(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 [deg]C (14 [deg]F), the integral tank must have a complete secondary barrier that meets Sec. 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 Sec. Sec. 154.605 through 154.630; and
(2) Be designed for the stresses resulting from the design temperature.
Table 3--Secondary Barriers for Tanks----------------------------------------------------------------------------------------------------------------
Cargo temperature (T) at atmospheric pressure
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Tank type T<-10 [deg]C (14 [deg]F)=-10 thn-eq>=55 [deg]C (-67 T<-55 [deg]C (-67
[deg]C (14 [deg]F) [deg]F) [deg]F)----------------------------------------------------------------------------------------------------------------Integral........................... No secondary barrier Tank type not usually Tank type not
required. allowed \1\. allowed.Membrane........................... ......do.............. Complete secondary barrier Complete secondary
\1\. barrier.Semi-membrane...................... ......do.............. ......do.................... Do.Independent:
Type A........................... ......do.............. ......do.................... Do.
Type B........................... ......do.............. Partial secondary barrier Partial secondary
\1\. barrier.
Type C........................... ......do.............. No secondary barrier No secondary barrier
required. 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]