Oxy-Acetylene Welding Tip Size Chart: Sizes and Pressures

A hobbyist spends an hour trying to weld two pieces of eighth-inch steel with a tip that is a size too small, watching the puddle crawl, the base metal glow, and the edges curl. A retired pipefitter picks up the same torch, spins on a different tip, resets both regulators, and lays a clean bead in under two minutes. The only thing that changed was the number stamped on a small copper nozzle, and that number is where most oxy-acetylene frustration begins.

Why Tip Size Decides Whether Oxy-Acetylene Welding Works

A hobbyist clamps two pieces of eighth-inch steel to the bench, strikes the flame, and settles in for a long fight. The puddle crawls. The base metal glows dull orange an inch from the joint, and the edges start to curl. An hour later the bead still looks like a row of grey slugs. A retired pipefitter picks up the same torch, spins on a different tip, resets both regulators, and lays a clean bead in under two minutes.

The only thing that changed was the number stamped on a small copper nozzle. That number is where most oxy-acetylene frustration begins, and understanding it is the fastest way out.

Here is the short answer: the number on an oxy-acetylene welding nozzle corresponds to a specific orifice diameter at the tip, and that orifice controls how much gas, and therefore how much heat, reaches the work. Every manufacturer publishes a chart pairing each tip number with a recommended metal thickness range and matching oxygen and acetylene pressures. That chart is the single most useful reference a gas welder owns.

Oxy-acetylene welding (OAW) joins metals by melting them with a flame produced by burning acetylene in pure oxygen. It is one of the oldest arc-free processes still in daily industrial use, and it remains uniquely versatile because the same torch can weld, braze, heat, and cut. Acetylene is the only fuel gas the American Welding Society treats as genuinely suitable for gas welding of steel in AWS C4.7/C4.7M:2020. Propane, propylene, and natural gas get used for cutting and heating, but not for welding steel.

What the tip number actually tells you

A Victor-style size 2 nozzle is rated for roughly 1/16 in. to 1/8 in. (1.6 to 3.2 mm) steel. A size 000 covers material up to about 1/32 in. (0.8 mm). Between those extremes sits a whole family of sizes — 00, 0, 1, 3, 4, 5 and beyond — each with its own orifice and its own comfortable thickness window.

The number is a capacity label, not a measurement. You cannot check it with calipers, because the outer copper shell is often identical across several sizes. What changes is the drilled hole inside, and the drill size used to make it usually appears on the chart right beside the thickness range.

The two tip families you will meet

• One-piece swaged nozzles. Tip and mixer are a single copper unit that screws onto the torch handle. Cheap, common in hobby kits, and replaced whole when the orifice wears.
• Two-piece tip-on-mixer designs. A separate mixer body stays on the torch and the nozzle screws onto it. Common on professional Victor, Harris, and Smith torches. The seat between the parts is a precision surface, and a damaged seat causes as many problems as a blocked orifice.

A tip only performs to its rated capacity if gas reaches it at the right pressure and ratio. A nozzle that looks fine but has a nicked seat will pop, sputter, or run a ragged flame no matter what the chart says.

Heat input, not flame size, controls the weld

Beginners judge a flame by how big and dramatic it looks. What governs weld quality is heat input: the mix of flame energy, cone-to-work distance, travel speed, and how long the torch lingers. A big soft flame held far away can put less usable heat into a joint than a small sharp flame held close. A neutral oxy-acetylene flame reaches roughly 6,300 °F (3,480 °C) at the inner cone tip, far above the melting point of mild steel. Tip size sets the ceiling on that heat; your technique decides how much of it the joint actually receives.

Welding tips are not cutting tips

This trips up almost every beginner. Welding tips have a single orifice and produce a soft, bushy flame meant to melt and fuse metal. Cutting tips have a central oxygen jet ringed by preheat holes, are sized by how thick a plate they can sever, and run oxygen pressures several times higher. Screwing a cutting tip onto a welding torch and expecting a weld wastes gas and is a good way to ruin a plate. This article deals only with welding tips. If you also run a small air-fuel torch for brazing, the principles overlap but the pressures do not; our guide to air acetylene welding torch basics covers that separate family.

What this article gives you

Over the next sections you will learn how tip numbers are assigned, how to read a full chart line by line, how to match a tip to joint geometry rather than thickness alone, how to set pressures and tune a neutral flame, and how to read the puddle when the chart is only approximately right. We also cover the costliest mistakes, a symptom-to-cause troubleshooting guide for backfires and bad beads, the cylinder and hose limits that override any chart, and how to build a sensible tip kit without buying twelve nozzles you never use.

One caution up front: charts assume healthy equipment, short hoses, and clean tips. Add fifty feet of undersized hose, a clogged flashback arrestor, or a worn seat, and the numbers on the page stop matching what happens at the work. The chart tells you where to start. The puddle tells you whether you got it right.

How Oxy-Acetylene Tip Sizes Are Actually Numbered

Flip a welding nozzle over and you will usually find a single digit, or maybe two, stamped into the copper. That number is not a measurement in inches, and it is not the diameter of the hole you can see. It is a capacity label, a shorthand that tells you how much gas the tip can pass and, by extension, how much heat it can put into the work. Once you understand the logic behind that label, the chart in the next section stops looking like a random grid and starts making sense.

The numbering sequence runs from 000 to 12

Most North American oxy-acetylene charts use the same basic sequence: 000, 00, 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, and 12. The zeroes multiply downward, so a 000 tip is the smallest in the family and a 12 is the largest. From size 1 upward, the number increases with orifice size and gas capacity. There is no size 9 or 11 on the standard sequence, which surprises people who assume the chart is a simple count.

