Transcript Session 1 – Fire-safety based Ship Design

International Marine and Offshore Engineering Conference
3&4 September 2014
Al Jubail–Kingdom of Saudi Arabia
Fire-safety based Ship Design
Using Consequence Analysis Tools
Case Study : Nile Floating Hotels
A. M. Salem, E. M. Dabess, A. A. Banawan
and H. W. Leheta
Alexandria University, Egypt
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Objective Of the work
 The objective of this work is to analyze the
consequences of a cabin fire scenario on board
Nile floating hotels by using Fire and evacuation
simulation program in order to propose new
alternative designs/arrangements that are
assumed to have an equivalent or higher level of
fire safety than the existing design.
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Introduction
 Nile-floating hotels are passenger ships operating in
the mild environment of the River Nile on short
cruises from Aswan to Luxor, or on long cruises
from Aswan to Cairo.
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Introduction
 These trips have acquired popularity among tourists
and have become one of their popular destinations,
so are considered of important impact on the
Egyptian economy.
 Unfortunately, the fleet of Nile-floating hotels, which
consists of about 280 units, is subjected to many
types of accidents which not only harmfully affect
the national income but also affect the safety of life.
 Statistical analysis of collected data of such
accidents that occurred during the last 10 years
showed that:
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Introduction
Sinking
1%
Fire
23%
Collision
30%
Stranding
Stranding
46%
Collision
Sinking
Fire
Although of being ranked third, fire
accident aboard a Nile floating hotel with
many crew and passengers on board is a
potential catastrophe.
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Introduction
 The current fire safety design of Nile-floating
hotels follows the national regulations of the
Egyptian Authority for River Transport (RTA),
and it seems that these descriptive
regulations are not sufficient to prevent such
accidents from recurring.
 This may lead to disasters with bad effect on
the reputation of Nile tourism and the
national economy of Egypt.
Introduction
Fire products affect the evacuation progress,
resulting in incapacitation and death.
These lethal cases mostly happen in spaces
connected through small paths and
corridors like accommodation spaces, where
toxic smoke has high potential to fill the
whole domain in short time.
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Introduction
 So, a fire scenario that is common to occur in
accommodation spaces on board passenger ships as
well as Nile-floating hotels was studied by using the
integrated fire and evacuation simulation program
“FDS+EVAC”, namely (FDS 5.5.3 & EVAC 2.2.1).
 A series of simulations was conducted involving an
existing design of such accommodation space as well
as four alternative designs/arrangements that are
assumed to have an equivalent or higher level of safety
than that of the existing design.
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Consequence Analysis Process
Fire consequence analysis tools can be used to
compare the fire safety level of an alternative
designs violating the prescriptive regulations
against an existing design that follows the
prescriptive regulations.
Due to lack of information needed to conduct
a frequency analysis, which is the core of any
fire risk assessment, it is decided to base the
comparison on the number of fatalities which
is the output of the consequence analysis.
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Case Study
An accommodation deck
onboard an
existing Nile floating hotel, which is designed
to carry 158 passengers occupying 66 cabins
and 3 suites distributed on its 4 decks, is
considered as a case study.
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Case Study
Blocked Exit
Forward
2
1
Fire Source
Exit 1
 The accommodation deck under consideration has a length of
56.4 m, width of 14.2 m, and height of 2.5 m, and is arranged
such as to accommodate 26 cabins and 2 suites connected via a
1.2 m wide longitudinal corridor.
 Walls and ceilings are consisting of three layers:
- PVC paint layer,
- galvanized steel layer and
- Rockwool insulation layer
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Design Fire Scenario
Blocked Exit
Forward
2
1
Fire Source
Exit 1
 The fire is assumed to break out in a 2 m2 bed mattress located in cabin #1
and is assumed to be unaffected by any fire fighting action.
 The door that connects the cabin of fire origin with the corridor is assumed to
be open all the time, while the cabin window is assumed to be closed.
 The smoke will propagate quickly into the corridor causing a worst condition
inside the cabin of fire origin as well as along the corridor.
 The close location of Cabin #1 to one of the main exits, in addition to the
ventilation conditions, make the fire scenario described above the worst-case
fire scenario that could occur in such deck arrangement.
