Section 1 General requirements

1.1.1 The requirements of this Chapter are additional to those of Pt 5, Ch 13 Ship Piping Systems and are applicable to ships which are intended for the carriage of oil in bulk.

1.1.2 The requirements are based on the assumption that the ships are of normal tanker type having the main propelling machinery aft. Departures from this arrangement will require special consideration.

1.1.3 The requirements are primarily intended for ships which are to carry flammable liquids having a flash point not exceeding 60°C (closed-cup test).

1.1.4 Where ships are intended to carry specific cargoes which are non-flammable or which have a flash point exceeding 60°C, the requirements will be modified, where necessary, to take account of the lesser hazards associated with the cargoes.

1.1.5 For list of cargoes which can be carried in oil tankers, see Table 9.1.2 Oil cargoes suitable for carriage in oil tankers, see Note 1 inPt 4, Ch 9 Double Hull Oil Tankers.

1.2.1 In addition to the plans and particulars required in Pt 5, Ch 13 Ship Piping Systems, the following plans (in a diagrammatic form) are to be submitted for consideration:

• Pumping arrangement at the fore and aft ends and drainage of cofferdams and pump-rooms.
• General arrangement of cargo piping in tanks and on deck.
• General arrangement of cargo tank vents. The plan is to indicate the type and position of the vent outlets from any superstructure, erection, air intake, etc.
• Arrangement of inert gas piping system together with details of inert gas generating plant including all control and monitoring devices.
• Piping arrangements for cargo oil (F.P. 60°C or above, closed-cup test).
• Ventilation arrangements of cargo and/or ballast pump-rooms and other enclosed spaces which contain cargo handling equipment.
• Arrangements for venting, purging and gas measurement for double hull and double bottom spaces.
• Details of alarms and safety arrangements required by Pt 5, Ch 15, 1.6 Cargo pump-room, see also Pt 6, Ch 1, 2 Essential features for control, alarm, monitoring and safety systems .

1.3.1 All materials used in the cargo pumping and piping systems are to be suitable for use with the intended cargoes and, where applicable, they are to comply with the requirements of Pt 5, Ch 12 Piping Design Requirements.

1.3.2 The requirements of Pt 5, Ch 15, 1.3 Materials 1.3.1 are also applicable to other piping systems which may come into contact with cargo.

1.4.1 All piping, valves and fittings are to be suitable for the maximum pressure to which the system can be subjected.

1.4.2 Piping subject to pressure is to be of seamless or other approved type, and is to comply with the requirements of Pt 5, Ch 12 Piping Design Requirements.

1.5.1 Engines, or any other equipment which could constitute a possible source of ignition, are not to be situated within cargo tanks, pump-rooms, cofferdams or other spaces liable to contain petroleum or other explosive vapours, or in spaces or zones immediately adjacent to cargo oil or slop tanks. The temperature of steam, or other fluid, in pipes (or heating coils) in these spaces is not to exceed 220°C. On gas tankers and chemical tankers, the maximum temperature is not to exceed that of the required temperature class of electrical equipment in the cargo area.

1.5.2 For definition of hazardous zones and spaces and requirements for electrical equipment within such spaces, see Pt 6, Ch 2, 14.2 Hazardous areas.

1.5.3 For the requirements for earthing and bonding of pipework for the control of static electricity, see Pt 6, Ch 2, 1.13 Bonding for the control of static electricity.

1.6.1 Control engineering systems are to be in accordance with the requirements of Pt 6, Ch 1 Control Engineering Systems.

1.6.2 Cargo pump-rooms are to be totally enclosed and are to have no direct communication with machinery spaces. For bilge drainage arrangements in pump-room, see Pt 5, Ch 15, 2.2 Cargo pump-room drainage.

1.6.3 Pump-rooms are to be situated within, or adjacent to the cargo tank area and are to be provided with ready means of access from the open deck, see also Pt 4, Ch 9, 13 Access arrangements and closing appliances.

1.6.4 In cargo pump-rooms any drain pipes from steam or exhaust pipes from the steam cylinders of the pumps are to terminate well above the level of the bilges.

1.6.5 Alarms and safety arrangements are to be provided as indicated in Pt 5, Ch 15, 1.6 Cargo pump-room 1.6.6 and Table 15.1.1 Alarms and safety arrangements. These requirements are applicable to pump-rooms where pumps for cargo, such as cargo pumps, stripping pumps, pumps for slop tanks, pumps for COW or similar pumps are provided and not for pump-rooms intended solely for ballast transfer. See also Pt 5, Ch 15, 1.6 Cargo pump-room 1.6.7.

