Soldering a 1" Lock Nut to Sanke Keg, with Pictures

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Quaffer

Well-Known Member
Joined
Dec 9, 2008
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Location
Snohomish
Today I decided it was time to drill the hole in the keg and solder a lock nut to it. Enough anxious procrastination.

I center punched the location of the hole and drilled a 13/64" pilot hole. This was just the first reasonable bit I found.

Then on to the real drilling. A few days ago I bought a 1-1/4" hole saw for this project. I had been debating how to cool and lubricate the saw. I decided to use plain water. Someone else had done that here on HBT and it went well. I, however, did not have a helper nearby to spray water while I drilled, so I filled a coffee can with water. I dipped the saw in the water and leaned fairly hard on the drill. I tried to go slow and it was mostly successful. At the first sign of steam, after 4-6 seconds of drilling, I stopped and dunked the saw again. It took about five minutes to finish with the hole saw. The saw had wobbled a little so the hole was slightly larger than 1-1/4".

I dressed the hole with a half-round file and now it was closer to 1-5/16" than 1-1/4". It turned out to be a good size though. Here's a picture of it at this stage.

Brewing_025.JPG


I needed to practice before doing the nut. Two years ago when I converted the keg I had silver brazed three steel tabs on the lid to hold it in place while I was heating the runoff. The tabs were a little too short so the lid did not stay on very securely. I decided to add the "washer" I had just cut out of the keg. I sanded it with 180 grit emery cloth, also the lid got this treatment. After that I wiped them down with acetone. Then, after three (3) hours of looking, I finally located the Stay Brite #8 solder so I could continue. I even went to work to look for it. Sigh. :rolleyes:

I worked at the front of the garage with the double door open. I applied liquid Stay Clean flux with an acid brush from the welding supply store, both to the washer and to the lid.

I heated with a MAPP torch, first several inches away from the washer, then progressively circled in closer. The flux boiled and started to turn color. Before the solder would melt the flux had turned as dark as stout. I applied a second dose of flux wich cleaned up much of the burnt flux. After a little more heat the solder flowed easily and I quit.

After several minutes of cooling I wiped down the lid with a wet rag. It removed most of the gunk. The next picture shows the lid after the wipe down. On the left you can see a small cup I used to hold a little flux and the brush.

Brewing_032.JPG


The next picture shows the bottom of the lid. The solder had flowed fairly well also here. You can see an area a couple of inches beyond the washer where I had applied too much heat.

Brewing_0341.JPG


Next I cleaned up the hole in the same way with emery cloth and acetone. The lock nut is cast and has a rough surface; it is almost impossible to get it super clean with emery cloth. It would turn out well anyway. It got the acetone wipe down, and here it is prepped and ready for flux.

Brewing_037.JPG


The nut was a lot harder to solder than the washer. I had to walk around the keg to get to all six sides. The flux discolored even more this time. I applied a liberal second dose of flux which helped a lot to clean it up. Solder melted and flowed in under the nut. A couple of places needed more persuasion with a third application of flux, but that did the trick.

I had to move the nut back to the center of the hole several times because I had bumped it. It would be better to clamp that nut in place for soldering.

I let it cool a little less this time and got after it with a wet rag while it was still hot enough to sizzle. Much gunk came off this way. Then I used a small stainless steel wire brush from BernzOmatic. It cleaned the solder joint beautifully and gave it a burnished look. It did not touch the dark flux stains though.

The next picture shows the keg being leak tested. It was water tight. All the joints looked good but there had been a few runs and other mishaps farther from the nut. You can still see the dark flux stains. The solder filled the larger gaps on the left and right sides well. The gaps are larger here because of the curvature of the wall. This is a feature of the Stay Brite #8 solder; it fills large gaps better than the standard offering. Supposedly it is so because it has 6% silver while the standard version has 4%.

Brewing_0521.JPG


After an hour and no leaks I declared it a success. I got out the emery cloth and it easily removed the flux stains.

Brewing_064.JPG


After this picture was taken I used a cold chisel and removed a few errant solder blobs. Now I need to re-passivate (?) the surface where I sanded. I don't remember what to use, but I think it is an acid of some type.

