Ship arrangements

Goal

To ensure that the cargo containment and handling system are located such that the consequences of any release of cargo will be minimized, and to provide safe access for operation and inspection.

3.1 Segregation of the cargo area

3.1.1 Hold spaces shall be segregated from machinery and boiler spaces, accommodation spaces, service spaces, control stations, chain lockers, domestic water tanks and from stores. Hold spaces shall be located forward of machinery spaces of category A. Alternative arrangements, including locating machinery spaces of category A forward, may be accepted, based on SOLAS regulation II-2/17, after further consideration of involved risks, including that of cargo release and the means of mitigation.

3.1.2 Where cargo is carried in a cargo containment system not requiring a complete or partial secondary barrier, segregation of hold spaces from spaces referred to in 3.1.1 or spaces either below or outboard of the hold spaces may be effected by cofferdams, oil fuel tanks or a single gastight bulkhead of all-welded construction forming an "A-60" class division. A gastight "A-0" class division is acceptable if there is no source of ignition or fire hazard in the adjoining spaces.

3.1.3 Where cargo is carried in a cargo containment system requiring a complete or partial secondary barrier, segregation of hold spaces from spaces referred to in 3.1.1, or spaces either below or outboard of the hold spaces that contain a source of ignition or fire hazard, shall be effected by cofferdams or oil fuel tanks. A gastight "A-0" class division is acceptable if there is no source of ignition or fire hazard in the adjoining spaces.

LR 3.1-01 Cargo tank holds are to be separated from each other by single bulkheads of all welded construction. Where, however, the design temperature as defined in 4.1.3 is below –55°C, cofferdams are to be adopted unless the cargo is carried in independent tanks and alternative arrangements are made to ensure the bulkhead cannot be cooled to below –55°C. Cofferdams may be used as ballast tanks subject to approval by LR.

3.1.4 Turret compartments segregation from spaces referred to in 3.1.1, or spaces either below or outboard of the turret compartment that contain a source of ignition or fire hazard, shall be effected by cofferdams or an A-60 class division. A gastight "A-0" class division is acceptable if there is no source of ignition or fire hazard in the adjoining spaces.

3.1.5 In addition, the risk of fire propagation from turret compartments to adjacent spaces shall be evaluated by a risk analysis (see 1.1.11) and further preventive measures, such as the arrangement of a cofferdam around the turret compartment, shall be provided if needed.

3.1.6 When cargo is carried in a cargo containment system requiring a complete or partial secondary barrier:

• .1 at temperatures below -10°C, hold spaces shall be segregated from the sea by a double bottom; and

• .2 at temperatures below -55°C, the ship shall also have a longitudinal bulkhead forming side tanks.

LR 3.1-02 The double bottom requirements of Pt 4, Ch 1,8 are to be applied regardless of the cargo temperature, see also LR 3.18.

3.1.7 Arrangements shall be made for sealing the weather decks in way of openings for cargo containment systems.

3.2 Accommodation, service and machinery spaces and control stations

3.2.1 No accommodation space, service space or control station shall be located within the cargo area. The bulkhead of accommodation spaces, service spaces or control stations that face the cargo area shall be so located as to avoid the entry of gas from the hold space to such spaces through a single failure of a deck or bulkhead on a ship having a containment system requiring a secondary barrier.

LR 3.2-01 Cargo service spaces as defined in 1.2.13 may be situated within the cargo area, provided all other relevant requirements of these Rules and the Rules for Ships are complied with.

3.2.2 To guard against the danger of hazardous vapours, due consideration shall be given to the location of air intakes/outlets and openings into accommodation, service and machinery spaces and control stations in relation to cargo piping, cargo vent systems and machinery space exhausts from gas burning arrangements.

3.2.3 Access through doors, gastight or otherwise, shall not be permitted from a non-hazardous area to a hazardous area except for access to service spaces forward of the cargo area through airlocks, as permitted by 3.6.1, when accommodation spaces are aft.

3.2.4.1 Entrances, air inlets and openings to accommodation spaces, service spaces, machinery spaces and control stations shall not face the cargo area. They shall be located on the end bulkhead not facing the cargo area or on the outboard side of the superstructure or deckhouse or on both at a distance of at least 4% of the length (L) of the ship but not less than 3 m from the end of the superstructure or deckhouse facing the cargo area. This distance, however, need not exceed 5 m.

3.2.4.2 Windows and sidescuttles facing the cargo area and on the sides of the superstructures or deckhouses within the distance mentioned above shall be of the fixed (non-opening) type. Wheelhouse windows may be non-fixed and wheelhouse doors may be located within the above limits so long as they are designed in a manner that a rapid and efficient gas and vapour tightening of the wheelhouse can be ensured.

3.2.4.3 For ships dedicated to the carriage of cargoes that have neither flammable nor toxic hazards, the Administration may approve relaxations from the above requirements.

3.2.4.4 Accesses to forecastle spaces containing sources of ignition may be permitted through a single door facing the cargo area, provided the doors are located outside hazardous areas as defined in chapter 10.

3.2.5 Windows and sidescuttles facing the cargo area and on the sides of the superstructures and deckhouses within the limits specified in 3.2.4, except wheelhouse windows, shall be constructed to "A-60" class. Sidescuttles in the shell below the uppermost continuous deck and in the first tier of the superstructure or deckhouse shall be of fixed (non-opening) type.

3.2.6 All air intakes, outlets and other openings into the accommodation spaces, service spaces and control stations shall be fitted with closing devices. When carrying toxic products, they shall be capable of being operated from inside the space. The requirement for fitting air intakes and openings with closing devices operated from inside the space for toxic products need not apply to spaces not normally manned, such as deck stores, forecastle stores, workshops. In addition, the requirement does not apply to cargo control rooms located within the cargo area.

