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 allowed 1 Tank type not allowed. Membrane ......do Complete secondary barrier 1 Complete secondary barrier. Semi-membrane ......do ......do Do. Independent: Type A ......do ......do Do. Type B ......do Partial secondary barrier 1 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]