Brazing copper

[Cord]

Anybody know how to braze copper pipe? Can I use a plumbing mapp torch or does it need to be a pencil tip? Rod and flux to use?

 

[CNC Dan]

I think you can get phosphor bronze filler from plumbing supply places.
It needs no flux, but you need to get the copper hot enough. I think you could do it with MAPP if it's not too big. Air-acetylene or oxy-acetylene if you need more heat on larger workpieces.

I think you could also use flux coated brass filler. Not sure what process needs more heat.

 

[dfkrug]

Back in the 70s, I used "silver solder" for copper pipes used for liquid nitrogen. This
type of brazing required higher temps, so we all used oxy/acetylene. MAPP gas
would probably work if your pipes are not big. We did not have it back then.

Acetylene/air would also work, like plumbers often use.

 

[MH8675309]

I used the silver solder also on brass stainless and sometimes copper. It's expensive since it really is made partly at least from silver.Use a paste type flux and go easy on the heat. If you scorch the metal it will turn black and you'll have to clean it to get the silver to stick to it. Silver solder is like braze but is thinner and will get down into the joint better.

 

[BethelHntr]

Silvaloy is what you need to braze copper, I used tons brazing copper refrigeration pipes when younger.

15 Silver Solder 1 2 Pound Lucas Milhaupt Silvaloy 15 14 Sticks 1 8 x 20" USA | eBay

 

[Cord]

Ever try the brazing rings? I need braze a bunch of 1/2" copper for gas use. I'll have to check to see if the fitting are all copper. There might be a brass one which looks like it would need a flux.

Videos | Sil-Fos
Sil-Fos® (Silvaloy®) | Sil-Fos

 

[BethelHntr]

No I have not done any work on rings.

Copper is pretty soft for gas (Gasoline I take it) and can crack easily with vibration and start fires, You are much better off with steel fuel line. What is this for?

 

[Cord]

Not gasoline, propane. I'm making some light fixtures for my off grid cabin.

 

[bigdeano]

I used silver solder with 40 to 50% silver content to braze the copper pipe in the floor for radiant heat in a house I built. It flows at a lower temp than the lower percentage. Shine the copper up with emery cloth and use the proper flux. Heat to a dull red. works every time. I had no leaks in dozens of joints.

 

[nikdfish]

Back in the day, just used bare bronze rods & cast iron flux with an oxy/acetylene rig with instrument tips for brazing just about anything/everything. Worked fine with copper, bronze, steel, etc. Just pick a rod size that will flow before the copper melts apart Was doing a lot of "found art" for pocket money (was a young & in school) but also used that combo for fair amount of fabrication & repair when other options weren't available. A good, "low temp" brazing job can be pretty strong.

Nick

 

[Tractor Seabee]

From and old pipefitter; certified sil brazer: Good info above but some not so good. If all your joints are copper to copper you can use what is called Phos Copper or Sil-phos. Both do not need flux on copper to copper. For 1/2 copper tube and fittings you should be ok with a prestolite air-acetylene torch, air/propane may be iffy. I have done up to 1 1/8" OD that way. Mapp gas and O/A are OK but easy to overheat. The joints are heated till the brazing metal sucks up onto the joint like soft solder does. Copper to steel or brass/bronze requires at least 15% silver alloy and flux. For all brazing the materials need to be bright and shiney. As pipes get larger mapp gas, propane/ox, or O/A are needed to get enough heat.

Terminology: Brazing is a lower temp process and the joints are filled by capillary attraction whereas Bronze Welding only deposists on the surface like other welding except it does not fuse with the base material.

 

[ray66v]

You guys know they stopped making MAPP gas in 2008?

All the stuff they sell today is fake. It's just hopped up propane.

I thought I was imagining things, when I noticed it was not heating as fast as it used to.

 

[meos1]

From and old pipefitter; certified sil brazer: Good info above but some not so good. If all your joints are copper to copper you can use what is called Phos Copper or Sil-phos. Both do not need flux on copper to copper. For 1/2 copper tube and fittings you should be ok with a prestolite air-acetylene torch, air/propane may be iffy. I have done up to 1 1/8" OD that way. Mapp gas and O/A are OK but easy to overheat. The joints are heated till the brazing metal sucks up onto the joint like soft solder does. Copper to steel or brass/bronze requires at least 15% silver alloy and flux. For all brazing the materials need to be bright and shiney. As pipes get larger mapp gas, propane/ox, or O/A are needed to get enough heat.

Terminology: Brazing is a lower temp process and the joints are filled by capillary attraction whereas Bronze Welding only deposists on the surface like other welding except it does not fuse with the base material.

Marked as answer - He is right on the money.