Choosing the right oxy-acetylene tip and setting safe regulator pressures is the difference between a clean cut and a torch that pops, sputters, or never severs the plate. This interactive chart matches steel thickness to a Victor-style tip number for cutting, welding, or heating, and gives starting oxygen and acetylene pressures, while keeping acetylene safely at or below 15 PSI.
How it works
Each operation has its own tip-versus-thickness table derived from manufacturer charts. Thicker steel needs a larger orifice tip and higher oxygen pressure to push the cut; acetylene pressure rises more slowly and is always capped:
tip number = lookup(operation, thickness)
oxygen PSI = rises with thickness and tip size
acetylene PSI= rises modestly, never above ~15 PSI (safety limit)Cutting uses a cutting attachment with a preheat ring plus a high-pressure oxygen jet; welding and heating use single mixing tips for a soft flame. The tool always reminds you to set a neutral flame for cutting and most welding.
Understanding the three flame types
The gas ratio determines which of three flame types you are running, and matching the flame to the operation is as important as picking the right tip:
Neutral flame — equal oxygen and acetylene, producing a single sharp bright inner cone with no visible secondary cone or feather. This is the correct setting for cutting, most welding, and fusion work. It is the safest starting point and the benchmark you adjust from.
Oxidizing flame — excess oxygen, shorter and pointed inner cone with a hissing sound. Used for brazing brass and bronze, where slight oxidation helps the filler flow. It will burn steel, so do not use it for welding iron or mild steel.
Carburizing (reducing) flame — excess acetylene, showing a feathery secondary cone around the inner cone. Used for hard-facing and for some non-ferrous metals. On steel it leaves a carbon-rich surface layer. The feather length shows how far off neutral you are — a long feather means a lot of excess acetylene.
When you first light the torch, open only acetylene until you see a small sooty flame, then slowly open oxygen until the feather disappears and a sharp single cone forms. That is neutral. From there you can enrich or oxidize as needed.
The 15 PSI acetylene limit
Acetylene stored in cylinders is dissolved in acetone packed into a porous filler. When drawn at high pressure it can decompose exothermically — the free gas becomes chemically unstable above roughly 15 PSI. The chart never recommends acetylene pressures approaching that limit, and regulator gauges in professional settings often include a red zone marker at 15 PSI. Drawing too fast from a cylinder also draws liquid acetone into the hose, which contaminates the tip orifice and causes erratic flames.
For high-volume cutting at thickness requiring large tips, work from multiple cylinders manifolded together rather than pushing a single cylinder past its safe draw rate.
Worked example: selecting a tip for cutting 3/8 in plate
Plate thickness 3/8 in (approximately 10 mm), material: mild steel, operation: cutting.
A typical Victor-style recommendation for this thickness is a size #1 cutting tip, with oxygen at approximately 30 to 40 PSI and acetylene at 5 to 7 PSI. The preheat cones should fully penetrate the top surface before you pull the cutting oxygen lever. Too little preheat and the cut stalls; too much and you overheat the kerf, producing dross that sticks.
For 1/8 in sheet under the same setup, a #000 tip at lower oxygen pressure prevents blowing through — the smaller orifice reduces gas volume and cut speed to match the thin material.
Safety checklist before lighting
- Inspect hoses and fittings for cracks, oil, or damage
- Open cylinder valves slowly and away from ignition sources
- Purge each hose briefly before connecting to the torch
- Set pressures with gas flowing (not static) to account for hose drop
- Have a striker ready — never use an open flame lighter
- Keep the working area clear of flammables
- Know where the cylinder shut-off is before you start