The drill-size column is where the numbering becomes concrete. Victor’s published nozzle data uses standard drill gauges to identify each orifice, and the gauge number moves in the opposite direction from the tip number.

Tip size	Drill gauge	Orifice diameter
000	75	0.022 in.
2	56	0.046 in.
4	49	0.073 in.
12	25	0.149 in.

A 75 drill is a tiny wire-gauge drill, while a 25 drill is much larger. That inverse relationship trips up beginners. The drill column exists for manufacturing and for choosing the right tip cleaner. It is not a suggestion to drill anything out.

The orifice, not the copper shell, controls the gas

Two nozzles can look nearly identical from the outside and behave completely differently because the drilled orifice is the real metering point. A larger hole passes more gas at the same regulator setting, which produces a larger flame and a hotter, wider puddle. A damaged or partially blocked orifice changes that flow even if the stamped number says otherwise. This is why a tip that has been reamed with the wrong wire, or dropped on its face, can act like a different size entirely.

Flow also explains why big tips demand more than a bigger regulator number. Victor’s data shows oxygen consumption running roughly 1.1 times acetylene consumption under neutral flame conditions, so a tip sized for a heavy plate pulls a substantial volume of both gases. Victor lists its size 12 nozzle for the HD310C torch handle and 3/8 in. hose, not the 1/4 in. hose used by small tips. A large nozzle on a light handle or a restrictive hose is a capacity mismatch, not a tuning problem.

Why a Victor size 3 is not a Harris size 3

Victor states that orifice sizes are common across its W, W-1, and W-J nozzle series. That shared orifice makes it easier to move between nozzle types without relearning a whole new size scale. The series still differ in duty rating and construction, so the same number may not be appropriate for the same workload on every handle. Check the handle rating, not just the number on the tip.

Other manufacturers use their own numbering systems. Harris, Smith, Oxweld, ESAB, and the generic import sets sold online do not all follow the Victor sequence. A size 3 from one brand may sit close to a size 2 or a size 4 from another, and the only reliable answer is that brand’s own chart. Metric nozzles add another layer because they are often marked in millimeters or with a metric series code rather than a North American number. Never assume that a “1” is a “1” across brands.

One-piece, two-piece, and unmarked tips

One-piece swaged nozzles combine the tip and mixer in a single copper body. Two-piece tip-on-mixer designs screw a replaceable nozzle onto a separate mixer, which lets you change the tip without replacing the whole assembly. In either design, the seat and mixer condition matter. A nicked seat can leak, cause a popping flame, or make the torch behave as though the tip is the wrong size. The smallest nozzles, 000 and 00, often appear in thin-sheet work and light-duty air-acetylene welding setups, where a soft flame matters more than raw heat.

If a tip has no markings at all, do not pick a pressure by feel and hope. Compare the orifice with a known drill gauge, check the threads and seat against the torch manufacturer’s parts list, and use the correct chart for that brand. An unidentified tip is a temporary tool at best and a backfire risk at worst.

Finally, remember that a larger tip needs more gas volume, not more acetylene pressure. OSHA 1910.253 caps acetylene delivery at 15 psig, which is why no legitimate welding chart lists a higher acetylene setting. The number stamped on the nozzle tells you what the torch can consume. The regulator and hose have to be able to supply it safely. For the office values behind these flow figures, Victor’s welding nozzle data is the reference to keep nearby.

The Oxy-Acetylene Welding Tip Size Chart, Explained Line by Line

A tip chart looks like a spreadsheet that got out of hand. Six columns, thirteen rows, numbers with slashes and decimal points, and a drill gauge column that seems to belong to a different hobby entirely. But it is not complicated once you know what each column is telling you. Every row answers one question: for this thickness of steel, which nozzle do I spin on, and what do I set the regulators to?

The table below is a condensed working chart built from Victor’s published welding nozzle data and standard shop practice. Your own brand’s sheet always wins if it disagrees, but this is the shape of the information you are working with.

The Working Chart

Tip Size	Metal Thickness (in.)	Metal Thickness (mm)	Orifice Drill	Oxygen (psig)	Acetylene (psig)	Acetylene Use (SCFH)
000	up to 1/32	up to 0.8	75	2–4	2–4	1–2
00	1/64–1/32	0.4–0.8	70	2–4	2–4	2–3
0	1/32–1/16	0.8–1.6	65	2–4	2–4	3–5
1	1/16–3/32	1.6–2.4	60	3–5	3–5	5–8
2	3/32–1/8	2.4–3.2	56	3–5	3–5	6–10
3	1/8–3/16	3.2–4.8	53	4–7	3–6	8–18
4	3/16–1/4	4.8–6.4	49	5–8	4–7	12–25
5	1/4–3/8	6.4–9.5	43	6–10	5–8	18–30
6	1/2–3/4	12.7–19	36	7–14	6–9	25–45

Reading Four Rows Out Loud

Tip 1 is the sheet metal workhorse. It covers 1/16 in. to 3/32 in. steel (1.6 to 2.4 mm) through a size 60 drill orifice, with 3 to 5 psig on both regulators and an acetylene draw of 5 to 8 SCFH. If you are welding car body panels or thin angle iron, this is home base.

Tip 3 is where most garage projects land. Victor lists it for 1/8 in. to 3/16 in. steel with 4–7 psig oxygen and 3–6 psig acetylene, burning 8–18 SCFH of acetylene. Notice the acetylene range is wide. That spread is not sloppiness, it is headroom for joint type and travel speed.

Tip 4 picks up at 3/16 in. and runs to 1/4 in., pushing 5–8 psig oxygen and 12–25 SCFH of acetylene. Past this point you are heating a lot of metal, and the torch starts to feel less like a welding tool and more like a small furnace.