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Design Fire Scenario
 The available collected data of the Nile floating
hotels showed that about 50% of the existing ships
are not equipped with an Automatic Fire
Suppression System (AFSS)
 So the existing design of the accommodation deck
under consideration is also not equipped with
AFSS. This would worsen the fire scenario under
consideration.
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Fire and Evacuation Simulation
Parameters
 The mesh used within the CFD model (FDS) has divided the domain
under consideration into 284,000 cells; each cell has the size of (0.2 x 0.2 x
0.2) m3.
 A total number of 163 measurement devices (154 inside the corridor and 9
inside Cabin of fire origin) are placed at a height of 1.6 m to record
temperature, CO, CO2, O2, fractional effective dose, smoke layer height,
volume fraction and smoke obscuration at every time step.
 The toxic effects of gaseous fire products are treated in this study by using
the fractional effective dose (FED) concept which should not reach the
incapacitation level [FED=1].
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Fire and Evacuation Simulation
Parameters
 The properties of agents used in the evacuation
simulation are:
Occupants Type
Adult
Child
Elderly
Female
Male
Occupant Speed
(m/sec)
Uniform
(0.95-1.55)
Uniform
(0.6-1.2)
Uniform
(0.5-1.1)
Uniform
(0.95-1.35)
Uniform
(1.15-1.55)
Detection
Time
(sec)
Reaction
Time
(sec)
Constant
(20)
Uniform
(10-100)
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EXISITNG DESIGN (CASE A)
 Smoke spread quickly into the corridor and reached the nose level of
agents trying to escape. This lead to a rapid accumulation of toxic
effects which is translated into reduction in agent speeds.
 As an outcome, 17 fatalities (out of 56 passengers) have occurred
because they were unable to reach a place of safe refuge before
reaching the untenable condition.
 So, in order to enhance this situation, the authors decided to examine
some alternative designs that can increase the level of fire safety
within the domain of concern.
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First Alternative Design (Case B)
 In this case, it was decided to increase the corridor
clear width from 0.9 m to 1.3 m in order to reduce
the initial agent density, which is expected to result in
reduction of congestion and queuing of occupants
during the evacuation process.
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Second Alternative Design (Case C)
Exit 2
Exit 1
 In this case, it was decided to replace Cabin #12, which is
located midway between the cabin of fire origin and the
only available exit (Exit 1), by a new second exit (Exit 2).
 It is expected that the time needed for evacuation of the
passengers will be decreased, resulting in much less
congestion and queuing in the corridor.
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Third Alternative Design (Case D )
 As a third alternative design, it was decided to use a smoke
extraction system consisted of 6 smoke extractors with
capacity of 0.6 m3/sec each, mounted into the corridor
ceiling.
 It is expected that this alternative design be able to
maintain a smoke-free clear path for the passengers to
escape safely from the available exit by extracting the
smoke at reasonable rate.
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Fourth Alternative Design(Case E )
 Finally, it was decided to examine the effect of using a
fire suppression system on the level of fire safety
within the domain.
 The system is a residential wet-pipe sprinkler system
consisting of 18 pendant sprinkler heads (16 in the
corridor and 2 in the cabin of fire origin).
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DISCUSSION of RESULTS
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Discussion of Results
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Concluding Remarks
 Fire and Evacuation Simulation models are essential
tools that could help ship designers analyze the
consequences of given fire scenarios and evaluate the
level of safety of their designs, hence reach the design,
which has a level of safety that is as high as reasonably
practicable.
 Consequence analysis tools could also help the
authorities having influence in changing, enhancing or
developing regulations concerning the fire safety
design of Nile-floating hotels.
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Concluding Remarks
Among the four tested alternative designs,
the design that showed the best result was the
one with sprinkler system installed. This
would support the conclusion that the 50% of
the fleet of Nile-floating hotels that work
without sprinkler systems are in great danger
if a similar fire scenario as the one considered
occurs.
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Concluding Remarks
Instead of giving relaxations to the owners
of that part of the fleet of the Nile-floating
hotels which are sailing without sprinkler
systems installed onboard, and in order to
save the lives of their passengers, the
authors advise licensing this type of ship to
either force the ship-owners to install
sprinkler systems or allow them to select
alternative design/arrangement with an
adequate level of protection against fires.
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Concluding Remarks
The authors recommend studying the effect
of merging one or more of the control options
used in the alternative designs tested in this
study expecting that the merged designs will
have better fire safety level.
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Thank You for Your Attention
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