LR 3.2-02 The closing devices detailed in 3.2.6 of the Code need not be operable from within the single spaces listed but may be located in centralised positions. The requirement for closing devices need not apply to the following spaces:

• engine room casings;

• cargo machinery spaces;

• electric motor rooms; and

• steering gear compartments.

LR 3.2-03 The closing devices detailed in 3.2.6 of the Code are to give a reasonable degree of gas tightness. Ordinary steel fire-flaps without gaskets/seals are not considered to be satisfactory.

LR 3.2-04 In addition to the requirements of LR 3.2-02 to LR 3.2-03, the closing devices are to be operable from outside of the protected space in accordance with SOLAS regulation II-2/5.2.1.1.

3.2.7 Control rooms and machinery spaces of turret systems may be located in the cargo area forward or aft of cargo tanks in ships with such installations. Access to such spaces containing sources of ignition may be permitted through doors facing the cargo area, provided the doors are located outside hazardous areas or access is through airlocks.

3.3 Cargo machinery spaces and turret compartments

3.3.1 Cargo machinery spaces shall be situated above the weather deck and located within the cargo area. Cargo machinery spaces and turret compartments shall be treated as cargo pump-rooms for the purpose of fire protection according to SOLAS regulation II-2/9.2.4, and for the purpose of prevention of potential explosion according to SOLAS regulation ll-2/4.5.10.

LR 3.3-01 The requirement of 3.3.1 is to be applied as follows:

Cargo machinery spaces shall be situated above the weather deck and located within the cargo area. Cargo machinery spaces and turret compartments shall be treated as cargo pump-rooms for the purpose of fire protection according to SOLAS regulation II-2/9.2.4. See also 11.1.1.1.

3.3.2 When cargo machinery spaces are located at the after end of the aftermost hold space or at the forward end of the foremost hold space, the limits of the cargo area, as defined in 1.2.7, shall be extended to include the cargo machinery spaces for the full breadth and depth of the ship and the deck areas above those spaces.

3.3.3 Where the limits of the cargo area are extended by 3.3.2, the bulkhead that separates the cargo machinery spaces from accommodation and service spaces, control stations and machinery spaces of category A shall be located so as to avoid the entry of gas to these spaces through a single failure of a deck or bulkhead.

3.3.4 Cargo compressors and cargo pumps may be driven by electric motors in an adjacent non-hazardous space separated by a bulkhead or deck, if the seal around the bulkhead penetration ensures effective gastight segregation of the two spaces. Alternatively, such equipment may be driven by certified safe electric motors adjacent to them if the electrical installation complies with the requirements of chapter 10.

3.3.5 Arrangements of cargo machinery spaces and turret compartments shall ensure safe unrestricted access for personnel wearing protective clothing and breathing apparatus, and in the event of injury to allow unconscious personnel to be removed. At least two widely separated escape routes and doors shall be provided in cargo machinery spaces, except that a single escape route may be accepted where the maximum travel distance to the door is 5 m or less.

3.3.6 All valves necessary for cargo handling shall be readily accessible to personnel wearing protective clothing. Suitable arrangements shall be made to deal with drainage of pump and compressor rooms.

3.3.7 Turret compartments shall be designed to retain their structural integrity in case of explosion or uncontrolled high-pressure gas release (overpressure and/or brittle fracture), the characteristics of which shall be substantiated on the basis of a risk analysis with due consideration of the capabilities of the pressure relieving devices.

3.4 Cargo control rooms

3.4.1 Any cargo control room shall be above the weather deck and may be located in the cargo area. The cargo control room may be located within the accommodation spaces, service spaces or control stations, provided the following conditions are complied with:

• .1 the cargo control room is a non-hazardous area;

• .2 if the entrance complies with 3.2.4.1, the control room may have access to the spaces described above; and

• .3 if the entrance does not comply with 3.2.4.1, the cargo control room shall have no access to the spaces described above and the boundaries for such spaces shall be insulated to "A-60" class.

3.4.2 If the cargo control room is designed to be a non-hazardous area, instrumentation shall, as far as possible, be by indirect reading systems and shall, in any case, be designed to prevent any escape of gas into the atmosphere of that space. Location of the gas detection system within the cargo control room will not cause the room to be classified as a hazardous area, if installed in accordance with 13.6.11.

3.4.3 If the cargo control room for ships carrying flammable cargoes is classified as a hazardous area, sources of ignition shall be excluded and any electrical equipment shall be installed in accordance with chapter 10.

3.5 Access to spaces in the cargo area

3.5.1 Visual inspection of at least one side of the inner hull structure shall be possible without the removal of any fixed structure or fitting. If such a visual inspection, whether combined with those inspections required in 3.5.2, 4.6.2.4 or 4.20.3.7 or not, is only possible at the outer face of the inner hull, the inner hull shall not be a fuel-oil tank boundary wall.

3.5.2 Inspection of one side of any insulation in hold spaces shall be possible. If the integrity of the insulation system can be verified by inspection of the outside of the hold space boundary when tanks are at service temperature, inspection of one side of the insulation in the hold space need not be required.

