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Homebrewing beer and galvanic corrosion

by coktail
Tags: beer, corrosion, galvanic, homebrewing
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coktail
#1
Jan16-14, 10:00 AM
coktail's Avatar
P: 118
Iíve started home brewing beer recently, and Iím assembling equipment for my first 5 gallon batch. The technique Iíll be using requires me to put grains into a nylon bag and then steep that bag of grains in hot water (approx 160į), much like a giant teabag. The trick is that the bag cannot touch the bottom of the stainless steel pot Iím using or I risk scorching the nylon bag. The typical way to avoid this is to put something between the bottom of the pot and the bottom of the bag. Often people will use a perforated pizza pan, such as this: http://www.foodservicewarehouse.com/...354/p7325.aspx

People will then put nuts and bolts through some of the holes in the pan to act as legs, which raises the pan slightly from the bottom of the kettle. The bag can then rest safely on the pan without risk of touching the bottom of the kettle and scorching.

However, this pan is aluminum, and my kettle is stainless steel, as are the recommended bits of hardware with which to make the legs. Iíve been doing some reading about galvanic corrosion, but I havenít been able to get a clear answer from the homebrew forums about wether or not this would be a problem for me. It seems like the metal could corrode over a long amount of time, but even if I take care to minimize this, Iím still worried about impurities getting into my beer. Iíd really just like to avoid any sort of nasty chemical reaction at all if possible.

I cannot for the life of me find a stainless steel perforated pizza pan. Of course theyíre available unperforated (just my luck), but I donít really feel like drilling hundreds of little holes into a non-perforated pan such as this: http://www.amazon.com/dp/B000SSVP5S/...I236KU0W4X222M

There is another option Iíve discovered which Iíve never seen mentioned on the homebrew forums, and thatís to use a steel-plated grill grate, such as this: http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

Iím not sure if steel-plated is good enough, or if it needs to be solid steel. Iím assuming that the steel used here is stainless, but I donít know for sure.

Lastly, some people will use a steam rack such as this: http://www.amazon.com/dp/B007WAC8H4/...=IQ4QURPIFT9B0

These are chrome-plated, and I donít know if thatís any better or worse than aluminum or steel-plated.

Any and all advice is greatly appreciated. Thank you!
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Lmuggs
#2
Jan16-14, 12:36 PM
P: 1
I'm going to assume you are using the brew in a bag technique and not just steeping specialty grains for an extract brew. If that's the case, I would get the water to 160 degrees without the bag or grains in the kettle and turn the flame off. Then add the bag and grains, stirring well and let it sit. If you need to raise the temperature (and you most likely will for an hour long mash in an un-insulated kettle) turn the flame on very low and stir. Stirring is key. If you wanted to add something to the bottom of the kettle to protect the nylon bag, maybe a stainless steel false bottom like this (this might be too big, not sure what size kettle you are using): http://www.northernbrewer.com/shop/a...-no-elbow.html or what about using a SS vegetable steamer basket that doesn't have the middle post like this: http://www.amazon.com/Norpro-176C-St...dp/B000LNP4C0/
coktail
#3
Jan16-14, 02:27 PM
coktail's Avatar
P: 118
You assume correctly! I am doing BIAB.

I have heard that stirring help to avoid scorching the bag, or that you can simply lift the bag while the heat is on. Or I could simply wrap my kettle in a blanket to keep the heat in during the steeping process.

Still, I’m interested in having something in the bottom of the pot just in case. Better safe than sorry, I say. The steamer you linked to is another good option, but I haven’t been able to fine one of the proper size. The other product you linked to looks good, but it’s $50, which is more than I’m hoping to spend.

Ultimately my question is about galvanic corrosion and whether it will occur with a stainless steel pot and an aluminum object inside of it. OR, if corrosion will occur between stainless steel and an object coated with a steel alloy, such as this: http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

Thanks for your response!

Borek
#4
Jan16-14, 03:40 PM
Admin
Borek's Avatar
P: 23,581
Homebrewing beer and galvanic corrosion

Galvanic corrosion requires both metals to be in electrical contact, so any insulator that will separate metals and survive the temperature (glass, plastic) will guarantee you are on the safe side.


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