By Jack Fulcer
When it comes to choosing and using a power source, companies and individual welding operators take great care. This equipment is a big investment. It must be appropriate for the application and the machine must be maintained diligently to ensure it will perform as expected when needed.
But what about the other parts of the welding system? There are factors here to consider as well.
Take the torch used during the GTAW process. This torch is an integral part of the whole welding system and is responsible for carrying and directing the welding current to the weld joint.
Choosing a durably constructed GTAW torch with reliable components, and properly maintaining it, will keep you welding longer and it can help lower costs for replacements.
There is, however, no hard and fast rule for selecting the “right” torch. Rather there are factors to consider with each component and the selection of each will depend on the individual application for which it will be used.
Here are some recommended guidelines.
First, there are two options when selecting hoses or cables for a GTAW torch: vinyl or rubber. These are available for both air- or water-cooled torches.
For either type of GTAW torch, rubber hoses and cables, especially braided ones, are recommended for their longevity and welding performance. They offer good heat resistance — up to 300 F (compared to 150 F to 200 F for vinyl) — and also resist kinking, which prevents disruption to the shielding gas flow that can lead to problems like porosity. Rubber hoses and cables also maintain their flexibility and durability in cold environments better than vinyl and offer good protection against high frequency leakage.
Note, vinyl hoses and cables are less expensive and practical for light-duty GTAW applications, but they don’t last as long as rubber ones.
Next, choose a GTAW torch with the right handle for the job, specifically one that is comfortable to hold and one that offers the appropriate cooling capacity needed for the application. Generally, there are two available types of handles: smooth (sometimes called knurled) or ribbed.
Ribbed handles help improve cooling capacity on air-cooled torches and are often shipped standard from the factory when you order this type of GTAW torch. Conversely, smooth handles offer good thermal conductivity for water-cooled torches. These two types of handles can be interchanged according to welding operator preference; however, it is important to be sure that both are made of durable, electrical grade plastic. This compound helps resist cracking and protects against high frequency shocks.
If the power source being used does not have a gas solenoid, choose a torch body that includes a gas valve control. This valve can be turned on and off as needed to minimize unnecessary shielding gas usage — a definite cost-saving factor.
The GTAW torch body should feature good insulation, as this protects against damage from day-to-day use, helps extend torch life and shields against high frequency leakage. Most GTAW torch manufacturers surround the torch body with silicon rubber insulation and some specifically use a high-dielectric type. High-dielectric silicon rubber aptly withstands higher voltages without breaking down, which helps lengthen the life of the torch. Silicon rubber insulated torch bodies are also more resilient than hard phenolic torch bodies (another option) to resist cracking if dropped.
To ensure good arc stability, and with it good welding performance, a GTAW torch body should feature heavy copper construction along with highly conductive copper components such as collets and collet bodies. In particular, collets and collet bodies composed of a tellurium-copper alloy offer the best conductivity; they are also more resistant to heat than standard copper ones and they resist twisting or elongating to hold the tungsten more securely. A secure tungsten equals a steady arc and good weld quality.
Backcaps are composed of an assortment of phenolic compounds which have varying degrees of heat resistance. Select a backcap that is composed of compounds that fit the amperage requirements of the application. For example, if the GTAW torch is used for general-duty applications, a backcap made of a low-temperature phenolic compound will suffice. A backcap with a higher thermal resistance should be selected for more demanding applications.
If greater shielding gas coverage is required for the GTAW application, or joint access is limited, you should add a gas lens to the GTAW torch. Select a gas lens comprised of a durable porous media (as opposed to multiple thin screens). These are more expensive — but they last longer and provide improved gas coverage while reducing unnecessary downtime.
Selecting the right nozzle for the application is also an important factor. Lava nozzles offer good crack resistance for medium-amperage applications, while silicon nitrate nozzles are suited for high-duty cycle GTAW applications that are also higher-amperage. Both are more expensive than alumina oxide nozzles, which are appropriate for low amperage applications, but they better resist cracking and melting.
Beyond the components
Components aside, you’ll also need to determine whether an air- or water-cooled GTAW torch is best. As a rule, an air-cooled torch is a good option for lower amperage applications (under 200 amps) and a water-cooled torch would be used for applications requiring more than 200 amps.
Air-cooled torches are heavier, as they rely on the surrounding air to cool them. Select one with a comfortable handle; it will help make the GTAW torch easier to maneuver. Consider where the welding will take place, too. Outdoor applications lend themselves to the more portable air-cooled GTAW torch, whereas shop applications can better accommodate a water-cooled torch and its accompanying water cooler.
Also, there are flexible necks available for most GTAW torches. These can be ordered factory-direct from most GTAW torch manufacturers and should be considered when you have particularly tight joints to weld or for welding in awkward positions.
Some torch body styles feature a modular design, which allows not only a flexible neck to be added, but also different head angles. These types of modular GTAW torches work well for complex joints and/or for applications with a variety of different angles that need to be reached. They can also help lower costs by allowing you to customize a single GTAW torch according to application, instead of having to buy a different torch for each application.
Remember, a GTAW torch, no matter the application, plays an important part in the overall welding process. Take care to select one that meets your needs and that complements your power source. It will save time, money, and a lot of headaches.
Jack Fulcer is product and marketing manager at Weldcraft, (800) 752-7620, www.weldcraft.com.
10 Easy Tips for Maintaining Your GTAW Torch
Once you’ve chosen the most appropriate GTAW torch and components for your application, routine inspections and some simple maintenance can help make them last.
1. Use a woven nylon cable cover with a plastic zipper to protect hoses and cables from cuts caused by dragging, and to help avoid high frequency problems that can lead to torch damage.
2. Periodically remove the collet and collet body and wire brush them to remove oxides that can lead to an erratic arc and shorten consumable life.
3. Make sure all threads on connecting points of the torch are tightened properly to prevent problems with electrical conductivity that can damage the torch’s front-end parts.
4. Visually inspect the nozzle to look for distortion, cracking, or blackening, as these are signs of wear that can lead to improper shielding gas coverage. Replace the nozzle if any such damage is evident.
5. Check for cracks in the handle by inserting a wooden dowel or your finger into the back end of the torch; this increases the diameter of the handle and makes for easier visual inspection. Replace (do not tape!) the handle if damaged in order to avoid injury from shocks.
6. Visually inspect the silicon rubber insulation surrounding the torch body for any cuts. Check a phenolic torch body for cracks. Replace either torch body if any irregularities are found.
7. Looks for cracks or signs of deterioration on the insert, or O-ring, attached to the back cap. If needed, replace to prevent aspiration (pulling of air into the torch body), as this can lead to weld discontinuities.
8. Keep the threads connecting the backcap and torch body clean, look for any signs of wear on the threads, and replace as necessary.
9. Test that the power connector is snugly tightened to the power source to prevent overheating and damage to the torch cable. Also be certain all gas and water fittings are secure to prevent leaks.
10. When using a water-cooled torch, periodically remove the handle to check water connections for leaks that can lead to torch overheating and damage.