3.5.3 Arrangements for hold spaces, void spaces, cargo tanks and other spaces classified as hazardous areas, shall be such as to allow entry and inspection of any such space by personnel wearing protective clothing and breathing apparatus and shall also allow for the evacuation of injured and/or unconscious personnel. Such arrangements shall comply with the following:

• .1 Access shall be provided as follows:

  • .1 access to all cargo tanks. Access shall be direct from the weather deck;

  • .2 access through horizontal openingş hatches or manholes. The dimensions shall be sufficient to allow a person wearing a breathing apparatus to ascend or descend any ladder without obstruction, and also to provide a clear opening to facilitate the hoisting of an injured person from the bottom of the space. The minimum clear opening shall be not less than 600 mm x 600 mm;

LR 3.5-01 The minimum clear opening detailed in 3.5.3.1.2 of Code, of 600 mm x 600 mm may have corner radii up to 100 mm maximum. If, as a consequence of structural analysis of a given design, the stress is to be reduced around the opening, it is considered appropriate to take measures to reduce the stress by making the opening larger with increased radii, e.g. 600 x 800 with 300 mm radii, within which a clear opening of 600 mm x 600 mm with corner radii up to 100 mm maximum can fit.

• • .3 access through vertical openings or manholes providing passage through the length and breadth of the space. The minimum clear opening shall be not less than 600 mm x 800 mm at a height of not more than 600 mm from the bottom plating unless gratings or other footholds are provided; and

LR 3.5-02 The minimum clear opening detailed in 3.5.3.1.3 of Code, of not less than 600 mm x 800 mm may have corner radii up to 300 mm, see Figure LR 3.7 Vertical Openings. An opening of 600 mm in height x 800 mm in width may be accepted as access openings in vertical structures where it is not desirable to make large vertical openings in structural members such as girders and floors in double bottom tanks.

LR 3.5-03 Subject to verification of easy evacuation of an injured person on a stretcher a vertical opening with maximum dimensions of 850 mm x 620 mm is considered an acceptable alternative, where the upper half is wider than 600 mm, and where the lower half is less than 600 mm, see Figure LR 3.8 Alternative Vertical Openings.

LR 3.5-04 If the bottom of a vertical opening is at a height of more than 600 mm above the deck, steps and handgrips are to be provided. In such arrangements it is to be demonstrated that an injured person can be easily evacuated.

• • .4 circular access openings to type C tanks shall have a diameter of not less than 600 mm.

• .2 The dimensions referred to in 3.5.3.1.2 and 3.5.3.1.3 may be decreased, if the requirements of 3.5.3 can be met to the satisfaction of the Administration.

• .3 Where cargo is carried in a containment system requiring a secondary barrier, the requirements of 3.5.3.1.2 and 3.5.3.1.3 do not apply to spaces separated from a hold space by a single gastight steel boundary. Such spaces shall be provided only with direct or indirect access from the weather deck, not including any enclosed non-hazardous area.

• .4 Access required for inspection shall be a designated access through structures below and above cargo tanks, which shall have at least the cross-sections as required by 3.5.3.1.3.

• .5 For the purpose of 3.5.1 or 3.5.2, the following shall apply:

  • .1 where it is required to pass between the surface to be inspected, flat or curved, and structures such as deck beams, stiffeners, frames, girders, etc., the distance between that surface and the free edge of the structural elements shall be at least 380 mm. The distance between the surface to be inspected and the surface to which the above structural elements are fitted, e.g. deck, bulkhead or shell, shall be at least 450 mm for a curved tank surface (e.g. for a type C tank), or 600 mm for a flat tank surface (e.g. for a type A tank) (see figure 3.1);

  • .2 where it is not required to pass between the surface to be inspected and any part of the structure, for visibility reasons the distance between the free edge of that structural element and the surface to be inspected shall be at least 50 mm or half the breadth of the structure's face plate, whichever is the larger (see figure 3.2);

  • .3 if for inspection of a curved surface where it is required to pass between that surface and another surface, flat or curved, to which no structural elements are fitted, the distance between both surfaces shall be at least 380 mm (see figure 3.3). Where it is not required to pass between that curved surface and another surface, a smaller distance than 380 mm may be accepted taking into account the shape of the curved surface;

  • .4 if for inspection of an approximately flat surface where it is required to pass between two approximately flat and approximately parallel surfaces, to which no structural elements are fitted, the distance between those surfaces shall be at least 600 mm. Where fixed access ladders are fitted, a clearance of at least 450 mm shall be provided for access (see figure 3.4);

  • .5 the minimum distances between a cargo tank sump and adjacent double bottom structure in way of a suction well shall not be less than those shown in figure 3.5 (figure 3.5 shows that the distance between the plane surfaces of the sump and the well is a minimum of 150 mm and that the clearance between the edge between the inner bottom plate, and the vertical side of the well and the knuckle point between the spherical or circular surface and sump of the tank is at least 380 mm). If there is no suction well, the distance between the cargo tank sump and the inner bottom shall not be less than 50 mm;

  • .6 the distance between a cargo tank dome and deck structures shall not be less than 150 mm (see figure 3.6);

  • .7 fixed or portable staging shall be installed as necessary for inspection of cargo tanks, cargo tank supports and restraints (e.g. anti-pitching, anti-rolling and anti-flotation chocks), cargo tank insulation etc. This staging shall not impair the clearances specified in 3.5.3.5.1 to 3.5.3.5.4; and

  • .8 if fixed or portable ventilation ducting shall be fitted in compliance with 12.1.2, such ducting shall not impair the distances required under 3.5.3.5.1 to 3.5.3.5.4.

LR 3.5-05 The requirements of LR 3.5-01 to LR 3.5-04 are to be applied unless specified otherwise by the National Administration.

