FIRE SAFETY IN HIGH SPEED LIGHT CRAFT
Karl M. Wikiund
Senior Principal Surveyor Det norske Ventas Classification
SUMMARY
This paper discusses the philosphy of fire safety in SOLAS and 1MO 373 and focuses on the important aspects of fire safety in
high speed light craft. The consequences to the industry
depends on the outcome of the ongoing revision of the 1MO Code
for high speed craft. The main philosophy of the revised
chapter 7 Fire Safety is quoted and outstanding questions are
mentioned. A comparison method to verify equivalent safety
standard is proposed.
INTRODUCTION
As you all know, the 1MO Res. 373(x) Code of Safety for high
speed craft is under revision. In addition to the SOLAS
Convention, this code has been the main document regulating
the development of high speed craft. Most countries have
high speed craft of aluminium or FRP and those craft do not fit into the SOLAS safety philosophy saying that a ship should be made of steel.
Domestic legislation in many countries has been forced to find equivalent solutions for this kind of craft leading to a
situation when the requirements may vary from country to country. In such a situation 1MO plays a very important role as an international standard setting body, not only to
establish an adequate
safety standard, but
also to facilitate free international trade by minimizing technical barriers totrade. This is the same goal as for the international
classification societies.
Sometimes we hear that rules and requirements are too rigid. But that may be the price we have to pay to have an
international standard recognized by all maritime authorities. Obviously we may find examples on less strict requirements on
some aspects in a domestic legislation, but that may well be caused by the fact that the country cannot afford more or due to more strict requirements on other aspects. Both for yards and owners it is of vital importance to have a craft which may trade all over the world without major modifications to comply with domestic legislations.
It is not fair to criticize international conventions if one has not been active to develop and improve the standards. The
1MO organization is a democratic body. Good and well argued
arguments will be heard. As we as a classification society believe in democratic developments of international standards, we like to inform about the content of the revised chapter 7 of the code so that you all may make up your minds and bring forward your comments through your representatives in 1MO. This way we can contribute to a democratic development of
international conventions.
1MO REVISIONS
When an 1MO text is to be developed, this is based on
proposals from various countries. The text is discussed and
agreed by a sub-committee or by a drafting group. Then the proposal is out for comments and will, when completed, be
approved by the marine safety council. It is therefore important to have a well prepared draft text to start with, otherwise it may be difficult to end up with a good proposal. The revision of chapter 7 started at IMO's Sub-committee on Fire Protection's 36th session (FP36) in 1991 and the text
will probably be completed by FP37 in 1992. Prior to the FP36
meeting we found that the various countries had very different
opinions about new requirements to fire safety. No proposed
document could be used as a unified draft text. When you know
that the subcommittee have worked for years to improve the fire safety of conventional passenger ships and ferries, the outcome of FP36 meeting was a draft proposal equivalent to the SOLAS text for steel ships. The 1MO proposal last summer was that future high speed light craft should be made of steel. DnV fully support strict requirements to passenger ship and that traditional and complex passenger ships should be
made of
steel.
But, if
steel should be a requirement for high speed craft, further developments of fast sea transportation based on new concepts would be very difficult. Neither could we understand that most countries accept aluminium and FRP on domestic vessels, but not on international. Some countries set a maximum number of persons for these materials. We find it unacceptable to have a lower safety standard for 150passengers keeping in mind that the large disaster with
"Scandinavian Star" was about that number of passengers. It was important to come up with an alternative proposal.
Consequently, Norway invited to an informal intersessional FP
meeting in October 1991. This meeting adopted a new text for
a draft proposal of revised chapter 7. The main principles are agreed, but still a lot of questions have to be concluded at the next FP meeting in London. Those questions will be of vital importance to the light craft industry as they are about what should be the building materials, the levels of f
COMPARISON METHOD
The basic safety standard for ships is the SOLAS convention. This standard is based on the philosophy that fires always will occur, regardless of any preventive actions.
Consequently, everything should be made of steel or at least non-combustible materials with necessary insulation. The "Scandinavian Star" is an example which clearly shows that
this is necessary. Somebody sets on fires onboard on 2 or 3
places at the same time. Even the latest example onboard STENA DANICA where one of the crew sets on a fire can be used to support the philosophy that fires always will occur.
