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  • Section 24 - Oil Tankers A 24 - 1

    Section 24

    Oil Tankers

    A. General

    1. Scope

    1.1 The following regulations apply to tankers whichare intended to carry oil in bulk having a flashpoint (closedcup test) not exceeding 60C and whose Reid vapourpressure is below that of atmospheric pressure and otherliquid products having a similar fire hazard.

    Unless specially mentioned in this Section the regulationsof Sections 1 - 22 apply.

    For double hull oil tankers and product tankers withL $ 150 m the IACS Common Structural Rules for DoubleHull Oil Tankers are applicable in lieu of B. to F.

    1.2 For the purpose of this Section "oil" means petroleumin any form including crude oil, refined products, sludgeand oil refuse (see also Product List 1 at the end of thisSection).

    1.3 For the purpose of this Section "crude oil" meansany liquid hydrocarbon mixture occurring naturally in theearth whether or not treated to render it suitable fortransportation and includes:

    - crude oil from which certain distillate fractions mayhave been removed, and

    - crude oil to which certain distillate fractions mayhave been added.

    1.4 Products listed in the Product List 2 (at the end ofthis Section) are permitted to be carried in tankers complyingwith the regulations of this Section. Products whose Reidvapour pressure is above that of atmospheric pressure mayonly be carried where the cargo tank vents are fitted withpressure/vacuum relief valves (see Rules for MachineryInstallations, Volume III, Section 15) and the tanks havebeen dimensioned for the set pressure of the pressure reliefvalves.


    1. In accordance with the provisions of MARPOL73/78, Annex II the carriage in bulk of category Z productsis permitted only on vessels holding an "InternationalPollution Prevention Certificate for the Carriage of NoxiousLiquid Substances in Bulk" issued by the FlagAdministration.

    2. The petrochemicals listed in the list of products ofthe IBC-Code, Chapter 17, and products of similar hazardare not subject to the provisions of this Section.

    1.5 The regulations of this Section include the provisionsof Chapter II-2 of SOLAS 74 applicable to tankers as faras provisions affecting the lay-out and structural design ofthe vessels are concerned.

    For the remaining fire safety measures of the above mentionedprovisions, see Section 22, F. and Rules for MachineryInstallations, Volume III, Section 12 and 15.

    1.6 Regulations for ships intended to carry dry cargo oroil in bulk see G.

    1.7 For tankers intended to carry liquids in bulk havinga flashpoint (closed cup test) above 60C only, therequirements of this Section concerning safety, e.g. as per4.4, 4.5, 9. etc., need not be complied with.

    Where, however, these products are heated to a temperatureabove 15C below their flashpoint the vessels will bespecially considered.

    1.8 Where cargo is intended to be heated Section 12, also to be observed.

    1.9 Oil or other flammable liquids are not permitted tobe carried in fore- or afterpeak.


    It is assumed that the provisions of Annex I and, as far asapplicable, of Annex II of MARPOL 73/78 will be compliedwith.

    Upon application a declaration confirming the compliancewith the provisions of MARPOL 73/78 will be issued.

    Tankers not complying with the Annex I provisions will notbe assigned the Notation "OIL TANKER" or "PRODUCTTANKER".

    For a type "A" ship, if over 150 m length, to which afreeboard less than type "B" has been assigned the ICLLRegulation 27.3 has to be considered.

    2. Character of Classification

    2.1 Tankers, built in accordance with the requirementsof this Section will have the following Notations affixedto their Character of Classification: OIL TANKER ifengaged in the trade of carrying "oil" as defined in 1.2 orPRODUCT TANKER if engaged in the trade of carryingoil other than "crude oil" as defined in 1.3.

    Oil tankers or product carriers will be assigned the symbolG for characterizing proof of damage stability accordingto MARPOL 73/78 Annex I. The following data will be

  • Section 24 - Oil Tankers A24 - 2

    entered into an appendix to the Certificate:

    code for the specification of the proof of damagestability according to Vol. I Rules for Classificationand Surveys, Section 2, C.3.1.2.

    2.2 Ships intended to alternatively carry dry cargo orliquids in bulk having a flashpoint (closed cup test) notexceeding 60C may have one of the following Notationsaffixed to their Character of Classification: "BULKCARRIER OR OIL TANKER", "RO-RO SHIP OROIL TANKER", "ORE CARRIER OR PRODUCTTANKER" etc.

    The regulations specified in G. are to be observed.

    2.3 Tankers intended to carry liquids of differentproperties and presenting hazards different from the criteriaof liquids mentioned in 1.2 will be specially considered as"tankers for special cargoes". These tankers may have theNotation: "SPECIAL TANKER", "ASPHALTTANKER", EDIBLE OIL TANKER", "WINETANKER", etc. affixed to their Character of Classification.