Figure LR 3.7 Vertical Openings

Figure LR 3.8 Alternative Vertical Openings

LR 3.5-06 For ships complying with the requirements for type A independent tanks, manholes will not be permitted through the secondary barrier, except through the upper deck in regions which are above the predicted surface of the cargo assuming total failure of the cargo tank and the ship at 30° heel port or starboard. Alternative structural arrangement will be specially considered.

3.5.4 Access from the open weather deck to non-hazardous areas shall be located outside the hazardous areas as defined in chapter 10, unless the access is by means of an airlock in accordance with 3.6.

3.5.5 Turret compartments shall be arranged with two independent means of access/egress.

3.5.6 Access from a hazardous area below the weather deck to a non-hazardous area is not permitted.

3.6 Airlocks

3.6.1 Access between hazardous area on the open weather deck and non-hazardous spaces shall be by means of an airlock. This shall consist of two self-closing, substantially gastight, steel doors without any holding back arrangements, capable of maintaining the overpressure, at least 1.5 m but no more than 2.5 m apart. The airlock space shall be artificially ventilated from a non-hazardous area and maintained at an overpressure to the hazardous area on the weather deck.

3.6.2 Where spaces are protected by pressurization, the ventilation shall be designed and installed in accordance with recognized standards^footnote.

3.6.3 An audible and visible alarm system to give a warning on both sides of the airlock shall be provided. The visible alarm shall indicate if one door is open. The audible alarm shall sound if doors on both sides of the air lock are moved from the closed positions.

3.6.4 In ships carrying flammable products, electrical equipment that is located in spaces protected by airlocks and not of the certified safe type, shall be de-energized in case of loss of overpressure in the space.

3.6.5 Electrical equipment for manoeuvring, anchoring and mooring, as well as emergency fire pumps that are located in spaces protected by airlocks, shall be of a certified safe type.

3.6.6 The airlock space shall be monitored for cargo vapours (see 13.6.2).

3.6.7 Subject to the requirements of the International Convention on Load Lines in force, the door sill shall not be less than 300 mm in height.

3.7 Bilge, ballast and oil fuel arrangements

3.7.1 Where cargo is carried in a cargo containment system not requiring a secondary barrier, suitable drainage arrangements for the hold spaces that are not connected with the machinery space shall be provided. Means of detecting any leakage shall be provided.

3.7.2 Where there is a secondary barrier, suitable drainage arrangements for dealing with any leakage into the hold or insulation spaces through the adjacent ship structure shall be provided. The suction shall not lead to pumps inside the machinery space. Means of detecting such leakage shall be provided.

3.7.3 The hold or interbarrier spaces of type A independent tank ships shall be provided with a drainage system suitable for handling liquid cargo in the event of cargo tank leakage or rupture. Such arrangements shall provide for the return of any cargo leakage to the liquid cargo piping.

3.7.4 Arrangements referred to in 3.7.3 shall be provided with a removable spool piece.

3.7.5 Ballast spaces, including wet duct keels used as ballast piping, oil fuel tanks and non-hazardous spaces, may be connected to pumps in the machinery spaces. Dry duct keels with ballast piping passing through may be connected to pumps in the machinery spaces, provided the connections are led directly to the pumps, and the discharge from the pumps is led directly overboard with no valves or manifolds in either line that could connect the line from the duct keel to lines serving non-hazardous spaces. Pump vents shall not be open to machinery spaces.

LR 3.7-01 Unless specified otherwise, the requirement within 3.7.5 of the Code for Pump vents not to be open to machinery spaces need only be applied to pumps in machinery spaces serving dry duct keels through which ballast piping passes.

LR 3.7-02 The requirement of LR 3.7-01 is to be applied unless specified otherwise by the National Administration.

3.8 Bow and stern loading and unloading arrangements

3.8.1 Subject to the requirements of this section and chapter 5, cargo piping may be arranged to permit bow or stern loading and unloading.

3.8.2 Bow or stern loading and unloading lines that are led past accommodation spaces, service spaces or control stations shall not be used for the transfer of products requiring a type 1G ship. Bow or stern loading and unloading lines shall not be used for the transfer of toxic products as specified in 1.2.53, where the design pressure is above 2.5 MPa.

3.8.3 Portable arrangements shall not be permitted.

3.8.4.1 Entrances, air inlets and openings to accommodation spaces, service spaces, machinery spaces and controls stations, shall not face the cargo shore connection location of bow or stern loading and unloading arrangements. They shall be located on the outboard side of the superstructure or deckhouse at a distance of at least 4% of the length of the ship, but not less than 3 m from the end of the superstructure or deckhouse facing the cargo shore connection location of the bow or stern loading and unloading arrangements. This distance need not exceed 5 m.

3.8.4.2 Windows and sidescuttles facing the shore connection location and on the sides of the superstructure or deckhouse within the distance mentioned above shall be of the fixed (non-opening) type.

3.8.4.3 In addition, during the use of the bow or stern loading and unloading arrangements, all doors, ports and other openings on the corresponding superstructure or deckhouse side shall be kept closed.

3.8.4.4 Where, in the case of small ships, compliance with 3.2.4.1 to 3.2.4.4 and 3.8.4.1 to 3.8.4.3 is not possible, the Administration may approve relaxations from the above requirements.

3.8.5 Deck openings and air inlets and outlets to spaces within distances of 10 m from the cargo shore connection location shall be kept closed during the use of bow or stern loading or unloading arrangements.

3.8.6 Firefighting arrangements for the bow or stern loading and unloading areas shall be in accordance with 11.3.1.4 and 11.4.6.

3.8.7 Means of communication between the cargo control station and the shore connection location shall be provided and, where applicable, certified for use in hazardous areas.

