Soldering Stainless steel

[Whut]

If I hadn't found this thread, I'd be paying $50 per weld for a local welder (weldor).

That's what I had to do but after finding this thread this evening not again. This has just opened up lots of other opportunities for me that I had been holding back on.

Wayne and Joe (and everyone else), thanks again for the thorough info.

Trace

 

[Boerderij_Kabouter]

OK. Maybe I have lost my brain, but I can't for the life of me find in this thread where it says I can get the supplies I need. I have a prop. torch, and would like to use the Stay-Brite 8 with the liquid flux. Do I just pick that up at the hardware store? It seems somewhat specialized????

Help a guy out.

...................................................

Also, I am hoping to solder in some fittings on a rubber coated keg. Comments? It is one of the sankey style kegs with hard plastic/rubber surrounding the SS vessel. My plan is to cut away a portion of the rubber, pull fittings, and solder. How hot does the surrounding metal get? Do you think I am going to melt the rubber?

 

[P-J]

A welding supply in your area should have it. This place has excellent pricing:
Harris Stay-Brite 8 solder
Harris Stay-Clean flux

If you are looking for a small kit:
Tower Hobbies has it at a very reasonable price.

 

[wyzazz]

Also, I am hoping to solder in some fittings on a rubber coated keg. Comments? It is one of the sankey style kegs with hard plastic/rubber surrounding the SS vessel. My plan is to cut away a portion of the rubber, pull fittings, and solder. How hot does the surrounding metal get? Do you think I am going to melt the rubber?

Maybe try a high output soldering iron? Damp rags on the rubber to keep it cool?

 

[Scut_Monkey]

Is it really worth it to buy stay brite solder in comparison to lead free "silver" plumbing solder. I have this stuff for copper pipe repairs. Is it suitable? Seems others have used similar stuff.
http://hand-tools.hardwarestore.com/69-407-solder/safe-flo-lead-free-silver-solder-602371.aspx

 

[pickles]

I've found that the stay-brite 8 is very difficult to flow on stainless. I eventually used standard lead-free plumbing solder.

 

[Scut_Monkey]

I've found that the stay-brite 8 is very difficult to flow on stainless. I eventually used standard lead-free plumbing solder.

I like it! That's my justification to cheap out and use what I got. Thanks Pickles.

 

[jfkriege]

I did not have any issues with Stay Brite 8 after I switched to a liquid flux. I have Stay Clean Flux and it works well (though the only container they had was half a gallon; I have a lot left).

Edit: I dont want to take away from your justification. I was typing this before you posted.

 

[Scut_Monkey]

I did not have any issues with Stay Brite 8 after I switched to a liquid flux. I have Stay Clean Flux and it works well (though the only container they had was half a gallon; I have a lot left).

Edit: I dont want to take away from your justification. I was typing this before you posted.

No big deal. I'm sure stay brite works well for some but if standard plumbing solder works well for others I would rather go that route. I already have standard solder and don't feel like throwing down the cash for expensive solder unless needed. Things become expensive enough when you are trying to surround yourself with stainless steel.

 

[pickles]

In all my tests and successful joints, Stay Clean Liquid flux is the only one that worked well. So defiantely buy liquid flux, they sell it at menards and any welding supply house.

 

[jfkriege]

I use the Stay Clean for regular plumbing solder now as well, and the stuff works like a champ. It is completely worth it, even if you have to buy a lot more than you think you might need.

 

[klyph]

From my experience, the critical elements of soldering are:

Quality solder/flux
Clean surfaces
Heat control
Applying the proper amount of solder

If you can master those four things, there's no reason you can't solder. My main problem when learning to solder was that I was using a terrible quality paste flux that simply did not work. Then I was overheating the joints and dumping too much solder on it to compensate.
Once I got quality flux, I could heat the joint until the flux started to sizzle, then I knew to pull the torch, and use just enough solder to wet the whole joint, no more. If you're going back and forth with the torch and the solder, you're doing it wrong.

 

[wyzazz]

I did not have any issues with Stay Brite 8 after I switched to a liquid flux. I have Stay Clean Flux and it works well (though the only container they had was half a gallon; I have a lot left).

Edit: I dont want to take away from your justification. I was typing this before you posted.

You should package some of that up in bottles and sell it to recoup a bit of your cost.

 

[jcojr72]

This is a great thread. I understand that stainless steel is the preferred material to use for valves/bulkheads/etc, however is there any reason nobody solders copper to their keggles. I have a bunch of copper fittings from miscellaneous household projects and was thinking of using them rather than buying new stainless pieces.

Thanks,
Jeremiah

 

[Henrythe9th]

My HERMS coil, sight glass and a few other fitting are copper to SS, sure copper is fine to a point

 

[Loptr]

WOW! Just WOW!

This is why I <3 the interwebz.

Now I dont have to teach myself to mig stainless and settle for a crappy lookin weld.

Between doing a dimple and the solder this is WINAH!

I am goin elec and this is going to be superior to the ideas I was mulling over.

Will try to post pics when I get started.

