CFR > Title 46 - Shipping > CHAPTER I—COAST GUARD, DEPARTMENT OF HOMELAND SECURITY > SUBCHAPTER O—CERTAIN BULK DANGEROUS CARGOES (parts 150 to 155) > PART 154—SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES > SUBPART C—Design, Construction and Equipment (§154.170 to §154.1440) > 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-522) 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-522) 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-522).
(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.

Code of Federal Regulations

( 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]