How To Convert a Retired Sanke (1/2 bbl) 15 Gallon Keg Into A Boil Kettle

March 10, 2008 at 11:11 am 16 comments

So my buddy Mike wanted a boil kettle, and since New Belgium practically gives away old kegs, I hooked him up. I also converted it for him, since I had the experience of a couple I converted for myself. Without further ado, here is the process:

Mike’s Brew Kettle

First off, materials:

  • $10-$100….1 old keg
  • $24-37……..1 weldless brass or stainless steel spigot (depending on how you roll, honestly it doesn’t make much of a practical difference, but some would argue)
  • $6…………….a short section of 1/2″ copper tubing
  • $1…………….a female threaded copper coupling (1/2″ Copper to 1/2″ MIP – to match the threads on the spigot)
  • $1…………….a 90 degree elbow (1/2″ copper)

And tools:

  • a 7/8″ hole saw (better yet would be a step bit)
  • a propane torch along with flux and lead-free solder for welding the copper
  • an angle grinder and appropriate metal-cutting blades (plan on using at least two per keg)
  • a drill

If your keg is still sealed (you cannot see into the keg from the top looking down), there’s a great youtube video by Bobby M with instructions on popping out the stem at the end or by clicking here.

After the stem is removed, it’s time to cut the top off of the keg. First, I gave a good rinse to get any sloshing beer out and then just filled it up a bit with water (just to cover the bottom) to hopefully cool down any flying shards of metal that land inside and keep them from sticking to the bottom. I found the best way to do the actual cutting is to butt your angle grinder right up to the side of the keg and use that as your guide. Last time I drew a circle and tried to follow it, but I ended up with a bunch of straight limes (think hexagon) insted of a circle. Here’s a visual:

If you watch the video at the end (Brewing with Bobby M), he makes a fancy jig just for this function, and I would recommend that if you are a real neat freak, but I got a pretty solid circle just by tracing the outside.

After the top is off, you need to sand the edges until you get all of the sharp points nice and rounded so you don’t lose a finger in your beer. I started with just emery cloth but ended up getting a grinding stone attachment for my drill, that sped things up quite a bit. You could also just use the grinder to smooth it out, but I found I didn’t have the degree of accuracy I wanted doing it this way.  Sand until you are confident it is child safe – not a dumb test.

So the top is beautiful and you aren’t going to die when you touch it. Now you need the hole for the spigot on the inside. I measured up 4 1/4″ from the bottom, just to match the last one I did. I have yet to find a standard measurement.

SIDENOTE: I want you to stop at this point and think hard about exactly where you want the spigot. I centered it between the two handles on the top, which I think was a good call.  The other part of this is if you are going to install a temperature gauge on the keg as well, think about your setup and where you want it to be. Most people just install the temperature dial directly above the spigot, but I installed mine to the side just because I wanted it to be low enough to pick up a temperature on relatively small batches. I wish that I would have installed the dial on my sparge tank 90º from the spigot. That way, I would have the spigot to the side (aimed directly at the mash tun) and the dial straight ahead so I wouldn’t have to lean over the mash tun to see the temperature.

Here’s where I’m going to drill the hole:

Hole Drilled

EXPLODING KEGS: You’ll notice above that on the bottom collar there is a hole there for drainage. If your keg does not have those, make sure to drill some on the bottom, otherwise you risk gas buildup and the eventual exploding keg.

After drilling the hole, again you need to sand it down so that it is not sharp. This is important because you will be putting an o-ring against this hole, and you don’t want it getting torn up.

That’s about it for the hard parts. The only other thing to do is to make the copper ‘L’ piece to go inside that goes from the inside of the spigot to the bottom of the keg to drain all the way to the bottom. This is just simple copper soldering. Cut your tubing the length you want it and then sand the edges to clean them (inside and out). Then put some flux all around the outside of the tubing and stick it in the fitting. Finally, heat up the fitting until the solder melts on contact to the copper (not directly in the flame). Make sure the solder fills all the way around the tube.

That’s basically all there is to it, it only took about 1 1/2 or 2 hours start to finish. It’s really easy and the best way to get into a 5 gallon or even 10 gallon boil with the addition of a propane burner.

APPENDIX – Using Your Brewpot:


  • a copper dish scrubber (find it at the grocery store)
  • teflon tape (in the plumbing section of the hardware store for a buck)
  • a stainless steel spoon, around 2 feet. Find a cheap one here.

After making the brewpot, you want to prep all the threads by putting teflon tape on all male threads ($0.99 at hardware stores). This will keep the threads from leaking: then put it all together in this order:

The spigot goes handle-side outside the brewpot, the threaded end through the hole in the keg (if you can’t figure that much out, you’re in trouble). On the inside, you’ll put on the O-ring, then the stainless steel washer, and finally the female threaded coupler. Coming out from that you will want the copper fitting you have soldered together screwed on, ending up facing down toward the bottom of the keg. It will look like this:

weldless spigot Inside of brewpot

Weldless Spigot on outside of Keg

Next time you’re at the store, pick up a copper dish scrubber. This will act as a screen for all the hops and trub (sidenote: it is pronounced ‘troob’) at the end of the boil. put this around the bottom of the copper ‘L’ fitting. When you get the scrubber, it has a hole right in the middle that is not very conducive to this project. Simply unroll the mesh and you will get something that looks like this and can be folded up and used as an effective screen:

Copper Mesh Filter

I recommend using a hop bag as well, to make sure you don’t get any clogs. There’s a great video for that:

You may think it’s overkill having two filters, but let me tell you – there is NOTHING worse than brewing all day, drinking a few homebrews on the way, getting tired, finishing the boil and opening your spigot to…nothing. I have had a couple clogged screens and that was enough.