LR 3.8-01 Full details of bow and stern loading and unloading arrangements, including fire-fighting arrangments, are to be submitted for consideration, see also Pt 7, Ch 6 of the Rules for Ships.

LR 3.9 General

LR 3.9–01 The scantlings and arrangements of the hull structure are to be in accordance with the appropriate Chapters of Parts 3 and 4 of the Rules for Ships, modified as indicated in the following paragraphs. All references within LR 3.9–02 to LR 3.26-01 are with respect to the Rules for Ships unless stated otherwise.

LR 3.9-02 The scantlings of structural items are to be verified by direct calculations, see LR III.5

LR 3.9–03 The following symbols used in these Rules, are defined in Pt 3, Ch 1,6:

LR 3.10 Distribution of continuous longitudinal material

LR 3.10-01 The minimum Rule scantlings are to be maintained for not less than 0,4L amidships, but may be required to be extended further depending on the arrangement of the hull structure. Thereafter, the scantlings may be tapered to the end thickness required by Pt 3, Ch 3,2.5 except where otherwise specified. The extent of any additional material required to be incorporated in the hull structure, and the tapering arrangements, will be specially considered.

LR 3.10-02 The scarfing arrangements at the ends of trunks and at other abrupt changes of section are to be such as to ensure adequate continuity of strength.

LR 3.11 Quality and grade of material

LR 3.11-01 The materials of the hull structure are to comply with the requirements of the Rules for the Manufacture, Testing and Certification of Materials. The requirements of Pt 3, Ch 2 of the Rules for Ships are also to be complied with, except as indicated otherwise, see 4.19.1 and LR 6.4. Proposals to use materials other than steel in the hull structure will be specially considered.

LR 3.11-02 In the determination of scantlings the higher tensile steel factor, k_L, is only to be applied when the extent of higher tensile steel fitted is in accordance with Pt 3, Ch 3,2.6. The scantlings of localized regions of higher tensile steel will be specially considered.

LR 3.12 Protection of steelwork and corrosion control

LR 3.12-01 The requirements of Pt 3, Ch 2,3 are to be adopted where applicable. Particular attention is to be given to protection in way of stainless steel inserts and other bi-metallic connections.

LR 3.13 Assessment of longitudinal strength

LR 3.13-01 Longitudinal strength calculations are to be made in accordance with the requirements of Pt 3, Ch 4. Where the structural analysis of the hull is carried out by direct calculation procedures, and these include the assessment of longitudinal strength, full details of the assumptions made and the calculations are to be submitted, see also LRIII.5.

LR 3.13-02 Ships intended for the carriage of liquefied gases are to be provided with an approved loading instrument as required by Pt 3, Ch 4,8.3.

LR 3.13-03 LR may require additional longitudinal strength and stiffness to take account of the behaviour of the hull structure and in particular the interaction between the cargo containment system and the hull structure.

LR 3.13-04 Where a continuous rigid trunk is fitted above the strength deck, the longitudinal material of the trunk may be taken into account when calculating the hull section modulus, and the vertical lever, z, is to be calculated in accordance with Pt 3, Ch 3,3.4.11. Where continuous open girders are fitted on the deck or trunk top, they may also be taken into account when calculating the hull section modulus as permitted by Pt 3, Ch 3,3.4.

LR 3.14 Local scantling reduction

LR 3.14-01 Local scantling reduction factors are generally to be in accordance with Pt 3, Ch 4,5.7.

LR 3.15 Deck plating

LR 3.15-01 The thickness of deck plating is to comply with the requirements of Table LR 3.1 Deck plating and longitudinals together with the hull buckling strength requirements in Pt 3, Ch 4,7. The thickness of deck plating of the fore and aft end structures are to be not less than required by Pt 3, Ch 5,2.2 and Pt 3, Ch 6,2.2. Increased scantlings may be required where local deflections of the structure could influence the behaviour of the cargo containment system and in way of anti-roll chocks, anti-flotation chocks or other similar items.

LR 3.15-02 Cross deck strips at the strength deck forming the top of a transverse bulkhead are, in general, to have a width, w, not less than:

In cases where a transverse bulkhead top box (or equivalent) is arranged, a reduced width of cross deck strip may be considered.

LR 3.15-03 Cross deck strips at the strength deck are, in general, to have a thickness, t, not less than the greatest of the following:

(a) t = 0,012s1

(b) t = 0,00083s1 + 2,5 mm

(c) t = 10 + 0,01L mm or 12 mm whichever is the lesser.

This thickness may be required to be increased locally in way of large access openings.

LR 3.15-04 Where the difference between the thickness of plating inside and outside the line of main deck openings exceeds 12 mm, a transitional plate of thickness equivalent to the mean of the adjacent plate thickness is to be fitted.

LR 3.15-05 Cross deck strips are to be sufficiently stiffened in the transverse direction.

LR 3.15-06 The thickness of deck plating supporting or forming part of the primary barrier may be required to be further increased.

