SS brazing

Hi all,

Looking for the voice of experience, I'm having a very difficult time making some repairs to a maple syrup arch. It sprung several leaks in one of the float pans due to age and years of I'll just add a bit more solder to fix it type repairs. My plan involves Stainless to Stainless and Stainless to Copper brazing. I started by removing the pan from the side of the arch and striping out all the globs of old solder and then grinding all the parts clean. Problems started on reassembly, I had a good fit up when I started but it went out the window with heat warping. I also had problems with the braze wetting and flowing.

I'm working with approx 16 gage SS (316 I believe) , some copper plumbing fittings & a sheet copper patch. I have several grades of silver braze and black flux to work with. I have better adhesion with the lower percentage silver braze then the higher (I expected otherwise). I did clean everything with stainless brushes and new abrasives. This thing is a clamping nightmare, I was thinking about placing some rivets and filling over them the help with the fitup & warping.

Any tips ?

Andrew

Reply to
AndrewV
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I also had problems with the

There are some grades of silver braze that have a little nickel . They are suppose to be better when brazing stainless. Try looking on the internet for H & H. Their website has lots of info.

Dan

Reply to
dcaster

If this is for food purposes, check that the silver brazing rod is free of Cadmium.

Chris

Reply to
Chris Jones

Whereabouts are you? In the US the system is slightly different to here in the UK - in the US they use special solder containing nickel and fairly ordinary flux for stainless, and in the UK they use special flux and a less-special special solder like normal high silver solder.

You could try using a fluoride flux, the main problem with that is flux removal afterwards. You should also be using grade of silver solder which is designed for stainless.

I have

'Tis a bit unusual, if you mean wetting. Perhaps the wrong solder?

I did clean everything with stainless brushes and new

If you're having wetting difficulties you can cheat a bit by prewetting the parts. The joint will be less strong, but probably still plenty strong enough. To prewet, just heat one unassembled part and apply flux and solder - typewriter correction fluid is good for limiting the wetted area, as surfaces painted with it won't wet and it just brushes off after. Non-toxic too (I assume you aren't using cadmium-containing solder).

Then wet the other part, then assemble the parts and join as normal.

To avoid warp problems, you can tack the parts together at intervals before making the final joint.

Also, a hotter torch is better as it tends to only heat the joint area - I use oxy-propane almost exclusively, except for preheating which you probably don't want to do - I don't know what a maple syrup arch is, but I'm imagining a large and slightly floppy structure made from thinnish sheet, in which case don't preheat it.

-- Peter Fairbrother

Reply to
Peter Fairbrother

Thanks for the replies,

The best solution proved to be purchasing an updated float pan that hangs on the side of the main evaporator pan and connects via pipe fittings. Better control and easier to clean. Buy the way to those concerned I was using lead & cadmium free solder/braze. I think most of the problem was due to warping and trying to work on the thing in the worst position possible in a building w/ no heat on a 20 deg night well after bedtime. (in other words I should of said "no" unless you can bring it to my warm shop where I can work comfortably with lots of clamps.)

Reply to
AndrewV

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