§ 154.459 - General.

§ 154.459 General.

(a) Each cargo tank must have a secondary barrier that meets Table 3 and except as allowed in Table 3, the hull must not be the secondary barrier.

(b) If the Commandant (CG-ENG) specially approves an integral tank for a design temperature at atmospheric pressure lower than −10 °C (14 °F), the integral tank must have a complete secondary barrier that meets § 154.460.

(c) If the Commandant (CG-ENG) specially approves a semi-membrane tank under the requirements of an independent tank type B, the semi-membrane tank may have a partial secondary barrier specially approved by the Commandant (CG-ENG).

(d) If Table 3 allows the hull to be a secondary barrier, the vessel's hull must:

(1) Meet §§ 154.605 through 154.630; and

(2) Be designed for the stresses resulting from the design temperature.

Table 3 - Secondary Barriers for Tanks

Tank type	Cargo temperature (T) at atmospheric pressure
	T≥−10 °C (14 °F)	T<-10 °C (14 °F)≥55 °C (−67 °F)	T<−55 °C (−67 °F)
Integral	No secondary barrier required	Tank type not usually allowed1	Tank type not allowed.
Membrane	......do	Complete secondary barrier1	Complete secondary barrier.
Semi-membrane	......do	......do	Do.
Independent:
Type A	......do	......do	Do.
Type B	......do	Partial secondary barrier1	Partial secondary barrier.
Type C	......do	No secondary barrier required	No secondary barrier required.

¹ The hull may be a secondary barrier.

(14 U.S.C. 632; 46 U.S.C. 369, 375, and 416; 49 U.S.C. 1655(b); 49 CFR 1.46(b))

[CGD 74-289, 44 FR 26009, May 3, 1979, as amended by CGD 82-063b, 48 FR 4782, Feb. 3, 1983]