Ask any TIG welder where a good weld starts and the answer is rarely the machine. It starts at the cup. On a WP-26 air-cooled torch, the alumina ceramic nozzle decides how the shielding gas leaves the torch, how stable the arc stays at a given current, and how much of the weld pool the operator can actually see. Choose the wrong size and the symptoms appear immediately: porosity, a wandering arc, a scorched cup or a tungsten that fails halfway through a run.
This guide sets out the practical rules used when matching a ceramic nozzle to a WP-26 torch, so that shops can standardise their consumable stock instead of guessing at the bench.
Nozzle size is not a cosmetic choice. Each cup size has a working current window, because the gas column has to stay large enough to cover the pool as the current rises. As a baseline for WP-26 torches running argon:
| Cup size | Orifice diameter | Typical current | Where it works best |
|---|---|---|---|
| #4 | 1/4" (6.4 mm) | up to 60 A | Thin sheet, tight joints, restricted access |
| #5 | 5/16" (8.0 mm) | 60 – 90 A | Light general work, small stainless parts |
| #6 | 3/8" (9.5 mm) | 90 – 130 A | General fabrication, most repair work |
| #7 | 7/16" (11.1 mm) | 130 – 170 A | Thicker sections, longer welds |
| #8 | 1/2" (12.7 mm) | 170 – 200 A | Maximum coverage at the top of the torch rating |
Two rules follow from the table. Going one size larger than the minimum is safer than going one size smaller, because excess gas coverage is forgiving while insufficient coverage is not. And on a WP-26, anything above roughly 150 A with a #4 or #5 cup is a shortcut to a cracked or discoloured nozzle.
Standard cups run on a 10N series collet body. They are inexpensive, quick to change and perfectly adequate for carbon steel and general stainless work. Gas lens cups use a 45V series collet body with a stainless screen that straightens the gas flow, which allows a longer electrode stick-out, better visibility of the joint and more reliable coverage on titanium, duplex and thin stainless where oxidation is not acceptable.
Three factors are behind most premature nozzle failures, and none of them are visible in a catalogue photo. First, alumina purity and wall thickness: a thin-walled cup with inconsistent ceramic density will not survive repeated thermal cycling. Second, thread concentricity, because a nozzle that sits off-centre creates an uneven gas envelope on one side of the pool. Third, gas flow setting, since over-flowing a small cup produces turbulence that pulls atmosphere into the arc, which looks exactly like a cup that is too small.
A simple shop rule: if porosity appears, increase cup size or reduce flow before blaming the gas supply, and replace any cup showing a white powdery surface or a chipped lip immediately. A chipped lip is not a cosmetic defect, it is a leak path.
Most production shops with WP-26 torches can run on three sizes: #5, #6 and #7, plus one gas lens cup of the same size used most often. Holding that set as a fixed stock item removes the daily search for a part, keeps welders from forcing an oversized cup into a tight joint, and makes consumption predictable enough to plan purchasing in bulk.
Full WP-26 nozzle sets in #4 to #8, standard and gas lens, are available for sample evaluation, with matched collet bodies, collets and back caps supplied from the same production batch for dimensional consistency.