Next you’ll want to test the setup for leaks, and while doing it, mark gallons as follows. Add water 1 gallon at a time (or 1/2 gallon at a time if you want to be more precise). At each point, mark on your metal spoon (and on the brew pot if you like) at the water level. This allows you to measure how much liquid you have left, allowing you to know when you get to your 5.5 gallon mark or whatever you are aiming for.

Now you’re ready to boil the beer! After the beer has boiled it’s course (60-180 minutes), you need to drain it out and cool it down before you pitch the yeast. The easiest way to accomplish this is to put your immersion chiller in the wort for the last 15-20 minutes of the boil to sanitize it, then chill it right in the brewpot. But, if you can’t get a water source to your propane setup like me, you’ll have to drain it into a bucket, take the bucket to where you have water access and then cool it there. If you are going to cool it in the brewpot, do that. If not, just keep reading.

Now before you drain the beer, it is best to create a whirlpool to get all of the hops and trub to the middle of the brewpot. Simply stir the wort in a circular motion getting it going as fast as you can, then let it sit for 10-15 minutes. After that, drain it through your already installed copper screen, and you will minimize the sediment that gets to the primary. This is why you put the copper ‘L’ drain on the side, and not into the middle. You won’t need to siphon because all that’ll be left is sediment. You’ll lose a little liquid, but not enough to make a fuss over. Just make sure to boil a little extra to make up for it. After you drain it, if you have not done so, cool it to yeast temperatures and pitch your yeast. If you are draining the beer while it is still hot (without cooling to yeast temperatures), you will need to use special heat resistant tubing, not just the nylon stuff you use for syphoning. You’re local homebrew store should have it.

It’s even easier once you get a pump and a counterflow or plate chiller. Then you just attach a hose from the spigot to the pump to the chiller to the fermenter, turn on the water and watch the magic work!

There you are! Enjoy using your brew pot (or as the cool people say, your keggle).

Other Good Links:


Entry filed under: Brewing Gadgets. Tags: , , , , , , , .

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16 Comments Add your own

  • 1. mikethehomebrewer  |  March 11, 2008 at 8:30 am

    Dude, that looks so amazingly awesome. Sweet howto also. I thought it was a 7.5G keg, so now I’m even more excited cause it’s twice as big. How much did you say it was to overnight that bad boy? 😉

  • 2. Alex  |  March 12, 2008 at 1:32 am

    you don’t want to know. I’m going to ship it today, I finally found a place open late enough.

  • 3. mikethehomebrewer  |  March 12, 2008 at 7:05 am

    Kick ass! Yeah, I’m hoping it doesn’t get held up somewhere. 🙂 Oh, email me what I owe you still for the mead and the rest of the brew pot stuff you added after I paypaled you for the keg.

  • 4. Update: How to Use Your Newly Converted Keg Brewpot «  |  March 19, 2008 at 1:32 am

    […] I also posted this comment with the keg conversion howto. […]

  • 5. Tim  |  May 9, 2008 at 1:53 am

    I am going to work on my keg today. Hopefully it goes well. Thanks in advance for the instructions.

  • 6. Ed  |  August 13, 2008 at 1:15 am

    Where can you get a keg from New Belgium? Do they advertise retired kegs on their website?

  • 7. Alan  |  August 22, 2008 at 1:28 am

    How long did it take to cut the top off the keg?

    What angle grinder blade type did you use?

  • 8. Steve Counts  |  February 28, 2009 at 5:49 am

    I was looking up above and see that you are able to get a keg for $15.00.
    Is that still true as of 2-27-09?
    And do you buy and ship for people who cannot get that type of deal?
    If so, where are you (for shipping purposes)and how would some one go about making the request to purchase a unit to convert?
    Please respond.

  • 9. Sparkes  |  March 24, 2009 at 5:23 am

    Is the keg aluminum? I thought you werent supposed to brew with aluminum because it leaves a metallic taste.

  • 10. jp  |  October 6, 2009 at 10:04 pm

    good article but didint cover how to release the pressure and drain all the old beer out without showering yourself with beer. any ideas? had considered shooting a hole in it but havent done anything yet

    • 11. Alex  |  October 7, 2009 at 12:41 pm

      I actually got my kegs with the top assembly already removed, so I did not have to deal with that problem. I have, however read posted instructions on how to let out the air and disassemble the connection parts of a keg. I can’t recall where I found that, but it is out there! Happy hunting!

  • 12. bazookoid  |  October 7, 2009 at 5:29 pm

    you can see how to remove the inner stem valve dealy here:

    it works like a charm! i am in the process of converting my first keg.. GREAT info!!

  • 13. new keggle - Home Brew Forums  |  December 28, 2010 at 3:13 pm

    […]… Has link to BobbyM's video, too. […]

  • 14. Mike S.  |  June 23, 2011 at 2:04 pm

    i just have one question, when measureing the hole for the spigot do you measure it from the very bottom of the bottom ring or where its welded to the ring on the bottom?

    • 15. Alex  |  July 27, 2011 at 9:19 am

      I measured from where the bottom plate is welded on.

  • 16. Keg to a Kettle, a newbies experience - Home Brew Forums  |  February 10, 2012 at 9:17 pm

    […] here is my experience so far of converting a keg to a kettle. Here is the guide i used.… After the keg was taken apart, i took a sharpie and drew a circle around the top. I then took a […]


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