46 USC 3706 – Product carrier minimum standards
(a) A new product carrier of at least 30,000 deadweight tons shall be equipped with protectively located segregated ballast tanks.
(b) A new product carrier of at least 20,000 deadweight tons shall be equipped with a cargo tank protection system consisting of a fixed deck froth system and a fixed inert gas system or, if the product carrier carries dedicated products incompatible with the cargo tank protection system, an alternate protection system authorized by the Secretary.
(c) An existing product carrier of at least 40,000 deadweight tons shall be equipped with segregated ballast tanks or may operate with dedicated clean ballast tanks.
(d) An existing product carrier of at least 20,000 deadweight tons but less than 40,000 deadweight tons, and at least 15 years of age, shall be equipped with segregated ballast tanks or may operate with dedicated clean ballast tanks.
(e) An existing product carrier of at least 40,000 deadweight tons, or an existing product carrier of at least 20,000 deadweight tons but less than 40,000 deadweight tons that is fitted with high-capacity tank washing machines, shall be equipped with an inert gas system.