1.6.6 A system for continuously monitoring the concentrations of hydrocarbon gases within the cargo pump-room is to be fitted. Monitoring points are to be located in positions where potentially dangerous concentrations may be readily detected. Gas analysing units with non-safe-type measuring equipment may be located outside cargo areas (e.g. in cargo control room, navigation bridge or engine room when mounted on the forward bulkhead) provided that:

1. sampling lines do not pass through gas safe spaces, except where permitted by Pt 5, Ch 15, 1.6 Cargo pump-room 1.6.6.(e);

2. the gas sampling pipes are fitted with flame arresters. Sample gas is to be led to the atmosphere with outlets arranged in a safe location, in the open atmosphere;

3. bulkhead penetrations of sample pipes between safe and dangerous areas are of an approved type. A manual isolating valve is to be fitted in each of the sampling lines at the bulkhead in the safe area;

4. the gas detection equipment including sampling piping, sampling pumps, solenoid valves and analysing units, are located in a fully enclosed steel cabinet, with a gasketed door, monitored by its own sampling point. At gas concentrations above 30 per cent LEL inside the steel cabinet, the entire gas-analysing unit is to be automatically shutdown; and

5. where the cabinet cannot be arranged on the bulkhead, sample pipes are to be of steel or other equivalent material and without detachable connections, except for the connection points for isolating valves at the bulkhead and analysing units. The sample pipes are to be led by their shortest route.

Sequential sampling is acceptable as long as it is dedicated for the pump-room only, including exhaust ducts, and the detection equipment is capable of monitoring from each sampling head location at intervals not exceeding 30 minutes.

1.6.7 Where items of equipment other than described in Table 15.1.1 Alarms and safety arrangements are located in the pump-room and are driven by shafts passing through bulkheads, the potential risk of ignition of hydrocarbon gas is to be assessed and proposals for mitigation submitted to LR for consideration.

1.7.1 In accordance with SOLAS 1974, as amended, Ch II-2/B, Reg. 4. 5.7 Gas measurement and detection, double hull and double bottom spaces of oil tankers with a deadweight of 20 000 tonnes and above that are not provided with a constant operative inerting system (COIS) are to be provided with a fixed hydrocarbon gas detection system.

1.7.2 Where a fixed hydrocarbon gas detection system is required by Pt 5, Ch 15, 1.7 Arrangements for fixed hydrocarbon gas detection systems in double hull and double bottom spaces of oil tankers 1.7.1, it is to be of an approved type and it is to meet the requirements of Chapter 16 - Fixed Hydrocarbon Gas Detection Systems of the FSS Code - Fire Safety Systems – Resolution MSC.98(73) .

1.7.3 Where a constant operative inerting systems (COIS) is provided in lieu of fixed hydrocarbon detection the arrangements are to be submitted for consideration.

1.8.1 Cargo pump-rooms and other closed spaces which contain cargo handling equipment, and to which regular access is required during cargo handling operations, are to be provided with permanent ventilation systems of the mechanical extraction type.

1.8.2 The ventilation system is to be capable of being operated from outside the compartment being ventilated and a notice to be fixed near the entrance stating that no person is to enter the space until the ventilation system has been in operation for at least 15 minutes.

1.8.3 The ventilation systems are to be capable of 20 air changes per hour, based on the gross volume of the pump-room or space.

1.8.4 The ventilation ducting is to be arranged to permit extraction from the vicinity of the pump-room bilges, immediately above the transverse floor plates or bottom longitudinals. An emergency intake is also to be arranged in the ducting at a height of 2 m above the pump-room lower platform and is to be provided with a damper capable of being opened or closed from the weather deck and lower platform level. An arrangement involving a specific ratio of areas of upper emergency and lower main ventilation openings, which can be shown to result in at least the required number of air changes through the lower inlets, can be accepted without the use of dampers. When the lower inlets are sealed off, owing to flooding of the bilges, then at least 75 per cent of the required number of air changes is to be obtainable through the upper inlets. Means are to be provided to ensure the free flow of gases through the lower platform to the duct intakes.

1.8.5 Protection screens of not more than 13 mm square mesh are to be fitted in outside openings of ventilation ducts, and ventilation intakes are to be so arranged as to minimise the possibility of recycling hazardous vapours from any ventilation discharge opening. Vent exits are to be arranged to discharge to a safe place on the open deck and comply with the requirements ofPt 5, Ch 15, 1.8 Cargo pump-room ventilation 1.8.6.

