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Fires, Explosions and Related Incidents at Work 1992 1993
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7/21/2019 Fires, Explosions and Related Incidents at Work 1992 1993
http://slidepdf.com/reader/full/fires-explosions-and-related-incidents-at-work-1992-1993 1/7
0950-4230(95)00035-6
J. Loss Prev. Proress Ind. Vol. 8 . No. 5. pp. 291-297, 1995
E lse v ie r Sc ie n ce L t d
Pr inted in Great Br i ta in
09504230/9 5 S IO.00 0.00
Fires explosions and related incidents at
work in 1992-1993
K A Owens and J A Hazeldean
Technical and Health Sciences Division, Health and Safety Executive, Magd alen
House, Bootle, Merseyside, L20 3QZ
Incidents in Great Britain reported to the Health and Safety Executive during 1992-1993 involv-
ing fires, explosions, runaway chemical reactions and unignited releases of flammable materials
are reviewed. Statistical comparisons are made against previous years based on the materials
involved, and a number of common themes and causes are identified.
Keywords: fires; explosions; unignited releases; exothermic reactions; carriage
This paper summarizes fires, explosions and related inci-
dents reported to the Health and Safety Executive (HSE)
in 1992 -199 3. It originally forme d part of a review sub-
mitted to the Advisory Committee on Dangerous Sub-
stances by the Explosive s and Flammables Unit of
HS E’s Technology and Health Sciences Division.
The information was compiled from an analysis of
accidents and dangerous occurrences reported to the
HS E under Regulation 3 of the Reporting of Injuries,
Diseases and Dangerous Occurrences Regulations 1985
(RIDD OR). An HSE booklet’ describes the types of
accidents and injuries reportable under RJD DO R. Th is
paper also includes information on incidents that
involved the manufacture, keeping and carriage of
explosives. These incidents were reported to the HSE
under Section 63 of the Explosives Act 187 5 and Regu-
lation 12(2) of the Road Traffic (Carriage of Explosives)
Regulations 1989.
The HS E investigates accidents and seeks to ensure
that any safety lessons are learned by the company con-
cerned to prevent similar accidents from occurring again.
Additionally, the HS E commu nicates findings from acci-
dent reports an d investigations more widely in guidance
booklets and other forms of advice. T he information col-
lected may also be used to identify the need fo r new
guidance and researc h, and to suppo rt national and inter-
national standards. The purpo se o f publishing this repor t
is to draw further attention to the hazards of flammable
materials and common accident scenarios in the hope
that reade rs may recognize particular situations and take
action before an accident occurs.
Overall statistics
The accidents repor ted in this review occurr ed in the
period 1 April 1992 to 31 March 1993 and involved fires,
explosions, runaway chemical reactions and unignited
releases o f flammable materials. They occurr ed during
wo rk activities at premises and sites whe re the Field
Operatio ns Division (Factory, Agriculture and Quarry
Inspectorates) and the Explosives Inspectorate of the
HSE enforce the Health and Safety at Work, etc. Act
1974 . The 675 injuries (including 2 1 fatalities) that
resulted from fires or explosions are a subset of 147 374
injuries (including 405 fatalities) suffered in all types of
accidents reported to the HSE.
There are an estimated 700000 fixed premises and
an additional unquantifiable number of transient sites
wh ere the Field Operation s Division has enforcemen t
responsibility. An estimated 15 million p eople are
employe d at these locations, and, of these, around 4.5
million are employ ed in manufacturing industries.
Explosives are manufacture d in about 12 4 licensed
explosives factories, varying in size from those
employing one or two people to those employing over
1000 people. In addition, explosives are held in 98
magazines licensed by the Explosives Inspectorate, and
around 200 compan ies are involved in carrying explos-
ives by road.
Some of the main types of accidents, and those that
caused or had the potential to cause serious conse-
quences, have been broken down into the main categor-
ies repor ted below and the overall ranking is shown in
Table 1 Categories of accidents
Category
of total incidents Fatalities
Flammable liquids
32
7
Flammable gases 23
1
Flammable solids
18
5
Liquefied petroleum gas
6 0
Exothermic reactions
3 5
Explosives 5 1
291
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2 9 2 F i r es e x p l o s i o n s a n d r e la t e d i n c i d e n t s a t w o r k i n 1 9 9 2 -1 9 9 3: K . A . Ow e n s a n d J . A . H a z e /d e a n
Table 1 The overall num bers of repo rted incidents in
these categories are presented in Table 2 for the last
five years.
