Cut / Weld Two Kegs for Increase Capacity?

The boil over on my 10 gallon batch yesterday got me thinking...
Anyone ever tried cutting two sanke's and welding them together to get a 20 or 25 gallon kettle? Seems like it could be done fairly easily. Anyone see any problems with this approach?

thegreatgumbino said:

The boil over on my 10 gallon batch yesterday got me thinking...
Anyone ever tried cutting two sanke's and welding them together to get a 20 or 25 gallon kettle? Seems like it could be done fairly easily. Anyone see any problems with this approach?

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I think the biggest problem is getting the cut ends square. Every thing else IMO is pretty easy if you have the patience. If you had the kegs laser cut you would be a lot further ahead. A few passes with a nice new file and then prep the outside and inside. Use a large hose clamp with holes in the band to hold things together and tack it up. You'll have the spigot hole to feed the inside with the purge gas. I would not cut the top off of the top keg until it was all welded up. This will help you in just needing to cover up a small section for the purge. Just a small hole at the top is all you'll want.


Edit: It might be a bit top heavy when it is full. A good solid base will be needed.

I don't think that is a good idea. However, try it anyways and post the pics while I wait in anticipation.

IMHO it seems like a lot of work/time/expense for a problem with a simple solution. Grab yourself some fermcap.

It's a bit of a pain in the ass. I've welded Cornelius kegs together, and I didn't enjoy the process one bit. Squaring the cut is terribly tedious, as GreenMonti says. I also found that butt welding thin stainless is not an easy task.

By the time you buy two kegs, cut them, square them, purge them, and weld them, it will have been worth a few extra bucks to just buy a bigger kettle (or use foam control drops like lackey suggests).

Yuri_Rage said:

It's a bit of a pain in the ass. I've welded Cornelius kegs together, and I didn't enjoy the process one bit. Squaring the cut is terribly tedious, as GreenMonti says. I also found that butt welding thin stainless is not an easy task.

By the time you buy two kegs, cut them, square them, purge them, and weld them, it will have been worth a few extra bucks to just buy a bigger kettle (or use foam control drops like lackey suggests).

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+1 - Totally agree with Yuri_Rage and GreenMonti.

to help with getting the cut square take your measurements around the keg and use tape to make a cut line. then follow the tape around with a cutoff wheel.

A keg is already a little too tall and skinny for good heat transfer and that would only make it worse. I'd buy a 20 gallon aluminum kettle before I asked a welder to do a 50" long TIG bead. You can seal up your drains on the top skirt to contain some boil overs.

Of course, I'm just one of those dream killing naysayers so don't listen to me.

I had another thought about this. Sanke kegs are not true in diameter all the way down. I am not just talking about the obvious places where there are bulged out bands. In between those bands the keg measures different diameters. On the one keg that I measured I got a difference of about .030" in diameter. That's a lot when your trying to weld them back together, with material that is only .040" thick to begin with. Trust me, purge/sanitary welding with miss match is a real PITA to make the inside nice and not get linear indications. If you happen to have a pie die handy (There is no way.....plus the shoes cut for the diameter) you could negate this problem.

When I measured the diameter of the keg I used a pie tape. This way I was absolute in the diameter measurement. If you happen to have a set of calipers that big you will get close but not dead on. After all the manufacturing process, the kegs aren't round anymore.

On the heat transfer, IIRC boilers are made tall and narrow cause it is a better design. I can't remember exactly why at the moment........I guess it also depends on how you plan to fire the kettle.

try aiming a small fan at the boil to help with boilover

Could you 'upgrade' to an old water heater? No welds necessary and it's still a tinkerer's project.

Fermcap imo

Depending on the different brands of keg manufactures and this includes keeping them all within same brand and brewery like working with all AB kegs only, the locations where your planning to cut the kegs the circumference differences will vary from 48 7/8" to 49 9/16" with AB kegs alone. Also with the same keg be it at the center weld area vs just above or below the roll rings from 1/4" to 7/16" difference in diameter alone that comes out as 0.785" to 1.374" in circumference. Add this to wanting a clean same diameter butt weld, see the problem your encountering or creating? Add to this once cut apart they warp all to hell from the original forced rolling process and will not be round. Your dealing with stainless that will fight you all the way with not wanting to be sprung into a round like working with dead soft aluminum or copper. Add your high level of time, labor, welding, frustration possible failure with two or more kegs destroyed you up to the challenge of creating big headaches? JMO as I cut a couple AB kegs apart as a large Bio Filtering tank for the Koi pond, this did not require clean looking or butt welds. There're many larger volume kettles available on the market if you weigh in your labor and materials building your own. I went thru this pond project 7 years ago plus add the reduction of availble free or cheap kegs these days. Not to stop or spoil your idea just that i've been there in the past. Good luck with your project especially getting perfect butting of the two kegs to weld should you have a matching set of keg circumferences alone. The only way to cut them for a perfect butt weld would be on a lathe which would not work being they are not perfectly round or a Bridgeport mill with a rortary table and tailstock support with mounting jig discs at both ends to support and slowly rotate with feed control with a carbide end mill that can be shattered plus not cheap.