Methane (LNG).

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 § 154.702; (b) A waste heat or catalytic furnace that burns boil-off gas, and: (1) Maintains the stack exhaust temperature below 535 °C (995 °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]