Cutting Nozzles

Understanding Gas Cutting Nozzles

All the nozzles we supply, whether ESAB or SWP branded, use the standard nozzle-mix (NM) principle. Oxygen and fuel gas travel down separate internal tubes through the torch body and only combine inside the head of the nozzle itself.

This is a critical safety feature: because mixed gases are never present inside the torch barrel or hoses, only a minimal volume of combustible mixture exists at any given moment. This drastically reduces the severity and likelihood of flashbacks. While we always mandate fitting certified flashback arrestors to both fuel and oxygen regulators as an essential safeguard, the nozzle-mix design serves as the torch's built-in first line of defence.

Acetylene vs. Propane Nozzles

• Acetylene (A-NM, A-NME): Solid, one-piece copper alloy construction. Because acetylene has a high flame velocity and rapid heat transfer, it requires a flat-faced tip to focus the preheat flame.
• Propane (P-NM, P-NME): Two-piece construction featuring a brass fluted inner core inside a copper outer sheath. Propane has a lower flame burning velocity than acetylene; the recessed two-piece design acts as a flame-retention cup to prevent the slower-burning flame from lifting off or blowing out under pressure.
• The "E" Designation: The "E" in ANME/PNME stands for Extended (typically 3.5" / 88 mm length compared to standard 3" / 75 mm ANM/PNM). It provides greater visibility, reach, and heat displacement away from the torch head without altering the gas mixing principle.

How the Preheat Flame Works

Around the central cutting oxygen bore, every nozzle features a ring of preheat orifices (or splines on propane nozzles). Pre-heat oxygen and fuel gas flow continuously through these channels, regulated by the torch’s preheat valves.

1. The operator lights and adjusts the valves to establish a stable, neutral flame.
2. The preheat ring brings the leading edge of the steel to its kindling temperature: around 870°C, glowing a bright cherry red.
3. The operator depresses the cutting oxygen lever, releasing a concentrated high-pressure stream of pure oxygen through the central bore.
4. This initiates a rapid, exothermic oxidation reaction that severs the steel (it literally burns the metal away) and blows the resulting molten slag clear through the bottom of the kerf.

Nozzle Size and Cutting Thickness

The number stamped on a nozzle (1/32", 3/64", 1/16" and so on) is the diameter of the central cutting oxygen bore, not an external measurement. A wider bore delivers more oxygen and can cut thicker plate, but needs higher pressure and uses more gas; too large a nozzle on thin sheet gives a rough, wide cut, while too small a nozzle on thick plate won't cut cleanly through. As a general guide:

Stocking the full range from 1/32" to 1/8" means we can supply the correct nozzle for anything from thin sheet steel through to heavy structural plate.