Page 364 - Ship Construction.DJ Eyres 6Ed

Ch32-H8070.fm Page 353 Wednesday, October 18, 2006 7:06 AM
Structural Fire Protection 353
service spaces, except smoke detection and manually operated alarm
points which are to be installed in all corridors, stairways and escape
routes.

‘Method IIc’ An approved automatic sprinkler, fire detection and fire
alarm system is installed in all spaces in which a fire might be expected to
originate, and in general there is no restriction on the type of divisions
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used for internal bulkheads.
‘Method IIIc’ A fixed fire detection and fire alarm system is installed in
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
all spaces in which a fire might be expected to originate, and in general
there is no restriction on the type of divisions used for internal bulkheads
except that in no case must the area of any accommodation space
bounded by an ‘A’ or ‘B’ class division exceed 50 square metres.

Crowns of casings of main machinery spaces are to be of steel construc-
tion and insulated. Bulkheads and decks separating adjacent spaces are
required to have appropriate A, B or C ratings depending on the fire risk
of adjoining spaces. Cargo spaces of ships 2000 gross tonnage or more are
to be protected by a fixed gas fire-extinguishing system or its equivalent
ึ
unless they carry bulk or other cargoes considered by the authorities to be a
low fire risk. Cargo ships carrying dangerous goods are subject to special
fire protection precautions.
In the construction of tankers, particular attention is paid to the exterior
boundaries of superstructures and deckhouses which face the cargo oil
tanks. Accommodation boundaries facing the cargo area are insulated to
A60 standard, no doors are allowed in such boundaries giving access to the
accommodation and any windows are to be of non-opening type and fitted
with steel covers if in the first tier on the main deck. Bulkheads and decks
separating adjacent spaces of varying fire risk are required to have appro-
priate A, B, and C ratings within the accommodation space. For new tankers
of 20 000 tons deadweight and upwards the cargo tanks deck area and cargo
tanks are protected by a fixed deck foam system and a fixed inert gas system
(see Chapter 26). Tankers of less than 2000 tons deadweight are provided
with a fixed deck foam system in way of the cargo tanks.

‘A’, ‘B’ and ‘C’ Class Divisions

‘A’ class divisions are constructed of steel or equivalent material and are to
be capable of preventing the passage of smoke and flame to the end of a
one-hour standard fire test. A plain stiffened steel bulkhead or deck has
what is known as an A–O rating. By adding insulation in the form of
approved incombustible materials to the steel an increased time is taken for