Section 1 General

1.1.1 This Chapter applies primarily to the arrangements and scantlings within the cargo tank region of sea-going tankers having integral cargo tanks, for the carriage of oil having a flash point not exceeding 60°C (closed-cup test), in association with the class notation indicated in Pt 4, Ch 9, 1.3 Class notation and applicable Rules for CSR Double Hull Oil Tankers 1.3.1 or Pt 4, Ch 9, 1.4 Class notation and applicable Rules for non-CSR Double Hull Oil Tankers 1.4.1. Except as indicated in Pt 4, Ch 9, 1.1 General 1.1.2, Pt 4, Ch 9, 1.1 General 1.1.3 and Pt 4, Ch 9, 1.1 General 1.1.4, the cargo spaces are to be bounded by side and bottom dedicated water ballast tanks or void spaces constituting a double hull for the ship, see Table 9.1.1 Cargo tank boundary requirements.

1.1.2 Double side tanks may be dispensed with for tankers of less than 5000 tonnes deadweight where each cargo tank capacity does not exceed 700 m³, see Table 9.1.1 Cargo tank boundary requirements.

1.1.3 Double bottom tanks may be dispensed with for tankers of 5000 tonnes deadweight or greater subject to compliance with the requirements of Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.18.

1.1.4 Double bottoms and double sides may be dispensed with for vessels less than 600 tonnes deadweight, see Table 9.1.1 Cargo tank boundary requirements.

1.1.5 Where only oils having flash points exceeding 60ºC are to be carried, the Rule requirements and class notation will be modified accordingly the additional class notation ‘F.P. exceeding 60ºC’ will be entered in the Register Book.

1.1.6 Oil cargoes listed in Table 9.1.2 Oil cargoes suitable for carriage in oil tankers, see Note 1 are those which are generally envisaged as being carried in ships classed in accordance with this Chapter.

1.1.7 The scantlings and arrangements of tankers intended for cargoes other than oil will be specially considered in relation to the characteristics of the cargo, and the class notation will be modified accordingly. A full list of such cargoes for a particular ship, with special requirements as applicable, can be provided by Lloyd’s Register (hereinafter referred to as ‘LR’) on application. Chemical cargoes listed in Chapter 18 of the Rules and Regulations for the Construction and Classification of Ships for the Carriage of Liquid Chemicals in Bulk (hereinafter refered to as the Rules for Ships of Liquid Chemicals) may be carried in ships for which the arrangements, scantlings and materials comply with the requirements of that Chapter. Special consideration will also be given to the carriage of cargoes with a relative density greater than 1,025, see also Pt 4, Ch 9, 1.3 Class notation and applicable Rules for CSR Double Hull Oil Tankers and Pt 4, Ch 9, 1.4 Class notation and applicable Rules for non-CSR Double Hull Oil Tankers.

1.1.8 The Regulations for classification and assignment of the above notations and other notations, as appropriate to the arrangements, scantlings and service are provided for in Pt 1, Ch 2, 2 Character of classification and class notations.

Table 9.1.1 Cargo tank boundary requirements

Deadweight (DWT) tonnes	Minimum double side width (ds ) metres		Minimum double bottom depth (db ) metres
DWT ≥ 5000	ds = 0,5 +		db =
	or		or
	ds = 2,0		db = 2,0
	whichever is the lesser, but not less than 1,0		whichever is the lesser, but not less than 1,0
	ds = 0,4 +		db =
600 ≤ DWT < 5000	or		or
	ds = 0,76		db = 0,76
	whichever is the greater, see Note 2		whichever is the greater,
DWT < 600	ds = 0		db = 0
Note 1. The symbols DWT, ds and db are defined in 1.5. Note 2. Where each cargo tank capacity does not exceed 700 m3, the value of ds is taken as 0 and the inner bottom line is to run parallel to the line of the midship flat of bottom as shown in Figure 9.1.2 Cargo tank boundary lines for oil tankers having double bottom arrangement (See) . Note 3. Where the double bottom tank is fitted, the centre girder depth is to be not less than as required by Pt 4, Ch 9, 9.3 Girders and floors in double bottom 9.3.3.

1.2.1 Double hull tankers with length, L, greater than or equal to 150 m with structural configuration as shown in Table 9.1.3 Structural arrangement are defined as ’CSR Oil Tankers’ and are to comply with Pt 4, Ch 9, 1.3 Class notation and applicable Rules for CSR Double Hull Oil Tankers.

