Chapter 3 - Vessel Design
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Chapter 3 - Vessel Design

 To ensure that the cargo containment and handling systems are located in such a way that the consequences of any release of cargo will be minimized, and to provide safe access for operation and inspection. This chapter describes the minimum containment and handling provisions for all liquid cargoes. Additional provisions for those products with higher levels of hazard are described in chapter 4.

3.1 Cargo segregation

3.1.1 Tanks containing cargoes, residues of cargoes or mixtures containing cargoes subject to the present Code should be segregated from machinery spaces as defined in 1.2.28 and 1.2.29, accommodation and service spaces and from drinking water and stores for human consumption by means of a cofferdam, void space, cargo pump-room, pump-room, empty tank, oil fuel tank, or other similar space.footnote On-deck stowage of permanently attached deck tanks or installation of independent tanks in otherwise empty hold spaces should be considered as satisfying this provision.

3.1.1.1 For pollution hazards only substances having a flashpoint exceeding 60C, the segregation provisions need only be met for accommodation spaces, drinking water and stores for human consumption.

3.1.2 Cargoes, residues of cargoes or mixtures containing cargoes which react in a hazardous manner with other cargoes or oil fuels should:

  • .1 be segregated from such other cargoes or oil fuels by means of a cofferdam, void space, cargo pump-room, pump-room, empty tank, or tank containing a mutually compatible cargo;

  • .2 have separate pumping and piping systems which should not pass through other cargo tanks containing such cargoes, unless encased in a tunnel; and

  • .3 have separate tank venting systems.

3.1.3 Cargo piping should not pass through any accommodation, service spaces or machinery space of category A.

3.1.4 If cargo piping systems or cargo venting systems are required to be separated, this separation may be achieved by the use of design or operational methods. Operational methods should not be used within a cargo tank or a cofferdam surrounding the cargo tanks, if entry into the cofferdam is required, and should consist of one of the following types:

  • .1 removing spool pieces or valves and blanking the pipe ends;

  • .2 arrangements of two spectacle flanges in series, with provisions for detecting leakage into the pipe between the two spectacle flanges; and

  • .3 blind flange valve with double shut-off and with provisions for detecting leakage in valve body.

3.1.5 Pumps, ballast lines, vent lines and other similar equipment serving ballast tanks should be separated from similar equipment serving cargo tanks and of cargo tanks themselves.

3.1.6 For access to all spaces, the minimum spacing between cargo tank boundaries and adjacent vessel structure should be 600 mm.

3.1.7 Cargo tanks other than those certified to carry substances subject to the provisions of chapter 4 may extend to the deck plating. Where cargo is handled on the deck area above a cargo tank, the cargo tank may not extend to the deck plating unless a continuous permanent deck sheathing of min 50 mm of wood or other suitable material of equivalent thickness and construction is fitted.

3.1.8 Cargoes subject to the present Code should not be carried in either the fore or aft peak tanks.

3.2 Accommodation, service and machinery spaces and control stations

3.2.1 Accommodation or service spaces or control stations should not be located within the cargo area.

3.2.2 For a vessel certified to carry safety hazard substances, entrances, air inlets and openings to accommodation, service and machinery spaces and control stations may be accepted in bulkheads facing the cargo deck area if they are located outside the deck area defined in 1.2.7.2.

3.2.3 Propulsion shafts may be routed through cargo pump-rooms.

3.3 Access to spaces in the cargo area

3.3.1 Unless expressly provided otherwise in chapter 4, the following should apply:

  • .1 For pollution hazard only substances, at least one access to cargo tanks should be direct from the open deck and designed such as to ensure complete inspection of those substances.

  • .2 For safety hazard substances, at least one access to each cargo tank, cofferdams and other spaces in the cargo area should be direct from the open deck and designed such as to ensure complete inspection of those substances.

  • .3 Access to double bottom spaces within the cargo area may be through a cargo pump-room, pump-room, deep cofferdam, pipe tunnel or similar dry compartments with their own direct access from open deck, subject to consideration of ventilation aspects. Where cofferdams are provided over integral tanks, small trunks may be used to penetrate the cofferdam.

3.3.2 For accesses defined in 3.3.1 and 4.1.8 through horizontal openings, hatches or manholes, the dimensions should be sufficient to allow a person with a self-contained air-breathing apparatus and protective equipment 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 should be not less than 600 mm by 600 mm.

3.3.3 For accesses defined in 3.3.1 and 4.1.8 through vertical openings, or manholes providing passage through the length and breadth of space, the minimum clear opening should be not less than 600 mm by 800 mm at a height of not more than 600 mm from the bottom shell or deck plating, unless gratings or other footholds are provided.

3.3.4 Smaller dimensions may be approved, if at least one main access defined in 3.3.1 and 4.1.8 has dimensions not less than those required in 3.3.2 and 3.3.3, respectively. The main access should be identified clearly in an access plan.

3.3.5 Cargo pump-rooms should be so arranged as to ensure unrestricted access to all valves necessary for cargo handling for a person wearing the required personal protective equipment.


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