INTERNATIONAL MARITIME ORGANIZATION
E
IMO
SUB-COMMITTEE ON FIRE PROTECTION
50th session
Agenda item 3
FP 50/INF.2
4 October 2005
ENGLISH ONLY
PASSENGER SHIP SAFETY
Measures to contain and extinguish electrical-origin fires within medium
and high voltage switchboard rooms
Submitted by Canada
SUMMARY
Executive summary:
This document highlights the risks associated with the lack of
adequate structural fire protection requirements for main switchboard
rooms containing electrical equipment routinely transmitting high
levels of power and indicates the need to provide such switchboard
rooms with independent connections to a fixed fire-fighting
installation
Action to be taken:
Paragraph 23
Related documents:
MSC 74/4/1, MSC 73/21, MSC 73/4/2 and MSC 72/21
Introduction
1
This information document was developed following an investigation carried out by the
Transportation Safety Board of Canada (TSB). Findings of interest are noted in this document.
The full investigation report is available on the TSB website: http://www.tsb.gc.ca.
2
On 4 August 2002, the large passenger vessel Statendam embarked passengers in
Vancouver, British Columbia, for a one-week cruise to Alaska and back. At 8.25 p.m. Pacific
daylight time, about three and a half hours after departure, the main circuit breaker for one of the
diesel generators (DGs) suffered a catastrophic failure. This started fires in the main switchboard
room and the adjacent engine control room. The crew successfully extinguished both fires using
portable CO2 extinguishers, and the vessel returned to Vancouver under tow.
3
The generated voltage aboard the Statendam is 6.6 kV. Two electric propulsion motors of
12 000 kW each, drive two controllable pitch propellers and the total power produced by
the 5 DG sets is 34.56 MW.
For reasons of economy, this document is printed in a limited number. Delegates are
kindly asked to bring their copies to meetings and not to request additional copies.
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4
The main circuit breakers for the DGs are of the SF6 gas-filled type. DG2’s circuit
breaker failed catastrophically and in all likelihood its failure was caused by a direct internal
short circuit across two (or three) phases.
5
The electrical arc generated by the short circuit seriously damaged circuit breakers,
relays, and switchgear in the adjacent panels. The bus bars in the immediate vicinity were
vaporized, and there was considerable damage to the high-tension and control cables. Radiant
heat from the switchboard room was rapidly transmitted to the engine control room through the
switchboard room deckhead, where it ignited electrical cables located beneath the deck plates.
6
The switchboard was enclosed within A-60 steel bulkheads and decks. However, the
deckhead was an A-0 division. The switchboard room was included in the CO2 fixed fire-fighting
system for the engine room.
7
Fire-fighting crews entered and successfully extinguished the fires in both compartments,
using a total of 58 (almost the entire stock) portable CO2 extinguishers in the process.
8
One half of the switchboard was ‘live’ throughout the fire-fighting process as DG3 kept
supplying power to the ship.
Discussion
9
One of the underlying principles of the structural fire protection regulations in SOLAS is
that a fire be detected, contained and extinguished in the space of its origin.
10
Upon first consideration, switchboard rooms containing medium-voltage or high-voltage
electrical switchgear (such as that on the Statendam) do not appear to contain large amounts of
combustible material capable of sustaining a fire long enough to threaten a neighbouring
compartment. However, such spaces do contain cables, switchgear, and associated equipment,
which may routinely be transmitting electrical power of 30 MW or more. As demonstrated by
this occurrence, in the event of a catastrophic failure of a circuit breaker - either directly, or
consequentially as a result of the failure of other electrical switchgear - the resulting arc has the
potential to release enough thermal energy to establish a fire in un-insulated contiguous
compartments.
11
Structural fire protection is the primary method of containing heat within a compartment;
however, current requirements for structural fire protection around main switchboard rooms do
not address the fire risk inherent in electrical systems that transmit high levels of power. As a
result, the Statendam had no fire retardant/thermal insulation between the main switchboard
room and the engine control room one deck above. The failure of the main breaker resulted in a
high-energy electrical discharge and the associated radiant heat was rapidly transmitted through
the bare steel deckhead, igniting electrical cables in the engine control room.
