(1) Ventilation ducts shall be of non-combustible material. Short ducts, however not generally exceeding 2 meters in length and with a cross-section not exceeding 0.02m need not be non-combustible, subject to the following conditions.
(a) The dusts shall be of a material which has a low fire risk.
(b) They may only be used at the end of the ventilation device.
(c) They shall not be situated less than 600 mm measured along the duct from an opening in a A or B class division including continuous B class ceilings.
(2) Where the ventilation ducts with a free-sectional area exceeding 0.02 m pass through class A bulkheads or decks the opening shall be lined with a steel sheet sleeve, unless the ducks passing through the bulkhead or decks are of steel in the vicinity of passage through the deck of bulkhead and the ducts and sleeves shall comply with the following-
(a)The sleeves shall have a thickness of at least 3 mm and a length of at least 900 mm. When passing through bulkheads, such length shall be divided preferably into 450mm on each side of the bulkhead. These ducts, or sleeves lining such ducts shall be provided with fire insulation. The insulation shall have at least the same fire integrity as the bulkhead or deck through which the duct passed. Equivalent penetration protection may be provided to the satisfaction of the Chief Surveyor with the Government of /India.
(b) Ducts with a free cross-sectional area exceeding 0.075m shall be fitted with fire dampers in addition to the requirements of clause.
(C) The fire damper shall operate automatically but shall also be capable of being closed manually from both sides of the bulkhead or deck. The damper shall be provided with an indicator which shows whether the damper is open or closed. Fire dampers are not requires, however, where duct pass through spaces surrounded by A class divisions, without serving those spaces provided those ducts have the same fire integrity as the divisions which they pierce.
(3) Ducts provided for the ventilation of machinery spaces of category A, galleys, car deck spaces, RO/RO cargo spaces or special category spaces shall not pass through accommodation spaces, service spaces or control stations unless the ducts are-
(i) constructed of steel having a tickles of at least 3 mm and 5 mm for ducts the widths or diameters of which are up to and including 300 mm and 760 mm and above respectively and, in the case of such ducts, the widths of diameters of which are between 300 mm and 760 mm having a tickles to be obtained by interpolation. (ii) Suitably supported and stiffene (iii) Fitted with automatic fire dampers close to the boundaries penetrated; and (iv)Insulated to A-60 standard from the machinery spaces, galleys, car deck spaces Ro/Ro cargo spaces or special category spaces to a point at least 5 m beyond each fire damper;
(i) Constructed of steel in accordance; and
(ii) Insulated to A-60 standard throughout the accommodation spaces, service spaces or control stations.
(4)Ducts provided for ventilation to accommodation spaces, service spaces or control stations shall not pass through machinery spaces of category A, galleys, car deck spaces, Ro/Ro cargo spaces or special category spaces unless
A.(i) The ducts where they pass through a machinery space of category A, galley, car deck space, Ro/Ro cargo space or special category space are constructed of steel;
(ii) Automatic fire dampers are fitted close to the boundaries penetrated; and
(iii) The integrity of the machinery space galley, car deck space, RO/Ro cargo space or special category space boundaries is maintained at the penetrations or
B.(i) The ducts where they pass through a machinery space of category A, galley, car deck space , RO/RO cargo space or special category space are constructed of steel ,
(ii) Are installed to A-60 standard within the machinery space, galley, car deck space. RO/RO cargo space, galley, car deck space. RO/RO cargo space or special category space.
(5) Ventilation ducts with a free cross-sectional area exceeding 0.02m2 passing through B class bulkheads shall be lined with steel sheet sleeves of 900 mm in length divided preferably into 450 mm on each side of the bulkheads unless the duct is of steel for this length.
(6) Such measures as are practicable shall be taken in respect of control stations outside machinery spaces in order to ensure that ventilation, visibility and freedom from smoke are maintained, so that in the event of fire the machinery and equipment contained therein may be supervised and continue to function effectively. Alternative and separate means of air supply shall be so disposed that the risk of both inlets drawing in smoke simultaneously is minimized .