Propylene instead of acetylene?

Id like to know the differences in using these two fuels for normal
around the farm cutting and brazing.
I understand that propylene is safer, has more in the tank, is
cheaper..and thats all I know.
Ive got an old S/V 100 torch handle and various cutting heads and
brazing tips, as well as an old Union Carbide cutting torch.
I have to change the cutting tips, correct? What about the existing
brazing tips?
How much does a tank of propylene cost versus acetylene?
Is there an issue with my hoses?
Regulators? Can a acetylene regulator be used for propylene?
In the past, an acetylene tank has lasted me a couple years, but Ive
sorta gotten the welding bug and Im doing all sorts of projects now.
Ive got tig/stick welders to weld with, but will be doing some brazing
and silversoldering (band saw blades, brazing cast iron..the usual)
Any good links to any good information or some hints and tips?
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Propylene is not necessarily safer. If acetylene leaks, it will rise and in most cases tend to disperse. Propylene, being heavier than air, will usually descend and travel to the lowest point and concentrate. If there is an ignition source, you will have a problem.
You need to at least change cutting tips. Better yet, get an injector style mixer, too. Check out Harris
You need to use grade T hoses, not the grade R hoses often used for acetylene.
You can use acetylene regulators.
You will use much more oxygen compared to acetylene because of the chemistry involved.
Check you local supplier for price.
Reply to
My understanding is that propane is ok for cutting but not a hot enough flame for welding. Propane is cheaper per unit energy that acetylene here in the UK. Propane cutting nozzles are markedly different - here in the UK they are of a two part concentric construction, the outer being the same copper alloy used with acetylene, but the inner is a brass, and they come apart for cleaing .
My personal opinion is that for general use acetylene is more versatile as you can weld as well, but I actually have both.
Not sure if it is recommended, but I'm using an acetylene regulator on a propane tank for my metal melting furnace. Beware that propane needs a special hose, as it disolves the rubber used on acetylene hoses.
Reply to
Andrew Mawson
Gunner was asking about propylene which is very similar to what we in the UK refer to as MAPP gas, although that is a brand name. Propane is a different gas and commonly used for cutting due to lower costs but I think it doesn't necessarilly gives as good a result.
Andrew Maws>
Reply to
David Billington
I haven't done cutting, but I did not have to change anything for brazing.
I have a tank about the size of a small propane tank - I forget the description, but it is maybe 15 Lbs or so, about 2.5 gallon size, I think. It has lasted years, and I suspect there are a few more years left in it. It is supposed to cost $10 - 15 for a refill.
I'm sure of that, as the guy at the local gas supplier refitted my regulators for his tanks and said everything was OK.
Reply to
Jon Elson
You can braze small parts with porpane/air and a "swirl-torch" - it has a gizmo in the torch after the venturi that creates a vortex and makes more heat.
Noisy, and the propane bottle a) gets cold b) doesn't last very long, but it works, and the torch is cheap, and you can carry it around in a backpack with all the orher tools you might need to fix something 8 miles out in the woods.
Reply to
Years ago - it's very low pressure - a fan blower, not a piston compressor. OK for brazing, but not much else. I do all my hot stuff with oxy-propane these days, or use a friend's gas forge with a Ron Reil propane injector / natural draught burner.
Blown air /
gas seems to have arisen with mains gas, because that's all they had in those days. Then someone discovered the injector trick and made powerful (but large) burners that didn't need the air blower. Bottled oxygen was cheap (if you've already bought oxy-acetylene welding kit) and that took over for small burners or intense heating. The blower kit is still around, but it seems to have been marginalised.
Here in the UK gas is "free" in comparison to our enormous cylinder rental costs (not propane, but certainly oxygen / acetylene). Once I've got the kit, then it costs me nothing extra to use it more.
Reply to
Andy Dingley
Why is it that here in the UK MAPP is still a rarity and using propylene as a fuel gas is unheard of ? Is it commonplace in the US?
Reply to
Andy Dingley
MAPP is a mix of gasses. Methyl-Acetylene Poly-Propylene.
It used to be more common in the US, but has been replaced by Propylene to a large degree. I prefer MAPP for heavy cutting, but it is difficult for a small shop to get the tanks.
For the last 2 years I have been using a Propylene mix called Flamal, and it works very well for cutting, and heating.
A mix I see a lot at professional flame cutting shops is called Chemtane II.
Propane and Natural gas are also used a lot by larger cutting shops.
Reply to
Ernie Leimkuhler
Hi all, Being a "hobbyist" with just enough knowledge to be dangerous, I have nothing to add to this discussion although I'm learning tons!!! I am curious about the term "cutting shop" Are these businesses that specialize in cutting metals or are they just big welding shops that also do a lot of cutting in their normal course of business??? Just curious as I had never heard the term used before. BTW Ernie...glad to see you posting more in the group. Finger getting better, I hope. Marc
Reply to
Burning shops do nothing but oxy-fuelgas cutting of heavy steel. Every major city has at least one.
