Section 13 Special requirements for tankers intended for the carriage in bulk of oil and other hazardous liquids

13.1.1 In addition to the requirements of other relevant Sections, the special requirements of this Section apply to:

1. Pt 6, Ch 2, 14 Additional requirements for tankers intended for the carriage in bulk of oil cargoes having a flash point of 60°C and below (closed cup test) – Tankers for the carriage in bulk of oil cargoes having a flash point of 55°C and below (closed cup test).

2. Pt 6, Ch 2, 15 Additional requirements for tankers intended for the carriage in bulk of other hazardous liquids– Tankers for the carriage in bulk of other hazardous liquids.

13.2.1 Bonding straps are required for cargo tanks, process plant and piping systems which are not permanently connected to the hull of the ship either directly or via their bolted or welded supports and where the resistance between them and the hull exceeds 1 MΩ.

13.2.2 Where bonding straps are required, they are to be of copper or other approved material, are to be protected against damage and, where necessary, electrolytic action.

13.2.3 Bonding straps are to be installed where they are clearly visible and in an accessible position to allow ease of installation and replacement.

13.3.1 The following systems of generation and distribution are acceptable:

1. d.c., two-wire insulated,

2. a.c., single-phase, two-wire insulated,

3. a.c., three-phase, three-wire insulated,

4. a.c., three-phase, four-wire with neutral solidly earthed but without hull return.

13.4.1 No current carrying part of an insulated distribution system is to be earthed, other than through an earth indicating device or through components used for the suppression of radio interference.

13.5.1 Rewireable type fuses are not to be fitted.

13.6.1 Electric cables are not to be installed in dangerous zones or spaces, except as permitted in certain paragraphs of this Section or Pt 6, Ch 2, 14 Additional requirements for tankers intended for the carriage in bulk of oil cargoes having a flash point of 60°C and below (closed cup test), or when associated with intrinsically safe circuits.

13.6.2 All cables which may be exposed to cargo oil, oil vapour or gas are to be sheathed with at least one of the following:

1. Copper sheath (for mineral insulated cable).

2. Lead alloy sheath plus further mechanical protection, e.g. armour or non-metallic impervious sheath.

3. Non-metallic impervious sheath plus armour (for mechanical protection and earth detection).

13.6.3 Where corrosion may be expected, non-metallic impervious sheath is to be applied over steel armour.

13.6.4 Cables installed on deck are to be protected against mechanical damage. Cables are to be installed so as to avoid strain or chafing, and due allowance is to be made for expansion or working of the structure. Where expansion bends are fitted, they are to be accessible for maintenance.

13.6.5 Where cables pass through gastight bulkheads or decks, separating dangerous zones or spaces from non-dangerous zones or spaces, arrangements are to be such that the gastight integrity of the bulkhead or deck is not impaired.

13.6.6 Cables installed in pump-rooms are to be suitably protected against mechanical damage.

13.6.7 Cables associated with intrinsically safe circuits are to be used only for such circuits. They are to be physically separated from cables associated with non-intrinsically safe circuits, e.g. neither led on the same casing or pipe nor secured by the same fixing clip.

13.7.1 Transmitting aerials should be sited well clear of the cargo zone as defined in Pt 6, Ch 2, 13.9 Dangerous zones or spaces.

13.8.1 Where reference is made to the following ‘safe’ types of equipment:

1. Intrinsically safe (symbol i).

2. Flameproof (symbol d).

3. Increased safety (symbol e).

4. Pressurized enclosure (symbol p).

Such equipment is to be certified for the gases and vapours involved. The construction and type testing is to be in accordance with IEC Publication 60079, Electrical Apparatus for Explosive Gas Atmospheres, or an equivalent National Standard. Where it is considered necessary to use certified ‘safe’ type equipment with protection types non-incendive (symbol n), encapsulated (symbol m), powder filled (symbol p) or special protection (symbol s) details are to be submitted for consideration by LR.

13.8.2 In addition, lighting fittings of the air driven type with a pressurized enclosure are considered to be a ‘safe’ type of lighting fitting.

13.8.3 When safe type equipment is permitted in dangerous zones or spaces, all switches and protective devices are to interrupt all lines or phases and are to be located in a non-dangerous zone or space unless specifically permitted otherwise. Such equipment, switches and protective devices are to be suitably labelled for identification purposes.

13.9.1 Dangerous zones or spaces are indicated in Pt 6, Ch 2, 14 Additional requirements for tankers intended for the carriage in bulk of oil cargoes having a flash point of 60°C and below (closed cup test), but the following general principals are to apply:

1. Spaces containing flammable cargo and all zones or spaces adjacent to cargo tanks are regarded as dangerous zones or spaces.

2. An enclosed or semi-enclosed space with direct access into a dangerous zone or space is regarded as a dangerous space.

3. An enclosed space located in a dangerous zone or space may be regarded as a non-dangerous space, provided that it is separated from the flammable liquid cargo by not less than two gastight steel bulkheads or decks, is mechanically ventilated and in addition, has no direct opening into a dangerous zone or space.

13.9.2 Where the ship is designed to allow visits to terminals where the whole ship is regarded as a dangerous zone or space, or the dangerous zones or spaces are otherwise extended, due to the loading terminal height in relation to the associated ship height, this capability is to be identified in the plans required by Pt 6, Ch 2, 1.2 Plans 1.2.2, including the associated extended dangerous zones or spaces. Electrical equipment and other components that can create sparks that are intended to be used in the extended hazardous areas during loading and discharging are to be of a safe-type or, alternatively, are to have a non-ventilated enclosure of ingress protection rating of at least IP55, or equivalent acceptable to LR.