Flamm able solids and dusts
The repor ted incidents (n = 200) in this cate gory
occurred across a wide range of work activities.
The largest nu mber of incidents relates to drying or
heating processes that go wrong. The range of materials
involved is wide, and includes clothing in a comm ercial
tumble drier, paper dust in a paper-mak ing machine, bis-
cuits and bread in large ovens, an adhesive coating in
a shoe factor y, foam backing in an oven at a carpet-
manufacturing plant, and soya and linseed grain pro-
ducts. M any of these incidents cause no injuries but may
cause extensive damage to the plant and prolonged shut-
down.
Seven incidents involved aluminium or magnesium
metals, and of these six involved the metal d ust. This
appears to be a disproportionate number considering the
relatively small number of premises that handle the se
dusts, and highlights the significant risks in processing
these substances. Metal dust fires are characterized by
intense heat and rapid fire grow th, and it is extremely
difficult to extinguish large tires before the pow der has
burnt out. Often the fire damage is so severe that there
is little prosp ect of confidently identifying the ignition
source. A recurring theme is that dust builds u p around
the process area or in extraction ducts. The H SE has
recently published guidance2 on the safe handling of
combustible dusts, which highlights the need for good
housekeep ing, including the frequent emptying of dust
extraction equipment and the regular inspection and cle-
aning of ducts.
Nine incidents involved substan ces described as
chemicals. The most no table led to the loss of 820 tonnes
of molten sulfur from a 900 tonne sto rage vessel. It was
suspected that corrosion under the lagging resulted in a
small hole a t the base of the tank. The sulfur did not
ignite but the leak continued for seven hou rs.
The only incident that caused offsite risk s was a
fire at a plant that was making chlorinated rubber. The
contents of a hot air drier caugh t fire, and a large p lume
of smoke drifted offsite. There were reports of nose and
throat irritation caused by the fumes.
Spontaneous combustion was identified as the cause
of a number of incidents even wh ere the hazard was well
understoo d in advance. One examp le involved a fire dur-
ing the unloading of a bulk ship’s cargo of raw cotton.
Three incidents occurr ed in carbon bed absorbe rs,
due to spontaneous combustion. Such absorbers are
likely to becom e more comm on due to environmental
controls requiring a reduction in the emission of organic
solvents. Fires in these units can be difficult to
extinguish because they may start deep within the carbon
bed, but instrumentation is available that allows fires to
be detected at an early stage and appropriate action to
be taken. As a result, although fires in these units are
repor ted every y ear, there is no significant record of
associated injuries.
Although not strictly a hazard derived from work
activities, arson remains a serious risk to many busi-
nesses. A notable incident involved a fire that started in
an outside storag e a rea for garden furniture and boxes.
Hundreds of tonnes of polypropylene goods and a large
factory were destroyed, but fortunately no-one was
injured.
Flammable liquids
The reported incidents (n = 359) involving flammable
liquids resulted in 172 injuries, including seven fatalities.
These figures continue to show a down ward trend in line
with the overall trend fo r all types o f accidents repor ted
to the HSE . The high number and wide variety of inci-
dents within this category reflect the extensive and
diverse uses that are found fo r flammable liquids w ithin
Table2 Accident statistics for fires and explosions from 1987/1988 to 1992/1993 (see text for the source and scope of accidents
included)
Category
1987/1988 1988/1989 1989/1990 1990/1991 1991/1992 1992/1993
Flammable solids Incidents 223
263 258 223 106 200
Injuries
144 154 157 158 101 113
Fatalities
7 7 5
1
5 5
Flammable liquids
Incidents 522
Injuries 325
Fatalities 9
232
9
469
447
411
359
247 232 217
172
11
12
8
7
Liquefied petroleum gas Incidents
124 95
89
90 75 61
Injuries 125 83 73 92 66 46
Fatalities 0
1 1 1
3
0
Flammable gases and oxygen Incidents 291
332
95
277 299 251
Injuries 228 232
195
194 2 9 139
Fatalities 0
1
2
4 1
1
Exothermic chemical reactions Incidents 63
38
52
60
50
37
Injuries 25
13
34
24
25
23
Fatalities 0
0 1 0 1 5
Explosives manufacture, storage,
carriage
Incidents 65
45
58
50 42 48
Injuries 34
141
18 20 17 26
Fatalities 2 3 0
1
1
1
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F i r es e x p l o s i o n s a n d r e la t ed i n c i d e n t s a t w o r k in 7 99 2 -1 9 9 3: K . A . Ow e n s a n d J . A . H a z e ld e a n 2 9 3
industry. Althoug h flammable liquids are often stored or
used in large quantities, whe re the potential for major
accidents exists, it is small-scale use or misuse that con-
tinues to give rise to the highest numbers of injuries
and fatalities.
