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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International Marine and Offshore Engineering Conference3&4 September 2014

Al Jubail–Kingdom of Saudi Arabia

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

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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Stranding46%

Collision 30%

Sinking1%

Fire23%

Stranding Collision Sinking Fire

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

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

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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.

Case Study

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Fire Source

Blocked Exit

1

2

Forward

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

Design Fire Scenario

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Fire Source

Blocked Exit

1

2

Forward

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.

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

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Occupants Type Occupant Speed

(m/sec)

Detection Time (sec)

Reaction Time (sec)

Adult Uniform

(0.95-1.55)

Constant (20)

Uniform (10-100)

Child Uniform (0.6-1.2)

Elderly Uniform (0.5-1.1)

Female Uniform

(0.95-1.35)

Male Uniform

(1.15-1.55)

The properties of agents used in the evacuation simulation are:

EXISITNG DESIGN (CASE A)

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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.

First Alternative Design (Case B)

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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.

Second Alternative Design (Case C)

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Exit 1

Exit 2

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.

Third Alternative Design (Case D )

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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.

Fourth Alternative Design(Case E )

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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).

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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