality and productivity may offset the extra cost.
Air-cooled torches typically have from 125 to 200 amps of welding capacity; however, options up to 300 amps are available. Higher-amperage, air-cooled GTAW torches usually feature larger power cables that are separate from the gas hose. You can attach a heavier extension cable to the power cable and extend the gas hose as needed to reach the job. These higher-amperage torches also have heavy copper components that can withstand higher heat levels without the need for an external water cooler. They are available with optional integrated gas valves for fingertip control of shielding gas flow. Their relatively lightweight bodies make them comfortable, particularly when You’re welding on continuous, heavy-duty applications.
Such GTAW torches are good for repair or production jobs that require high-amperage welding capabilities and portability, since bringing a water cooler to a work area is not always feasible.
As with the GTAW process itself, a learning curve is associated with using fingertip controls on a GTAW torch. There also are benefits. Fingertip controls are good for applications that require a high volume of out-of-position welding, because they eliminate the need to maneuver a foot pedal or reach the weld at an awkward angle. Fingertip controls are especially useful if you are welding on pipe or doing contract work as well, because you may need to go to the work rather than have it nearby. Fingertip controls also can offer finer amperage control, which is beneficial if you need quick ramp-up on an application.
Fingertip controls fasten to the GTAW torch by way of small Velcro® straps and have a cord and plug. They typically are available in one of three styles: side-to-side rotary-motion; north/south rotary motion; or push-button, which allows you to select the option that is best for your particular welding requirements or your preference. Most fingertip controls can be adapted to any GTAW torch, but you will have to select the correct fingertip control for your specific GTAW power source.
The key to using a fingertip control is practice. If you find yourself climbing on, around, or under your work area, learning how to use this control may be well worth the effort.
It is not uncommon for a welder to try to make his welding application fit the tool, especially if he’s trying to avoid welding in small or complex joints. Doing so, however, isn’t always necessary. Modular kits allow you to configure a GTAW torch to meet the needs of the application, even if it contains small or complex joints. For example, a kit typically offers the option of a flexible neck that can be adjusted to multiple angles to provide you with access to hard-to-reach joints. It also contains heads of various sizes that you can adjust to suit your needs. Having multiple neck and head options also allows you to reconfigure your GTAW torch for various applications without incurring the cost of buying a new torch for every job.
Many GTAW torch manufacturers also offer micro-GTAW torches, which are small, lightweight, pencil-like torches that permit access into very small joints. Check with your local welding distributor for options.
Remember, as with any welding application, there is no “one size fits all” answer when it comes to GTAW equipment. Some applications are better suited to using a water-cooled torch, while others can benefit from an air-cooled model. The important thing is to separate fact from myth when it comes to making your selection and practicing your skills.