§ 157.19 Cargo tank arrangement and size.

(a) With the exception of those vessels listed in paragraph (b) of this section, this section applies to:

(1) A U.S. or foreign vessel that is delivered after January 1, 1977;

(2) A U.S. vessel that is delivered before January 1, 1977, for which the building contract is awarded after January 1, 1972, or, if there is no building contract, the keel is laid or the vessel is at a similar stage of construction after June 30, 1972; and

(3) A foreign vessel that is delivered before January 1, 1977, for which the building contract is awarded after January 1, 1974, or, if there is no building contract, the keel is laid or the vessel is at a similar stage of construction after June 30, 1974.

(b) This section does not apply to U.S. or foreign oil tankers delivered on or after January 1, 2010.

(c) As determined in accordance with the procedures contained in appendix A of this part, each cargo tank must be of such size and arrangement that:

(1) The hypothetical outflow for side damage (O_c) or for bottom damage (O_s) anywhere within the length of the vessel must not exceed O_A (30,000 cubic meters or (400) × (3√ DWT) whichever is greater, limited to a maximum of 40,000 cubic meters);

(2) The volume of each wing tank and center tank is less than the allowable volume of a wing tank (VOL_W) and the allowable volume of a center tank (VOL_C) respectively; and

(3) The length of a tank is less than the allowable length of a tank (l_a).

(d) If a cargo transfer system interconnects two or more cargo tanks, the system must have valves to segregate the tanks from each other.

(e) If a line of piping that runs through a cargo tank in a position less than t_c from the vessel's side or less than v_s from the vessel's bottom as defined in appendix A of this part, has a branch, that branch must have a stop valve:

(1) Within each cargo tank into which the branch opens; or

(2) Outside each tank into which the branch opens in a location that is immediately adjacent to the point at which the branch enters the tank.

(f) If piping that serves suction wells is installed within a double bottom, that piping must be:

(1) Fitted with valves located at the point of connection to the tank served to prevent oil outflow in the event of damage to the piping; and

(2) Designed to be installed as high from the bottom shell as possible.

[CGD 74–32, 40 FR 48283, Oct. 14, 1975, as amended by CGD 75–240, 41 FR 54180, Dec. 13, 1976; CGD 76–088b, 48 FR 45720, Oct. 6, 1983; USCG–2000–7223, 65 FR 40058, June 29, 2000; USCG–2010–0194, 80 FR 5938, Feb. 4, 2015]