6.9 Structural Integrity:

Purpose

(1) The purpose of this paragraph is to maintain structural integrity of the ship, preventing partial or whole collapse of the ship structures due to strength deterioration by heat. For this purpose, materials used in the ships' structure shall ensure that the structural integrity is not degraded due to fire.

Material of Hull, Superstructures, Structural Bulkheads, Decks and Deckhouses

(2) The hull, superstructures, structural bulkheads, decks and deckhouses shall be constructed of steel or other equivalent material and for the purpose of applying the definition of steel or other equivalent material the "applicable fire exposure" shall be according to the integrity and insulation standards given in Tables 6.1 and 6.2; for example, where divisions such as decks or sides and ends of deckhouses are permitted to have "B-0" fire integrity, the "applicable fire exposure" shall be half an hour.

Structure of Aluminium Alloy

(3) Unless otherwise specified in subsection(2), in cases where any part of the structure is of aluminium alloy, the following shall apply-

• (a) the insulation of aluminium alloy components of "A" or "B" class divisions, except structure which, in the opinion of the Administration, is non-load-bearing, shall be such that the temperature of the structural core does not rise more than 200°C above the ambient temperature at any time during the applicable fire exposure to the standard fire test; and

• (b) special attention shall be given to the insulation of aluminium alloy components of columns, stanchions and other structural members required to support lifeboat and liferaft stowage, launching and embarkation areas, and "A" and "B" class divisions to ensure-

  • (i) that for such members supporting lifeboat and liferaft areas and "A" class divisions, the temperature rise limitation specified in paragraph (a) above shall apply at the end of one hour; and

  • (ii) that for such members required to support "B" class divisions, the temperature rise limitation specified in the said paragraph (a) shall apply at the end of half an hour.

Machinery Spaces of Category A

(4) Subject to subsection (5), the boundaries of all machinery spaces of category A, including crowns and casings, shall be of steel construction and shall be insulated as required by Tables 6.1 and 6.2 as appropriate.

(5) The Administration may permit the boundaries of Category A machinery spaces, including crowns and casings, to be constructed of aluminium provided that-

• (a) the space is provided with an equivalent water-mist fire-extinguishing system complying with MSC/Circ.1165^footnote that will provide total flooding of the space in the event of a fire in that space; and

• (b) the space is provided with a fixed local application fire-extinguishing system of the water-mist type in accordance with MSC/Circ.913^footnote, MSC/Circ.1082^footnote and MSC.1/Circ.1276^footnote, applicable to machinery spaces of any size; and

• (c) the space and the divisions forming the crowns and casings shall be constructed and insulated to “A-60” class standard on both sides as demonstrated by a fire test conducted in accordance with the relevant provisions of the FTP Code; and

• (d) where the hull forms part of the boundary of the machinery space then the internal surface of the hull shall be insulated in accordance with paragraph(c) down to at least 450mm below the line of the lightest sea-going draft.

(6) The floor plating of normal passageways in machinery spaces of Category A shall be constructed of steel.

Materials of Overboard Fittings

(7) Materials readily rendered ineffective by heat shall not be used for overboard scuppers, sanitary discharges, and other outlets which are close to the waterline and where the failure of the material in the event of fire would give rise to danger of flooding.