Tip 6 handles 1/2 in. to 3/4 in. steel at 7–14 psig oxygen and 6–9 psig acetylene, consuming 25–45 SCFH. That consumption number matters more than the pressure number, because it tells you whether your cylinder and hose can actually feed the tip. You can see the full published table in Victor’s welding and heating nozzle guide.

Why the Thickness Ranges Overlap

Look closely and you will find that adjacent tips share territory. A size 1 and a size 2 can both claim 1/16 in. That is deliberate. The chart does not know whether you are running a butt weld on fresh sheet or a fillet on a heat-sinking chunk of angle iron, so it gives you a window instead of a point.

How to choose inside the overlap:

• Go smaller for thin sheet, tight fit-up, vertical or overhead position, and joints backed by copper or a heat sink.
• Go larger for thick sections, poor fit-up with a gap to fill, heavy tacks, and flat-position work where speed matters.
• Start in the middle of the listed range and adjust by feel once the puddle tells you something.

Welding Nozzle Chart vs. Cutting Tip Chart

These are two different documents and beginners mix them up constantly. A welding nozzle is sized by the thickness it can fuse. A cutting tip is sized by the thickness it can sever, and it runs oxygen pressures that would destroy a welding nozzle. On Victor’s cutting chart, a 000 tip is listed for roughly 1/16 in. to 1/8 in. material, which has nothing to do with a 000 welding nozzle. The reference is available in this Victor oxy-fuel cut chart. If you also run a small air-acetylene torch for brazing, those tips follow yet another scale, which our air acetylene welding guide covers separately.

A Worked Example: 1/8 in. Lap Joint on Mild Steel

Two pieces of 1/8 in. hot-rolled plate, lapped about 3/8 in., welded flat on the bench. Thickness says tip 2 or tip 3. The lap joint doubles the heat sink, so the larger of the two is the safer starting point: tip 2 at the top of its range, or tip 3 at the bottom.

1. Spin on the tip, check the nut is snug but not gorilla-tight.
2. Set oxygen to 3–5 psig and acetylene to 3–5 psig with the torch valves open, then close them.
3. Light the acetylene, add oxygen, and tune to a neutral flame with a short, sharp inner cone.
4. Test on a scrap offcut. If the puddle forms in three or four seconds and wets both edges, you are right. If it crawls, go up one size.

That is the whole method. Read the row, pick your starting point, then let the puddle overrule the paper.

Matching Tip Size to Joint Type, Not Just Metal Thickness

Put three pieces of 1/8 in. mild steel on the table: a square butt joint, a lap joint, and a fillet on a length of angle. The chart gives all three the same starting row, yet they will not weld the same with the same tip. The butt has two thin edges in open air, the lap has twice the metal under the puddle, and the angle acts like a heat sink bolted to the bench.

That is why the chart is a lookup, not a decision. The decision comes from looking at the joint.

Why One Thickness Can Need Different Tips

Oxy-acetylene welding covers wide ground. AWS C4.7/C4.7M:2020 lists steel pipe and tubing, sheet metal, and small structural shapes and bars. A 1/8 in. tube wall, a 1/8 in. sheet panel, and a 1/8 in. bar read the same on a gauge but present different heat paths.

Three things matter more than that number:

• Mass under the puddle. A lap joint puts two layers in the heat path; a fillet on heavy angle pulls heat into a thick leg.
• Access to the root. A tight butt lets the flame reach both edges; a fillet hides the root behind one plate.
• Gravity and position. A puddle that behaves flat can run once the work turns vertical.

Joint (1/8 in. steel)	What the heat sees	First move
Square butt, tight fit	Thin edges melt fast	Start mid-range; watch keyholing
Lap joint	Two layers wick heat from the top sheet	Same tip, slower travel
Fillet on angle	Heavy leg is a heat sink	Size up one step if the puddle stays lazy
Vertical or overhead	Gravity limits puddle control	Drop one size from the flat setting

Edge Preparation Changes the Effective Thickness

A chart row also misleads when the edges are beveled. Victor’s nozzle guide specifies that base metals 1/8 in. (3.2 mm) or less generally need no bevel, while thicker material takes single-V or double-V preparation. Up to about 1/8 in., a square butt with a tight gap is enough. Above it, the flame cannot reach the bottom of a square edge without blowing a hole through the top.

A single-V butt joint on 1/4 in. and thicker plate is commonly cut with a 60-degree included angle and a root face. The bevel lets flame and filler reach the root, while the root face keeps a controlled amount of metal at the bottom. That trims the volume of metal to melt at the root. The plate is not thinner overall, but the heat demand where the weld starts changes.

That is why a beveled 1/4 in. joint often welds better with a tip sized for 3/16 in. than with the full 1/4 in. tip: the open root is easier to penetrate, and a smaller flame controls the bevel faces without overheating them. Read the chart for the thickest section, then drop a step when the prep opens the root.

Tacks, Backing, Heat Sinks, and Position

Tack welds change the starting condition. Four solid tacks hold the gap and drain heat at each one, so the first inch may want a slightly larger tip or a gentle preheat. Sloppy tacks that close the gap do the opposite: the edges touch, the flame cannot penetrate, and the weld sits on top.

Copper backing bars are another variable. Copper drains heat from the root, which helps prevent melt-through on thin sheet but can leave the weld cold if the tip is already small. A heavy steel table, a pipe clamp, or any fixture touching the joint does the same. Clamped to a big heat sink? Start one size up or preheat gently.

Position is the simplest correction. Flat work lets you use the chart setting. Vertical and overhead work need a smaller puddle that freezes faster, so drop one tip size and keep the cone close.