13.9.3 Where Pt 6, Ch 2, 13.9 Dangerous zones or spaces 13.9.2is applicable, other electrical equipment, and other components that can create sparks, that do not satisfy the constructional requirements of Pt 6, Ch 2, 13.9 Dangerous zones or spaces 13.9.2and are located in the extended dangerous zones or spaces are to be marked red and are to be automatically isolated and shutdown during loading and discharging, see also Pt 6, Ch 2, 13.13 Spaces maintained at overpressureand Pt 6, Ch 2, 13.14 Automatic isolation overrides.
Note: Compliance with the requirements and operating practices of the relevant statutory authorities during visits to such terminals is the responsibility of the Owner.

13.10.1 Semi-enclosed spaces are considered to be spaces limited by decks and/or bulkheads in such a manner that the natural conditions of ventilation are sensibly different from those obtained on open deck.

13.11.1 A suitable earthing connection is to be provided between metalwork of the hulls to ensure equal potential of all entrained ships. These connections, preferably bolted, may be incorporated in the mechanical coupling arrangements, see Pt 6, Ch 2, 2.23 Connections between entrained ships.

13.12.1 Where the cargo is liable to damage materials normally used in the construction of electrical apparatus, special consideration is to be given to the materials selected for conductors, insulation and metal parts and/or the protection thereof.

13.13.1 Where spaces are maintained at an overpressure to prevent the space being considered a hazardous zone or space, the requirements of this sub-Section are to be complied with.

13.13.2 Arrangements are to be provided to maintain spaces at an overpressure of at least 0,1 kPa relative to external hazardous areas by ventilation from a non dangerous area.

13.13.3 Air intakes are to be located at least 2 m from hazardous zones and at least 2 m above the deck. Hazardous zones are considered to be:

• The tank deck and spaces up to 3 m above or away from the deck (the tank deck is considered to start from the deck above the cofferdam bulkhead not adjacent to the tank and to extend upwards at an angle of 45° towards the tank to the height of 3 m); and
• zones within a 2 m radius around any pipe, flanged joint or tank opening or glands or other openings through which leakage of cargo oil or other hazardous liquids may occur under normal operating conditions.

In the case of gas or vapour having a relative density of more than 0,75, the hazardous zone is considered to extend vertically downwards.

13.13.4 Electrical equipment, and other components that can create sparks, required to operate upon loss of overpressure or gas detection in spaces maintained at overpressure are to be of a safe-type or, alternatively, are to have a non-ventilated enclosure of ingress protection rating of at least IP55, or equivalent acceptable to LR.

13.13.5 The space pressure is to be monitored continuously and on loss of pressurisation:

• equipment in those spaces that does not satisfy the constructional requirements of Pt 6, Ch 2, 13.13 Spaces maintained at overpressure 13.13.4 is to be automatically isolated; and
• alarms are to be provided in the accommodation to indicate the loss of space pressure.

The arrangements are to prevent automatically isolated equipment being energized until the atmosphere within the space is made safe.

13.13.6 A permanently installed system of gas detection equipment is to be provided in spaces maintained at overpressure and is to satisfy the requirements of Pt 6, Ch 2, 13.13 Spaces maintained at overpressure 13.13.7.

13.13.7 The positions of gas detector heads are to be determined with due regard to the dilution resulting from compartment purging or ventilation and to areas where pockets of gas may accumulate. Due regard is to be given to locating gas detector head at entrances or windows, at ventilation intakes and in appropriate lower positions in spaces where it is intended to carry cargoes with associated gas that is heavier than air.

13.13.8 Gas detection systems are to be suitable for measuring gas resulting from leakage from the intended cargoes of concentrations of 0 to 100 per cent by volume.

13.13.9 Gas detection equipment is to be capable of continuous monitoring. Alternative proposals for sequential detector sampling and analysing may be submitted for consideration where it can be demonstrated that an acceptable level of safety is achieved in all applicable spaces.

13.13.10 When a gas concentration of 20 per cent of the lower explosive limit (LEL) of the gas resulting from leakage from the intended cargoes is detected:

• equipment that does not satisfy the constructional requirements of Pt 6, Ch 2, 13.13 Spaces maintained at overpressure 13.13.4 is to be automatically isolated in the relevant space(s), see also Pt 6, Ch 2, 13.14 Automatic isolation overrides; and
• alarms are to be provided in the accommodation, wheelhouse, and spaces maintained at overpressure to indicate detection of gas in the relevant space(s).

The arrangements are to prevent automatically isolated electrical equipment being energized until the atmosphere within the space is made safe.

13.13.11 Gas detection equipment is to be so designed that it may be readily tested. Testing and calibration is to be capable of being carried out at regular intervals. Equipment in fan casings is to allow calibration to take into account airflow.

13.13.12 Gas detection systems are to be ‘fail-safe’, see also Pt 6, Ch 1, 2.4 Safety systems – General requirements 2.4.6.

13.14.1 Where it would prevent the non-availability of essential services for the propulsion and safety of the ship, arrangements are to be provided on the bridge to allow the overriding of the automatic isolation and shutdown measures required by Pt 6, Ch 2, 13.9 Dangerous zones or spaces 13.9.3 and Pt 6, Ch 2, 13.13 Spaces maintained at overpressure 13.13.10 that can be operated during normal voyage mode, see also Pt 6, Ch 1, 2.4 Safety systems – General requirements 2.4.9.