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Regulation
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Interpretations
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II-2/21.1 Application
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Interpretation 1
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Horizontal Fire Zones
(special category and ro-ro spaces) should not be included in the count of
the number of the Main Vertical Zones.
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II-2/21.1 Application
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Interpretation 2
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Where electrical or
machinery installation, fire safety, or lifesaving appliances of a ship have
been approved following the methodology of SOLAS
regulations II-1/55, II-2/17 or III/38 respectively (Alternative design and
arrangements), the effect on the ship essential system capability should be
explicitly included in the analysis required by the above regulations.
Special attention is to be given to the determination and assignment of Safe
Areas and compliance with the requirements of SOLAS
regulation II-2/22.
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II-2/21.2 Purpose
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Interpretation 3
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For the purpose of
assessing the ship systems' capabilities, fire casualties and flooding
casualties may be considered as not occurring at the same time.
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II-2/21.3 Casualty threshold
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Interpretation 4
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"A" class boundaries
refers to both bulkheads and decks.
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II-2/21.3 Casualty threshold
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Interpretation 5
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The rating of "A" class
boundaries does not affect the application of this regulation. However, a
trunk closed at all boundaries constructed to "A-60" standard and containing
ducts, cabling and/or piping is considered operational when passing through
a space of origin.
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II-2/21.3 Casualty threshold
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Interpretation 6
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The lay-out of special
category and ro-ro spaces, normally extending for more than the length of
one MVZ, does not properly fit with the casualty threshold. However, during
the assessment of the ship systems' capabilities it has to be verified that
a casualty in such spaces would not compromise the operation of the
essential systems in the remaining fire zones of the ship.
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II-2/21.3.2 Casualty threshold
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Interpretation 7
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Where a space of origin
is not protected by a fixed fire-extinguishing system, for determining the
"nearest "A" class boundaries, which are not part of the space of
origin":
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a) only the spaces within the same Main Vertical Zone
need to be considered; and
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b) casualty threshold includes spaces one deck
upwards.
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II-2/21.3.2 Casualty threshold
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Interpretation 8
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Spaces in which the risk
of a fire originating is negligiblefootnote need not be considered as spaces of origin of a fire.
Examples of such spaces include but may not be limited to:
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a) spaces with restricted accessibility for inspection
and/or maintenance only, such as:
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.1 void spaces;
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.2 trunks closed at all boundaries only containing
pipes and/or electrical cables; and
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.3 cofferdams;
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II-2/21.3.2 Casualty threshold
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Interpretation 8 (cont'd)
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b) tanks;
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c) chain lockers;
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d) ventilation trunks except those containing ducts
presenting fire hazard such as galley range exhaust ducts, laundry
exhaust ducts, category "A" machinery spaces ducts, special category and
ro-ro spaces ducts;
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e) cross flooding ducts connecting void spaces. In the
case where connected spaces are not with a negligible fire risk, ducts
should be separated from those spaces by non-watertight fire resistant
boundaries to be considered as a space where fire risk is negligible;
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f) vertical escape trunks from machinery spaces,
service spaces, control stations and other crew accommodation spaces;
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g) store rooms for gaseous fixed fire-extinguishing
systems;
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h) busbars enclosed in "A" class divisions;
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i) "A" class enclosures within spaces of Category 1,
2 or 4 only containing isolation valves or section valves forming part of
the fixed fire-extinguishing system for the protection of accommodation
spaces, service spaces and control stations; and
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j) shaft tunnels only used for this purpose, i.e. no
storage is allowed.
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II-2/21.3.2 Casualty threshold
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Interpretation 9
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Concealed spaces (spaces
above ceilings, behind bulkheads linings) are considered as part of the
space of origin. Lack of a fixed fire-extinguishing system above ceilings or
behind linings need not be considered under regulation
II-2/21.3.2.
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II-2/21.3.2 Casualty threshold
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Interpretation 10
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In case of manual
actions, equipment and systems the controls of which cannot be reached
without accessing the space affected by the casualty should not be
considered operational.
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II-2/21.3.2 Casualty threshold
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Interpretation 11
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For passenger ships
carrying not more than 36 passengers space of origin is any space bounded by
"A" class boundaries or divisions of steel or equivalent material. Where the
deck between two spaces is constructed of steel or equivalent material it
should be considered to form part of the "A" class boundary provided all
penetrations are tight to prevent the passage of flame or smoke.
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