soldering stainless steel


I am modifying a water distiller by adding a tube nipple to the side of the boiler, to use for filling and draining the boiler.
I need some advice about choosing a combination of solder, flux, and torch.
The boiler is 22 ga. (0.031") 304 stainless, and I want to solder a two-inch length of 3/8" 304 tube (wall thickness 0.020") into a 3/8" hole I will drill in the boiler.
I got some 22 ga. 304 sheet to practice on. I am able to drill 3/8" holes in the practice sheet, and I can cut lengths of tube.
However the result was abysmal when I tried to solder the tube in the hole.
I hope to use my propane torch, and I don't see why I should need anything hotter. The joint is not going to suffer much mechanical stress, so I expect a soldered joint to be more than strong enough. The temperature will be up to the boiling point and down to say 55 degF, but again I wouldn't expect that to be very stressful.
I did not use a wire brush to clean the tube for my first (failed) attempts. Should I have?
I used the NSF-approved Radnor Stay-Brite Silver solder Kit # 54001776 by Harris. That is a combo of 3/64" solder and a 1/2 oz. bottle of Stay-Clean Flux (liquid).
The first thing I noticed is that the flux did not want to stick to anything---it would not easily soak into the flux brush, and it beaded up on the metal. I guess I was able to get the metal wet to some degree and I did get solder to stick in some places.
I desoldered the joint and tried again with Oatey Sta-Flo 95/5 1/8" solder, and the result was at least as bad.
There is a paste version of the Stay-Clean flux. Do you think maybe I should be using that instead?
I have some experience soldering electronics and copper tube. Stainless seems to be about a hundred times more difficult. What am I doing wrong?
Reply to
Patrick

"Patrick" wrote...
You have the correct solder/flux (Stay-Brite). Do not use the paste flux. I'd suggest that you clean the surfaces with Bar Keepers Friend and then wash and dry them well. Warm the area with the propane torch and then apply the liquid flux. Do not apply the heat directly to the soldering area. Allow the heat to conduct to the joint. This will prevent it from being overheated. When you apply the solder it should melt on/in the joint _not_ in the flame. If it does not easily coat the metal, apply more flux and continue.
You should be able to get an excellent result. I use that solder flux combination all the time.
Reply to
PJ
Why not?
I believe, as you indicate, that I am probably overheating the work. Then I guess the chemicals in the flux get used up and the protective oxides form again on the surface.
I'm thinking that an application of paste is going to have a lot more oxide-removing chemicals than the thin film of liquid flux, so that it will keep working even if the work stays hot a long time. Also wouldn't the paste help by keeping the air away?
Reply to
Patrick

Try it.. Then let us know how it works. Be careful with the torch. The paste flux will burn easily.
Reply to
PJ

Soldering is more an 'art' than a 'science'. Perhaps viewing the below reference YouTube video will be helpful ->
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Reply to
Billy
Thanks, that video really hits the spot. I am trying to do once almost exactly what that guy seems to have done dozens of times.
What kind of torch is he using?
So I need only solder on one side of the bulkhead, it seems.
Reply to
Patrick

: > Soldering is more an 'art' than a 'science'. Perhaps viewing the below : > reference YouTube video will be helpful -> : > : >
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: : : Thanks, that video really hits the spot. I am trying to do once almost : exactly what that guy seems to have done dozens of times. : : What kind of torch is he using? : : So I need only solder on one side of the bulkhead, it seems.
@ Patrick,
The person in the referenced YouTube video is using an Oxy/Acetylene torch - he explains how to adjust the Oxygen to obtain a Neutral Flame.
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Billy
Reply to
Billy

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