Copper welding

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Copper welding

Postby AussieDistiller1989 » Sat May 18, 2013 5:48 pm

Hello.

I was woundering if anyone can give me some tips on oxy welding
Copper to copper and brazing copper to stainless.
As I have never done it before and I'm sick of waiting
For my mate to come and do it.

What is the better flux and rods for me to buy.
And for the brazing is 15% or 5% silver better
For brazing

Thank you
A.D
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Copper welding

Postby Dominator » Sat May 18, 2013 6:01 pm

I use 15% for copper to copper and 45% for copper to stainless. I am not sure on the name of the flux tho.

The trick with oxy welding is using the heat to your advantage. The solder will tend to flow towards the heat, so by working your way around your workpiece with your heat the solder will flow its way around.
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Re: Copper welding

Postby AussieDistiller1989 » Sat May 18, 2013 6:31 pm

Thank you that's a good tip.
What's the other thing apart from lead I don't want in my flux
And rods
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Copper welding

Postby Dominator » Sat May 18, 2013 8:03 pm

Not sure about flux but you also want to avoid antimoney in your solder.
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Re: Copper welding

Postby AussieDistiller1989 » Sat May 18, 2013 8:33 pm

Cheers I knew there was one other just couldn't remember.

Caint wait to get this dam still built I have 150 lt bourbon ferment nearly
Ready smallish bloody great and a 150l ferment of hook rum that stalled just need
To warm it up and that will be ready in a couple
Days just gotta wait for the post office to open so
I can pick my hear belts up
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Location: Victoria
equipment: 50lt pot still with a 30lt thumper with a
2" gooseneck and a Liebig

Copper welding

Postby P3T3rPan » Sat Jul 27, 2013 10:27 pm

AussieDistiller1989 wrote:Thank you that's a good tip.
What's the other thing apart from lead I don't want in my flux
And rods

Most fluxes remain on the surface where you can chip or wash them off.


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Copper welding

Postby P3T3rPan » Sun Jul 28, 2013 12:15 am

AussieDistiller1989 wrote:Thank you that's a good tip.
What's the other thing apart from lead I don't want in my flux
And rods


Most brazing fluxes remain on the surface where you can chip or wash them off.
Silver brazing alloys (silfos for instance) usually are food grade.
The higher the silver content the easier it is to use. The 15% (silfos) stuff is what plumbers use the most on water supply. The lower grade (silbralloy) is used on waste pipes and the higher grade (easyflow) is used to join dissimilar metals (ss for instance) to copper.
Dominator got it right re using the heat to control where the silver brazing alloy goes.
Joint preparation also allows you to control where the silfos (or whatever the silver brazing alloy is called) will go. This can be used to advantage on more difficult joins.
It is important to realize that the strength of any join is in the surface area joined, not in how thick you apply the filler rod, whether it be soft soldering (solder, lead solder), brazing (silfos,bronze etc) or welding in all its forms.
When brazing old dirty copper, bring it to a cherry red then quench it in cold water. This will bring the oxides and filth to the surface to flake off. Prep your join with emery cloth and go for it.
Silfos has a proprietary flux but it is only needed when brazing filthy copper or brazing copper to brass.
Most times I don't bother with the quenching or the prepping or the flux, but i have been doing it for 46 years, just wait a second or two with the gas off the heated work and it will go from cherry red to black and shed the oxides, then straight back to brazing, with little loss of heat.
Brazing copper with silfos is easy, fast, very strong, very controllable, and fun. (Some will say that it is expensive but for me time is money and soldering is too slow and too weak and too prone to leaking for the pressures in town water supplies and at the bottom of tall waste stacks, and usually involves corrosive fluxes that end up on the clients carpet or my skin)
Find some test bits and have a go.
Use a 'soft' (almost carburizing) flame. Keep your flame moving.
Heat the work,not the rod.
When the work is the right temp the rod will melt on contact with it.
Concentrate your heat on the thickest part of your work and watch the rod suck into the join.
While simple straight socket joins and lap joins can be done with air-fuel gas very successfully, oxy-fuel gas (especially acetylene) makes multiple close together joins and joins in larger diameters much easier.



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