    2.4 Where it is intended to carry liquids having a flashpoint (closed cup test) above 60C only, the followingremark will be entered in the Certificate:

    "Not suitable for products with flashpoints of 60Cand less".

    2.5 Where special structural measures (separation ofpiping, tank coating etc) permit simultaneous carriage ofvarious oils and oil products, the following remark maybe entered in the Certificate:

    "Suitable for the carriage of various oil products".

    2.6 Where the cargo tanks are not segregated from otherspaces in fore and aft ship (see 4.3.6) the following remarkwill be entered in the Certificate:

    "No cofferdams at the forward and/or aft ends".

    3. Cargo Tank Arrangement

    3.1 General

    3.1.1 Every oil tanker of 600 tdw and above shall complywith the double hull requirements of MARPOL 73/78,Annex I, Reg. 19.

    3.1.2 Tanks or spaces within the double hull required inaccordance with the provisions of 3.2 and 3.3 are not tobe used for the carriage of cargo and fuel oil.

    3.1.3 For access to spaces in the cargo area A.13 is to beobserved.

    3.1.4 Concerning the definition of "deadweight" (tdw)reference is made to MARPOL 73/78, Annex I, Reg. 1.23.


    The aggregate capacity of wing tanks, double bottom tanks,forepeak tanks and afterpeak tanks shall not be less thanthe capacity of segregated ballast tanks necessary to meetthe requirements of MARPOL 73/78, Annex 1, Regulation18. Wing tanks, spaces and double bottom tanks used to meetthe requirements of MARPOL 73/78, Annex 1, Regulation18 shall be located as uniformly as practicable along thecargo tank length. For inerting, ventilation and gasmeasurement see Rules for Machinery Installations,Volume III, Section 15.

    3.2 Double hull requirements for oil tankers of5.000 tdw and above

    3.2.1 The entire cargo tank length is to be protected by adouble side (wing tanks or spaces) and double bottom tanksor spaces as outlined in the following paragraphs.

    3.2.2 Double Side

    Wing tanks or spaces are to extend for the entire cargo tanklength and for the full depth of the ship's side or from thetop of the double bottom to the uppermost deck, disregardinga rounded gunwale, where fitted. They are to be arrangedsuch that the cargo tanks are located inboard of the mouldedline of the side shell plating, nowhere less than the distancew which is measured at every cross section at right anglesto the side shell, as specified below (see Fig.24.1):

    w = [m] or

    = 2,0 m; whichever is the lesser

    wmin = 1,0 m.

    3.2.3 Double Bottom

    At any cross section the depth of each double bottom tankor space is to be such that the distance h between the bottomof the cargo tanks and the moulded line of the bottom shellplating measured at right angles to the bottom shell platingis not less than specified below (see Fig.24.2):

    h = [m] or

    = 2,0 m, whichever is the lesserhmin = 1,0 m

    In the turn of bilge area or at locations without a clearlydefined turn of bilge, where the distances h and w aredifferent, the distance w shall have preference atlevels exceeding 1,5 h above the baseline. For details seeMARPOL 73/78, Annex I, Reg. 19.3.3

  • Section 24 - Oil Tankers A 24 - 3

    Fig. 24.1 Cargo Tank Boundary Lines

    Fig. 24.2 CargoTank Boundary Lines

    3.2.4 Suction wells in cargo tanks

    Suction wells in cargo tanks may protrude into the doublebottom below the boundary line defined by the distance hprovided that such wells are as small as practicable and thedistance between the well bottom and bottom shell platingis not less than 0,5 h.

    3.2.5 Alternative cargo tank arrangements

    Double bottom tanks or spaces as required above may bedispensed with, if the provisions of MARPOL 73/78,Annex I, Reg. 19.4 or 19.5 are complied with.

    3.2.6 Double bottom in pump room

    The cargo pump room is to be provided with a double bottom,the distance h of which above the ship's base line is not lessthan the distances required in 3.2.3.


    For pump rooms, the bottom plate of which is above thisminimum height, see 22.3 of MARPOL 73/78, Annex II.

  • Section 24 - Oil Tankers A24 - 4

    3.3 Double hull requirements for oil tankers of lessthan 5.000 tdw

    3.3.1 Double Bottom

    Oil tankers of less than 5.000 tdw are at least to be fittedwith double bottom tanks or spaces having such a depththat the distance h specified in 3.2.3 complies with thefollowing:

    h = [m] or

    hmin = 0,76 m

    3.3.2 Limitation of cargo tank capacity

    The capacity of a each cargo tank of ships of less than5000 tdw is limited to 700 m3, unless wing tanks or spacesare arranged in accordance with 3.2.2 complying with:

    w =