The moto r vehicle re pair industry is associated with
a small proportion (7 ) of the overall incidents reporte d,
yet these incidents were the cause of four fatalities. Two
were mechanics who were caught up in fires when spilt
petrol ignited during the draining of vehicle fuel tanks.
In another accident, the proprietor, who was the sole
worker in a garage, accidentally cut through a vehicle
fuel line with an oxyacetylene torch and received fatal
burns in the ensuing fire. The fourth fatality occurr ed
when a garage owner used flammable liquids near to a
lit stove. Th e liquids ignited and the owne r was engulfed
in flames. The hazar ds and precautions in these circum-
stances are well-documented. The HSE has conducted
special initiatives relating to this industry, and, although
there has been a noticeable reduction in incidents,
significant accidents still occur.
The small-scale manual handling of highly flam-
mable liquids across all industries accounts for approxi-
mately 15 of the incidents in this category . Operation s
within this group include the use of solvents for clean-
ing, decanting liquids between containers, filling the fuel
tanks of portable equipment with petrol, and solvent
handling in laboratories. In most instances, an easily
identifiable ignition source, such as a naked flame or
unprotected electrical e quipment, was present, but the
operators either ignored or were unaware of the hazard.
Althoug h these appea r to be relatively minor incidents,
the consequen ces can often be severe. There is clearly
a lack of understanding or appreciation of the risks
involved, especially in small businesses, and the HSE is
preparing guidance on the safe use of flammable liquids.
The brightening of fires with flammable liquids and
other deliberate misuse, including horseplay , account for
a further 1 0 of incidents, further demonstrating the
ignorance and contempt that many people have with
regard to the hazards and properties of flammable
materials.
The use of flammable liquids in coating operations,
either with hand-held equipment or with continuous
plant, gave rise to 22 fires (6 ) but generally only a few
injuries. How ever, one incident resulted in fatal burns to
the operator who was spraying a flammable liquid-based
woo d preservative in the loft of a domestic building. The
liquid that was being sprayed in the confined space wa s
ignited by unprotected electrical equipment (either a live
junction box or a hand lamp that was used to provide
light for the work) despite the preservative can being
marked with appropriate warnings.
Poor wor k proced ures during maintenance activities
wer e directly responsible for 18 Aamm able liquid fires
(5 ). Hot work was listed as the source of ignition in
the majority of fires associated with maintenance. In one
accident, a highly experienc ed plant fitter was fatally
injured when a fine mist of hydraulic oil was released
from a valve and ignited after an oxypropane torch was
used to cut off bolts during the overhaul of hydraulically
pow ered plant. In another incident, whe re fortunately no-
one was injured, a storage tank exploded after it had
been cleaned f or maintenance but flammable liquids
were able to re-enter from the supply pipes which had
not been correctly disconnected.
Inadequate or lack of maintenance of plant led to
a number of fires and potentially serious leaks at proce ss
and storage facilities. Leak s of highly flammable liquids,
some of which developed into fires, were reported as
resulting from poorly maintained hoses, pipes and
valves. Other similar incidents occurr ed when plant had
been returned to service a fter maintenance but with
faulty workm anship including missing blanking plugs or
plates, open valves and the use of incorrect gaskets or
seals. In one incident, approx imately 5 tonnes of hexane
were released from a polymerization process w hen a
transfer line failed after it had been removed to clear a
blockag e and then replaced incorrectly. Incidents also
occurre d due to the lack of inspection or planned mainte-
nance. As examples, 2 tonnes o f petroleum were released
during a manufacturing proce ss when a section of pipe
sheared off at a joint, 4 tonnes of isopropanol were
released during transfer when flexible bellows split, and
fires occurred during other processing operations when
bearings failed.
