pickling tanks

[dereknobleluke]

Hello all.

I went to the MBAA conference in NH this past weekend and listened to alot of great information. One thing that was discussed was the pickling of new kegs. Well we got in some new tank awhile back and I was just wondering if there was a dirrerence in pickling vs passivation?

any ideas out there?

[South County]

Pickling vs. passivation

Passivation is removing excess iron compounds from the surface of stainless by chemical dissolution. Usually done with Nitric acid and depending on the stainless type and use, a post rinse with sodium dichromate is employed to ensure the generation of a chromic oxide film often for resisting weather and exterior conditions. Pickling (usually on unused stainless) on the other hand is the use heavier concentrations of nitric and hydrofluoric acids to actually remove or "etch" a layer of the metal to recondition heat stressed weld areas where chromium contents have been reduced. I have also heard of the pickling method of running a "dudd" batch of beer or product to condition the tank for the process that is being used. The thought being that beer, ketchup or salt and vinegar rich solutions for example will etch the surface and those metal/mineral ions will know be in the product which must be dumped. Hence the term "pickling". Most of use can afford to use beer to do this, so the correct acid solutions would be my choice.