Tig brazing with silicon bronze versus silver soldering stai

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blackwaterstout
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Tig brazing with silicon bronze versus silver soldering stai

Post by blackwaterstout »

I received my shipment of stainless ferrules and need to connect them with my copper pipe. Been reading tutorials on silver soldering them and sounds like it's kind of a pain in the butt.

I've got a tig welder and I've seen people tig braze stainless to copper using silicon bronze filler rods. has anyone done this in the making of stills or is this more for non-food grade applications.

Silicon bronze filler is much cheaper than silver solder.
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corene1
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Re: Tig brazing with silicon bronze versus silver soldering

Post by corene1 »

I have been doing some reading on this trying to learn a bit about it. I have used silicon bronze to TIG weld some race car parts for a friend, both pieces were 4130 chrome moly. It was the first time I had seen this done and it was from a certified chassis builder so I assumed it is a standard practice. I used 2% ceriated tungsten with tip ground to a 60 degree point. Machine set DECN, start only spark on. It welded very nice, quite smooth and controllable. Never thought of trying it on copper to stainless, but that is on my to-do list now. Data sheets show it as a blend of copper and tin with some silicon in it . I couldn't find anything hazardous in it but I will keep looking. Try doing it on some scrap pieces first just to see what happens.
blackwaterstout
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Re: Tig brazing with silicon bronze versus silver soldering

Post by blackwaterstout »

It can definately be done to join copper with stainless. I've used 2% thoriated tungsten with success. My concern is if it is safe in this siutation. I'd think it's if copper and tin then it's probably just as safe as the lead free plumbing solder we all use on copper fittings.
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corene1
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Re: Tig brazing with silicon bronze versus silver soldering

Post by corene1 »

Well the answer is , yes you can. I gave it a try today and it works well and is a very strong connection. As stated in an earlier post 2% thoriated tungsten works well . I have 2% ceriated at work and it works well. Used DCEN and a 60 degree sharp point on the tip. Had to keep more of the heat on the copper and flow it down to the stainless. I welded these flat and then after cooling bent the copper 90 degrees with no problem.
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blackwaterstout
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Re: Tig brazing with silicon bronze versus silver soldering

Post by blackwaterstout »

corene1 wrote:Well the answer is , yes you can. I gave it a try today and it works well and is a very strong connection. As stated in an earlier post 2% thoriated tungsten works well . I have 2% ceriated at work and it works well. Used DCEN and a 60 degree sharp point on the tip. Had to keep more of the heat on the copper and flow it down to the stainless. I welded these flat and then after cooling bent the copper 90 degrees with no problem.
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Nice. How thick was both metals and how many amps did you run? The old adage for tig brazing is 50% of normal tig welding.
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corene1
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Re: Tig brazing with silicon bronze versus silver soldering

Post by corene1 »

blackwaterstout wrote:
corene1 wrote:Well the answer is , yes you can. I gave it a try today and it works well and is a very strong connection. As stated in an earlier post 2% thoriated tungsten works well . I have 2% ceriated at work and it works well. Used DCEN and a 60 degree sharp point on the tip. Had to keep more of the heat on the copper and flow it down to the stainless. I welded these flat and then after cooling bent the copper 90 degrees with no problem.
PC220002.JPG
Nice. How thick was both metals and how many amps did you run? The old adage for tig brazing is 50% of normal tig welding.



18 gauge 304 stainless and 32 ounce copper sheet. Don't know the exact amperage. I set my machine at 12 amps to start and a maximum of 60 amps and control the heat with the amptrol while I am welding. It is not a fixed current machine.
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Re: Tig brazing with silicon bronze versus silver soldering

Post by ozone39 »

ER309L filler material also works well......3/32" ER309L rod, 125" dia 2% thoride @ 60deg bevel, DCEN, 90 to 130 AMPS (depending on thickness)....have to focus more heat on the copper since it dissipates (conducts) heat at a higher rate....Lead free soft solder works as well, just have to use an acid etch flux...Depends on the application that joining the two requires (strength, structural, or just a seal joint, ect)...I generally stay away from bronze, it has a high lead content...
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Re: Tig brazing with silicon bronze versus silver soldering

Post by emptyglass »

On small scale non structural stuff like a still, you can weld the copper to stainless using stainless filler rods

The proper rods are nickel based and cost a packet, but stainless filler does work. Be aware this is a weld, not a braze. Not like the SilPhos rods will do.
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