Used Sanke keg. SS or aluminum?

[winvarin]

I was at my LHBS recently and they had a couple of used 15.5 gal sankey kegs. I am in the process of gathering materials for a Brutus 10 build and have been scouring the area for used kegs for kettle/mlt/hlt.

One was from Miller. The other, I think, was a Boulevard keg. Both were a bit lighter than I had expected when I picked them up.

Before I plunk down the money on them, is there a way to tell if they are aluminum or SS? Or are all kegs SS? No experience in buying these used so I want to make sure I don't get steered wrong.

 

[Schnitzengiggle]

Most kegs are stainless steel, much older kegs may be aluminum, you might just be stronger than you think .

 

[Hex]

Magnet.

 

[winvarin]

heh. I think I just lost what miniscule amount of science cred I had

 

[Brandonovich]

Magnet will not stick to either - ?

 

[Ace_Club]

Magnet will not stick to either - ?

Yeah, I think the magnet theory has been busted on this forum several times over.

 

[Schnitzengiggle]

Magnet will not stick to either - ?

Correct.

 

[JetSmooth]

Magnet,

Y U KNO STIK TO METALS!?

 

[Schnitzengiggle]

If anyone is interested in develooping a brass magnet, I am all ears.

 

[Golddiggie]

Just out of curiosity I tested on one of my 1/6 barrel Sanke kegs with a magnet pulled from a hard drive. There is enough of a pull to notice. I also tried with another magnet (fridge type) and got no pull at all. So, if you have any rare-earth magnets on hand, you can test with them... Otherwise, look for markings on the kegs. But, if they're Sanke style, they should be stainless steel... If they look ancient, and have a bung hole in the side, it could be aluminum.

 

[dutchoven]

Find a hidden edge, like near the handles, and test it with a file. If its aluminium, you'll be able to remove a decent amount of material with minimal effort.

 

[winvarin]

well. now I am completely confused. They had 2 kegs and I went to test them at lunch. I had a magnet with me and it didn't stick. So is the file method going to be my best bet? They have them at a pretty decent price and I would like to pick them up if I can be sure they are steel

 

[Hex]

Fridge magnet sticks noticeably to all my stainless...

 

[L0stm4n]

Weak magents won't stick to my stainless kegs. The magnet out of a hard drive will have some pull but not enough to stick.

 

[winvarin]

I am pretty sure they're stainless. I called a different LHBS, one that I know to be run by an ex pro brewer. I described the kegs and asked him if there was a way to tell. He recommended the scrape test (screwdriver or file) but said to his knowledge, almost nobody uses aluminum or hasn't for some time anyway. He asked what breweries they were from and said that he was "99% sure" that they were stainless.

 

[Schnitzengiggle]

bung hole.

You said bung hole, awesome!:rockin:

 

[Golddiggie]

Fridge magnet sticks noticeably to all my stainless...

I just tested the same fridge magnet on my stainless steel pot (16qt) and it won't stick at all... Zero pull to the pot too.

I do know that there are different grades of stainless as well as too many stainless steel alloys to swing a dead cat at..

You said bung hole, awesome! :rockin:

Ok Beavis... heheh heheh heheh heheheheheheh
Or are you The Great CornHolio!?

 

[SamuraiSquirrel]

I have several miller kegs all of which are stainless. I have never seen an aluminum miller keg or any other modern day keg for that matter.

 

[Golddiggie]

Pretty sure any Sanke style keg will be stainless... The OLD style kegs might not be... I don't see any material composition markings on the Sanke kegs I have...

If you have any rare-earth magnets on hand, use one to test it... Otherwise, I would say that if it's a Sanke, then it's stainless steel...

 

[Raider-11]

The most popular stainless steel is Type 304, which contains approximately 18 percent chromium and 8 percent nickel. At room temperature, the thermodynamically stable crystal structure of 304 stainless steel is bcc; nevertheless, the alloy's nickel concentration, as well as the small amounts of manganese (about 1 percent), carbon (less than 0.08 percent) and nitrogen (about 0.06 percent), maintains an fcc structure and therefore the alloy is nonmagnetic. If the alloy is mechanically deformed, i.e. bent, at room temperature, it will partially transform to the ferritic phase and will be partly magnetic, or ferromagnetic, as it is more precisely termed.

Popular ferritic stainless steels are iron-chromium binary alloys with 13 to 18 percent chromium. These alloys are ferromagnetic at room temperature. Like all ferromagnetic alloys, when heated to a high enough temperature--their Curie temperature--the ferritic stainless steels lose their ferromagnetism and become paramagnetic--that is, they do not retain their own magnetic field but continue to be attracted to external ones.

 

[Golddiggie]

So we now know who the metallurgist is of the members here.

I know just enough to be dangerous. Mostly from when I was making knives and would compare the alloys there to get the best steel I could.

So, from the info Raider-11 posted, it sounds like Sanke kegs are cold (or room temp) formed. Makes sense, all things considered. Not sure if the tops are cold or hot pressed, but I would suspect some heat is generated in the process. You can see the weld lines in them, but it's hard to tell if it's just the collars/guards that are welded, or if the tops are too. I can see the weld lines for the spear openings.

I haven't checked my corny keg to see how magnetic it is... Not that it matters much, since we know those are stainless...

 

[Hex]

...If the alloy is mechanically deformed, i.e. bent, at room temperature, it will partially transform to the ferritic phase and will be partly magnetic, or ferromagnetic, as it is more precisely termed....

Yeah, what I said.

 

[winvarin]

I won't even pretend to know much more about metal than it's usually sturdy and can be shaped into stuff. I brought a file with me today and am going back by the shop today and will scrape it. (I can never quit this job. I can be to my LHBS and back during lunch and still have time to eat)

If it scrapes a lot, I will assume it's aluminum and "maybe" not buy it (I read one of the aluminum vs. SS rant threads yesterday and am not convinced that brewing in aluminum will kill me or cause me to forget where I left my car keys. But that's another subject for a different thread)

If it barely scrapes at all, I will definitely buy it. The price the guy is asking is ridiculously low. Even buying all the after market fittings and valves, I will likely be able to beat the price of a reconditioned keggle online by about $100 or more.

 

[Raider-11]

Winvarin

Did you find out what metal the keg is?

 

[winvarin]

I could barely make a scrape in it with a file and all the research I could find indicated that aluminum kegs are becoming more and more scarce. While not empirical evidence, I used that to be confident enough to spend $40 each on the kegs.

Now I just have the guy on the lookout for one more

 

[Raider-11]

Thats great and happy brewing.