27 CFR §25.144

1. (a)A brewer may not use a barrel or keg which bears the name of more than one brewer, and except as provided in § 25.231, may not use a barrel or keg bearing the name of a brewer other than the producing brewer.
2. (b)A brewer who purchases or otherwise obtains barrels or kegs from another brewer shall permanently remove or durably cover the original marks and brands after notifying the appropriate TTB officer of the proposed action. A brewer may use the barrels or kegs obtained without removing or covering the original marks and brands if the brewer:
   1. (1)Adopts a trade name substantially identical to the name appearing on the barrels or kegs; or
   2. (2)Succeeds to a brewer who has discontinued business, in which case the brewer may add marks or brands, in accordance with § 25.141, which indicate ownership.