Table LR 3.1 Deck plating and longitudinals

Item, see Fig. LR 3.4	Requirement
(1) Thickness of strength or trunk deck plating, see Notes 1 and 2	The greater of:
	(a) t = 0,001s1 (0,059L1 + 7) mm
	(b) t = 0,00083s1f + tc mm (but not less than 6,5 mm)
(2) Thickness of upper deck, see Notes 2, 3 and 4	For weather part
	(a) t as for (1)
	For deck inboard
	(b) t = 0,012s1 mm
	In way of the crown of a tank
	(c) t = 0,004sf + 3,5 mm
(3) Thickness of inner deck	The greater of:
	(a) LR 3.22-03
	(b) 6,5 mm
	In way of a tank, not less than:
	(c) t = 0,004sf + 2,5 mm
(4) Strength or trunk deck longitudinals and Upper deck longitudinals, see Note 3	Modulus, in cm3	Inertia, in cm4
	(a) Z = 0,043s k hT1le2F1	-
	In way of the crown or bottom of a tank, not less than	I =
	(b)
(5) Section modulus of inner deck longitudinals	LR 3.22-03
Symbols
L, k, kL, s, S as defined in Pt 4, Ch 1,1.5.1
FD as defined in Pt 3, Ch 4,5.7
ρ = relative density (specific gravity) of liquid carried in a tank but is not to be taken less than 1,025
F1 = 0,25c1
hT1 = greater of or 1,20 m
h4 = tank head as defined in Pt 3, Ch 3,5
le = effective length of stiffening member, in metres, but not to be taken less than 1,5 m, see Pt 3, Ch 3,3
L1 = L but need not be taken greater than 190 m
s1 = s, but not to be taken less than the smaller of
tc = 1 mm, if space is void space
tc = 2 mm, if space is for ballast water
f = 1,1 – but not to be taken greater than 1,0
γ = see Table LR 3.2
NOTES
1. The deck thickness is to be not less than the basic strength deck end thickness for taper as given in Pt 3, Ch 3, Table 3.2.1 Taper requirements for hull envelope.
2. Where separate maximum sagging and hogging still water moments are assigned, FD, may be based on the maximum sagging moment.
3. For the upper deck FD may be factored to the actual stress at location.
4. The thickness of deck plating forming the boundary of a ballast tank is not to be less than that required by Table 1.4.1(3) in Pt 4, Ch 1.

LR 3.16 Shell plating

LR 3.16-01 The scantlings of the shell envelope are to comply with the requirements of Table LR 3.2 Bottom shell, bilge and side shell plating and longitudinals together with the hull buckling strength requirements in Pt 3, Ch 4,7. Increased scantlings may be necessary to meet local strength requirements. The scantlings of the keel, bottom and side shell plating of the fore and aft end structures are to be not less than required by Pt 3, Ch 5,3 and Pt 3, Ch 6,3.

Table LR 3.2 Bottom shell, bilge and side shell plating and longitudinals

Item, see Fig. LR 3.4	Requirement
(1) Thickness of bottom shell and bilge plating, see Note 1	The greater of:
	(a) Pt 4, Ch 1, Table 1.5.2
	(b) t = 0,004sf mm
(2) Thickness of side shell plating and sheerstrake, see Note 1	The greater of:
	(a) Pt 4, Ch 1, Table 1.5.3
	(b) t = 0,004sf mm
3) Bottom and bilge longitudinals	The greater of:
	(a) Z = γ1 s k hT2 le 2 F1 cm3
	(b) Z = γ1 s k hT3 le 2 F1 Fsb cm3
	(c) Z =
(4) Side longitudinals in way of double skin tanks or deep tanks	The greater of:
	(a) Z as from (5)
	(b) Z from (3) (c)
(5) Side longitudinals in way of dry spaces	The lesser of:
	(a) Z = 0,056s k hT1 le 2 F1 Fs cm3
	(b) Z from (3) (a) evaluated using s, k, le for the longitudinal under consideration and the remaining parameters evaluated at the base line
Symbols
D, L, k, kL, s, S as defined in Pt 4, Ch 1,1.5.1
D1 = D2 , in metres, but is not to be taken less than 10 and need not be taken greater than 16
D2 = D, in metres, but need not be taken greater than 1,6T
FB, FD = as defined in Pt 3, Ch 4,5.7
ρ = relative density (specific gravity) of liquid carried in a tank but is not to be taken less than 1,025
T = see Pt 3, Ch 1,6
hT1 = Cw , in metres, for longitudinals above the waterline, at draught T, where is not to be taken less than for Type 'B-60' ships and the greater of or 1,20 m for Type 'B' ships = , in metres, for longitudinals below the waterline, at draught T hT1 need not exceed 0,86 for F1 ≤ 0,14 and
hT2 = T + 0,5Cw , in metres, but need not be taken greater than 1,2T
hT3 = h4 – 0,35T, at the base line, in metres = h4 , at and above 0,35T from the base line, in metres, intermediate values by linear interpolation
h4 = for plating the distance from a point one third of the height of the plate above its lower edge to the top of the tank, or half the distance to the top of the overflow, whichever is the greater
h4 = for stiffeners, the distance from the middle of the effective length to the top of the tank, or half the distance to the top of the overflow, whichever is the greater
h5 = vertical distance, in metres, from longitudinal to deck at depth, D2
h6 = vertical distance, in metres, from the waterline at draught T to the longitudinal under consideration
Fsb = fatigue factor for bottom longitudinals = 0,5 (1 + Fs )
Where Fs is to be calculated at 0,6D2 above base.
Fs is a fatigue factor for side longitudinals to be taken as follows: (a) For built sections and rolled angle bars at 0,6D2 above the base line = 1,0 at D2 and above, and Fsb at the base line intermediate values by linear interpolation (b) For flat bars and bulb plates Fs may be taken as 0,5
bf1 = the minimum distance, in mm, from the edge of the face plate of the side longitudinal under consideration to the centre of the web plate, see Fig. LR 3.5
γ = 1,4 for rolled or built sections and double plate bulkheads = 1,6 for flat bars
ω = as defined in Pt 4, Ch 1, Table 1.9.1
Cw = 7,71 x 10–2 Le–0,0044L where L is not to be taken greater than 227
γ1 = 0,002le1 + 0,046
f = see LR 3.22-03(a)
le1 = le in metres, but is not to be taken less than 2,5 m and need not be taken greater than 5,0 m
le = effective length of stiffening member, in metres, but is not to be taken less than 1,5 m except in way of the centre girder brackets required by Pt 4, Ch 1,8.5.3 where a minimum span of 1,25 may be used
F1 = see LR 3.22-03(b)
Fλ = 1,0 for L ≤ 200 m = [1,0 + 0,0023(L-200)] for L > 200 m
NOTES
1. The bottom shell, bilge and side shell plating thickness is to be not less than the basic shell end thickness for taper as given in Pt 3, Ch 3, Table 3.2.1 Taper requirements for hull envelope.
2. The ratio of the web depth, dw , to web thickness, t, is to comply with the following requirements:
(a) Built-up profiles and rolled angles:
(b) Flat bars: when continuous at bulkheads when non-continuous at bulkheads
3. Where struts are fitted midway between transverses in way of double bottom tanks, or double skin construction, the modulus of the bottom or side longitudinals may be reduced by 50k per cent from that obtained from the locations (3), (4), or (5) as applicable.
4. Where the bilge radius exceeds the Rule height of a double bottom the modulus of the longitudinal above this nominal height is to be derived from the location (4) or (5) as applicable.
5. Where no bilge longitudinals are fitted and bilge brackets are required by location (3) in Pt 4, Ch 1, Table 1.5.2, at least two brackets are to be fitted.

