Unless a cargo tank carrying methane (LNG) can withstand the pressure build up due to boil-off for 21 days, the pressure in the cargo tank must be maintained below the set pressure of the safety relief valve for at least 21 days by:
(a) A refrigeration system that meets Sec. 154.702;
(b) A waste heat or catalytic furnace that burns boil-off gas, and:
(1) Maintains the stack exhaust temperature below 535 [deg]C (995 [deg]F);
(2) Exhibits no visible flame; and
(3) Is specially approved by the Commandant (CG-OES);
(c) Boilers, inert gas generators, and combustion engines in the main propelling machinery space that use boil-off gas as fuel; or
(d) Equipment for services, other than those under paragraph (c) of this section, that use boil-off gas as fuel and that are located:
(1) In the main propelling machinery space; or
(2) a space specially approved by the Commandant (CG-OES). [CGD 74-289, 44 FR 26009, May 3, 1979, as amended by CGD 82-063b, 48 FR 4782, Feb. 3, 1983]