Another noticeable feature of a number of incidents
relates to the maintenance of control systems and moni-
toring devices. During the bulk transfer of 60 ethanol,
approximately 20 tonnes of product were spilt because
of a broken level indicator and a malfunctioning auto-
matic trip-out system. In two separa te incidents, bitumen
storage tanks exploded when the low-level cut-off
switch es failed to operat e, allowing the heating coils to
be expo sed and ignite the bitumen vapour. Othe r inci-
dents included releases of between 1 and 10 tonnes of
flammable liquids during tank filling when contents
gauges failed to give correct readings.
The failure to follow pr ocess instructions or pro-
cedures correctly during chemical manufacturing or
other processes where highly flammable liquids were
being used resulted in six reportab le incidents.
Five repor ted incidents involved flammable liquids
at petrol refineries but these were dealt with safely and
did not escalate into fires. In one incident. approxim ately
700 tonnes of high-flash point oil were released through
an atmosp heric relief valve during the start-up of a distil-
lation system. The distillation column was overfilled as
a result of a malfunctioning level record er, and produ ct
flowed out from the column for several hours before it
was discove red. In another incident, approx imately 2
tonnes of highly flamma ble liquid were released from
leaking flanges that had failed due to the hydraulic shock
waves generated when a pump was started. A significant
‘near miss’,
where no product was released, occurred
when a 0.5 m diameter flare line was displaced 2 m from
its raised suppor ts. The incident occurr ed during start-
up when an operator neglected to reset some interlocks,
with the result th at the flare knock-ou t pot overfilled and
sent a slug of liquid down the flare line. The incident
had training and design implications.
A fatality a ssociated with oil-fired equipment
occurr ed when a stove, fuelled by waste oil, caught fire.
Two people escaped from the fire but one of them re-
entered the workshop, probably to telephone the fire
brigade, and was trapped. The person suffered 20
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294 Fires, explosions and related incidents at work
i n 1992-1993:
K. A. Owens and J. A. Haze/dean
burns and died after being critically ill in hospital for
three weeks. The reason that the stove caught fire could
not be determined, but the incident demon strates the
speed at which fires develop and the need to evacuate
buildings quickly and prevent re-entry unless told that it
is safe by the fire brigade.
Liquefied petroleum gases LPG)
The number of incidents (n = 61) in this category has
again fallen, and is now half the number record ed in
1987 /1988 . The number of injuries (n = 46) has also
fallen, to less than 40 of the 1987/1988 figures.
Almost 25 of incidents occurre d during start-up
of equipment and a further 13 occurred at times other
than normal operation, such as during maintenance.
These figures highlight the need for extra care during
such operations. Typically, injuries resulted from flash-
backs that occurred when there was a delay between
turning on the gas and igniting it. The incidents usually
resulted in burn injuries to the hand an d face. Another
common type of incident involved the leakage of LPG,
overnight, into a confined space such as a Portacabin.
When th e gas eventually found an ignition source, t he
result was a flash fire or explosion.
Several cases of blatant misuse d emonstrated a lack
of understanding of the hazards associated with LPG.
These include an incident where a propane torch was
used to thaw out a propane cylinder that had begun to
frost over when it was used to supply gas for the removal
of road markings. A pipe blew off the cylinder, the gas
ignited and the subsequent fire caused significant dam-
age to a lorry cab and cylinder rack.
Several incidents resulted from leaks of LPG from
poorly maintained or dama ged flexible hose s. In one
incident, a burning-machine opera tor received burns to
his arm and hand when a hole develo ped in the flexible
hose feed line and the released propane ignited. In
another incident, a welder was using a propane torch to
preheat a piece of work when hot metal was projected
onto the hose and caused it to leak. As the welder picked
up the hose, the hole became larger and the propane
ignited. The resultant jet flame caused burns to his face.
