Brass compression fittings, ok to use in the boil?

I initially posted this in the DIY forum this morning but no one has even looked at it so I thought maybe I should move it over here.


I built an immersion chiller using 1/2" copper tubing but wasn't able to find a tubing bender for 1/2" (other than the crappy spring one that just smashed the tubing). So I decided to use some 3/8" tubing and brass compression 1/2" to 3/8" reducers so I could get the bends I needed. My question is, is it safe to use brass in the boil? I searched and couldn't find anything that specifically said brass was being used in the boil, just want to be safe.

Thanks.

IMHO gleaned from past experience in different varied applications, compression fittings are not a great choice for critical applications as the compression nuts can crack and fail if overly tightened. The brass itself is not so much of a problem.

i have some compression nuts in my keggle, no problems in the many many boils i've had in them.

Yup, like I said, they can crack when overtightened. They may not ever fail, it just is a potential failure point. Be aware of it is all.

Well they're already leaking, I just figured I didn't tighten them enough. I've used them on my misting system in the back yard without issue but if something leaks out there it's no big deal, if it leaks in my beer I'd be a little upset! Maybe I'll just return all the compression fittings and learn how to sweat fittings on to the copper, then I wouldn't have to use the 3/8" tubing.

If you can use a propane torch you can sweat a copper joint. Just make sure you have a lead-free solder and use plumber's flux.

I. Use flare fittings for wort chillers. You will need a flare tool. Home Depot sells the fittings, flar tool, and a lever tubing. Bender. If course by the time that you buy all that you could have just bought a pre add wort chiller.

krackin said:

IMHO gleaned from past experience in different varied applications, compression fittings are not a great choice for critical applications as the compression nuts can crack and fail if overly tightened. The brass itself is not so much of a problem.

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Compression fittings (mostly Swagelok) are used in pretty much every R+D lab, I use them for hydrogen electrolyzers and fuel cells on a daily basis. They work great and are incredibly quick and easy to use, and very reliable as long as you know how to use them. Yes they can fail if overtightened, but most things in this world don't work if they're used improperly. They're good to very high pressure (1000 psi for the lower end I think), and much quicker and easier to work with than alternatives (say, NPT).

Brass is ok in a boil, but the surface may release trace amounts of lead. If this concerns you, it can be "cleaned"

From Palmer,

"Some brewers use brass fittings in conjunction with their wort chillers or other brewing equipment and are concerned about the lead that is present in brass alloys. A solution of two parts white vinegar to one part hydrogen peroxide (common 3% solution) will remove tarnish and surface lead from brass parts when they are soaked for 5 minutes or less at room temperature. The brass will turn a buttery yellow color as it is cleaned. If the solution starts to turn green and the brass darkens, then the parts have been soaking too long and the copper in the brass is beginning to dissolve, exposing more lead. The solution has become contaminated and the part should be re-cleaned in a fresh solution."

All of this would be so much easier if I could just find a 1/2" tubing bender!

I don't mean to imply that you can't use compression fittings, just be careful when installing them, test the chiller and slightly tighten any leaking fittings. Repeat as needed. What you don't want is a sudden failure diluting your wort. If you are not happy with the results it isn't a problem to repair. You should also try to avoid the 3/8" restriction for maximum performance. Granted it would increase velocity on the supply side but reduce flow at the waste side for no realistic gain.

I actually managed to find a 1/2" tubing bender at Harbor Freight. The bends aren't very pretty but it got the job done.

I have a bit of experience in the Navy with compression fittings and I have built testing rigs for hydrostatic tests at very high pressures. My general rule of thumb is not to tighten a compression fitting more than one quarter of a turn past finger tight. Tighter than this risks damage to the fitting and subsequent leakage.

Just my .02

RuffRider said:

I have a bit of experience in the Navy with compression fittings and I have built testing rigs for hydrostatic tests at very high pressures. My general rule of thumb is not to tighten a compression fitting more than one quarter of a turn past finger tight. Tighter than this risks damage to the fitting and subsequent leakage.

Just my .02

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Yup. When initially "swaging" a swagelok/parker compression fitting onto a tube, the recommended procedure is to go finger tight, then an additional 1.25 turns (for plastic tubing or smaller than 1/4", 0.75 turns). If you're tightening a fitting with the ferrule already in place, 1/8 to 1/4 of a turn past finger tight is all you need. The dual-ferrule fittings, like Swagelok, are a little different than standard compression fittings you get at a hardware store.

I've done this with stainless, copper, PFA, Teflon, Nylon, etc. For bigger metal tubing (1/2"+ OD) you can get a swaging tool that you use to set the ferrule ex-situ, so as not to damage the compression nut. As long as you don't overtighten, they're awesome.