Any idea on the proper parts to make a 3/8" bulkhead "dimple"?

Loptr

 

[nostalgia]

Any idea on the proper parts to make a 3/8" bulkhead "dimple"?

Hmm...McMaster doesn't seem to have anything smaller than the one I used. However, you should be able to use the same parts and only pull the coupler part way through.

Alternately, you could make your own if you have a belt grinder. I used a 1/2" NPT brass nipple for the tool I used to make dimples for 1/4" NPT couplers. It fits over the same 5/8" bolt.

-Joe

 

[Loptr]

Alternately, you could make your own if you have a belt grinder. I used a 1/2" NPT brass nipple for the tool I used to make dimples for 1/4" NPT couplers. It fits over the same 5/8" bolt.


-Joe

Thanks Joe,
I have been reading about the problems of stainless getting "polluted" by other metals and the resulting rust issues. Has this not been the case with your brass?

 

[wyzazz]

Thanks Joe,
I have been reading about the problems of stainless getting "polluted" by other metals and the resulting rust issues. Has this not been the case with your brass?

If you re-passivate with something like BKF I think you'd probably be OK.

 

[nostalgia]

Well, it certainly didn't affect how it soldered. As for passivating, I don't know the science behind it. My gut feeling is that since brass is non-ferrous that it won't be an issue, but I dunno.

Time will tell.

-Joe

 

[ScubaSteve]

Actually...I think it's a hell of an idea.....probably better than using galvanized metals. Easier to grind down too. Still cheap. When I did this, I used PVC for the "main coupler"...I was trying to pull a 1" fitting through the kettle wall and couplers that size were mega bucks for just a 1 time use. So, in short, you can use PVC as long as you're safe and wear eye/hand protection.

 

[klyph]

The solder I use contains a small amount of copper, so I doubt scraping brass across the surface would contaminate it. It might even help "tin" the surface.

 

[klyph]

Here's mine. The bottom drain was the first, and I didn't spread the flux wide enough so the solder beaded up around the fitting, I might sand it down smooth, but it doesn't bother me too much. The subsequent fittings turned out much nicer.

 

[Bobby_M]

You can likely just apply heat again and drop flux down into the solder. Is that Harris Staybrite?

 

[ScubaSteve]

Klyph, those look great....the keg tool is kind of a PITA but it is so worth it. My bottom drain looks the same....I didn't get the hang of it until my 2nd or 3rd fitting. It should be fine, but if I do it again, I'll put a loop of solder into the gap then just heat the whole joint. It makes things perfectly flat.

 

[klyph]

You can likely just apply heat again and drop flux down into the solder. Is that Harris Staybrite?

It was silv something 100, I'll check next time I'm in the shop.

Klyph, those look great....the keg tool is kind of a PITA but it is so worth it. My bottom drain looks the same....I didn't get the hang of it until my 2nd or 3rd fitting. It should be fine, but if I do it again, I'll put a loop of solder into the gap then just heat the whole joint. It makes things perfectly flat.

You're not kidding, I started doing these over the weekend and I think this is the third weekend and I'm finally done. It was a LOT more work than I anticipated, but now that all 3 vessels are done, I'm glad I did it.

I didn't have any luck with the placing a loop of solder in the joint. In fact, (maybe my flux is contaminated) I couldn't even flux the joint without heating it until the solder started to melt, then apply just enough flux to get the solder flowing. If I fluxed it first, the flux would evaporate and then burn into a black coating before the solder would melt preventing a good solder joint. Very frustrating, but with trial and error I nailed down a decent way to get it done. I might try and get some fresh flux paste, mine has turned brown and I think this is affecting it's effectiveness.

 

[Boerderij_Kabouter]

Your flux is not matched to the solder you are using. The flux shouldn't burn before the solder melts.

 

[Bobby_M]

It's very hard to get the piece hot enough without burning the flux especially on such a huge heat sink. I learned that applying indirect heat to the 6" diameter around the hole for about 3 minutes really helped. You slowly circle in closer and closer and by the time you hit the fitting, the solder is flowing. The flux burns a bit, but a quick squirt of fresh flux on the joint just before you take the heat away cleans it up.

 

[BrewBeemer]

No burning of flux when using cut muriatic acid as flux, SS solders easier than cleaned copper, flows just the same by capillary action once heated to the right temp for the solder to flow. Just don't overheat it, use a acid brush to apply more acid. Stop if overheated, sand the stainless bright and start over. This with soft sodering not silver soldering.
A propane torch or a natural gas torch requiring compressed air is what I use to even silver solder parts vs O/A if Tig is not wanted for the joint.

 

[ScubaSteve]

So what do you cut the muriatic acid with, and in what proportion? Stay-Clean is good stuff, but I did notice it'd burn off before I reached the solder's melting point. I had to reapply it but it was difficult to find something that wouldn't burn...q-tips would just burn and contaminate the area. I ended up filling a small eye-dropper with flux and it was enough to drop a controlled amount over the joint to kind of wash out the burnt flux. Tinning the fitting was also difficult in spite of the fact that I cleaned the hell out of it....