1.2.2 The applicable Rules for double hull tankers with length, L, greater than or equal to 150 m of unusual hull form or structural arrangements will be specially considered.

1.2.3 Double hull tankers with length, L, less than 150 m are defined as ‘Non-CSR Oil Tankers’ and are to comply with Pt 4, Ch 9, 1.4 Class notation and applicable Rules for non-CSR Double Hull Oil Tankers.

1.2.4 Any dry tanks, or tanks intended for water ballast and thus empty in the loaded condition, are to be so arranged that they cannot be used for any other purpose.

1.2.5 Cofferdams are to be provided at the forward and after ends of the oil cargo spaces; cofferdams are to be at least 760 mm in length and are to cover the whole area of the end bulkheads of the cargo spaces.

1.2.6 A pump-room, fuel oil bunker or water ballast tank will be accepted in lieu of a cofferdam.

Table 9.1.3 Structural arrangement

Arrangement	Typical configuration		L < 150	L ≥ 150
No longitudinal bulkhead			Non CSR	CSR (specially considered)
One or two longitudinal bulkhead(s)			Non CSR	CSR
Trunk deck in association with longitudinal bulkhead(s) (see Ch 10,6)			Non CSR	CSR
Double deck in association with a centreline bulkhead			Non CSR	CSR (specially considered)
Mid-deck in association with a centreline bulkhead or centreline girders			Non CSR	CSR (specially considered)

1.2.7 Where the lower portion of the pump-room is recessed into the machinery space, the height of the recess is not, in general, to exceed one-third of the moulded depth above the keel, see also Pt 5, Ch 15, 1 General requirements.

1.2.8 Where a compartment or tank, such as a fore peak tank, forms a cofferdam, access is to be from the open deck. Alternatively, any space through which it is necessary to pass in order to obtain access is to conform to the requirements of Pt 6, Ch 2, 14 Electrical equipment for use in explosive gas atmospheres or in the presence of combustible dusts. Engine or electrically driven pumps are not to be sited in the space containing the access to such cofferdams.

1.2.9 A cofferdam is also to be arranged between a cargo oil tank and accommodation spaces, and between cargo oil tanks and spaces containing electrical equipment, other than spaces where the only items of electrical equipment are lighting fittings complying with Pt 6, Ch 2, 14 Electrical equipment for use in explosive gas atmospheres or in the presence of combustible dusts. Where a corner to corner situation occurs, protection may be formed by a diagonal plate across the corner. The scantlings and testing arrangements are to comply with Rule requirements for cofferdam bulkheads, and arrangements are to be made to enable the space to be filled with water ballast to assist in gas freeing, see also Pt 5, Ch 15, 3 Cargo handling system. Suitable corrosion protection, drainage and gas-freeing arrangements are to be provided to such spaces.

1.2.10 Passages or tunnels passing through, or adjacent to, a cargo oil tank and not separated from it by a cofferdam, are to be provided with mechanical ventilation, and any access is to be from the open deck.

1.2.11 Arrangements are to be provided to enable double bottom and vertical wing tanks to be filled with water ballast to assist in gas freeing these tanks, see Pt 5, Ch 15, 3 Cargo handling system.

1.2.12 Fittings within cargo tanks and pump-rooms are to be securely fastened to the structure.

1.2.13 Accommodation, control and service spaces are to be located clear of the cargo tank region such that a single failure of deck or bulkhead will not allow cargo fumes into these spaces. Navigation positions, where fitted above the cargo tank region, are to be separated from the cargo tank deck by means of an open space with a height of at least 2,0 m.

1.2.14 Where spill retainment flats are fitted at the sides of the weather deck, separate arrangements are to be provided for freeing the deck of oil and water respectively, see also Pt 3, Ch 10, 5.1 Continuity and alignment 5.1.1.

1.2.15 Alternative arrangements which are proposed as being equivalent to the Rules will receive individual consideration, taking into account any relevant National Authority requirements.

1.2.16 Reference should also be made to the relevant Regulations of the International Convention for the Safety of Life at Sea, 1974 and applicable amendments.

1.2.17 Cargo spaces are to be bounded by double bottom and double side tanks or void spaces such that the distance between the cargo tank boundary and the shell plating is not less than that given in Table 9.1.1 Cargo tank boundary requirements and Figure 9.1.1 Cargo tank boundary lines for oil tankers having double bottom and double side tank arrangements (See Table 9.1.1 Cargo tank boundary requirements ) , except as otherwise specified in Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.18 and Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.19. Cargo or fuel oil are not to be carried in double bottom or double side tanks.