A Simple Decision Sequence

1. Measure the thickest part of the joint, not the neatest edge.
2. Identify the joint type and count how many layers sit under the puddle.
3. Check the fit-up gap. Tight gaps need less heat; open gaps need more filler and often less flame.
4. Pick the middle of the chart range for that thickness, then adjust for bevel, backing, or position.
5. Test on scrap from the same material. A tip 4 can consume up to 25 SCFH while a tip 2 runs about 5 to 10 SCFH, so one step is a real jump in heat input.

Thin sheet under about 1/32 in. deserves its own approach. A 000 or 00 tip with a soft, neutral flame beats fighting a larger tip at low pressure, and many thin joints are better brazed than fusion welded. The same logic drives thin aluminum, where fit-up and heat sinks dominate; our guide to aluminum boat welding shows those choices on real hulls.

Use the chart for a starting point, then let the joint confirm it. The next section turns those numbers into regulator settings and a neutral flame.

Setting Regulator Pressures and the Neutral Flame for Your Tip

You have the chart open and the tip matched to the metal. Now comes the step that trips up more beginners than any other: turning those two numbers into a working flame. A chart entry reading “3–5 psig oxygen, 3–5 psig acetylene” is not something you can eyeball. It is the start of a sequence that has to run in the right order, with the right checks, or the best tip in your box will still run a bad bead.

Static vs. Dynamic Pressure: The Reading That Matters

A regulator gauge measures pressure, not flow. With the torch valve closed, it shows static pressure — gas sitting in the line with nowhere to go. Open the valve and the gauge drops to dynamic pressure, the pressure actually available at the tip while the torch is running.

That gap explains why “set it and forget it” with the valve closed gives you a flame that runs cold. Set 5 psig acetylene with the torch shut off and you may only have 2 or 3 psig feeding the tip once gas starts moving. Chart numbers assume a working flow, so set your pressures with the torch valve open and the flame lit, then re-check after a minute of running.

The Setup Sequence, Step by Step

1. Crack the cylinder valves. Open the acetylene valve no more than one and a half turns, and preferably no more than three-quarters of a turn, as required by OSHA 1910.253(b)(5)(iii)(K) — the limit lets you shut the fuel off fast in an emergency. Open the oxygen valve fully.
2. Back the regulator screws out before opening the cylinders so no pressure spike hits the diaphragms.
3. Set acetylene first. Open the torch acetylene valve, adjust to the chart value, then close the valve.
4. Light the acetylene. A small, soft, yellow, smoky flame is correct here. Hold the striker at the tip, not over it.
5. Add oxygen slowly until the yellow disappears and the cone forms.
6. Adjust to neutral and re-check both gauges with the flame burning.

Order matters. Oxygen first and then fuel gives a flame that is hard to read and easy to over-pressurize. Acetylene first, oxygen second, is what every instructor teaches and every manufacturer’s manual repeats.

Reading the Three Flame Types

Flame Type	What You See	What It Does
Carburizing	Feathery secondary cone beyond the inner cone, slightly bushy	Excess acetylene; adds carbon to the weld. Generally too cold and dirty for mild steel.
Neutral	Sharply defined inner cone, no feather; clean, steady, quiet	The correct flame for most mild steel welding.
Oxidizing	Shorter, hissing cone with a pointed, aggressive look	Excess oxygen; causes porosity, black specks, and burned edges on steel.

That inner cone is your reference. Adjust until the feather just disappears — that is neutral, and it is where you stay for most mild steel work with a correctly sized tip. Flame type also interacts with tip size: a tip too large for the metal often needs a slightly reducing flame to avoid melting through, which is a sign you picked the wrong tip, not that you need a new technique. If you are constantly fighting to keep the flame soft, size down.

The OSHA 15 psig Limit (and Why Your Chart Stops There)

No legitimate oxy-acetylene chart lists acetylene above 15 psig, and that is not a rounding choice. OSHA 29 CFR 1910.253(a)(2) prohibits acetylene from being generated, piped, or used above 15 psig (103 kPa) or 30 psia. Above that threshold the gas becomes unstable and can decompose violently, so the cap is a hard physical safety limit.

Victor’s chart keeps every acetylene range at or below 15 psig, with the largest tips at 12–15 psig. A chart recommending 20 psig acetylene for a big tip is wrong and dangerous. If a tip needs more acetylene than 15 psig can deliver, the answer is a different tip or a different process — never a higher regulator setting.

Signs Your Pressure Is Wrong

• The flame snaps off the tip. Usually too much oxygen pressure, or a tip that is loose or partly blocked.
• The inner cone keeps growing. Regulator creep, a failing seat, or a cylinder running down.
• The tip roars. Excess pressure for the orifice size — gas is being forced through faster than the tip was designed for.
• The puddle will not form. Not enough heat, often because dynamic pressure sits below the chart value.

If the pressures check out and the flame still misbehaves, suspect the tip before the regulators. A dirty or damaged orifice, or a leaking tip seat, mimics a pressure fault every time. Clean or replace the tip before you start turning screws.

Hose Size and Line Loss

Chart numbers assume a normal hose run. A 25-foot 1/4-inch hose behaves very differently from a 50-foot run with a flashback arrestor at each end and a small-bore fitting in the middle. Each restriction adds pressure drop, so the regulator has to work harder to deliver the same flow at the tip.

If the flame looks weak at chart settings, raise the regulator slightly and watch the flame, not the gauge. But if you are pushing well past the chart to get a usable flame, stop — your hose is too small or too long for the tip, and the fix is hardware, not pressure. The same principle carries across processes, as these guides on air acetylene welding torch basics and safety show in a lighter-duty system.

One last habit: check working pressures every time you change a cylinder or switch tips. Settings drift, and a five-second gauge check before you light saves a ruined joint.