LR 3.17 Longitudinal and transverse framing and deck beams

LR 3.17-01 The scantlings of deck longitudinals are to comply with the requirements of Table LR 3.1 together with the hull buckling strength requirements in Pt 3, Ch 4,7. The scantlings of deck longitudinals of the fore and aft end structures are to be not less than required by Pt 3, Ch 5,2.3 and Ch 6,2.3 with h₀ derived as a dry cargo ship. The scantlings for topside tank structure are to be in accordance with Pt 4, Ch 7,7.

LR 3.18 Double bottom

LR 3.18-01 The extent and depth of double bottom is to be not less than required by Chapters 2 and 3 of these Rules for the ship type and intended cargoes. The scantlings and arrangements are also to comply with Pt 4, Ch 1,8, Pt 3, Ch 5,5 and Pt 3, Ch 6,5 of the Rules for Ships. Where the structural arrangements are considered such as to necessitate it, LR may require further verification by direct calculations.

The thickness of the inner bottom plating may be required to be increased locally in way of tank support structure. Where the double bottom is common with wing or side ballast tanks, the scantlings of the inner bottom are to be not less than that given by LR 3.22-03(d). At the intersection of inner bottom and hopper plating, collars are to be fitted to any unavoidable scallops in the floors, to minimise stress concentrations in these regions.

LR 3.18-02 The depth, at centreline, of the double bottom of ships with independent spherical Type B tanks is to be determined by direct calculation taking into account the access requirements of Ch 3,3.5.3. The inner bottom may be sloped downwards towards the ship’s centreline such that the minimum double bottom depth is not less than 0,7dDB or 1000 mm, whichever is the greater, where dDB is the Rule depth, in mm, derived from Pt 4, Ch 1,8 of the Rules for Ships for general cargo ships.

LR 3.18-03 Where the inner bottom forms part of the cargo containment system or provides direct support to the containment system, the requirements of LR 3.22-03 are to be applied. The scantlings are also to be sufficient to meet the requirements of the containment system design.

LR 3.19 Strengthening of bottom forward

LR 3.19-01 The bottom forward is to be strengthened as required by Pt 3, Ch 5,1.5.

LR 3.20 Primary support structure of deck

LR 3.20-01 Deck girders and transverses are to have a section modulus not less than that required by Pt 4, Ch 1,4 and Pt 4, Ch 7,7.5 as appropriate, but additional strengthening may be required to take account of the pressures, loads or moments transmitted from the cargo containment system.

LR 3.20-02 Where the deck structure acts as the structural support for the cargo containment system and the primary structure is fitted in one direction only, the section modulus and moment inertia of the member are, in general, to be not less than:

LR 3.21 Transverse bulkheads

LR 3.21-01 Where the cargo containment system incorporates independent tanks, and provision for floodable cofferdams between holds is not made (see LR 3.1–02), the scantlings of bulkhead plating and stiffening are to be as required for a watertight bulkhead by Pt 4, Ch 1,9.

LR 3.21-02 Where floodable cofferdams are fitted, the scantlings are to be as required for a deep tank bulkhead by Pt 4, Ch 1,9.

LR 3.21-03 Where the bulkhead forms part of the cargo containment system or provides direct support to the containment system, the scantlings are to be sufficient to meet the requirements of the containment system design and the loads imposed by it. In addition, where the transverse bulkheads are directly loaded by the cargo the requirements of LR 3.21-04 are to be applied. In this case, the transverse bulkheads should be able to withstand a collision force corresponding to one half the weight of the cargo in the forward direction and one quarter the weight of the tank and cargo in the aft direction without deformation likely to endanger the tank structure, see also 4.15.1. The scantlings are to be in accordance with the requirements of LR 3.21-06. The scantlings are also to comply with Pt 4, Ch 1,9 as required for a watertight bulkhead.

