27 CFR § 24.168 - Identification of tanks.
(a) General. Each tank, barrel, puncheon, or similar bulk container, used to ferment wine or used to process or store wine, spirits, or wine making materials will have the contents marked and will be marked as required by this section.
(b) Tank markings.
(1) Each tank will have a unique serial number;
(2) Each tank will be marked to show its current use, either by permanent markings or by removable signs of durable material; and
(3) If used to store wine made in accordance with a formula, the formula number will be marked or otherwise indicated on the tank.
(c) Puncheon and barrel markings. Puncheons and barrels, or similar bulk containers over 100 gallons capacity, will be marked in the same manner as tanks. A permanent serial number need not be marked on puncheons and barrels, or similar bulk containers of 100 gallons capacity or less, used for storage, but the capacity must be permanently marked.
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