1.2.18 Where DWT ≥ 5000 tonnes, double bottom tanks as required by Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.17 may be dispensed with, provided the following requirements are complied with:

1. The cargo height, h_c , in contact with the bottom shell plating is to be not greater than:

   

   where the symbols are defined in Pt 4, Ch 9, 1.6 Information required for CSR Double Hull Oil Tankers.

2. Where a mid-deck dividing the cargo oil tanks into upper and lower spaces is arranged, it is to be located at a height of not less than the lesser of or 6 m, but

   not more than 0,6D, above the base line.

3. Below a level 1,5d_b above the base line, the cargo tank boundary line may be vertical down to the bottom shell plating as shown in Figure 9.1.3 Cargo tank boundary lines for oil tankers having mid-deck arrangement (See Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.18 ) .

1.2.19 Alternative arrangements which are equivalent to Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.17 will receive individual consideration, taking into account any relevant National Authority requirements.

1.2.20 The length of each cargo tank is not to exceed 10 m or the appropriate value obtained from Table 9.1.4 Permissible length of cargo tanks, see Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.20 , whichever is the greater.

1.2.21 Where DWT ≥ 5000 tonnes, the cargo pump-room shall be provided with a double bottom such that at any cross-section the depth of each double bottom tank or space shall be such that the distance d _c, as defined in 1.5, is not

less than the lesser of and 2 m

d_c is in no case to be less than 1 m.

In the case of cargo pump-rooms whose bottom plate is located above the base line by at least the minimum height required, there will be no need for a double bottom construction in way of the cargo pump-room.

1.2.22 Notwithstanding the requirements of Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.21, above, where the flooding of the cargo pump-room would not render the ballast or cargo pumping system inoperative, a double bottom need not be fitted.

Figure 9.1.1 Cargo tank boundary lines for oil tankers having double bottom and double side tank arrangements (See Table 9.1.1 Cargo tank boundary requirements )

Figure 9.1.2 Cargo tank boundary lines for oil tankers having double bottom arrangement (See Table 9.1.1 Cargo tank boundary requirements )

Figure 9.1.3 Cargo tank boundary lines for oil tankers having mid-deck arrangement (See Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.18 )

Table 9.1.4 Permissible length of cargo tanks, see Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.20

Number of longitudinal bulkheads inside cargo tanks		One (on centreline)	Two	Three (one on centreline)	Where no longitudinal bulkhead is arranged or where longitudinal bulkheads are perforated across breadth of cargo tanks
Length of wing cargo tank			0,2LL	0,2LL
Length of centre tank	bi ≥ 0,2B	—	0,2LL	0,2LL port and starboard	or
	bi ≥ 0,2B	—		port and starboard	0,2LL whichever is the lesser
Note The symbols LL , B and bi are defined in Pt 4, Ch 9, 1.5 General definitions and symbols.

1.3.1 In general, CSR Double Hull Oil Tankers are to comply with Pt 4, Ch 9, 1.3 Class notation and applicable Rules for CSR Double Hull Oil Tankers 1.3.2 to Pt 4, Ch 9, 1.3 Class notation and applicable Rules for CSR Double Hull Oil Tankers 1.3.7 and the IACS Common Structural Rules for Bulk Carriers and Oil Tankers (CSR) for the draught required and will be eligible to be classed 100A1 Double Hull Oil Tanker CSR, ESP.

1.3.2 Class notations applicable to CSR double hull oil tankers are defined as follows:

• CSR

Identifies the double hull oil tanker as being compliant with the IACS Common Structural Rules (CSR)

• ESP

Identifies the double hull oil tanker as being subject to an Enhanced Survey Programme as detailed in Pt 1, Ch 3, 3 Intermediate Surveys - Hull and machinery requirements and Pt 1, Ch 3, 7 Special Survey - Oil tankers (including ore/oil ships and ore/bulk/oil ships) - Hull requirements, see also Pt 1, Ch 2, 2.3 Class notations (hull) 2.3.12.

1.3.3 Materials are to comply with the Rules for the Manufacture, Testing and Certification of Materials (hereinafter referred to as the Rules for Materials). Corrosion protection is to comply with Pt 3, Ch 2, 3 Corrosion protection and Ch 15 Corrosion Prevention of the Rules for Materials.

