Need help with stainless soldering

[Cement102]

Hello all

I am hoping to get some help with a soldering project I am working on. I have dimpled a stainless pot and am trying to solder a stainless half coupler to it. I am encountering a lot of problems and for the amount I have spent on solder trying to get this done, could have just bought a brewery! I am using stay brite solder and stay clean acid flux and a propane torch. Here is what I am encountering:
1. The pot heats up, expands and the coupler falls out. I had to wire it in to hold it. Is this normal?
2. If my pot is not perfectly level, the solder just pools to one corner.
3. The flux does a great job allowing the solder to bond to the coupler, but not the pot wall. I sand, wire brush, flux. All I get is no stick and a thick black oily residue after trying. ????? It was pristine when I started heating!

Any help on what's going wrong would be appreciated. I'll post some pictures.

 

[Cement102]

Photos

 

[BigJim_inFLA]

Is your flux the liquid or the paste? I had similar trouble using Stay clean paste flux. It looks like your getting the kettle too hot, and the flux burns. Once that happens you have to start over.

 

[wyzazz]

First, clean everything off with Bar Keepers Friend, then scuff the coupler and pot up with some sandpaper or emery cloth. Next clean the joint and coupler with some Isopropyl Alcohol or Laquer Thinner. Put the coupler in the pot and hold it level with the coupler facing down, I set mine on my SS Deep Sink to do this, put a ring of solder around the coupler and pour/squirt a little pool of flux on to the joint. If your coupler is falling out than brace that up as well.

Now begin to heat the COUPLER ONLY. Try to heat it evenly moving the torch around the coupler, by the time the coupler is heated the pot will be hot as well and the solder should begin to flow. I keep heating until I see the solder wick through to the other side of the coupler then I cut the heat and leave the joint to cool for 5 minutes or so.

Hope this helps...

 

[Huaco]

^^^^^^
This.
Should turn out looking something like this...

 

[Cement102]

I think I am burning the flux. Since I am using a half coupler I only have about 1/3 of an inch for the flame. Should input in a nipple or something to he's to get more distance. I am soldering on the inside and heating on the outside.

 

[wyzazz]

I think I am burning the flux. Since I am using a half coupler I only have about 1/3 of an inch for the flame. Should input in a nipple or something to he's to get more distance. I am soldering on the inside and heating on the outside.

I did 3 half-couplers last night, just focus on the bottom part of the coupler and put a pool of flux on there. Worked for me on this new 100qt kettle and multiple keggles.

 

[christpuncher123]

Sounds like The solder isn't sticking to the pot either because your material is dirty, or too hot! Remember that the material on the pot is way thinner than the coupler and is very easy to overheat! Focus almost all of your heat on the coupler, if you get the pot too hot it wont take!

 

[Cement102]

Ok, so I tried again tonight wiht everyone's suggestion to no avail. Sticks to the coupler beautifully, but not he put. So I cleaned up a portion of the exterior with a dremmel wire bit, fluxed and just tried to streak. No dice. Jut rolls off. I can almost get it to stick with no flux. The flux goes from liquid to black goo within 4 seconds of applying indirect heat to the back. I have done 100s of copper fittings and never heard of a flux that burns immediately and at a fraction of the solders melting temp. I see no way to met the solder without burning the stay-clean. Thoughts? The picture below shows a cleaned up area with a drop of flux. Applied heat 2 inches away on the back side. Flux burn in about 3-4 seconds and at nowhere nears he solders melting point.

 

[Huaco]

can you post a picture of the container the flux is in?

On a side note, are there any alloys of SS that are Non-soderable? (is that even a word?) lol...

 

[wyzazz]

Yes, let us have a look at that Stay-Clean container. Also, you shouldn't really apply any heat to the pot. The heat will transfer from the fitting to the pot. How thick/thin is your pot? Maybe it's too thin?

 

[OMJ]

Are you sure the kettle is SS and not aluminum?

 

[Cement102]

Thanks for everyone's help. Here is a picture of my flux. Also, as an update I took one of my corny kegs last night and sanded fluxed and just set a small bead. Flux still burns fast, but the bead was perfectly adhered to the keg. So the pot may be the culprit. I'm going to try to find a new cheapo as pot to do some experimenting & practicing on.

 

[Cement102]

Mystery solved! After pulling out the angle grinder and grinding some of the rim... No sparks. Non ferrous. Aluminum!!! I guess the mirror finish fooled me. Auyways, I'm going to pick up a cheap ss put to do some practicing on before attacking my nice 80 quart. Thanks for all the help!

 

[lorglath]

Just read this and had a chuckle and learned something, thanks for all of the posts everyone!