Reading the Puddle: When to Size Up or Down From the Chart

The chart gets you into the right neighborhood; the puddle gives you the exact address. Every experienced gas welder runs the same feedback loop: pick a tip from the chart, light a neutral flame, touch the cone to the work, then read the first few seconds of the pool. If the signals look wrong, you change one thing — usually tip size — and try again. That loop, repeated honestly, is most of the skill.

What a Correctly Sized Tip Looks Like

A properly sized tip brings the joint to a fluid puddle within a few seconds of applying the inner cone. Not a minute, and not thirty seconds of hovering while the metal slowly reddens. If you are standing there waiting, the tip is too small or the flow is too low.

Watch for four things in a well-matched setup:

• The pool forms quickly and spreads evenly across the joint faces.
• It wets both edges instead of balling up and sitting on top of the metal.
• It stays bright and fluid without bubbling, hissing, or throwing sparks.
• The heat-affected zone stays tight — roughly a quarter inch of discoloration either side of the seam, not three inches.

When all four are true, travel speed finds a natural rhythm. You move, the puddle follows, the filler dips in and flows out. Nothing feels forced.

Too-Small Tip Symptoms

An undersized tip is the most common beginner error because it feels safe. It is not. It wastes gas, warps the part, and produces welds that look joined but are not.

Signs you need to size up:

• Slow, pasty puddle. The pool takes forever to form and never turns shiny and liquid.
• Wandering heat. You chase the seam like a stick electrode, because the heat is too concentrated and too shallow to open the joint.
• Cold lap. Filler sits on the surface and rolls off the edge instead of fusing into the parent metal.
• The urge to linger. You hold the torch in one spot longer than feels right.
• Discoloration creeping away from the joint. Broad blue and straw bands mean you are soaking the plate trying to get local heat.

One size up usually fixes it. Jumping two sizes at once is a mistake, because it multiplies gas use fast. Increasing tip size raises both heat output and acetylene consumption, and on the Victor chart moving up two sizes can multiply gas use several times over. A size 2 burning a few SCFH becomes a size 4 burning well over ten, plus a much larger oxygen draw.

Too-Large Tip Symptoms

The oversize tip announces itself immediately, and it is harder to recover from because the metal is already damaged.

• Instant melt-through. The pool appears and drops out before you can add filler.
• A keyhole that will not close. On thin sheet the hole opens and keeps opening no matter how fast you move.
• Excessive spatter and sparks. The metal is boiling, not melting.
• Burned, ragged edges and heavy distortion, especially on long seams.

Drop one size and slow down slightly. If you are on the smallest tip you own and still burning through 22-gauge sheet, the problem is technique — most often cone distance — rather than tip selection.

The Three Variables That Interact With Tip Size

Travel speed, torch angle, and cone distance all trade against tip size. Change one and the others must follow.

Variable	Effect	Adjustment
Travel speed	Faster travel reduces heat per inch	Speed up before sizing down on thin metal
Torch angle	Steeper angle concentrates heat; trailing angle spreads it	Use 60–70° lead for penetration, flatter for sheet
Cone distance	Closer cone = hotter, narrower spot	Lift slightly to widen and cool the pool

This is why a welder can sometimes make a slightly oversized tip work on thin sheet by speeding up and lifting the cone a touch. That is a correction, not a substitute for the right tip.

Three Real Scenarios

1. 1/16 in. mild steel lap joint, tip 1. The puddle forms, but the lap edges barely fuse and you keep stopping to let heat build. Correction: step to tip 2, keep the neutral flame, and move at a steady pace. The pool wets both sheets within three seconds.

2. 1/4 in. plate, single-V butt, tip 5. The root opens and drops through before you can keyhole it. Correction: drop to tip 4, feather the flame slightly off neutral, and work the root with a short arc-like motion. The bevel reduces effective thickness at the root, so the chart’s 1/4 in. entry was optimistic.

3. 3/16 in. angle iron fillet, tip 3. The vertical leg undercuts while the flat leg sits cold. Correction: this is usually angle, not size — flatten the torch and let the puddle wash up the vertical leg. Resize only if the pool still refuses to wet both faces.

Different Metals, Different Rules

These cues are written for carbon steel. Aluminum conducts heat away so fast that it needs a larger tip than thickness alone suggests, and the oxide skin hides the puddle until it suddenly collapses — which is why pre-cleaning with a dedicated aluminum cleaner for welding matters as much as tip choice. Cast iron is welded hot and slow with a slightly reducing flame and preheat. Brazing runs lower acetylene pressures and a softer flame, and the puddle you watch is filler, not parent metal.

One more limit worth knowing: OAW is generally not recommended for high-strength heat-treatable steels, and AWS C4.7/C4.7M:2020 reflects the industry position that gas welding is no longer accepted for automotive collision repair by ICAR. No tip size fixes that.

The chart is the starting point. The puddle is the final authority — and it will tell you the truth every single time if you know what to look for.

The Most Common Tip Size Mistakes (and How to Avoid Them)

Almost every “bad torch” complaint traces back to a tip decision, not a broken regulator. The good news is that these mistakes repeat in predictable patterns, which means they’re easy to spot once you know what to look for. Here are the ones that show up again and again in hobby shops and production floors, each paired with a fix you can apply today.

