13.5.4 Filling and Overflow
13.5.4(a) Bunker lines. The bunkering of fuel oils is to be effected by means of permanently installed lines either from the open deck or from bunkering stations located below deck which are to be isolated from other spaces without danger. Bunker stations are to be so arranged that the bunkering can be performed from both sides of the vessel. Alternatively, one bunkering line capable of being extended to both sides of the vessel may be accepted provided the bunkering stations are so arranged that visual communication with the bunker vessel can be assured. The bunkering lines are to be fitted with blind/blank flanges on deck or suitable alternative means of isolating the lines.
13.5.4(b) Fuel oil tank filling and overflow. In general, filling lines are to enter at or near the top of the tank; but if this is impracticable, they are to be fitted with a non-return valve at the tank. Alternatively, the filling line is to be fitted with a remotely operable valve as required by 4-6-4/13.5.3(a). Overflows from fuel oil tanks are to be led to an overflow tank with sufficient volume to accommodate the overflows (normally 10-minutes at transfer pump capacity). A high level alarm is to be provided for the overflow tank. Overflow lines are to be self-draining.
13.5.5 Heating Arrangements in Tanks
13.5.5(a) Flash point. Fuel oil in storage tanks is not to be heated within 10°C (18°F) below its flash point. Where fuel oil in service tanks, settling tanks and any other tanks in the supply system is heated, the arrangements are to comply with the following:
i) The length of the vent pipes from the tanks and/or cooling device is to be sufficient for cooling the vapors to below 60°C, or the outlet of the vent pipes is located at least 3 m (10 ft) away from a source of ignition.
ii) There are no openings from the vapor space of the fuel tanks leading into machinery spaces, except for bolted manholes.
iii) Enclosed spaces, such as workshops, accommodation spaces, etc., are not to be located directly over the fuel tanks, except for vented cofferdams.
iv) Electrical equipment is not to be fitted in the vapor space of the tanks, unless it is certified to be intrinsically safe.