So in summary, I think the MAPP gas torch is overpowered for this application. Perhaps that is why I had such hard time with the flux burning. It did the job though.

This method creates a compact installation of the heater element. If it is leak free in the first test, it should remain so for a very long time.

I wouldn't call this easy, but after some practice it will become easier.
 
Yes, thanks for sharing this. I really want to try this for attaching the elements in my system...when I progress that far that is.
 
Finally, a project that seems to be in line with my own soldering skills. Great job, and thanks for sharing.
 
Lookin good! It takes practice but its such a good feeling when you get a nice joint!
 
I experimented a lot with the flux doing multiple test solders. I really don't think it's the MAPP gas that is to blame. I had the same results with propane and being very particular with my technique. In order to avoid the flux from burning I found heating the parts quickly and thereby melting the solder quickly worked the best. As soon as the solder melted I would quickly remove the heat and cool the part with water which removed a good deal of the burnt flux. Heating it slowly seemed to worsen things for me. Additionally, having a shallow "film" of flux burnt much more easily compared to a small pool of it. In most instances it was impossible to keep the flux from burning and I used the same technique to prep with acetone/sanding etc.

In the end the burnt flux is removed with sandpaper and it works great for our purposes.
 
I experimented a lot with the flux doing multiple test solders. I really don't think it's the MAPP gas that is to blame. I had the same results with propane and being very particular with my technique. In order to avoid the flux from burning I found heating the parts quickly and thereby melting the solder quickly worked the best. As soon as the solder melted I would quickly remove the heat and cool the part with water which removed a good deal of the burnt flux. Heating it slowly seemed to worsen things for me. Additionally, having a shallow "film" of flux burnt much more easily compared to a small pool of it. In most instances it was impossible to keep the flux from burning and I used the same technique to prep with acetone/sanding etc.

In the end the burnt flux is removed with sandpaper and it works great for our purposes.

That is good input. Maybe it is supposed to turn color? It works OK so why not. The hardest part of the job for me was to clean out the burnt flux to get good adhesion, all while the hot nut slid around like a hockey puck. I will definitely try to clamp it down next time.
 
Actually, flux removes flux. You can get a bit on the cloth and wipe it down. Works great...but you need to wait at least 60 secs so you don't disturb the joint.
 
Does lacquer thinner remove the burnt flux? If so I would rather do this than use sandpaper.

Yes especially when using soldering paste or rosin-core solder that has become a brown and black tar just requires a little rubbing with a soaked rag.
I prefer to clean it off than scratch up the solder and base metal, like plumbers with a damp rag wiping a joint for that clean professional look.
 
I experimented a lot with the flux doing multiple test solders. I really don't think it's the MAPP gas that is to blame. I had the same results with propane and being very particular with my technique. In order to avoid the flux from burning I found heating the parts quickly and thereby melting the solder quickly worked the best. As soon as the solder melted I would quickly remove the heat and cool the part with water which removed a good deal of the burnt flux. Heating it slowly seemed to worsen things for me. Additionally, having a shallow "film" of flux burnt much more easily compared to a small pool of it. In most instances it was impossible to keep the flux from burning and I used the same technique to prep with acetone/sanding etc.

In the end the burnt flux is removed with sandpaper and it works great for our purposes.

After doing a few kegs now, I have a method that works well for me. Pre-heat about a 1 square foot area of the keg where you're going to solder. If you get this up to like 200F, it won't be sucking heat away from the joint once you focus the heat there. Slowly work the heat closer and closer to the joint but never put the flame directly on the area that's fluxed. Basically the MAPP flame is way hotter than flux can take, but the 430F melting point of the solder is not.

If you do burn the flux and you notice it's fouling up your work, drop some flux on it and it will clean up even if you're done applying the solder.
 
+1...I find it helps to keep the flux in a medicine dropper (clearly labelled flux)....that way you don't go putting a brush on the hot surface and potentially melt the brush/foul the joint.
 
Acid brushes are made with hair not nylon, no melting of contamination problems just the brush into the torch flame this a hand eye control problem.