1.8.6 The vent exits from pump-rooms are to discharge at least 3 m above deck, and from the nearest air intakes or openings to accommodation and enclosed working spaces, and from possible sources of ignition.

1.8.7 The ventilation is to be interlocked to the lighting system (except emergency lighting) such that the cargo pump-room lighting may only come on when the ventilation is in operation. Failure of the ventilation system shall not cause the lighting to go out.

1.9.1 The air gap between impeller and housing of the fan is to be not less than 0,1 of the impeller shaft bearing diameter or 2 mm whichever is the larger, subject also to compliance with Pt 5, Ch 15, 1.9 Non-sparking fans for hazardous areas 1.9.2.(e). Generally, however, the air gap need be no more than 13 mm.

1.9.2 The following combinations of materials are permissible for the impeller and the housing in way of the impeller:

1. impellers and/or housings of non-metallic material, due regard being paid to the elimination of static electricity,

2. impellers and housings of non-ferrous metals,

3. impellers and housings of austenitic stainless steel,

4. impellers of aluminium alloys or magnesium alloys and a ferrous housing provided that a ring of suitable thickness of non-ferrous material is fitted in way of the impeller,

5. any combination of ferrous impellers and housings with not less than 13 mm tip clearance,

6. any combination of materials for the impeller and housing which are demonstrated as being spark-proof by appropriate rubbing tests.

1.9.3 The following combinations of materials for impellers and housing are not considered spark-proof and are not permitted:

1. impellers of an aluminium alloy or magnesium alloy and a ferrous housing, irrespective of tip clearance,

2. impellers of a ferrous material and housings made of an aluminium alloy, irrespective of tip clearance,

3. any combination of ferrous impeller and housing with less than 13 mm tip clearance, other than permitted by Pt 5, Ch 15, 1.9 Non-sparking fans for hazardous areas 1.9.2.(c).

1.9.4 Electrostatic charges both in the rotating body and the casing are to be prevented by the use of antistatic materials (i.e. materials having an electrical resistance between 5 x 10⁴ ohms and 10⁸ ohms), or special means are to be provided to avoid dangerous electrical charges on the surface of the material.

1.9.5 Type tests on the complete fan are to be carried out to the Surveyor's satisfaction.

1.9.6 Protection screens of not more than 13 mm square mesh are to be fitted in the inlet and outlet of ventilation ducts to prevent the entry of objects into the fan housing.

1.9.7 The installation of the ventilation units on board is to be such as to ensure the safe bonding to the hull of the units themselves.

1.10.1 The requirements in Pt 5, Ch 15, 1.10 Slop tanks 1.10.2 to Pt 5, Ch 15, 1.10 Slop tanks 1.10.7 are applicable to ships intended for the carriage of ore or oil when oil residues are to be retained in the slop tanks and the ship is otherwise gas free, see also Pt 4, Ch 9, 11.3 Structural configuration and ship arrangement.

1.10.2 Slop tanks are to be provided with an approved independent venting system, see Pt 5, Ch 15, 4 Cargo tank venting, purging and gas-freeing.

1.10.3 Appropriate numbers and types of portable instruments are to be available on board for gas detection and measurement, see Pt 5, Ch 15, 4.4 Gas measurement.

1.10.4 Means are to be provided for isolating the piping connecting the pump-room with the slop tanks. The means of isolation is to consist of a valve followed by a spectacle flange or a spool piece with appropriate blank flanges. This arrangement is to be located adjacent to the slop tanks, but where this is unreasonable or impracticable it may be located within the pump-room directly after the piping penetrates the bulkhead. A separate permanently installed pumping and piping arrangement is to be provided for discharging the contents of the slop tanks directly to the open deck for transfer to shore reception facilities when the ship is in the dry cargo mode. When this transfer system is used for slop transfer in dry cargo mode, it shall have no connection to other systems. Separation by means of removal of spool pieces may be accepted.

1.10.5 Adequate ventilation is to be provided for spaces surrounding slop tanks, see also Pt 4, Ch 9, 11.3 Structural configuration and ship arrangement.

1.10.6 Warning notices are to be erected at suitable points detailing precautions to be observed prior to the ship loading or unloading, or when the ship is carrying dry cargo with liquid in the slop tanks.

1.10.7 In order to satisfy the requirements of certain National and/or Terminal Authorities, it may be necessary to provide an inert gas system for blanketing the slop tank contents.

1.11.1 Where steaming out and/or fire-extinguishing connections are provided for cargo tanks or cargo pipe lines, they are to be fitted with valves of the screw-down non-return type. The main supply to these connections is to be fitted with a master valve placed in a readily accessible position clear of the cargo tanks.