On the other hand an airplane is not built of steel and if it was, it would not add anything to the safety of aviation. The
aircraft regulations are based on preventing fires to occur
and redundancy. Some fire restricting materials are used, but
mainly early detection and extinction. Perhaps even more important, the airplane shall be able to fly even in case of
fire in one engine. This way the air traffic has coped with
the fire hazards in an even better way than at sea. One may say that the fire safety at sea is provided by
repairing any situations which may occur and the aircraft fire safety is provided by preventing fires to develop into
hazardous situations. To be able to compare these two
philosophies, it is important to find a fair method which can consider the effect of both the preventing and repairing
efforts. Such methods are often used to evaluate military
activities, space and offshore industry and was used by DnV to find a basis for an alternative fire safety philosophy.
The method is rather simple. First fire scenarios for the various compartments of the craft have to be established i.e. for engine room, accommodation, car deck, cargo space etc. Then the relative importance of the various elements of the
scenario has to be established. This is made by a pair by
pair comparison method, which
means that
the importance is related to eachother in such a way that the sum is 100 percent although it is achieved by preventing or repairing actions ora combination of both. Each scenario has then got a profile
of importance i.e. for fire in an accommodation it is of vital importance to get persons away from the fire, but in an engine room it is important to shut down the compartment and restrict any spread of a fire. Having such scenarios and safety
profiles actual design or rules may be evaluated by
quantifying how well the various aspects are considered. A total score for a specific scenario may then be calculated and various safety standards or philosophies may be compared.
NEW SAFETY PHILOSOPHY
The traditional SOLAS fire safety philosphy is that one shall be able to stay onboard in at least one hour before evacuation as a fire is restricted to spread due to fire insulation.
The previous 1MO 373 philosophy has been that fires in fire hazard areas shall be restricted to spread until the craft is evacuated and the craft is supposed to be assisted.
Consequently such craft are to operate within restricted service areas.
A new philosophy has been introduced based on the findings from the comparison of the two above. This philosophy says that the persons onboard shall be able to escape from a fire to another safe place onboard the craft and in addition the craft shall be operable in case of fire or other damage in any
one compartment onboard. This is the same as requiring that
an airplane shall be able to fly in case of fire in one engine.
The new draft proposal contains two fire safety strategies of high speed light craft. One based on the previous philosophy
requiring rescue assistance. This philosophy is applicable to
craft with a limited number of persons onboard operating in waters where adequate and fast rescue assistance is available. For example in Hong Kong waters any high speed craft on
regular route may be assisted by another high speed craft within 15 minutes. The other level of fire safety is
applicable to craft with large numbers of passengers and/or on routes where adequate rescue assistance may not be provided.
In such cases the craft should be able to handle the situation by itself, by providing a safe accommodation of the persons onboard and maintain the operation of all main functions onboard even in case of fire in one major compartment.
This way it can be proved that an equivalent safety to a SOLAS ship is achieved with an alternative fire safety philosophy, even with a craft built of non steel materials.
NEW CHAPTER 7
To include the new fire safety philosophy a new preamble and general requirement to chapter 7 is drafted as follows:
Quote:
Chapter 7 is applicable only to vessel which comply fully with the undernoted conditions in this preamble otherwise Chapter
11/2 of SOLAS as amended is applicable.
1. Vessels shall be of light weight and high speed
Separation and duplication of machinery and controls are provided in order that in the event of a fire or other
casualty destroying the functions of any one compartment the vessel can return to a port of refuge under its own power otherwise rescue facilities should be readily available as required in Chapter 1.
Vessels should be engaged in the transportation of
passengers and (private) vehicles only, and no dangerous goods
or flammable cargo should be carried. Passenger access to
vehicle spaces is prohibited during the voyage.
No enclosed passenger sleeping berths are provided. All passengers and crew are provided with a seat. General
7.1 The following basic principles underlie the regulations in this chapter and are embodied in the regulations as
appropriate, having regard to the type of craft and the potential fire hazard involved:
7.1.1 maintenance of the main functions and safety systems of
the craft, including propulsion and control, fire detection, alarms and extinguishing capability of unaffected spaces, after fire in one of any compartment onboard;
7.1.2 division of the accommodation area, in such a way that
the occupants of any compartment can escape to an alternative safe area or compartment in case of fire;
7.1.3 subdivision of the craft by fire resisting boundaries; 7.1.4 restricted use of combustible materials and materials generating smoke and toxic gases in a fire;
7.1.5 detection, containment and extinction of any fire in
the space of origin;
7.1.6 protection of means of escape or access for fire
fighting;
7.1.7 immediate availability of fire-extinguishing
appliances;
7.2 The requirements in this chapter are based on the following conditions:
(a) Where a fire is detected, the crew immediately puts into action the fire-fighting procedures, informs the port or base port of the accident and prepares,
if necessary, for the escape of passengers to
alternative safety area of compartment, or for the evacuation of passengers.
