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.
(2) Service spaces.
(3) Accommodation 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.