1.3.4 The rudder and rudder stock are to comply with Pt 3, Ch 13, 2 Rudders.

1.3.5 Ice strengthening is to be in accordance with Pt 8 Rules for Ice and Cold Operations.

1.3.6 The ShipRight notation CM is mandatory for CSR double hull oil tankers greater than 150 m in length, see Pt 4, Ch 9, 1.4 Class notation and applicable Rules for non-CSR Double Hull Oil Tankers 1.4.6.

1.3.7 The ‘ShipRight Procedures’ for the hull construction of ships are detailed in Pt 3, Ch 16 ShipRight Procedures for the Design, Construction and Lifetime Care of Ships and the classification notations and descriptive notes associated with these procedures are given in Pt 1, Ch 2, 2 Character of classification and class notations.

1.4.1 In general, non-CSR Double Hull Oil Tankers are to comply with Pt 4, Ch 9, 1.4 Class notation and applicable Rules for non-CSR Double Hull Oil Tankers 1.4.2 to Pt 4, Ch 9, 1.4 Class notation and applicable Rules for non-CSR Double Hull Oil Tankers 1.4.8 for the draught required and will be eligible to be classed 100A1 Double Hull Oil Tanker, ESP.

1.4.2 The notation ESP serves to identify the ship as being subject to an Enhanced Survey Programme as detailed in Pt 1, Ch 3, 3 Intermediate Surveys - Hull and machinery requirements and Pt 1, Ch 3, 7 Special Survey - Oil tankers (including ore/oil ships and ore/bulk/oil ships) - Hull requirements, see also Pt 1, Ch 2, 2.3 Class notations (hull) 2.3.12.

1.4.3 At the Owner's request, the notation MARPOL 20.1.3 may be appended to the notation100A1 Double Hull Oil Tanker for vessels not meeting the minimum double side width (d_s ) requirements of Table 9.1.1 Cargo tank boundary requirements but which comply with MARPOL Annex I, Regulation 20.1.3.

1.4.4 At the Owners request, the notation MARPOL 21.1.2 may be appended to the notation 100A1 Double Hull Oil Tanker for vessels of less than 5000 tonnes deadweight which have a double hull in accordance with MARPOL Annex I, Regulation 21.1.2.

1.4.5 The ShipRight notation CM is mandatory for non-CSR double hull oil tankers greater than 150 m in length, see Pt 4, Ch 9, 1.4 Class notation and applicable Rules for non-CSR Double Hull Oil Tankers 1.4.6.

1.4.6 Where the length of the ship is greater than 190 m, or where the structural arrangements are considered such as to necessitate it, the scantlings of the primary supporting structure are to be assessed by direct calculation and the ShipRight notations SDA, FDA and CM are mandatory, see Pt 4, Ch 9, 1.4 Class notation and applicable Rules for non-CSR Double Hull Oil Tankers 1.4.6 and Pt 4, Ch 9, 14 Direct calculations.

1.4.7 The ‘ShipRight Procedures’ for the hull construction of ships are detailed in Pt 3, Ch 16 ShipRight Procedures for the Design, Construction and Lifetime Care of Ships and the classification notations and descriptive notes associated with these procedures are given in Pt 1, Ch 2, 2 Character of classification and class notations.

1.4.8 The disposition of transverse bulkheads is to comply with the requirements of Pt 3, Ch 3, 4 Bulkhead requirements, as applicable to ships with machinery located aft.

1.4.9 Arrangements and scantlings forward and aft of the cargo tank region are to comply with Pt 3, Ch 5 Fore End Structure, Pt 3, Ch 6 Aft End Structure and Pt 3, Ch 7 Machinery Spaces. The remaining requirements of Part 3 are also to be complied with as appropriate to the intended arrangements.

1.4.10 Arrangements pertaining to gangways, bulwarks and rails are to comply with the requirements of Pt 3, Ch 8 Superstructures, Deckhouses and Bulwarks.

1.4.11 The structural configurations may include one or more of the arrangements shown in Table 9.1.3 Structural arrangement. These provisions do not preclude the fitting of additional bulkheads or the perforation of longitudinal bulkheads.

1.4.12 The bottom shell, inner bottom and deck are generally to be framed longitudinally in the cargo tank region where the ship length, L, exceeds 75 m. However, consideration will be given to alternative proposals for ships of special design.

1.4.13 The side shell, inner hull bulkheads and longitudinal bulkheads are generally to be longitudinally framed where the ship length, L, exceeds 150 m, but alternative proposals, taking account of resistance to buckling, will be considered.

