using alum. propane tanks

So I was wondering if someone knew anything about this. I have access to aluminum propane tanks, like the ones they use on fork trucks, they probably hold around the same volume as a keg, and I would like to use them for my home brew set-up in place of kegs because they are extremely available and very cheap. So I guess my question is; being that they held propane, is this going to contaminate anything? I would of course give the tank walls and good cleaning and sterilization, but I don't know how porous aluminum is and being that it was pressurized with propane if any significant propane traces could be soaked into the walls of the tank. Any comments would be appreciated. Thanks.

and I apologize if I posted this in the wrong section, I couldnt decide between this and the equipment section.

Short answer: I have no idea...

Longer answer: ... but propane is pretty volatile so I would guess that you'd be ok as long as you gave them an excellent clean and boiled a full batch volume's worth of water for an hour. That should clean it up and build up an oxide layer on the inside. I suspect that any residual propane would boil off and leave under all that heat, and you'd be left with a decent oxide layer to keep your beer off the aluminum.

That is to say, I would use one to make a keggle. I don't think you could actually convert such a thing to be a keg.

I'd wait for someone with more expertise, though, before doing anything.

While I have no problem using an aluminum brew kettle and even use a scrubby to clean it out (supposedly a no-no), I'd be hesitant to store beer in aluminum long term. Between the alcohol and the slight acidity, I would have to think that the aluminum would slowly corrode. Even if this didn't cause any metallic flavors or health effects, you'd still eventually end up with a badly pitted surface that's impossible to clean.

Besides, by the time you end up rigging a dip tube, welding on some threaded studs for posts, and pressure testing everything, I think you're far better off paying 30-40 bucks for a corny keg.

I appreciate the input. I am not planing on using these tanks to keg in or to even ferment in. Just the steps leading up to. Thanks