Oxy-acetylene hose is usually bought by the coil and specified in one line: “twin welding hose, 1/4 inch, red and green.” That line leaves out the questions that decide whether the hose is legal to use where it is going and whether it is safe with the gas it will carry: which fuel gas, which market’s colour code, and which connection on each end.
This guide walks through the decisions in order, and flags the mistakes that turn up most often on welding hose orders.
The five decisions, in order
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Name the fuel gas
Acetylene, propane, LPG and MAPP do not all place the same demands on the hose tube. The fuel gas decides the hose grade you need.
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Name the destination market
The market decides the colour code. Red and blue is not interchangeable with red and green.
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Choose the bore
The bore follows the torch, the work and the length of the run — not habit.
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Choose single lines or bonded twin hose, and the length
Twin hose keeps the pair together on the shop floor; single lines suit fixed manifolds and long runs.
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Specify the end fittings
Bare hose, or made up with connectors, check valves and flashback arrestors — and in which thread size.
Step 1 in detail: fuel gas and hose grade
In North American practice, oxy-fuel hose is graded by the fuel gas it can carry. Grade R hose is for acetylene only. Grade T hose is for all common fuel gases, including propane, LPG and MAPP, whose effect on some rubber compounds rules Grade R out. In Europe the equivalent requirements sit in EN ISO 3821, which also covers which gases a hose is suitable for.
A hose bought for acetylene and later put on propane or LPG may not be rated for it. If there is any chance a site will switch fuel gas, specify a hose rated for all fuel gases from the start, and tell us which gases it will see when you order.
Our hose uses an SBR and NBR tube compounded for acetylene, propane, LPG, MAPP and oxygen service, with a high-tensile PE braid. We build to the standard named on your order and supply the matching test evidence.
Step 2 in detail: welding hose colour codes by market
| Market | Oxygen | Acetylene / fuel gas | LPG, propane |
|---|---|---|---|
| Europe, Australia, NZ and most of Asia EN ISO 3821 | Blue | Red | Orange |
| North America CGA / ANSI Z49.1 practice | Green | Red | Red |
The red line is the same in both systems; the oxygen line is not. That is why twin hose is made as red + blue or red + green rather than one universal pair, and why the destination market has to be on the order. A hose in the wrong colours for its market is non-compliant even if it is otherwise identical.
Step 3 in detail: choosing the bore
The bore has to deliver enough gas for the largest tip you will run, over the length of hose you will use. A longer run needs a larger bore to deliver the same flow at the torch.
| Nominal ID | ID (mm) | OD (mm) | Typical use |
|---|---|---|---|
| 3/16″ | 4.8 | 11.5 | Light welding, brazing and small torch kits, short runs |
| 1/4″ | 6.3 | 13.5 | General workshop welding and cutting — the most common size |
| 5/16″ | 8.0 | 15.5 | Heavier cutting, or general work on longer runs |
| 3/8″ | 9.5 | 17.5 | Heavy cutting and heating tips, long runs |
| 1/2″ | 12.5 | 21.5 | Large heating torches and manifold supply |
All sizes in our standard range are rated 20 bar (300 psi) working and 60 bar (900 psi) burst, for continuous service from −30 °C to +70 °C. Check the torch manufacturer’s flow figures for your largest tip if you are unsure which bore you need.
Step 4 in detail: twin or single, and length
Bonded twin hose joins the oxygen and fuel-gas lines along a web, so the pair lies flat, does not tangle and tears apart cleanly at the torch end. It is the normal choice for portable sets and workshop use. Single lines make sense on fixed manifolds and where the two gases are routed differently.
Keep runs as short as the job allows. Extra length adds pressure drop and more hose to inspect and damage. We supply cut lengths from 3 m to 100 m, or bulk coils.
Step 5 in detail: end fittings and safety devices
Oxy-fuel connections are deliberately made so they cannot be cross-connected. The fuel-gas nut has a left-hand thread and a notched hex; the oxygen nut is right-hand and plain. Never adapt one to the other.
- Thread size. In North American practice, connections come in A, B and C sizes; B-size (9/16″-18 UNF) is the most common on full-size equipment and A-size on small torch kits. European equipment commonly uses G1/4 and G3/8 connections. Match what is on your regulators and torches.
- Check valves at the torch stop reverse flow of gas into the hose.
- Flashback arrestors stop a flame front travelling back into the hose and regulator. They are required in some jurisdictions and are good practice everywhere.
We supply hose bare by the coil, or made up with 9/16″-18 UNF, G1/4, G3/8 or your nominated connector, with check valves and flashback arrestors on request.
When to replace welding hose
Inspect the hose before each use. Replace the length — do not tape it — if you find cracks, cuts through the cover, burns, soft or swollen sections, or any section that has been exposed to oil or grease on the oxygen line.
Before you send an enquiry
- Fuel gas or gases the hose will carry
- Destination market, or the standard named on your tender (for example EN ISO 3821 or AS/NZS 1335)
- Nominal bore, twin or single, and cut lengths or coil length
- End fittings, check valves and flashback arrestors, if made up
- Quantity, and whether you need your own legend printed on the cover
Get welding hose from the factory
We extrude, braid and vulcanise oxy-acetylene and twin welding hose in our own plant in Taiwan, with every coil pressure tested and hydrostatic testing verified by SGS. Send your specification and we will come back with a factory quotation within 24 hours.
Request a quotation