Fires have resulted when cylinders and cartridge s
were change d in unsafe locations. For examp le, an
employe e at a dental p ractice was changing a small
butane cylinder close to the main ga s central heating
boiler. Butane ignited and the employe e suffered burns
to the hand and face. In another incident, an opera tor
was changing a gas cartridge on a hot air gun. He had
placed the new cartrid ge in the gun and was fastening
the retaining plate when he dropped the plate and the
cartridge fell out. The cartridge had already been punc-
tured and leaking gas was ignited by a gas torch on a
nearby bench. The operator jumped out of the way of
the flames but not before his clothing had caugh t fire.
Flammable gases and oxygen
The incidents (n = 25 1) in this category
under two sub-categories: piped natural
flammable gases and oxygen.
are discussed
gas and other
Piped natural gas
Nearly two-th irds of the repor ted incidents in the flam-
mable gases and oxygen category are associated with
piped supplies of natural gas. The number of incidents
in this sub-category
n =
156) is approximately the same
as for the last two years. Howev er, there has been a small
reduction in the number of injuries sustained (n = Sl),
and there was only one fatality.
The fatality o ccurred when an experienced service
engineer was commissioning a burner unit on a new
horizontal gas-fired multi-tubular steam boiler. After
several failed attempts to ignite the burner, a modifi-
cation was attempted without an assessment of the risks
from any failures, and, on a subsequent attemp t to ignite
the burner, the boiler exploded. Incidents have occurre d
during the commissioning of gas-fired equipment and it
has been recognized that there is a need for adequate
instructions and recomme ndations for this activity. The
Institution of Gas Engineers has recently published Util-
isation Proced ures IGE/U P/4 ‘Comm issioning of gas-
fired plant on industrial and comme rcial premises’
(available from the Institution of Gas engineers, 17
Grosvenor Crescent, London SW 1X 7ES).
A common cause of gas leaks is accidental damage
to the mains pipework during excavation work. Most of
these leaks ar e dealt with without incident, but all have
the potential to cause subsequent injuries. In one such
incident, a gas technician was carrying out remedial
work on a flanged joint in order to replace a damaged
section of 14” low-pr essure cast iron main. T he escaping
gas ignited and the technician suffered burns to the hands
and face.
Gas is able to travel within the ground, in an unpre-
dictable way, som e distance from a leak to adjacent
buildings. The following incident illustrates the potential
consequenc es of this phenomeno n. A passer-by informed
the gas supplier about a suspected leak and an emerg-
ency team attended to carry out a site investigation. All
prope rties in the vicinity were checke d and found to be
clear of gas, and excavation work w as started to locate
the source of the leak. On several occasions, buildings
were monitored and found to be free of gas. However,
during the excavation work, a supervisor entered one of
the buildings, and, as he was leaving, gas ignited within
the building and he suffered burns to the hands, face and
hair. Neither the route th e gas took into the building or
the source of ignition could be identified.
Other flammable gases and oxygen
Of the incidents
n =
95) in this sub-category , 20, mainly
associated with gas welding equipment, resulted from
leaking or burst acetylene, fuel gas and oxygen hoses.
A guidance note on gas welding is in preparation and it
contains advice on appropriate standards for hoses and
other equipment and gives guidance on maintenance of
the equipment.
Seven further incidents occurre d w hen acetylene
hoses burst or became detached as a result of a flashback.
The pro blem in this type o f incident is that the gas con-
tinues to flow from the cylinder. Heat-sensitive cut-off
devices are available to stop the passag e of acetylene
after a flashback and are therefore recommended to pre-
vent escalation of the incident.
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F i re s e x p l o s i o n s a n d r e la t e d i n c i d e n t s a t w o r k in 1 99 2 -1 9 9 3: K . A . Ow e n s a n d J . A . H a z e ld e a n 2 9 5
The next largest group of accidents occurred during
battery charging, jump starting, and connection and dis-
connection of battery leads. Battery explosions usually
occur when hydroge n, evolved during charging, is
ignited by a spark. T he explosion usually results in injur-
ies from acid burns and fragments of the battery casing.
