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:

1. (a) A refrigeration system that meets § 154.702;

2. (b) A waste heat or catalytic furnace that burns boil-off gas, and:

   1. (1) Maintains the stack exhaust temperature below 535 °C (995 °F);
   2. (2) Exhibits no visible flame; and
   3. (3) Is specially approved by the Commandant (CG-OES);
3. (c) Boilers, inert gas generators, and combustion engines in the main propelling machinery space that use boil-off gas as fuel; or

4. (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. (1) In the main propelling machinery space; or
   2. (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]