(b) [The use of fuel with a f lashpoint below 43°C is not recommended. However, fuel with a lower f lashpoint, but not lower that 35°C, may be used provided
suitable precautions, to be developed by the
Organization, are taken against the risk of fire and explosion. J
(C) Passengers are appropriately instructed regarding fire, escape and evacuation procedures in an
emergency situation, to a standard to be development by the Organization.
Members of the crew are aware of the instructions approved by the Administration which specify the actions of the crew in the event of fire on the
craft and that these instructions are permanently on board the craft and appropriate drills of the crew are arranged at least weekly.
The repair and maintenance of the craft is carried out in accordance with the requirements given in chapter 17 and 18 of this code.
Craft shall comply with both the requirement for redundancy and escape to an alternative safe area on board, given in 7.1.1 and 7.1.2 and point 2 of the
preamble. Craft which do not are to operate only on
routes where rescue assistance to the craft is available on all parts of the route and which is capable of dealing with the total number of persons on the craft, and is given as a condition in the
"Permit to Operate" Certificate. End of quote
FIRE HAZARD AREAS
The SOLAS standard in principle defines all areas onboard as
fire hazard areas. The basic requirement is AO which means an
uninsulated steel bulkhead. For an aluminium craft this is equivalent to an A60 standard due to the low melting point of aluminium.
The revised code defines three different levels of fire hazard areas, major, moderate and minor fire hazard. This way it is possible to simplify the requirements compared with the
insulation matrix of the SOLAS text.
A major fire hazard area is where a major fire may be expected and developed within a short period of time, i.e. where there
is a risk of explosions or flammable liquids together with sources of ignition.
A moderate fire hazard area is where a fire may develop local fire within some time if not extinguished.
A minor fire hazard area is where fires may not be expected to start and develop i.e. unattended void spaces, fuel tank
compartments and also such accommodations where all activities are supervised like in an aircraft accommodation.
The basic idea was to provide fire-resistance when exposed to a standard fire test according to the following:
major fire hazard area 60 minutes fire resistance moderate fire hazard area Local fire prevention by
fire restricting materials + 30 minutes fire resistance minor fire hazard area Low flame spread
requirements
All compartments onboard should then be defined within one of
the above categories. There are still discussions going on
both with regard to the above definitions and what compartments to be put into the various categories.
Consequently, to obtain a democratic development of a revised code for high speed craft, it is of vital importance that the industry and the operators in the various countries study the proposals and discuss with their authorities prior to the next meetings in 1MO.
ALTERNATIVE CONSTRUCTIONS
The shipping industry has been used to only one way to
establish fire resistant constructions i.e. steel bulkheads insulated with inorganic materials covered by steel or a
limited thickness of combustible materials. Today there is a remarkable development of alternative materials, in particular
in the US. We have seen towels impregnated to an extent that
they have become non-combustible, we have seen fire insulation materials made of organic components, we have seen wooden
constructions made fire restricted. The most important to
obtain by this revision of the code is to set functional requirements to fire safety instead of specifying a specific
material. In principle all materials that meet those test
requirements should be acceptable with respect to fire safety. Cost effective fast sea transportation can only be provided if
the weight is kept as low as possible. Both air, rail and
road transportation aim for the same goal. Sea transportation should also utilize the technical developments, but only to achieve at least an equivalent level to SOLAS. That can be done on high speed craft within the concept of the code when all activities onboard should be supervised like in an
aircraft cabin, no dangerous goods are taken onboard and the craft is operated under strict permissions.
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For conventional passenger ships with all their complexity which makes it difficult to control what is going on onboard
in enclosed cabins, dark discoteques, hidden corridors we still think that the steel concept is the best for an
international shipbuilding standard.
References:
SOLAS Convention as amended 1MO Resolution A.373 (x)
Code of safety for dynamically Supported Craft
Revision of 1MO 373 Ch. 7 by a drafting group set down by sub-committee on Fire Protection FP 36
Revision of 1MO 373 Ch. 7 by an informal meeting after FP 36.
DnV report 520 14 252 Safety evaluation of fire philosophies, A comparison and ranking analysis Saaty, T.L.: "The Analytic Hierarchy Process"
Mae Graw-Hill, New York, 1980
DnV report 91-0260 Demonstrations of fire resisting qualities of high speed light craft panels.
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