Section 5 Hull construction

5.1.1 The hull structure is to comply with the relevant requirements of Pt 3 Ship Structures (General) and Pt 4 Ship Structures (Ship Types), except where stated otherwise in this Section.

5.1.2 The location of substance and effluent tanks structures within the ship’s hull are to comply with Chapters 2 and 4 of the Rules for Ships for Liquid Chemicals. Alternative proposals demonstrating equivalent or increased protection against damage in the event of collision or grounding may be considered.

5.1.3 Substance and effluent tanks are to be protected from mechanical damage. This may be achieved either by installation in spaces where there are no cargo or vehicle movements and where no heavy lifting operations are expected, or by mechanical protection, if installed in spaces where such operations may take place.

5.1.4 Where necessary, the probable temperature variations during operations and the thermal stress considerations are to be stated. Where it is necessary either to heat or cool chemical storage tanks, the arrangements are to utilise either pipe coils or ducts for circulating a heating or cooling medium within the chemical storage tank or a heat exchanger through which the chemical and a heating or cooling medium is circulated. Active heating and cooling systems are to have the capacity to maintain the chemical in the designated tank within the specified temperature limits, see Pt 5, Ch 24, 3.3 Chemical substances 3.3.3, Pt 5, Ch 24, 3.4 Mechanical equipment 3.4.4 and Pt 5, Ch 24, 7.1 General 7.1.9 under the following conditions:

5.1.5 Where independent tanks are used for chemical substances, these are to be arranged as far as practicable so as to contain spillage.

Tanks and spill containment arrangements are to be fitted with alarms and safeguards, in accordance with Pt 5, Ch 24, 9.1 General 9.1.11.

5.1.6 Proposals are to be made for the dimensioning of containment arrangements, relative to the potential leakage which may require containment. Where it is not practicable to contain the potential leakage fully and where this leakage can pose a hazard to personnel, proposals are to be submitted, demonstrating that leakage will be transferred to a suitable retention tank, and the means of transfer shall be capable of operating in a dead ship condition and shall be fitted with a flow detection alarm, in accordance with Pt 5, Ch 24, 9.1 General 9.1.11.

5.1.7 Chemical storage tanks and any other tanks which may contain liquids hazardous to personnel are to be arranged such that residues and slops can be pumped out, drained or otherwise removed from the tank without exposing personnel.

5.1.8 Chemical storage tanks containing substances which are used for emissions abatement plant are subject to special consideration where they are located in the same space as essential services, e.g. main combustion machinery and equipment. Tanks for chemical substances are not to be situated where spillage or leakage therefrom can constitute a hazard by dripping or spraying onto combustibles or hot surfaces.

5.1.9 Arrangements for venting and gas freeing chemical tanks required by emissions abatement plant are to meet the requirements of Pt 5, Ch 13, 12 Air, overflow and sounding pipes and they are to be independent of the air pipes and venting systems of other tanks and/or compartments of the ship. Sounding pipes are to be led to the safe position on the open deck. Alternatively, sounding devices of approved type may be used in lieu of sounding pipes. Tank venting systems are to minimise the possibility of chemical vapour accumulating on the decks, entering accommodation, service and machinery spaces, and control stations and, in the case of flammable vapours, entering or collecting in spaces or areas containing sources of ignition. Tank venting systems are to be arranged to prevent entrance of water into the chemical tanks. The venting systems shall be connected to the top of each chemical tank. As far as practicable, they are to be self-draining back to the chemical tanks under all normal operational conditions of list and trim.

5.1.10 Tank vent piping connected to tanks constructed of corrosion-resistant material, or to tanks which are lined or coated to provide corrosion resistance, are to be similarly lined or coated, or constructed of corrosion-resistant material.

5.2.1 Where flammable or toxic chemicals, gases or vapours are present, as identified in Pt 5, Ch 24, 3.3 Chemical substances 3.3.1 and Pt 5, Ch 24, 3.3 Chemical substances 3.3.2, service and control stations essential to the operation of the plant are to meet the requirements of Pt 5, Ch 24, 9.1 General 9.1.4, and should, wherever possible, be located so that access thereto is from a defined safe space. If such a location is not possible, the station is to be specially ventilated.

5.2.2 Arrangements are to be made in spaces occupied by emissions abatement plant, in order that substances which are flammable, corrosive, toxic or likely to present a hazard due to reaction when mixed are kept separate unless they are fully contained within a part of the emissions abatement plant which has been designed for the safe mixing of such substances.

5.3.1 Where integrity of water or gastightness is required between compartments containing the plant, it is to be maintained in way of pipe tunnels or duct keels where these traverse such compartments.

5.3.2 Installations and the spaces in which they are installed are to be, in all cases, compliant with applicable National and International requirements for prevention, detection and extinction of fire.

5.4.1 Decks and other structures supporting the plant are, in general, to comply with the requirements of Pt 3 Ship Structures (General). Such structures can, however, be considered on the basis of an agreed uniformly distributed loading in association with local loads at plant support points, provided that adequate transverse strength of the ship is maintained.