5.1.1 The ship, ship system(s), component(s),
space(s) and/or equipment subject to the analysis should be thoroughly
defined. This includes the ship or system(s) representing both the
alternative design and arrangements and the regulatory prescribed
design. Depending on the extent of the desired deviation from prescriptive
requirements, some of the information that may be required includes:
detailed ship plans, drawings, equipment information and drawings,
fire test data and analysis results, ship operating characteristics
and conditions of operation, operating and maintenance procedures,
material properties, etc.
5.1.2 The regulations affecting the proposed alternative
design and arrangements, along with their functional requirements,
should be clearly understood and documented in the preliminary analysis
report (see paragraph 5.4). This should form the basis
for the comparative analysis referred to in paragraph 6.4.
5.2
Development of fire scenarios
5.2.1 Fire scenarios should provide the basis
for analysis and trial alternative design evaluation and, therefore,
are the backbone of the alternative design process. Proper fire scenario
development is essential and depending on the extent of deviation
from the prescribed design, may require a significant amount of time
and resources. This process can be broken down into four areas:
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.1 identification of fire hazards;
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.2 enumeration of fire hazards;
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.3 selection of fire hazards; and
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.4 specification of design fire scenarios.
5.2.1.1 Identification of fire hazards
This step is crucial in the fire scenario development process
as well as in the entire alternative design methodology. If a fire
hazard or incident is omitted, then it will not be considered in the
analysis and the resulting final design may be inadequate. Fire hazards
may be identified using historical and statistical data, expert opinion
and experience and hazard evaluation procedures. There are many hazard
evaluation procedures available to help identify the fire hazards
including HAZOP, PHA, FMEA, “what-if", etc. As a minimum, the
following conditions and characteristics should be identified and
considered:
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.1 pre-fire situation: ship, platform, compartment,
fuel load, environmental conditions;
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.2 ignition sources: temperature, energy, time
and area of contact with potential fuels;
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.3 initial fuels: state (solid, liquid, gas, vapour,
spray), surface area to mass ratio, rate of heat release;
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.4 secondary fuels: proximity to initial fuels,
amount, distribution;
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.5 extension potential: beyond compartment, structure,
area (if in open);
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.6 target locations: note target items or areas
associated with the performance parameters;
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.7 critical factors: ventilation, environment,
operational, time of day, etc.; and
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.8 relevant statistical data: past fire history,
probability of failure, frequency and severity rates, etc.
5.2.1.2 Enumeration of fire hazards
All of the fire hazards identified above should be grouped into
one of three incident classes: localised, major, or catastrophic.
A localised incident consists of a fire with a localised affect zone,
limited to a specific area. A major incident consists of a fire with
a medium affect zone, limited to the boundaries of the ship. A catastrophic
incident consists of a fire with a large affect zone, beyond the ship
and affecting surrounding ships or communities. In the majority of
cases, only localised and/or major fire incidents need to be considered.
Examples where the catastrophic incident class may be considered would
include transport and/or offshore production of petroleum products
or other hazardous materials where the incident effect zone is very
likely to be beyond the ship vicinity. The fire hazards should be
tabulated for future selection of a certain number of each of the
incident classes.
5.2.1.3 Selection of fire hazards
The number and type of fire hazards that should be selected
for the quantitative analysis is dependent on the complexity of the
trial alternative design and arrangements. All of the fire hazards
identified should be reviewed for selection of a range of incidents.
In determining the selection, frequency of occurrence does not need
to be fully quantified, but it can be utilised in a qualitative sense.
The selection process should identify a range of incidents which cover
the largest and most probable range of enumerated fire hazards. Because
the engineering evaluation relies on a comparison of the proposed
alternative design and arrangements with prescriptive designs, demonstration
of equivalent performance during the major incidents should adequately
demonstrate the design's equivalence for all lesser incidents and
provide the commensurate level of safety. In selecting the fire hazards
it is possible to lose perspective and to begin selecting highly unlikely
or inconsequential hazards. Care should be taken to select the most
appropriate incidents for inclusion in the selected range of incidents.
5.2.1.4 Specification of design fire scenarios
Based on the fire hazards selected, the fire scenarios to be
used in the quantitative analysis should be clearly documented. The
specification should include a qualitative description of the design
fire (e.g., ignition source, fuel first ignited, location, etc.),
description of the vessel, compartment of origin, fire protection
systems installed, number of occupants, physical and mental status
of occupants and available means of escape. The fire scenarios should
consider possible future changes to the fire load and ventilation
system in the affected areas. The design fire(s) will be characterised
in more detail during the quantitative analysis for each trial alternative
design.
5.3
Development of trial alternative designs
At this point in the analysis, one or more trial alternative
designs should be developed so that it can be compared against the
developed performance criteria. The trial alternative design should
also take into consideration the importance of human factors, operations,
and management as reflected in part E of SOLAS chapter II-2. It should be recognized that well defined operations
and management procedures may play a big part in increasing the overall
level of safety.
5.4
Preliminary analysis report
5.4.1 A report of the preliminary analysis should
include clear documentation of all steps taken to this point, including
identification of the design team, their qualifications, the scope
of the alternative design analysis, the functional requirements to
be met, the description of the fire scenarios and trial alternative
designs selected for the quantitative analysis.
5.4.2 The preliminary analysis report should be
submitted to the Administration for formal review and agreement prior
to beginning the quantitative analysis. The report may also be submitted
to the port State for informational purposes, if the intended calling
ports are known during the design stage. The key results of the preliminary
analysis should include:
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.1 a secured agreement from all parties to the
design objectives and engineering evaluation;
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.2 specified design fire scenario(s) acceptable
to all parties; and
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.3 trial alternative design(s) acceptable to all
parties.