• Buying one tip and forcing it to do every job. A single mid-range nozzle will half-work on thin sheet and stall on quarter-inch plate, so the operator compensates by lingering, which overheats the head and distorts the part. Fix: build a small range covering the thickness you actually weld, and swap tips instead of fighting the flame.
• Assuming a size 3 is a size 3 everywhere. Harris, Smith, Oxweld, ESAB and import sets number their nozzles on different scales, and Victor’s W, W-1 and W-J series share orifice sizes but differ in duty rating. Fix: look up the chart for the exact brand and series stamped on your mixer, never a generic chart.
• Using a cutting tip or heating nozzle for welding. Cutting tips are sized for cut thickness and run far higher oxygen pressures; a rosebud heating nozzle floods the joint with heat. Neither produces a controlled weld puddle. Fix: match the accessory to the operation — if you’re unsure which torch body you have, start with a look at air-acetylene torch basics before buying anything.
• Running a big tip on a small handle or 1/4 in. hose. Victor warns that a tip with too much capacity for the torch can starve or choke the tip, causing the head to overheat and a backfire to occur. Fix: respect the handle’s rated capacity and step up hose size before you step up tip size. Details are in Victor’s nozzle and tip guide.
• Setting pressures from memory. Two identical tips can want different regulator settings once hose length, fittings and flashback arrestors enter the picture. Fix: set from the chart every time, with the torch valve open, then re-check after lighting.
• Ignoring the 1/7 acetylene withdrawal rule. Pulling more than about one-seventh of a cylinder’s contents per hour pulls acetone into the hose, chills the cylinder and starves the flame. Larger flows need a manifold or vaporizer. Fix: size the tip to the cylinder, not the other way around — see OSHA 1910.253.
• Cleaning the orifice with whatever wire is handy. A too-large wire or a drill bit reams the hole oversize and ruins the flow characteristics permanently. Note: 29 CFR 1910.253 requires clogged tip openings to be cleaned with suitable cleaning wires or drills designed for that purpose, not by enlarging the orifice. Fix: use the correct tip cleaner size and ream gently from the tip end.
• Over-tightening the nozzle. Cranking a tip nut crushes the seat, and a damaged seat leaks, pops and eventually backfires. Fix: snug by hand with a proper wrench, and inspect the seat whenever the flame misbehaves.
• Mixing oxygen and fuel hoses, or letting grease near oxygen fittings. The standard requires oxygen regulator gauges to be marked USE NO OIL, and cylinders, valves, regulators and hoses kept free of oil and grease. Fix: dedicate hoses by color and thread, and never handle oxygen fittings with greasy gloves.
• Never leak-testing. A slow leak at the tip nut or hose connection is invisible until it flashes. Fix: brush soap solution on every joint at the start of each session and watch for growing bubbles.
• Reading the chart against the wrong thickness. Measure the parent sheet, not the bevel face or the weld prep. And remember that two pieces of 1/16 in. sheet in a lap joint present 1/8 in. of heat sink, because the lower plate pulls heat out of the puddle too. Fix: add the material the heat actually has to travel through before you pick a number.

None of these fixes are expensive. Most cost nothing more than a moment of checking before you strike the sparkler, which is a bargain compared with a warped panel or a scorched regulator.

Troubleshooting Tip-Related Problems: Backfires, Popping, and Bad Beads

Most gas welding trouble announces itself at the tip before it ever shows up in the weld. A pop, a snap, a flame that suddenly shrinks, a bead that looks scorched on one edge and cold on the other: each sound and each defect points to a short list of causes. Learn to read them and you stop guessing at the torch and start fixing the actual problem.

Backfire vs. Flashback: Know the Difference

A backfire is a momentary pop or flash at the tip, and the flame usually relights or goes out briefly. A flashback is far more serious: the flame travels backward into the hose or the regulator. Both demand the same immediate response. Shut the torch valves first, then the cylinder valves, and let everything cool before you touch it. Never relight a hot tip.

• Dirty or damaged orifice: soot, spatter, or a bell-mouthed opening disturbs gas flow. Clean or replace the tip.
• Loose tip nut: gas leaks at the seat and ignites unevenly. Snug it, do not gorilla it.
• Wrong pressures: too low lets the flame crawl back into the mixer. Reset from the chart.
• Overheated head: a tip run past its duty cycle gets hot enough to pre-ignite the mixture. Cool it in water, dry it fully, and step down a size.
• Empty cylinder or contaminated hose: a starving acetylene supply or oil in the line can both trigger a flashback.

Flashback arrestors and check valves are not optional accessories. OSHA 1910.253(e)(3)(ii)(C)(3) requires approved flashback protection that prevents flame from passing into the fuel-gas system.

Popping and Snapping

A rhythmic pop with the flame jumping off the tip usually means the tip is partially blocked or the seat is leaking. Ream the orifice with the correct cleaner size, then check that the tip nut seats squarely. If the torch pops only at high settings, the tip is too large for the handle, or the pressure is set too low for that orifice. A two-piece tip with a scored or dirty mixer seat behaves the same way, so pull the tip and look at the mating surface before blaming the regulators. Air-acetylene setups show identical symptoms, which our guide to air acetylene welding torch basics, brazing and safety covers in more detail.

Porosity and Black Specks in the Weld

Black flecks and pinholes are a chemistry problem, not a technique problem. An oxidizing flame is the usual culprit, so add a touch more acetylene until the inner cone loses its feather. Dirty base metal comes second: mill scale, oil, paint, and galvanizing all boil into the puddle. Wrong filler wire and moisture on the rod or in the hose round out the list. Clean to bright metal, use the filler the job calls for, and drain any water traps in the line.

Uneven Bead Width and Undercut

If the bead wanders wide and narrow, look at travel angle and speed before you look at the tip. A consistent 60 to 70 degree push angle with steady movement fixes most of it. Undercut along one edge usually means the tip is a size too large, or the torch lingered while the puddle overheated. Drop one size, move faster, and watch the puddle wet both edges evenly.

