What's inside
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What matters when welding thin stainless tube
Thin stainless tubing punishes excess heat. A long arc or a slow pass can burn through a wall under 1 mm, pull the joint out of alignment, or leave a wide, discolored heat-affected zone. For repair work, a TIG machine needs stable low-amp output, predictable starts, and enough control to make short, repeatable welds. Good fit-up, clean material, and a proper purge matter just as much as the welder.
For most small-bore tube repairs, look for a machine that can start and hold an arc around 5–10 amps, has a foot pedal, and offers adjustable post-flow. High-frequency start is useful because it starts the arc without touching the tungsten to the work. AC output is not needed for stainless steel; DC TIG is the relevant process. A machine with AC/DC capability can still be a good buy if you also weld aluminum, but you pay for a feature this job does not use.
Which type of TIG welder to buy
A compact DC TIG inverter is usually the sensible choice for stainless tube. Machines in the roughly 120–200 amp range can handle thin tubing and many general repair jobs without the size or cost of a larger shop unit. Check the minimum stable amperage, not just the maximum output printed on the case. Low-end arc behavior varies, so reviews and return policies are worth checking.
If the welder will also be used for aluminum, consider an AC/DC TIG machine. It is more versatile, but it adds cost and settings to learn. A budget DC unit is fine if your work is stainless, mild steel, and other DC-compatible metals. If you need to weld frequently for production, want advanced pulse controls, or run long welds, a more capable machine may justify its price.
Browse DC TIG welders with a foot pedal and high-frequency start for a practical starting point. Verify what is included: some packages omit the pedal, torch consumables, regulator, or gas hose, and those extras can change the real cost.
Quick comparison
| Option | Best for | Trade-off |
|---|---|---|
| Compact DC TIG, 120–200 A | Stainless and steel tube repairs | No aluminum welding; controls may be basic |
| AC/DC TIG, around 200 A | Stainless work plus aluminum | Higher cost and more setup choices |
| DC TIG with pulse | Managing heat on small or awkward joints | Pulse helps, but does not replace good fit-up or technique |
Features worth paying for
A foot pedal lets you reduce current as the joint heats up, which is especially useful on thin tube. A torch-mounted amperage control can work in tight spaces, but check that it is compatible with the machine. Pulse TIG alternates between peak and background current; it can help limit heat input and steady travel on small parts, though it takes practice to set. It is not essential for occasional repairs.
Pre-flow and post-flow settings also matter. Post-flow shields the tungsten and hot weld as they cool; too little can contaminate the electrode, while a starting point of roughly 5–10 seconds is common for modest currents. Use a regulator and flowmeter to set gas flow rather than guessing from the cylinder regulator alone. Excessive flow can cause turbulence and draw air into the shield.
For most repair work, a standard air-cooled torch is adequate. A water-cooled torch is more comfortable for long, high-current sessions but adds a cooler, hoses, and maintenance. Spend first on stable low-current performance, a usable pedal, and dependable gas control.
Setup for a thin stainless tube repair
Clean the joint until it is free of oil, paint, oxide, and marker residue. Use a dedicated stainless brush and clean filler rod; carbon-steel contamination can leave rust-prone spots. Fit the tube tightly. A gap wider than the wall thickness makes burn-through much more likely, particularly on a tube with a wall around 0.5–1 mm. Tack at several points around the joint before welding so the parts do not shift.
Use argon shielding gas, a sharp 1.0 or 1.6 mm tungsten, and filler close to the base metal grade when filler is needed. Start with a small cup and moderate gas flow, often around 10–15 cubic feet per hour in a sheltered area, then adjust for cup size and drafts. For tubing that must resist corrosion on the inside, use a backing purge of argon. Without it, the root can oxidize into rough, dark “sugaring,” weakening the joint and trapping contamination.
Begin around 20–40 amps for very thin tube and adjust to the material, joint, and machine response. That is a starting range, not a universal setting: a 1 mm wall may need more current briefly to establish the puddle, while a lap joint or poor fit-up may need less. Make short sections, let the part cool, and avoid lingering at the end of the weld. If the puddle suddenly widens or the tube edge rolls away, pull back on the pedal and move on; adding filler to a hole is difficult and often leaves a weak, uneven repair.
Before you buy
Check the machine’s duty cycle at the amperage you expect to use, input-voltage requirements, torch connection, pedal compatibility, and warranty support. A 120 V machine is convenient for home and field repairs, but its output and duty cycle may be limited. A 240 V unit generally offers more headroom; it is not automatically better for thin tubing if its arc is unstable at low current.
If your repairs are occasional and involve short welds, a basic DC TIG machine with a decent low-amp arc is often enough. If you work on sanitary, food, or exhaust tubing where the inside of the joint matters, budget for purge plugs or a purge setup and practice on scrap of the same diameter and wall thickness first. For that work, a stainless tube TIG purge kit can be more valuable than extra maximum amperage.