Section 3 Auxiliaries and Piping Arrangement

301. Vent pipes

1. General

The structural arrangement of all tanks is to be such as to permit the free passage of air and gases from all parts of the tanks to the vent pipes. Vent pipes are to be arranged to provide adequate drainage under normal conditions.

2. Size

(1) The diameter of each vent pipe is not to be less than 38 mm inside diameter for fresh water tanks and 63 mm inside diameter for oil tanks unless specially approved otherwise.

(2) Where tanks are to be filled by pump pressure, the aggregate area of the vents in the tank is

to be at least 125 % of the effective area of the filling line. However, the vents need not ex- ceed the above minimum sizes when overflows of which the area is to be at least 125 % of the effective area of the filling line are fitted. Notwithstanding the above, the pump capacity and pressure head are to be considered in the sizing of vents and overflows.

302. Sounding pipes

1. General

Tanks are to be fitted with sounding pipes not less than 38 mm inside diameter and where a sounding pipe exceeds 20 m in length, the minimum internal diameter is to be at least 50 mm. They are to be led as straight as possible from the lowest part of the tank to a position which is always accessible.

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2. Gauge glasses

(1) Tanks may be fitted with suitable gauge glasses in lieu of sounding pipes, provided they are fitted with a valve at each end of the gauge and adequately protected from mechanical damage.

(2) Gauge glasses on tanks containing combustible liquids are to be of flat shape and of heat re-

sisting quality, and to have approved self-closing valves at each end.

303. Fuel oil systems

1. General

Fuel oil pumping arrangements are to be distinct from the other pumping systems as far as practi- cable, and means are to be provided for preventing dangerous interconnection.

2. Pipes in fuel oil tanks

(1) Oil pipes and other pipes, where passing through fuel oil tanks, are to be of steel, except that other materials may be considered where it is demonstrated that the material is suitable for the intended service.

(2) All packing is to be of a composition not affected by oil.

3. Drip pans

Pumps, strainers, etc., requiring occasional examination are to have drip pans.

4. Valves on fuel oil tanks

(1) Where pipe lines emanate from oil tanks at such a level that they will be subjected to a static head of oil from the tank, they are to be fitted with positive closing valves located at the tank or where the pipe line enters the machinery space. Arrangements are to be provided for closing them from a readily accessible and safe location outside of the compartment in which the valve is located.

(2) Where independent filling lines are fitted, they are to enter at or near the top of the tank; but if this be impracticable, they are to be fitted with non-return valves at the tank.

5. Remote shutdown of pumps

Fuel oil transfer pumps, fuel oil unit pumps and other similar fuel pumps are to be fitted with re- mote controls situated outside the space concerned so that they may be stopped in the event of a fire arising in the space in which they are located.

6. Fuel oil tanks and drains

(1) The fuel oil overflows, drains from fuel and lubricating oil tanks and from drip pans of oil pumps and tanks are to be led to a drain tank fitted with air and sounding pipes and an in- dependent suction from the fuel oil transfer pumps.

(2) Non-return valves are to be fitted in drain lines entering the drain tanks where backflow would present a hazard. Suitable means are to be provided for pumping out these drain tanks.

(3) Tanks not forming part of the platform structure are to have suitable drip pans.

(4) Service tanks are to be located at a sufficient height to permit gravity flow to the service pump

section.

304. Fuel oil storage for helicopter facilities

1. Areas where fuel oil storage tanks for helicopters are located and fueling operations conducted are to be suitably isolated from areas which contain a source of vapor ignition.

2. Fuel oil storage tanks are to be provided with vents in accordance with 301. The vents are to ex- tend to at least 2.4 m above the deck.

3. Fuel oil storage tanks are to be of approved metallic construction. Special attention is to be given to the design, mounting and securing arrangements and electrical bonding of the tank and fuel oil transfer system.

4. The storage and handling area is to be permanently marked.

5. Coamings or other similar arrangements are to be provided at each fuel oil storage tank and are to

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be sufficient in provided.

height to retain the contents of the storage tank plus fire-extinguishing agents where

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