How to Set Up a 9 Series Air-Cooled TIG Torch for 125A Welding

Quick answer

To set up a 9 Series air-cooled TIG torch for 125A welding, match the torch's 25 Dinse power connector and 5/8-18 RH gas fitting to your welder, then assemble the torch, connect gas and power, and check for leaks before welding. Use a 25 Dinse adapter with flow-through gas if your machine has a 25 Dinse (3/8") outlet. Tighten fittings snugly but do not overtighten, and always leak-test with shielding gas before striking an arc.

Match the torch connections to your welder

The 9 Series torch uses a 25 Dinse (3/8" OD) power/current supply and a 5/8"-18 RH gas fitting. Check your welder's outlet: if it has a 25 Dinse connection, you can attach the torch directly. If your machine uses a different size, you'll need an adapter. For 9 and 17 Series torches on a 25 Dinse outlet, the 25 Dinse adapter with flow-through gas (product ID 1278973) provides both power and gas delivery. If your welder has a 35 Dinse (1/2") outlet and you're using a water-cooled torch, you'd need a different adapter (product ID 1283102), but that's not applicable for this air-cooled setup. Always confirm the gas fitting gender and thread: the torch has a 5/8"-18 RH fitting, so your gas hose must have a matching 5/8"-18 RH connection.

Inspect and prepare the torch and cable

Before assembly, inspect the torch body, cable, and fittings for damage. The 9 Series torch features a one-piece cable design with a flexible silicone rubber hose and nylon braided weave overlay, which stays flexible even in cold weather. Check that the O-rings on the Dinse connector and gas fitting are intact and free of debris. A small nick or missing o-ring-2-2e02e04a90bbbbbc601f0d0e-1282409">O-ring can cause gas leaks or poor electrical contact. Wipe the fittings clean with a lint-free cloth.

Install the tungsten electrode-9-a554e77b4a5b91c0cb7f391d-1278857">electrode-11-7b726d9e4c3ff3d4e0808c1f-1278856">electrode and collet

Select a tungsten electrode size appropriate for 125A welding—typically 3/32" (2.4mm) or 1/8" (3.2mm) for DCEN on steel. Insert the electrode into the collet and collet body, then screw on the ceramic cup. The electrode should protrude about 1/8" to 1/4" beyond the cup for most applications. Tighten the back cap by hand; it only needs to be snug to hold the electrode. Over-tightening can crack the collet body or strip threads.

Connect the torch to the welder

If using a 25 Dinse adapter, screw the adapter onto the torch's power cable fitting first, then insert the adapter into the welder's 25 Dinse receptacle and twist to lock. For the gas connection, attach your shielding gas hose to the torch's 5/8"-18 RH fitting. Use a wrench on the torch fitting's hex flats to prevent twisting the cable. Hand-tighten the gas fitting, then snug it with a wrench—about 1/8 turn past hand-tight is sufficient. Do not use thread sealant on flare fittings.

Leak-test and set gas flow

Turn on the shielding gas at the regulator and set flow to 15–20 CFH for a 9 Series torch. With the gas flowing, brush soapy water on all connections—the gas fitting at the torch, the adapter-to-welder joint, and the regulator outlet. Bubbles indicate a leak. If you find a leak, tighten the fitting slightly and retest. Never strike an arc until the system is leak-free; gas leaks waste shielding gas and can cause porosity in your weld.

Step-by-step setup with checkpoints

1. Verify connections: Match the torch's 25 Dinse power connector and 5/8"-18 RH gas fitting to your welder. If needed, use a 25 Dinse adapter with flow-through gas (product ID 1278973). Checkpoint: The torch should seat fully and lock without force. If it doesn't, you may have the wrong adapter.
2. Inspect torch and cable: Look for cuts, abrasions, or missing O-rings on the Dinse connector and gas fitting. The one-piece cable should be flexible and free of kinks. Mistake to avoid: Ignoring a damaged O-ring can cause gas leaks and poor weld quality.
3. Install tungsten and cup: Insert the tungsten into the collet, screw on the collet body and ceramic cup, and secure with the back cap. Use 3/32" or 1/8" tungsten for 125A. Checkpoint: The tungsten should be centered and protrude 1/8"–1/4" beyond the cup.
4. Connect power and gas: Attach the adapter to the torch, insert into the welder, and twist to lock. Connect the gas hose to the 5/8"-18 RH fitting and tighten snugly with a wrench. Mistake to avoid: Over-tightening gas fittings can damage the seal. Stop at 1/8 turn past hand-tight.
5. Leak-test and set flow: Turn on gas, set flow to 15–20 CFH, and apply soapy water to all connections. Bubbles mean a leak—tighten and retest. Checkpoint: No bubbles before you weld. A leak-free system prevents porosity and saves gas.

Key product details

• 9 Series (125A) Air-Cooled Torch w/25 Dinse & 5/8"-18 RH Gas Fitting: 9 Series (125A) air-cooled TIG welding torch with a 25 Dinse (3/8" OD) power/current supply and a 5/8"-18 RH gas fitting. This torch is rated for up to 125A, making it suitable for light-to-medium TIG welding. The 25 Dinse connector and 5/8"-18 RH gas fitting must match your welder's outlets or you'll need adapters.
• 25 Dinse (3/8") Adapter with Flow Thru Gas for 9 and 17 Series TIG Torches: 25 Dinse (3/8") adapter designed for use with 9 and 17 Series TIG torches, featuring flow-through gas capability. If your welder has a 25 Dinse outlet, this adapter lets you connect the torch and route shielding gas through the same connection, simplifying setup.