A Flame That Keeps Going Out

Check the acetylene cylinder first. As pressure falls near empty, the flame weakens and dies. If the cylinder is fine, suspect regulator creep: gauge pressure climbing with the valve closed means a rebuild is due. A stuck check valve or a kinked hose produces the same intermittent outage. Our AllGas welding supply guide to gases and safety explains what a healthy cylinder swap should look like.

Tip Maintenance That Prevents a Repeat

• Ream only with a tip cleaner matched to the orifice. A drill bit removes metal and ruins the size.
• Inspect the seat for scratches and the orifice for cracks or a bell-mouthed shape.
• Store tips in a dry box with the caps on, away from grit and moisture.
• Retire any tip with a cracked, oval, or flared opening. No amount of cleaning brings it back.

Note: When a symptom survives a clean tip, fresh pressures, and a neutral flame, stop welding and inspect the whole torch. Chasing a bad bead with a damaged tip only adds heat, distortion, and risk.

Cylinder, Hose, and Safety Limits That Override Any Chart

A tip size chart tells you what the torch can do. Your cylinders, hoses, and the rules around them decide what you’re allowed to do. Ignore those limits and even a perfectly matched tip will sputter, overheat, or create a genuine hazard. This is the part of gas welding where “close enough” is not worth keeping.

The Two Numbers You Should Never Argue With

Acetylene is unstable above roughly 15 psig. That is why OSHA 1910.253(a)(2) caps acetylene use at 15 psig, and why no legitimate chart lists a higher working pressure for the fuel side. Free acetylene also has to come out slowly. The long-standing 1/7 rule limits withdrawal to one-seventh of the cylinder’s capacity per hour, so a 100 cu ft cylinder should not feed more than about 14 SCFH continuously. Pull harder and you drag acetone into the hose, the flame goes ragged, and the cylinder chills and loses pressure.

That single rule explains a lot of “my torch keeps dying” complaints. If your tip needs more acetylene than the cylinder can safely deliver, the answer is a manifold or a bigger cylinder, not a higher regulator setting.

Hoses, Flashback Arrestors, and Check Valves

Hose bore has to match the demand. A 3/16 in. hose is fine for jewelry work and thin sheet, 1/4 in. is the common general-purpose size, and 5/16 in. or larger belongs on heavy work and long runs. Undersized hose on a big tip gives you a soft, starved flame no matter what the gauge says. Keep hoses as short as the job allows, protect them from sparks and traffic, and never substitute one gas for another. Oxygen hose is green, fuel hose is red, and the fittings are deliberately different.

Flashback arrestors at the regulator and check valves at the torch are cheap insurance against a flame traveling back up the line. They do add a small pressure drop, which is one more reason to set pressures with everything connected rather than guessing from a chart. Crack cylinder valves open slowly, and never open an acetylene valve more than about one and a half turns so you can shut it fast in an emergency.

Fumes, PPE, and the Metal in Front of You

OAW is not a low-fume process. Galvanized steel releases zinc oxide fume that can cause metal fume fever. Painted, oily, or dirty plate puts who-knows-what into your breathing zone. Work outdoors or under local exhaust, and grind or strip coatings back from the joint before you light up. The NIOSH welding safety checklist is a solid backstop: confirm acetylene stays under 15 psig and that every piece of apparatus is approved for its intended use.

For eye protection, shaded goggles or a helmet with the correct filter matter more as the tip grows. Small tips on thin sheet sit around shade 3 to 4; heavier work with a size 4 or 5 tip pushes you toward shade 5 or 6. Add leather gloves, sleeves, and FR clothing. Cotton is better than synthetic, which melts into skin.

Cylinder Handling and Storage

Secure cylinders upright with a chain or strap, valve caps on when moving, and never lift one by the valve. Store oxygen and fuel gas at least 20 ft apart, or separate them with a noncombustible barrier at least 5 ft high with a half-hour fire rating, as required by OSHA 1910.253(b)(4)(iii). Keep grease, oil, and oily rags away from oxygen fittings. Oxygen plus hydrocarbon is a fire waiting for an excuse.

If you also run a small air-acetylene torch for brazing, remember it follows the same fuel rules with even tighter limits. For the full consensus standard behind these numbers, see ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes, referenced in AWS C4.7/C4.7M.

Pre-Light Safety Checklist

• Cylinders upright, secured, and separated correctly
• Hoses inspected for cracks, burns, and leaks (soap solution, never a flame)
• Flashback arrestors and check valves fitted and in date
• Acetylene setting at or below 15 psig; withdrawal within 1/7 of capacity
• Ventilation adequate for the coating and base metal
• Goggles, gloves, sleeves, and FR clothing on
• Grease-free oxygen fittings; no oil on gloves or rags
• Fire extinguisher within reach and area cleared of combustibles

ANSI Z49.1 and OSHA 1910.253 set the floor, not the ceiling. The manufacturer’s instructions for your specific torch, regulators, and arrestors govern the details. When a chart and a safety limit disagree, the safety limit wins every time.

Building a Practical Tip Kit and Putting the Chart to Work

After learning how to read pressures and the puddle itself, all of this information needs to be put into action. The goal isn’t to own every tip ever manufactured, it’s to build a kit that is tailored towards the work that will actually end up on your bench.

Picking Your Starter Kit

For the vast majority of hobbyists and light fabricators, less is more. A practical kit of 000 through 3 covers roughly 1/32 in. through 3/16 in. of steel on Victor-style charts, which matches most sheet metal and light fabrication work. As your projects grow, you can expand your collection based off of these guidelines:

• Sheet and light plate: Stick to 000, 00, 0, 1, 2, and 3 for the majority of your jobs.
• Mid plate: Add tips 4 and 5 if you find yourself regularly welding around 1/4 in. to 1/2 in.
• Heavy plate: Only purchase tips size 6 and up if your torch handle and hose can support them. As an example, Victor requires an HD310C handle and 3/8 in. hose for size 12 tips and larger. Throwing a massive tip onto an undersized torch will only lead to erratic flow and unnecessary strain onto your equipment.

