silver brazing SST pipe threads

[Cliff Rohrabacher]

It's not like sweating copper.

Making Bulkhead fittings on the cheap
I used a 56% cad free silver
1/2" NPT: nipple, coupler, straight thread lock nut. Gotta get an o-Ring for each.

Ya gotta pre-tin the threads (make & female) with silver first. If you assemble them and hope the high percentage silver to flow in you will have about as much success as other things all full of hope tend to have.
Pre-tinning the threads is absolutely mandatory 'cause high silver doesn't flow like lead.

Unless you have some way to achieve tight control over the heat ya gotta use unfluxed silver brazing material and A high Temp flux. I used Harris Safty-Silv Black high Temp flux. It's for those apps like mine, where heat control is dicey. I used a MAPP torch, not a brazing furnace.

Then with the pipe fittings so hot (not glowing red) that the silver braze is liquidus ya gotta screw the parts together gingerly.
Bulkhead fittings 001.jpg

Bulkhead fittings 002.jpg

Clean up with file, abrasives, SST wire brush, passivate in Ascorbic Acid

[Jerry Bruette]

Cliff
I've used a Harris product called stay-brite, it's lead and cadmium free. I used it to solder on gun sights and it seemed to flow almost like soft solder. I bought a kit from a place called Brownells and it came with a bottle of "stay clean" all purpose flux.

Was curious though could you have used a generous amount of red loctite and achieved the same results?

Jerry

PS whatcha brewin anyways?

[Bill Cunningham]

I used to silver solder a LOT of High pressure stainless fittings. Always used 'silver' wire, high temp flux, and a acetylene torch. A straight mapp gas torch with no O2 was never hot enough. Start by dipping the parts in the flux, if the fitting is too close, then simply wiping the flux liberally on the joint will work, because the heat will melt it into the joint. The whole secret is it has to be 'hot' and you will need a #3 lens in your goggles. When the flux melts, and turns from a yellow in the flame to clear, then wipe on the silver keeping the heat on the joint. When the silver fills the joint, remove the heat and let stand for a bit. You can then plunge it into water if you have to.. All of our joints were used for a minimum of 5000 psig air and/or helium/oxygen mixtures in the diving industry

[Cliff Rohrabacher]

Always used 'silver' wire, high temp flux, and a acetylene torch. A straight mapp gas torch with no O2 was never hot enough.

All I have is MAPP - no O2.
It works. Takes a while, but it'll get things hot enough to get the braze to flow. But surely MAPP wouldn't work for production or for getting really clean results with those nice clean fillets you can get with an Acetylene rig.

[Cliff Rohrabacher]

Cliff
I've used a Harris product called stay-brite, it's lead and cadmium free.

It's mostly tin. Wort is relatively high pH and can dissolve ionic tin. Ionic tin is one of those metals that one is best to limit one's intake of.

Was curious though could you have used a generous amount of red loctite and achieved the same results?

Hard to know. The parts have to go to 212F for extended periods and most epoxy molecules unzip at temperatures approaching 150F. Plus I don't think I'd want the flavors of Loc tite in my beer. It tastes strong and awful.

PS whatcha brewin anyways?

Beer~!! It's ale about the beer man.
I'm building an Electric Brewery with microprocessor & computer controls.