My radiator repair shop friend always takes a acid brush and applies acid to a wet joint to quick freeze it without any problems for over 50 years resoldering thin brass tubes to tank bases.
 
What do you use on the threads of the heating element to insure there's no leak from the threads? Or do you just use an O-Ring between the element and the lock nut?
 
Okay, I see...
So how will you cover up your electrical connections to insure they don't get accidentally pulled off or splashed?
 
Okay, I see...
So how will you cover up your electrical connections to insure they don't get accidentally pulled off or splashed?

There are different methods for this. One popular method that I will be using is to place on a 3/4 PVC coupler and fill this with potting compound. You will see pictures of them on various electrical threads. Another method is detailed by Kal at the electricbrewery.com.
 
There are different methods for this. One popular method that I will be using is to place on a 3/4 PVC coupler and fill this with potting compound. You will see pictures of them on various electrical threads. Another method is detailed by Kal at the electricbrewery.com.

In regards to the method detailed by Kal at electricbrewery, is it possible to use that method with this sort of set up (a lock nut welded to the outside of the keg)?

I'm having a keg custom made for me to use for my HLT and I'm trying to decide what kind of fitting to have welded on. I really want to make a nice clean electrical box around the element like Kal's, but I'm not sure if I'll be able to do it with a simple 1" locknut welded to the outside of the keg? The other option would be to use a threaded coupler like OhioEd's set up here: (https://www.homebrewtalk.com/f170/e-hlt-help-202955/)?
 
In regards to the method detailed by Kal at electricbrewery, is it possible to use that method with this sort of set up (a lock nut welded to the outside of the keg)?

I'm having a keg custom made for me to use for my HLT and I'm trying to decide what kind of fitting to have welded on. I really want to make a nice clean electrical box around the element like Kal's, but I'm not sure if I'll be able to do it with a simple 1" locknut welded to the outside of the keg? The other option would be to use a threaded coupler like OhioEd's set up here: (https://www.homebrewtalk.com/f170/e-hlt-help-202955/)?

Kal's setup is for weld-less. I don't know how much you must change his plan to work for your welded nut.

If you want a welded nut then Tiber_Brew has it figured out in this post. Look at the last picture in that post. The element is inside the box, the gasket must be going through the box to seal against the welded nut. He probably tightens down the element until the box is sandwiched between the element and the nut, but you will have to get the details from him.

Come to think of it, using a box like that would cover up my solder runs. :D
Meh, I want a nice clean PVC fitting. ;)
 
I used a 1" SLB conduit elbow....it makes for a nice install. Takes a little work, but it was totally worth it :mug:
 
Kal's setup is for weld-less. I don't know how much you must change his plan to work for your welded nut.

If you want a welded nut then Tiber_Brew has it figured out in this post. Look at the last picture in that post. The element is inside the box, the gasket must be going through the box to seal against the welded nut. He probably tightens down the element until the box is sandwiched between the element and the nut, but you will have to get the details from him.

What I did was weld the 1" locknut with grove facing out on the outside of the keg. Then drill a 1.25" hole in the aluminum box, slide the element into the box, and slide the supplied rubber gasket (NOT THE RED O-RING) on after that. So, you have the keg, locknut, black gasket, box, element, in that order. I also used teflon tape on the element threads. The gasket forms a seal between the box and the locknut (inside the groove to keep it from rolling or slipping), and the element is in direct contact with the box, providing a good bonding path for ground. Absolutely zero leaks, no silicone, and many tests + 5 batches so far.

Let me know if you need any more clarification or pictures.

TB
 
What I did was weld the 1" locknut with grove facing out on the outside of the keg. Then drill a 1.25" hole in the aluminum box, slide the element into the box, and slide the supplied rubber gasket (NOT THE RED O-RING) on after that. So, you have the keg, locknut, black gasket, box, element, in that order. I also used teflon tape on the element threads. The gasket forms a seal between the box and the locknut (inside the groove to keep it from rolling or slipping), and the element is in direct contact with the box, providing a good bonding path for ground. Absolutely zero leaks, no silicone, and many tests + 5 batches so far.

