(a) This section applies to OSVs of at least 6,000 GT ITC (500 GRT if GT ITC is not assigned).

(b) Cargo tanks containing flammable or combustible liquids must not be located beneath the accommodations or machinery space. Separation by cofferdams is not acceptable for meeting this requirement.

(c) Except for OSVs complying with paragraph (d)(1) of this section, each OSV must carry at least two approved semiportable dry chemical fire extinguishers for the protection of all weather deck areas within 10 feet (3 m) of any tank openings, pumps, flanges, valves, vents, or loading manifolds. Each extinguisher must have—

(1) A minimum capacity of 135 kg. If the protected area exceeds 90 m 2, additional extinguishers must be provided to supply a total combined capacity of dry chemical in kilograms equal to the total combined protected area in square meters multiplied by 3;

(2) A minimum flow rate of 3 kg/min from each discharge hose;

(3) A sufficient number of discharge hoses of adequate length to protect the areas required above without moving any of the extinguishers; and

(4) The frame or support for each semi-portable dry chemical fire extinguisher welded or otherwise permanently attached to the vessel's structure.

(d) Each OSV with fixed cargo tanks that have an aggregate capacity of 3,000 cubic meters or more intended for the carriage of flammable or combustible liquids with a closed-cup flashpoint of 60 °C or below must have:

(1) An approved fixed-deck foam system arranged as follows:

(i) If the flammable or combustible liquid tanks extend vertically to the weather deck, the foam system must comply with §§ 34.20-10 and 34.20-15 of this chapter, and protect the entire weather deck cargo area, including any tank openings, pumps, flanges, valves, vents, or loading manifolds. If petroleum products are carried, the minimum foam system discharge rate in liters per minute must be determined by multiplying the total cargo deck area by 6 lpm/m 2. If polar solvent cargoes are carried, the minimum foam system discharge rate in liters per minute must be determined by multiplying the total cargo deck area by 10 lpm/m 2, unless the approved foam system design manual specifies a different rate for the cargoes carried.

(ii) If the flammable or combustible liquid tanks do not extend vertically to the weather deck, the foam system must be capable of protecting all weather deck areas within 10 feet (3 m) of any tank openings, pumps, flanges, valves, vents, or loading manifolds. The foam system must consist of at least one hoseline, and either fixed-foam monitors or fixed-foam nozzles that provide foam coverage of all required areas. The minimum foam system discharge rate must be calculated in accordance with paragraph (d)(1)(i) of this section, using the combined horizontal area of all parts of the deck requiring protection, instead of the total deck area.

(iii) All foam liquid concentrate must be compatible with all flammable or combustible liquids carried.

(iv) Sufficient foam liquid concentrate must be carried to allow operation of the system at its maximum discharge rate for at least 20 minutes.

(2) A fixed-gas fire-suppression system complying with § 34.05-5(a)(4) of this chapter, or other approved fire-extinguishing system determined acceptable by the Commandant, for the protection of any accessible below-deck cargo pump rooms or other spaces that have tank openings, pumps, flanges, valves, or loading manifolds associated with tanks carrying flammable or combustible liquids with a closed cup flashpoint of 60 °C or below.