12
The number of vessels, particularly cruise ships, equipped with diesel-electric propulsion,
continues to grow as owners embrace the benefits of improved operating efficiencies and lower
operating costs. There are eight ships similar to the Statendam in main switchboard room
arrangement. A review of passenger cruise ships due to be delivered between 2005 and 2008
indicates that the majority will feature electric propulsion.
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13
In the last fifteen years there have been at least 5 other instances of switchboard fires.
One of these was associated with a medium-voltage circuit breaker failure; while another, the
Sun Vista, sank in the Malacca Straits forcing all passengers and crew to abandon the ship.
14
On the Statendam the fire-fighting crews were effective in extinguishing the fire.
However, electrical fires are particularly dangerous, not only because melting or burning
insulation can cause conductors to short circuit, but because exposed conductors can electrocute
anyone coming into contact with them.
15
Using the fixed CO2 smothering system to extinguish the fire was given consideration
during the fire-fighting operations. It was not used because the main switchboard room is located
inside the engine room and falls within its fire zone. Releasing CO2 into the entire engine room
would thus not only have caused DG3 to shut down, but it would also have used up most of the
vessel’s stock of CO2 bottles. Therefore, it was considered a last resort, to be used only after all
other methods had proved unsuccessful.
16
A variety of different circumstances, such as navigational and weather-related concerns,
or internal shipboard considerations, such as the need to prevent panic amongst the passengers,
can impose conditions where it may not be considered prudent to disable the propulsive
capability of a vessel, or to impose a partial ‘black out’ in the accommodation areas. In such
circumstances, the DG sets will not be shut down and the emergency generator will not be used
to supply emergency power.
17
On the Statendam, fire-fighting crews chose to enter the main switchboard room, a
narrow confined space, in conditions of near-zero visibility because of the smoke, knowing that a
section of the switchboard was live and knowing that other sections had been badly damaged, yet
not knowing to what extent the damage had affected the live section of the switchboard. This
decision exposed the crew to undue risk because they could not adhere to the primary principle of
fighting a shipboard electrical fire: isolate the fire from all sources of electrical supply before
directly confronting it.
18
It is common on all types of vessels to provide smaller high-risk spaces such as paint
lockers and galleys with independent smothering systems. The main switchboard room on the
Statendam, similar to switchboard rooms on many other vessels, was not fitted with its own
independent system. Providing the main switchboard room with such a system, or its own
independent connection to the main CO2 smothering installation would provide an effective and
safer fire-fighting alternative.
Past Action taken by IMO
19
In 2000, the Working Group on Large Passenger Ship Safety established by the Marine
Safety Committee (MSC) reported to MSC 73 and noted, “that the rapid extinguishment was
another key element for avoiding fires from becoming catastrophic.”
20
At the seventy-fourth session of the Maritime Safety Committee (30 May to 8 June 2001),
the Committee directed the Sub-Committee to evaluate 19 fire-protection tasks for both existing
and future large passenger vessels. The objective was to improve fire protection and prevention
measures, thus improving ship survivability. The areas of concern included main vertical and
horizontal zone requirements, and how to link fire prevention and protection measures to the fire
risk of specific spaces not generally covered by the existing general categorization and
regulations. Subsequently, at the next meeting of the Sub-Committee, the United States tabled a
document analysing gaps in IMO instruments pertaining to fire safety on large passenger vessels.
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The document recommended that the FP Sub-Committee consider measures to “develop
enhanced structural and active fire protection requirements for traditional high risk areas
(e.g., laundry areas, carpenter shops, solvent cleaning rooms) and for spaces with fire hazards
involving innovative designs not envisaged by SOLAS chapter II-2.”
Conclusion
21
Once started, shipboard fires can spread rapidly and exponentially. Restricting their
spread, containing them within their space of origin, and extinguishing them quickly with the
least possible risk to life are critically important considerations in designing safe vessels. The
capacity of structural fire protection and fixed fire-extinguishing systems to adequately restrict
and extinguish a fire is vital.
22
In light of the above, it is suggested that a review of requirements for structural fire
protection and fire-extinguishing systems be done, in order to ensure that the fire risks associated
with compartments containing high levels of electrical energy are adequately assessed, and that
the provisions of the 1974 International Convention for the Safety of Life at Sea (SOLAS), as
amended, dealing with structural fire protection and fixed fire-extinguishing systems are
appropriately addressed.
Action requested of the Sub-Committee
23
The Sub-Committee is invited to note this information and take action as appropriate.
___________
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