Most of the accidents could be avoided by following the
guidance contained in a HS E leaflet” on electric storage
batteries. The leaflet was produced in 1993 which w as
too late to have h ad any impact on the accident statistics
for 1992/1993.
Four incidents occurre d during the operation of
valves on oxygen cylinders. Ignition is usually caused
by adiabatic com pression, contamination with grease or
particle impact. Regular maintenance and prevention of
contamination are important to minimize such accidents.
The vulnerability of gas cylinders to fire engulfment
continues to be demonstrated. In 1992/1993, two fires
resulted in the bursting of oxygen cylinders and one
resulted in the bursting of an acetylene cylinder. In one
of these incidents, a fire in the engine of a rescue vehicle
spread rapidly to involve oxygen cylinders that were
carried on the vehicle.
One incident, which involved hydroge n, illustrates
that hazar ds can arise in unexpec ted situations. A wet
pick-up vacuum cleaner explo ded while it was being
used to clean u p aluminium swarf . It is though t that the
aluminium reacted with the cleaning fluid, which con-
tained hydrochloric acid, to produce hydrogen which
ignited The use of the cleaning fluid was subsequently
proh:>tted on the site and the matter was taken up with
th,: supplier.
Several incidents involved the release of significant
quantities of flammable gases during bulk storage , trans-
port and use. There is a need for adequ ate maintenance
of equipment and for prop er systems to ensure that main-
tenance and modifications are carried o ut safely and
without threatening the integrity of the plant or equip-
ment. The following incidents illustrate the conse-
quences when defects occur.
A leak occurred on a ship that was being loaded with
1100 tonnes o f propylene. The leak occurred when a
valve assembly blew out and left a 20 mm hole. It
took 11 hours to stop the leak, and 7-l 0 tonnes of
propylene wer e lost during this time. Fortunately the
gas did not ignite and there were no injuries.
Approximately 25 kg of ethylene exploded in a
high-pre ssure polyethylene plant. The investigation
showed that there had been a leak through holes at
the base of the reactor that had not been plugged fol-
lowing modification work. Two operators suffered
shock, and there was onsite damage to lightweight
structures and cladding and some breakage of glass
offsite.
In another incident, 14 tonnes of butadiene escape d
through a pressure relief valve on a cryogenic storage
vessel following the failure of a pressure switch
which allow ed excess nitrogen into the vessel. The
gas did not ignite but the incident was exacerbate d
because the control room wa s unmanned and the leak
was undetected for one hour.
4. During maintenance of a storag e sp here, air leaked
into the pneumatic supply line to a valve and caused
the valve to open. It was estimated that 1-2.5 tonnes
of vinyl chloride monom er wer e released. No injuries
were sustained.
Exothermic chemical reactions and
energetic substances
Incidents in this categor y include runaw ay chemical
reactions and unintended chemical interactions and
decomp ositions. They generally involve the release of
dangerou s chemicals but are not necessarily associated
with fires or explosions. The total number of incidents
n = 37) showed a decrease on the previous year’s fig-
ures. How ever, two of these incidents clearly fulfilled
the potential of certain chem ical reactions and decom po-
sitions to have serious consequenc es, in terms of both
human life (five fatalities) and environmental dama ge.
The five fatalities and one major injury all occurr ed
in one major incident at a large chemical company dur-
ing the cleaning out of a still. The still residues wer e
being heated , to aid removal, using a steam coil. The
temperature of the coil was not adequately controlled
and this lead to the violent decomp osition of the still
residues, which consisted of unstable nitro-compoun ds.
The incident was attributed to a change from the original
proce ss and the failure to plan and implement a safe sys-
tem of work. The process change lead to an increase in
the rate of deposition of thermally unstable materials. A
flame, in excess of 55 m long, issued from an access
hatch on the still, burnt throug h a control cabin in its
path, and impinged on an office block. Four people in
the control cabin wer e killed and one in the office block.
As a result o f this incident, compan ies are being advised
to review the design and location of control and other
buildings near chemical plants which process significant
quantities of flammable or toxic substances. The review
should be based on an assessment of the potential for
fire and explosion or toxic releases. The HSE have pub-
lished a report4 on this incident and the repor t high lights
further importan t lessons to prevent similar incidents.