Storage, Inspection, and Brand Compatibility

Your tips are precision orifices, not hammers. Due to this, they need to be treated as such. Keep them in a dry, labeled tip holder, inspect the orifice and seat before every use, and only ream them with the correct sized tip cleaner.

Most importantly, two brands should not be mixed on the same torch without checking seat geometry. A tip may thread on by hand, however, if the taper doesn’t match its mixer, it will never properly seal. With that being said, manufacturer manuals take precedence over generic charts because seat geometry, mixer design, and flow data differ between brands. When in doubt, trust the manual for your exact torch set.

Your Go-To Decision Flow

Instead of guessing at the bench, run through this process for every new joint. This is the exact workflow that experienced gas welders use to get a clean start every time:

1. Measure: Take the thickness of the parent metal at the joint, not the stacked height of a lap or the filler buildup.
2. Identify the joint: Take heat sinking into consideration. A fillet or lap joint will require more heat than a narrow butt joint of the same thickness.
3. Pick your tip from the chart: Select a tip from your chart that falls within the thickness range, opting for the middle if it’s on the border between two tips.
4. Set your pressures: Start with the chart’s recommended pressures, staying well within the confines of OSHA 1910.253 and your cylinder’s 15 psig acetylene limit.
5. Light and dial to a neutral flame: Crack your valves, set acetylene first, ignite, add oxygen, and adjust until you have a crisp inner cone with no feather.
6. Test on scrap: Always test a new tip and pressure setting on scrap of the same thickness before welding a finished part. This is the most skipped, yet most important step.
7. Adjust by puddle behavior: If the puddle is sluggish, size up ever so slightly. If it’s melting through instantly, size down and increase your travel speed. Let the puddle have the final say.

The Five Rules To Prevent Most Problems

• 1) Fit the flow: Match your tip to your torch handle and hose capacity. A tip is only as good as the setup feeding it.
• 2) Trust your source: Follow your brand’s manual over any generic chart. Every mixer is different for a reason.
• 3) Test, don’t assume: No matter how many times you’ve welded 1/8 in. steel, test any new tip before touching your finished piece.
• 4) Respect your limits: Obey the 1/7 acetylene withdrawal rule, the 15 psig cap, and all ventilation requirements. These override any number on a chart.
• 5) Fix by feel, not force: If your setup is fighting you, change one variable at a time, starting with your tip size, before turning your regulators up to extremes.

Conclusion

At the end of the day, the oxy-acetylene welding tip size chart is a starting point, and skill is the finishing tool. Buying a small, versatile kit, taking care of your tips, and running them through your tested workflow will take you farther than buying every tip that you can get your hands on. So before you commit to that real joint, take the extra minute to practice on scrap. It’s that one minute that separates a frustrating puddle, from a clean, solid bead.

Frequently Asked Questions

What tip size do I need for 1/8 inch steel?

On a Victor-style chart, 1/8 in. steel falls in the size 2 range (1/16 in. to 1/8 in.) and at the low end of the size 3 range (1/8 in. to 3/16 in.). For a butt joint on clean sheet, start with a size 2 at about 3-5 psig oxygen and 3-5 psig acetylene, then move to a 3 if the puddle forms too slowly or the joint has heavy heat sinking.

Does a bigger tip number always mean a bigger flame?

Within one manufacturer’s series, yes: higher numbers have larger orifices and higher flow capacity, so they produce a larger flame and more heat. Across brands, the numbering is not standardized, so a size 3 Harris tip is not necessarily equivalent to a size 3 Victor tip. Always use the chart published for your specific torch and nozzle series.

Can I use a cutting tip for welding?

No. Cutting tips are designed to deliver a central stream of cutting oxygen plus preheat flames, and they are sized by cut thickness rather than weld thickness. Using one for welding gives poor flame control, wrong heat distribution, and a much higher risk of damage to the work and the tip.

Why does my chart say 3-5 psig when my regulator gauge reads higher?

Regulator gauges show delivery pressure at the regulator, not flow at the tip, and readings change between static (torch valve closed) and dynamic (torch valve open) conditions. Long hoses, restrictive fittings, and flashback arrestors can also cause a pressure drop, which is why some manufacturers recommend slightly higher settings as tip size increases.

What is the 1/7 rule for acetylene cylinders?

Acetylene is dissolved in acetone in a porous cylinder mass, and withdrawing gas too fast pulls acetone out with it and can destabilize the cylinder. The rule of thumb is to draw no more than about one-seventh of the cylinder’s capacity per hour, so a 175 cubic foot cylinder supports roughly 25 SCFH, which is around the top of a size 4 tip’s range.

How do I know if my tip is worn out?

Look for a bell-mouthed, cracked, or chipped orifice, a damaged or scored seat, a tip that will not hold a stable flame at normal pressures, or a flame that keeps popping despite cleaning. Any of these means the tip should be replaced rather than reamed or forced back into service.

Can I weld thicker metal by simply turning up the pressure?

Only within the tip’s rated range. Raising pressure beyond the chart does not reliably increase heat output and often causes a harsh, unstable flame, excessive spatter, and overheating. If the metal is thicker than the tip’s range, move up a tip size and confirm your torch handle and hose are rated for the additional flow.

Do oxy-acetylene tip charts work for brazing and heating?

Not directly. Brazing and heating use different nozzles and different pressure settings, and heating tips are sized by heat output rather than weld thickness. Use the chart for the specific operation and nozzle type, and remember that brazing generally calls for a softer, slightly reducing flame rather than a neutral weld flame.