(a) Except as provided by this part, the design, installation, testing, and inspection of materials, machinery, pressure vessels, and piping for OSVs of less than 6,000 GT ITC (500 GRT if GT ITC is not assigned) must comply with subchapter F of this chapter.

(b) Except as specifically provided by § 128.310, the design, plan approval, installation, testing, and inspection of materials, machinery, automation, pressure vessels, and piping for OSVs of at least 6,000 GT ITC (500 GRT if GT ITC is not assigned) must comply with subchapter F of this chapter.

(c) This part contains requirements for equipment and systems commonly found on an OSV. If additional or unique systems, such as for low-temperature cargoes, are to be installed, they must comply with subchapter F of this chapter.

The plans required by subchapter F of this chapter need not be submitted if the plans required by § 127.110(d) of this subchapter have been.

(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) Systems for fill, transfer, and service of fuel oil.

(2) Fire-main systems.

(3) Fixed gaseous fire-extinguishing systems.

(4) Bilge systems.

(5) Ballast systems.

(6) Steering systems and steering-control systems.

(7) Propulsion systems and their necessary auxiliaries and control systems.

(8) Systems for transfer and control of cargo, for integral tanks or fixed independent tanks, in compliance with § 125.110 of this subchapter.

(9) Ship's service and emergency electrical-generation systems and their auxiliaries vital to the vessel's survivability and safety.

(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.

(b) For the purpose of this subchapter, a system not identified by paragraph (a) of this section is a non-vital system.