Another major incident in this category occurre d at
a top-tier ‘major hazar d’ site. In this incident, the
decomp osition of a self-reactive substance led to an
intense fire in a storeroo m in the raw materials ware-
house. The fire spread rapidly to the remainder of the
warehouse and outdoor chemical drum storage area and
destroyed about 2500 tonnes of various chemicals.
Although none of the company employees were injured,
33 people , including three residents and 30 emergenc y
services personnel, were taken to hospital, where they
were primarily treated for smok e inhalation. This inci-
dent has been reported as a major accident to the Euro-
pean Comm ission, as required by the ‘Seveso D irective’,
and is the subject of a published HSE reporP. The HSE
report emphasizes the need to include storage areas in
the assessment of safety-related matters.
The need to carry out a risk assessment when
departing from accepted techniques for the synthesis of
chemicals is well illustrated by an incident that resulted
in laceration injuries to a postgra duate researc h student.
The student was synthesizing tertiary-butyl peroxyn itrate
by reacting tertiary-butyl hydro peroxid e with dinitrogen
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296 Fires, explosions and related incidents at work in 1992-7993: K. A. Owens and J. A. Hazeldean
pentoxide, and, for analytical reasons, used toluene
rather than carbon tetrachlorid e as a solvent. The nitrat-
ing solution probably reacted with the toluene to produ ce
trinitrotoluene which explod ed in a glass vial.
The importance of the correc t labelling of chemi-
cals was demo nstrated in another incident which caused
major chemical burn injuries. A plating technician
poured liquids from two separate drums, both labelled
96 sulfuric acid, into a beaker. One of the drums had
been mislabelled by the supplier and contained 50
caustic soda. Consequently, there was a violent reaction
between the concentrated acid and alkali, and corrosive
chemicals were ejected out of the beaker onto the tech-
nician, w ho was not wearing protective equipment.
Explosives
The number of incidents (n = 48) that occurr ed during
the manufacture, storage and carriage of explosives
increased slightly over th e previous year (n = 42). In
addition, there was one fatality. No significant trends
wer e discernible, although there was an increase in the
incidents associated with the manufacture of military
propellant.
In one accident, a man wa s killed and seven oth ers
who were present in the building were lucky to escape
injury when a fire occurred and consumed about 720 kg
of rocke t propellants. In the subsequent investigation,
serious shortcomings were found in the systems of work
and maintenance of plant. In particular, nitroglycerine
(NC) could evaporate from propellant as it was heated
in metal tanks and condense on the underside of the lids.
The lids were not being cleaned properly and therefo re
deposits of NG could accumulate, especially around the
hinges. In addition, some years previously, the material
of construction of the tanks had been changed from
wood to aluminium. No reasons for the change of
material or any assessment of any possible new risks
involved could be found. How ever, one of the conse-
quences was that metal-to-metal impact between the lid
and the tank body bec ame possible. Such an impact is
more likely to cause NG to explode than a wood-on-
wood impact. It is thought that the employee who died
was opening or closing the lid of a heated tank when a
deposit of NG exploded. The explosion ignited the pro-
pellant in the tank and the decomp osition spread to the
remainder of the propellant in the room and through
open doors, which should have been kept shut, to
adjacent work rooms where the other employees were
working.
In a second incident in the propellant sector, two
men suffered burns w hen they were cleaning a shredder
plate used in the preparation of comp osite propellant.
They w ere engulfed in a fireball from residual propel-
lant.
In one of the incidents in the pyrotechnic sector,
about 16.5 tonnes of fireworks were consumed in a fire
in a licensed magazine. The fire burned for more than
24 hours. The source of ignition was a spark from a
welding operation that was being undertaken by a con-
tractor to repair a weat her strip on the door . Initially, the
fire only involved firewo rks contained in a single box.
How ever, first-aid fire-fighting failed to extinguish the
fire, which spread to other boxes of rockets and other
fireworks. Fortunately, nobody suffered harm and the
fire caused only minor d amag e to the building and the
local environment. The fire was not able to spread to
adjacent buildings, which also contained explosives,
because of the separation of the buildings required by
the site licence.