LR 3.21-04 Scantlings of transverse bulkheads providing direct support to the containment system are to comply with the following, see also LR 3.21-05:

1. Boundary plating

   The thickness, t, of plating forming the boundaries of cargo tanks is to be not less

   

   but not less than 7,5 mm

2. Rolled or built stiffeners

   The section modulus of rolled or built stiffeners on plating forming tank boundaries is to be not less than:

   

   where

   • P_eq = the internal pressure head, in MPa, as derived from 4.28.1.1 of these Rules
   • s,k,l_e, f = as defined in LR 3.22-03
   • γ, ω₁, ω₂ = as defined in Table 1.9.1 in Pt 4, Ch 1.

LR 3.21-05 Where it is proposed to use higher tensile steel for secondary stiffeners, the effect on fatigue performance of the connection details between secondary members and the primary supporting structure should be taken into consideration. The containment design should also be adequate to cope with the increased deformations expected with the use of higher tensile steel.

LR 3.21-06 When determining scantlings for the transverse bulkhead in dry space cofferdams, due to the loads arising from the collision case mentioned in LR 3.21-03, the following requirements are to be complied with. An additional 1 mm is to be added to the thickness derived below if the cofferdam is floodable.

1. The plating:
   

   where

   s, f and k are as defined in LR 3.22-03

   P_COLL = collision pressure, in MPa, as derived from LR 3.21-03, see also 4.15.1.

2. Rolled or built stiffeners:
   

   where

   γ = 1,3.

LR 3.21-07 The local and overall strength of the bulkhead may be required to be increased in way of the tank supporting structure, collision chocks, anti-flotation chocks or similar items.

LR 3.21-08 Where horizontal and vertical girders are used to support the bulkhead, the bulkhead scantlings may be determined using direct calculation procedures. The assumptions made and the calculations are to be submitted.

LR 3.22 Longitudinal bulkheads and inner hull

LR 3.22-01 Longitudinal bulkheads and the inner hull, where these items are fitted, are to comply with the requirements given above for transverse bulkheads.

LR 3.22-02 In addition, the scantlings of plating and longitudinal framing are to be sufficient to meet the longitudinal strength and shear force requirements given in LR 3.13-01and Pt 3, Ch 4. Inner bottom plating and longitudinals are to meet the requirements of Pt 4, Ch 1,8.4.

LR 3.22-03 Where the longitudinal bulkhead provides direct support for the containment system, a structural analysis of the hull structure will be required using direct calculation procedures which are to be agreed with LR at as early a stage as possible.

When determining scantlings for the inner hull, the following requirements are to be complied with:

1. Plating:

   The thickness of plating should be not less than:

   
   where

   t	=	derived plate thickness, in mm
   s	=	stiffener spacing, in mm
   k	=	higher tensile steel factor, see Pt 3, Ch 2,1
   Peq	=	the internal pressure head, in MPa, as derived from 4.28.1.1 of these Rules
   f	=	but need not exceed 1,0
   S	=	overall length of stiffeners, in metres, between support points.

2. Rolled or built stiffeners:

   The section modulus of rolled or built stiffeners should not be less than:

   Z = 4,7s k P_eq l_e²F₁ cm³

   where

   k	=	higher tensile steel factor, see Pt 3, Ch 2,1
   Peq	=	the internal pressure head, in MPa, as derived from 4.28.1.1 of these Rules, but is not to be taken as less than MPa or (0,0001L1 + 0,007) MPa, whichever is the greater
   L1	=	L, but need not be taken as greater than 190 m
   s	=	stiffener spacing, in mm
   le	=	effective length of stiffeners, in metres
   c	=	at deck, see definition of depth D
   	=	1,0 at
   	=	at base line

   • Intermediate values of c are to be obtained by linear interpolation

   F1	=	, for longitudinals above
   	=	, for longitudinals below

   • but is not to be taken as less than 0,12

   h	=	distance of longitudinal below deck at side, in metres
   	=	distance of longitudinal below trunk deck at side, in metres, for ships fitted with a trunk deck
   D	=	depth of ship, in metres, as defined in Pt 3, Ch 1,6.1.4
   	=	depth of ship to trunk deck at side for ships fitted with trunk deck
   FD	=	as defined in Pt 3, Ch 4,5
   FB	=	as defined in Pt 3, Ch 4,5

3. Connection of inner hull longitudinals to primary members:

   In considering these connections, the requirements of Pt 3, Ch 10,5.2 are to be applied as for oil tankers taking account of the dynamic pressure heads determined by 4.28.1.1 of these Rules.

4. Where the inner hull is common with wing or side ballast tanks the scantlings of the inner hull are to be not less than:

   Plating:

   
   but not less than 7,5 mm

   Rolled or built stiffeners:

   

   where

   s, f, k, ρ, h4, γ, ω1 and ω2 are as defined in Table LR 3.2.

LR 3.23 Primary support structure of the side shell and inner hull

LR 3.23-01 Transverses supporting side longitudinals are to be arranged in line with the floors in the double bottom to ensure continuity of transverse strength. The section modulus of side transverses and moment inertia are, in general, to be not less than:

Z = 48ρ k S h l_e² cm³

LR 3.24 Strengthening for navigation in ice

LR 3.24-01 Where an ice class notation is desired, additional strengthening is to be fitted, as required by Pt 8.

LR 3.25 Strengthening for wave impact loads

LR 3.25-01 The side structure in the forward portion of the hull is to be strengthened against wave impact pressure in accordance with Pt 4, Ch 2,4.3 and 5.2. The side structure requirements taken from Pt 4, Ch 2,5.2 must in no case be taken as less than those required by these Rules.

LR 3.26 Additional requirements

LR 3.26-01 The scantlings and arrangements of ventilators, air pipes and discharges, closing arrangements and ship control systems are to comply with the appropriate Chapters of Parts 3 and 4 of the Rules for Ships, except where required otherwise by these Rules.