Let me know if you need any more clarification or pictures.

TB

Thanks, that's what I'm hoping I'll be able to do. Did you have enough clearance of the box away from the wall of the keg? I worry that the box would hit the raised ridge that wraps around the keg wall?
 
Did you have enough clearance of the box away from the wall of the keg? I worry that the box would hit the raised ridge that wraps around the keg wall?

No issues there. Browse my thread for pictures of the element box; you might get a good look at it there. Let me know if you need me to take a better picture.

TB
 
Thanks, I've read through your thread and your build is awesome! Nice work. I'll be stealing ideas from you as I upgrade my system in the near future:)
 
Hey Quaffer, where did you source the lock nut you used? I am a long way from the east coast, but not that far from Snohomish, here in snowy (???) Renton.
 
i have been using 1" couplings from bargain fittings, butt-soldered to kegs with great success. even though they are bigger, i think they are easier to solder than a lock nut. i'll take pics the next time i solder one, but basically cut your hole with a step drill bit, clean up the areas to be soldered with 220 grit sand paper, and solder away. the harris stay-clean (i think that's the stuff) works miracles.
 
Hey Quaffer, where did you source the lock nut you used? I am a long way from the east coast, but not that far from Snohomish, here in snowy (???) Renton.

Hello from snowy Snohomish, (almost) neighbor.
I found the nuts at bargainfittings.com.
My kids were out of school today and again tomorrow, on account of inclement weather. I was home on a snow day as well, but tomorrow it is back to the grind for me.
 
i have been using 1" couplings from bargain fittings, butt-soldered to kegs with great success. even though they are bigger, i think they are easier to solder than a lock nut. i'll take pics the next time i solder one, but basically cut your hole with a step drill bit, clean up the areas to be soldered with 220 grit sand paper, and solder away. the harris stay-clean (i think that's the stuff) works miracles.

I'd be very interested in seeing pictures of this. Yes, the Harris Stay Clean is what I used as well.
 
I can't believe it was November when I did the last one. High time for an update.

The BK got a 1" nut today. It is a Bayou 62 quart s.s. stock pot. I got it for its flat bottom because I plan to whirlpool in my next brewery.

Wise from my last attempt, this time I clamped the nut in place. I used a ratchet tiedown and a piece of scrap wood pushing on a faucet wrench. The wrench was a perfect fit, half is underneath the nut, half is above. This way the nut could not slide out of place. It worked great. In this picture I am finished soldering, ready for cleanup.
SolderNut6.JPG


Close-up of soldered nut before cleanup.
SolderNut7.JPG


After cleaning up with warm water and a dish brush, then a wet rag with Bar Keepers Friend.
SolderNut8.JPG


Different side of cleaned up nut.
SolderNut9.JPG


This time I used a propane torch instead of the MAPP gas torch I used last time. It was a much better experience. I recommend using a propane torch for this work. Things worked smoothly and there was not much burning of the flux. Of course, I have a lot more experience this time which accounts for some of the easier soldering, but still, I think propane just works better.
 
How has the durability of this solder been? It seems a lot like brazing and I wonder how the durability is compared having it welded?

What kind of solder did you go with this time?
 
How has the durability of this solder been? It seems a lot like brazing and I wonder how the durability is compared having it welded?

What kind of solder did you go with this time?

I used all the same stuff as last time, save the propane. Solder is Stay Brite #8.

I can't speak to the durability of the solder. I have heated water only a few times in the HLT (so far so good) and none in the BK.
 
The only difference between soldering and brazing as far as I know is temperature required. The filler material always has a lower melting point than the two materials being joined.
 
I used the same solder on my keg to fasten the 1" locknut and the other fittings. After probably 20 batches they are holding up great. To braze the fittings you need to get an actual brazing material, which basically has more silver in this application. The technique is similar, but the key is that the brazing rod will have a much higher melting point than the silver solder. I tried brazing one of the fittings on my system, and after about an hour of messing aroung with mapp gas I decided it wasn't worth the trouble. If the solder fails I'll just weld the fittings in, but right now it's holding up excellently.
 
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