1.4.14 Where the side shell is longitudinally framed, the inner hull bulkheads are to be similarly constructed.

1.4.15 Provided the ship length, L, does not exceed 200 m the longitudinal bulkheads may be horizontally corrugated. Vertically corrugated centreline bulkheads may also be considered on the basis of direct calculations.

1.4.16 In general, the primary member scantlings will require to be determined by direct calculation, see also Table 9.1.3 Structural arrangement.

1.4.17 Alternative arrangements, which are proposed as being equivalent to the Rules, will receive individual consideration. Particular attention is to be paid to deflection of members and to the ability of the structure to resist buckling. Where necessary, additional calculations will be required.

1.4.18 For additional requirements for single hull oil tankers, see Pt 4, Ch 10 Single Hull Oil Tankers.

1.4.19 The scantlings of structural items may be determined by direct calculation.

1.5.1 The following symbols and definitions are applicable to this chapter unless otherwise stated:

L, L_L, B, D, T as defined in Pt 3, Ch 1, 6 Definitions.

=

the moment of inertia, in cm4, of a primary or secondary member, in association with an effective width of attached plating determined in accordance with Pt 3, Ch 3, 3 Structural idealisation

1.5.2 Where symbols not defined in Pt 4, Ch 9, 1.5 General definitions and symbols 1.5.1 are used these are defined at the head of the Section concerned.

1.5.3 For oil tankers of double hull configuration the main structural and spatial terminology within the cargo length, as used in this Chapter, is shown in Figure 9.1.4 Structural and spatial terminology.

1.5.4 The expression ‘primary member’ as used in this Chapter is defined as a girder, floor, transverse, vertical web, stringer, cross-tie or buttress. ‘Secondary members’ are supporting members other than primary members.

Figure 9.1.4 Structural and spatial terminology

1.6.1 Plans and supporting documents/calculations are to be submitted for approval in accordance with the requirements of the CSR.

1.6.2 In addition, where not already required by the CSR, plans and supporting documents/calculations are to be submitted for approval as required by Pt 3, Ch 1, 5.2 Plans and supporting calculations.

1.6.3 A Ship Construction File (SCF) is to be provided on board of the ship containing information to facilitate inspection/survey, repair and maintenance. As a minimum it is to include documentation and plans in accordance with the requirements of the CSR.

1.6.4 For CSR double hull oil tankers subject to SOLAS - International Convention for the Safety of Life at Sea Chapter II-1 - Construction - Structure, subdivision and stability, machinery and electrical installations Part A-1 - Structure of ships Regulation 3-10 – Goal-based ship construction standards for bulk carriers and oil tankers, the SCF is to be provided instead in accordance with the requirements specified therein in SOLAS - International Convention for the Safety of Life at Sea and for these goal-based standard ships an SCF contents list is to be prepared and submitted for approval.

1.6.5 These SCFs are also to include the documentation and plans as listed in Pt 3, Ch 1, 5.3 Plans to be supplied to the ship, where not already required by the CSR or SOLAS - International Convention for the Safety of Life at Sea Chapter II-1 - Construction - Structure, subdivision and stability, machinery and electrical installations Part A-1 - Structure of ships Regulation 3-10 – Goal-based ship construction standards for bulk carriers and oil tankers.

1.7.1 In addition to the plans required by Pt 3, Ch 1, 5 Information required, plans showing the connections for all longitudinals and other framing members and arrangements at intersections of transverse and longitudinal framing are also to be submitted.

1.7.2 Any dry tanks, or tanks for water ballast only, are to be indicated on the principal structural and arrangement plans.

1.7.3 The information required by Pt 3, Ch 4, 4 Information required is to be forwarded as soon as possible and preferably when the midship section is submitted.

1.7.4 A docking plan is to be submitted for consideration of strength requirements in association with the intended docking condition.

1.7.5 A plan showing the location of all openings in the deck is to be submitted. Where it is intended to provide holes in the deck for staging wires, these holes are also to be shown. Full particulars of the proposed closing arrangements for all deck openings are to be submitted.

1.7.6 Information is required indicating the equipment provided for the acceptable means of access to meet the minimum requirements for Close-up Surveys, see also Pt 4, Ch 9, 13.2 Access to spaces in the cargo area 13.2.8, Pt 4, Ch 9, 13.2 Access to spaces in the cargo area 13.2.9 and Pt 1, Ch 3, 7 Special Survey - Oil tankers (including ore/oil ships and ore/bulk/oil ships) - Hull requirements.

1.7.7 A diagrammatic plan verifying compliance with the requirements of Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.17 or Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.18 as appropriate is to be submitted.