46 CFR § 153.233 - Separation of tanks from machinery, service and other spaces.
(a) To prevent leakage through a single weld failure, the following spaces must be separated from a cargo by two walls, two bulkheads, or a bulkhead and a deck not meeting in a cruciform joint:
(1) Machinery spaces.
(4) Spaces for storing potable domestic, or feed water.
(5) Spaces for storing edibles.
(1) Dedicated ballast tanks.
(2) Cargo pumprooms.
(3) Ballast pumprooms.
(4) Tanks not carrying a cargo listed in this part. 3
(6) Double walled piping or a piping tunnel.