46 CFR §182.710

1. (a)Vital systems are those systems that are vital to a vessel's survivability and safety. For the purpose of this part the following are vital systems:
   1. (1)Fuel system;
   2. (2)Fire main;
   3. (3)Carbon dioxide, Halon 1301, and clean agent systems;
   4. (4)Bilge system;
   5. (5)Steering system;
   6. (6)Propulsion system and its necessary auxiliaries and controls;
   7. (7)Ship's service and emergency electrical generation system and its necessary auxiliaries; and
   8. (8)A marine engineering system identified by the cognizant OCMI as being crucial to the survival of the vessel or to the protection of the personnel on board.
2. (b)For the purpose of this part, a system not identified in paragraph (a) of this section is a non-vital system.
3. (c)Piping used in a vital system must:
   1. (1)Be composed of ferrous materials except when:
      1. (i)Nonmetallic piping materials are permitted by § 182.720; or
      2. (ii)Nonferrous metallic piping materials are permitted by § 182.730; and
   2. (2)If subject to a pressure of more than 1,034 kPa (150 psig), be designed, fabricated, and inspected in accordance with the principles of ANSI B 31.1 (incorporated by reference; see 46 CFR 175.600) or other standard specified by the Commandant.