Brazing with Propane

[dkroth]

Can an oxy-propane rig like this one be used for brazing?

Looking at replacing my oxy-acetylene rig with oxy-propane and I don't want to lose the capability to braze. Can I just buy some brazing tips and I'm good to go?

I know oxy-propane can't be used for gas welding. I'm not concerned about that.





.

 

[OccupantRJ]

I run oxy/propane in my shop and cut, braze, and silver solder with no problem.

 

[VocaTexas]

I have actually seen a couple of old-timers weld thin material with a propane torch. One of them said he much preferred acetylene, but propane would work.

 

[cnttxmdc]

It depends on the size of material you’re working with... I’ve always preferred ocyacetylene for everything, including brazing. For smaller stuff you’ll probably be fine with a propane/oxygen setup, but you’ll be at the upper range of its limits in my opinion.

 

[Habrot]

Seems to depend a lot on the quality of hose that you buy. Several people on here have noted that with good hose you can get by with R rated for some time. On the other hand I've had cheap Chinese hose that didn't last a year even with acetylene. If you have a good name brand hose it doesn't seem to be an immediate issue.

 

[MoonRise]

You already have an oxy-acetylene rig?

Some sort of 'name' brand one?

Then all you have to do to switch over to oxy-propane usage is:

- replace hose with T-rated (any fuel) rated from your most likely R-rated (acetylene use ONLY) hose

- replace the tip(s) with the desired appropriately-sized oxy-propane tips

- maybe replace the fuel regulator with one 'rated' for propane (the acetylene regulator maxes out at 15 psi because of acetylene's instability at pressures higher than that when in gas form)

The torch handle is compatible with any fuel gas AFAIK (Victor, Harris, Smith handles are all like that, at least for anything 'recent').

Remember that the oxygen flow rate is 4x higher with propane than with acetylene for similar sized tips.

No withdrawal-rate limit with propane (except for frosting up the propane cylinder under high withdrawal flow rates ), unlike acetylene with the 1:7 flow rate safety limit. Rosebud, ahoy!

Cut, heat, or braze is usually no problem with oxy-propane with the APPROPRIATELY sized tip(s).

 

[rlitman]

Can an oxy-propane rig like this one be used for brazing?...

Yes. However, you will find that oxy-propane behaves very differently from oxy-acetylene. Oxy-propane has a dimmer flame. So dim in fact that I find it more comfortable to use dark sunglasses (around shade 1.5) than the normal shade 5 welding glass you'd use with oxy-acetylene. That also makes it a little difficult to find your neutral mixture.

Next, the flame is quite a bit softer. This is probably a good thing for most brazing, unless you're working with jewelry.

Seems to depend a lot on the quality of hose that you buy. Several people on here have noted that with good hose you can get by with R rated for some time. On the other hand I've had cheap Chinese hose that didn't last a year even with acetylene. If you have a good name brand hose it doesn't seem to be an immediate issue.

No. Grades R and RM hoses are rated for acetylene ONLY. Propane will slowly eat their interiors. Grade T hose is the only hose rated for propane.

 

[rlitman]

You already have an oxy-acetylene rig?

Some sort of 'name' brand one?

Then all you have to do to switch over to oxy-propane usage is:

- replace hose with T-rated (any fuel) rated from your most likely R-rated (acetylene use ONLY) hose

- replace the tip(s) with the desired appropriately-sized oxy-propane tips

- maybe replace the fuel regulator with one 'rated' for propane (the acetylene regulator maxes out at 15 psi because of acetylene's instability at pressures higher than that when in gas form)

The torch handle is compatible with any fuel gas AFAIK (Victor, Harris, Smith handles are all like that, at least for anything 'recent').

Remember that the oxygen flow rate is 4x higher with propane than with acetylene for similar sized tips...

MOSTLY agreed.

Yes, grade T hose.

No, brazing tips are brazing tips. You use the same brazing tips for oxy-acetylene as you use for oxy-propane. Cutting and heating tips are different. However, oxy-acetylene cutting tips can be converted to work with oxy-propane. Force the tip into a piece of copper tubing that forms a rim which extends past the surface up to 1/8". That will keep the flame from blowing away.

Yes, your acetylene regulator will be just fine. The low gauge numbers stop at 15 PSI, but you probably won't need that much anyway, and most acetylene gauges will allow the needle to go up to 30 PSI, though they blindly indicate a numberless red line there.

Yes, the same handle is fine for both.

Yes, the oxygen goes faster. But you cannot just turn the knobx on a torch to 4x the flow. It's more of an art. Oxy-propane doesn't have a visible "feather" like oxy-acetylene, and the flame is too dim to adjust when viewed through shade 5 goggles. The best I can say is to try it and see what you see. You'll notice the flame sharpen when it gets to be oxidizing (which you don't want). Also, because oxy-propane burns slower, the flame will sound quieter than oxy-acetylene. As you start to get the hiss you've learned to expect with acetylene, you blow the flame away from the tip. So, to get comparable heat, you'll need to use bigger tips than you're used to.

edit: Not mentioned above are the different dangers of propane. While acetylene has it's dangers, propane presents its own unique risks. Propane will pool, as it is heavier than air (unlike acetylene), so it isn't safe to bring a large (20 pound) propane tank inside a structure, or use over a basement or near a drain.

 

[monkeyspanners]

Propylene/Mapp pro gives a bit more heat than propane, its what I mainly use now for brazing copper hvac lines.

 

[shirk]

I fillet braze bikes with Oxy-propane. The handle is a Uniweld 71 and I use the Victor UN-J mixer and TEN multi fuel rated tips. From my understanding you'll want the multi fuel tips instead of the regular acetylene tips. The common comment with the bike builders that use propane is they braze with one tip size larger in propane.

On the oxy side I used an oxygen concentrator instead of bottled oxygen. It's a medial unit that puts out 5lpm and is enough to run the smaller aircraft sized torch for my use. Nice never needing to refill an oxygen bottle after buying the used concentrator.

Some great info on the use of oxy - propane in this thread aimed at bike builders.

https://www.velocipedesalon.com/forum/f10/acetylene-vs-propane-30480.html?highlight=Propane