46 CFR §128.130

1. (a)Vital systems are those systems that are vital to a vessel's survivability and safety. For the purpose of this subchapter, the following are vital systems:
   1. (1)Systems for fill, transfer, and service of fuel oil.
   2. (2)Fire-main systems.
   3. (3)Fixed gaseous fire-extinguishing systems.
   4. (4)Bilge systems.
   5. (5)Ballast systems.
   6. (6)Steering systems and steering-control systems.
   7. (7)Propulsion systems and their necessary auxiliaries and control systems.
   8. (8)Systems for transfer and control of cargo, for integral tanks or fixed independent tanks, in compliance with § 125.110 of this subchapter.
   9. (9)Ship's service and emergency electrical-generation systems and their auxiliaries vital to the vessel's survivability and safety.
   10. (10)Any other marine-engineering system identified by the cognizant OCMI as crucial to the survival of the vessel or to the protection of the personnel aboard.
2. (b)For the purpose of this subchapter, a system not identified by paragraph (a) of this section is a non-vital system.