46 CFR § 153.208 - Ballast equipment.
(a) Except for the arrangement described in paragraph (b) of this section no piping that serves a dedicated ballast tank that is adjacent to a cargo tank may enter an engine room or accommodation space.
(1) Within the part of the tankship where a containment system may be located under § 153.234;
(2) That allows liquid to flow only towards that ballast tank (such as a check valve); and
(3) That enables a person to shut off the fill line from the weatherdeck (such as a stop valve).
(c) Except as prescribed in paragraph (d) of this section, pumps, piping, vent lines, overflow tubes and sounding tubes serving dedicated ballast tanks must not be located within a cargo containment system.