The older shops use electric eye pantographs to follow a line drawing. The newer shops are all CAD-CAM.
A lot of them have added laser, plasma and waterjet tables to augment their burning tables, but oxy-fuelgas is still the cheapest way to cut heavy steel. The other processes are better for aluminum, stainless steel and sheet metal.
Monday night at school, I laid my first decent TIG welds since the accident 10 weeks ago. Tuesday I went in for revision surgery and nail ablation. Full general anesthesia is not my idea of fun. 3 hours dissapeared, no dreams, and then 2 hours of trying to get my eyes to focus, and another hour trying to remeber how to walk. My right hand is back to a big bundle of gauze bandages. They removed the vestigial fingernail, and reshaped both finger tips.
Oxycodone takes the edge off the pain.
Reply to
Ernie Leimkuhler
Propane and air, at atmospheric pressure, will certainly get you there but you need to confine the heat. And that's rather useless unless you want to burn a few tanks making a *very* wide, *very* sloppy, *very* well fused weld on a few pieces of steel. ;-)
I imagine it would have more gusto if you mixed it at high pressure behind a nozzle, say 15 or 30PSI.
I know I've heard of oxypropane for cutting (and anything else like brazing), but not welding. Matter of fact, can someone explain why?
-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @
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Reply to
Tim Williams
I've been using oxy-propylene for a few months now--here's what I've learned...
I found you can use standard acetylene tips for brazing, but they need to be *much* larger. I am using a drilled-out #4 to do brazing on 1/8" to 1/4" steel (forgot how big... just kept drilling till it heated fast enough... I can check if helpful). The little tips blow out very easily, and the big ones will, too, if I try to braze close into a 3 sided inside corner, or i/s a tube. I am told if you countersink the orifice .060 or so it helps keep the flame on the tip. Also, to get enough heat the torch will hiss loudly. The flame is not real precise like w/ acetylene, but for most brazing it is fine.
I had no success using an acetylene cutting tip--wouldn't stay lit--but I think others have done it. I bought a 2 pc. #1 fuel gas cutting tip and it lights and cuts great.
Like others said, use "T" hoses (which happen to be std on Victor equipment, I found). Acetylene regulators are fine, unless you are doing really serious cutting where you might need more than 15psi.
The flux that seemed to be most recommended was Gasflux Type B "Blue Paste":
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The only authority I could find on flame adjustment is here (for MAPP):
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Figure 11-3 and the text below.
Good luck! David
(from the link:)
1. A carburizing flame looks much the same with MAPP gas or acetylene. It has a yellow feather on the end of the primary cone. Carburizing flames are obtained with MAPP gas when oxyfuel ratios are around 2.2:1 or lower. Slightly carburizing or "reducing" flames are used to weld or braze easily oxidized alloys such as aluminum.
2. As oxygen is increased, or the fuel is turned down, the carburizing feather pulls off and disappears. When the feather disappears, the oxyfuel ratio is about 2.3:1. The inner flame is a very deep blue. This is the neutral MAPP gas flame for welding, shown in figure 11-3. The flame remains neutral up to about 2.5:1 oxygen-to-fuel ratio.
3. Increasing the oxygen flame produces a lighter blue flame, a longer inner cone, and a louder burning sound. This is an oxidizing MAPP gas flare. An operator experience with acetylene will immediately adjust the MAPP gas flame to look like the short, intense blue flame typical of the neutral acetylene flame setting. What will be produced, however, is a typical oxidizing MAPP gas flame. With certain exceptions such as welding or brazing copper and copper alloys, an oxidizing flame is the worst possible flame setting, whatever the fuel gas used. The neutral flame is the principle setting for welding or brazing steel. A neutral MAPP gas flame has a primary flame cone abut 1-1/2 to 2 times as long as the primary acetylene flame cone.
Reply to
David Malicky
No, that's not it.
Steel isn't cut by "propane and oxygen", or even "acetylene and oxygen". The fuel gas is just there to heat the steel to ignition temperature, the actual cut is done by a reaction between pure oxygen and steel. If you do try and cut with just heat rather than oxidation, you'll find the kerf fills with molten iron slag anyway. In a big cut and a thermic lance, you can even take the heating torch away and run with a pure oxygen feed to a pure steel flame.
Air is only 21% oxygen, which isn't enough to cut steel by burning it. If you tried you'd also have an excess of notrogen in there which would be "robbing" the oxygen and contributing little heat. You can't even fix this by using high-pressure compressed air.
Reply to
Andy Dingley
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Uh huh. Well aware of that. Can also cut slabs at the rolling mill with just oxygen jets since it's already hot from the process.
-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @
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Reply to
Tim Williams
So what ? Reil's burners don't use oxygen and they get hot. What's your point ? They still won't cut steel, no matter how hot you get it. You don't cut steel by _melting_ it out of the way.
Reply to
Andy Dingley

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