SC301

SCSC
301
301

(May2024)(cont)SOLAS Regulations II-2/9.7.2 and 9.7.5.1 –Separation of ducts from spaces
SOLAS Regulation Ch II-2/9.7.2 states as amended by IMO Res. MSC.365(93):
7.2 Arrangement of ducts
7.2.1 The ventilation systems for machinery spaces of category A, vehicle spaces, ro-rospaces, galleys, special category spaces and cargo spaces shall, in general, be separated fromeach other and from the ventilation systems serving other spaces. However, the galley
ventilation systems on cargo ships of less than 4,000 gross tonnage and in passenger ships
carrying not more than 36 passengers need not be completely separated from other ventilation
systems, but may be served by separate ducts from a ventilation unit serving other spaces. Insuch a case, an automatic fire damper shall be fitted in the galley ventilation duct near theventilation unit.
7.2.2 Ducts provided for the ventilation of machinery spaces of category A, galleys, vehicle
spaces, ro-ro spaces or special category spaces shall not pass through accommodation
spaces, service spaces, or control stations unless they comply with paragraph 7.2.4.
7.2.3 Ducts provided for the ventilation of accommodation spaces, service spaces or control
stations shall not pass through machinery spaces of category A, galleys, vehicle spaces, ro-rospaces or special category spaces unless they comply with paragraph 7.2.4.
7.2.4 As permitted by paragraphs 7.2.2 and 7.2.3 ducts shall be either:.1.1 constructed of steel having a thickness of at least 3 mm for ducts with a free crosssectional area of less than 0.075 m2, at least 4 mm for ducts with a free cross-sectional
area of between 0.075 m2 and 0.45 m2, and at least 5 mm for ducts with a free crosssectional area of over 0.45 m2;.1.2 suitably supported and stiffened;.1.3 fitted with automatic fire dampers close to the boundaries penetrated; and.1.4 insulated to "A-60" class standard from the boundaries of the spaces they serve toa point at least 5 m beyond each fire damper;
or.2.1 constructed of steel in accordance with paragraphs 7.2.4.1.1 and 7.2.4.1.2; andNote:1.
This UI is to be uniformly implemented by IACS Societies for vessels contracted forconstruction on or after 1 July 2025.
2.
The “contracted for construction” date means the date on which the contract to build thevessel is signed between the prospective owner and the shipbuilder. For further details
regarding the date of “contract for construction”, refer to IACS Procedural Requirement (PR)No. 29.
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SC301

SC301(cont).2.2 insulated to "A-60" class standard throughout the spaces they pass through, except
for ducts that pass through spaces of category (9) or (10) as defined in paragraph2.2.3.2.2.
7.2.5 For the purposes of paragraphs 7.2.4.1.4 and 7.2.4.2.2, ducts shall be insulated over their
entire cross-sectional external surface. Ducts that are outside but adjacent to the specified
space, and share one or more surfaces with it, shall be considered to pass through the specified
space, and shall be insulated over the surface they share with the space for a distance of
450 mm past the duct*.
7.2.6 Where it is necessary that a ventilation duct passes through a main vertical zone division,an automatic fire damper shall be fitted adjacent to the division. The damper shall also becapable of being manually closed from each side of the division. The control location shall bereadily accessible and be clearly and prominently marked. The duct between the division andthe damper shall be constructed of steel in accordance with paragraphs 7.2.4.1.1 and 7.2.4.1.2
and insulated to at least the same fire integrity as the division penetrated. The damper shall befitted on at least one side of the division with a visible indicator showing the operating positionof the damper.
Note: * Sketches of such arrangements are contained in the Unified Interpretations of SOLAS chapter II2 (MSC.1/Circ.1276/Rev.2).

SOLAS Regulation Ch II-2/9.7.5.1 states:
7.5.1 Requirements for passenger ships carrying more than 36 passengers
7.5.1.1 In addition to the requirements in sections 7.1, 7.2 and 7.3, exhaust ducts from galley
ranges shall be constructed in accordance with paragraphs 7.2.4.2.1 and 7.2.4.2.2 andinsulated to "A-60" class standard throughout accommodation spaces, service spaces, orcontrol stations they pass through. They shall also be fitted with:.1 a grease trap readily removable for cleaning unless an alternative approved grease
removal system is fitted;.2 a fire damper located in the lower end of the duct at the junction between the duct
and the galley range hood which is automatically and remotely operated and, inaddition, a remotely operated fire damper located in the upper end of the duct close to
the outlet of the duct;.3 a fixed means for extinguishing a fire within the duct*;.4 remote-control arrangements for shutting off the exhaust fans and supply fans, for
operating the fire dampers mentioned in paragraph 7.5.1.1.2 and for operating the fireextinguishing system, which shall be placed in a position outside the galley close to theentrance to the galley. Where a multi-branch system is installed, a remote means
located with the above controls shall be provided to close all branches exhausting
through the same main duct before an extinguishing medium is released into thesystem; and.5 suitably located hatches for inspection and cleaning, including one provided close to
the exhaust fan and one fitted in the lower end where grease accumulates.

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SC301(cont)

7.5.1.2 Exhaust ducts from ranges for cooking equipment installed on open decks shall conformto paragraph 7.5.1.1, as applicable, when passing through accommodation spaces or spaces
containing combustible materials.
Interpretation
With respect to the application of SOLAS regulations II-2/9.7.2 and 9.7.5.1, for determining
fire insulation for trunks and ducts which pass through an enclosed space, the term “passthrough” pertains to the part of the trunk/duct contiguous to the enclosed space.
The following sketches are given as examples:

Examples of ducts contiguous to enclosed space

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