Incidents also arose during the use of explosive and
pyrotechnic devices. A volunteer helper at a firework
display was badly injured when a display mortar
exploded whilst it was being handled after it had failed
to go off. Seven spectators at another display received
slight burns when a display mortar exploded at low level
after a misfire. Two further accidents occurred during
quarrying and tunnelling operations. Three men received
major injuries when they were clearing debris after a
blasting operation in a tunnel and their mechanical tools
detonate d an unexplod ed device. In the other incident, a
man was knocked unconscious when he was struck by
a stone during blasting at a quarry despite being outside
the declared danger zone. He was saved from worse
injuries by his safety helmet. O ther incidents reporte d as
being due to the use of explosives involved the disposal
by burning of a small quantity of surplus gunpo wder and
the laboratory preparation of a new substance.
Carriage of dangerous goods
These incidents are included under the appro priate
material category in
Table 2
but are discussed separately
here because of their relevance to specific legislation and
their potential to involve the general public in major
accidents.
The reported incidents (n = 89) associated with the
carriage and transport of dangero us substances resulted
in only one minor injury, altho ugh the accidents detailed
below could have had more severe consequences. These
incidents exclude road traffic accidents whe re the load
was not affected, as they are not reportable under
RIDD OR. Of these incidents, 60 occurred during loading
or unloading of the product and 29 occurred during tran-
sit. The majority of incidents involved spills or leakage
of produ ct, with fire occurring in only one of the
unloading incidents and in six of the transit incidents.
The injury occurr ed during a delivery of LPG as a result
of a cryogenic burn from contact with spilt produ ct
rather than from a fire or explosion.
Overfilling during th e loading of petrol tankers con-
tinues to account for the greatest proportion of incidents,
and, although the terminals are designed to cope with
such incidents, many could have been prevented by the
provision of overfill protection systems. Six tankers w ere
repor ted as having ov erturned during transit, and, of
these, one resulted in the spillage of 3 tonnes of petrol
onto the public highwa y. Fortunately there was no
ignition of the spilt produ ct. In another incident, a com-
partment containing petrol ruptured when the tanker col-
lided with a parked lorry, but, although the contents were
lost, again th ere w as no ignition of the produ ct. In con-
trast, at another accident involving the carriage of diesel
fuel, which is not classified by regulations as a danger-
ous substance for carriage, there was a large fire when
produ ct release d from an overturned tanker ignited.
A fire occurr ed during the unloading of a white
spirit-based resin for paint manufacture. The produ ct was
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normally dischar ged under air pressure from an on-board
comp ressor, but a number of difficulties were experi-
enced on this occasion and eventually a second com-
presso r on another tractor unit had to be used. During
the many attempts to move the product, white spirit
entered the compressor and was ignited by carbon par-
ticles. Flames spread to the tanker causing an explosion
and an ignition of the resin in the tanker. The fire was
brough t under control without any injuries but the tanker
hatches were projected 150 m by the explosion. This
incident demonstrates the need to assess the hazards
when deviations are made from standard procedures.
Four spills, which did not ignite, occu rred during
the off-loading of ships, with the most significant involv-
ing the loss of 19 tonnes of benzene. The incident was
caused by the regular and improper use of a spare con-
nection point valve to take a sample, and on this
occasion the valve w as not closed properly.
Another significant incident involved the loss of 2.5
tonnes of carbon disulfide, which , desp ite its low flash
point and auto-ignition tempe rature, did not ignite. In
this incident, an atmosp heric vent valve was inadver-
tently left closed du ring loading, causing a build-up of
pressure in the tanker. When the delivery pipe was dis-
connected to investigate the reason wh y the product was
not loading properly, the pressure caused the product to
be dischar ged out of the tanker and into the loading bay.
The produ ct was safely contained in the water-filled
bund and recovered.
In another incident, the driver of a tanker of LPG
swerved to avoid an articulated lorry that was coming
towards him in the centre of the road, and then attempted
to steer the tanker away from a bank at the side of the
road. The nearside wheels appeared to lose grip and the
tanker veered across the road and rolled onto its side.
When the tanker hit the road, the housing that encased
the valve assemblies was seriously damaged and gas was
released. The tanker was subsequently hit by a car but
fortunately the gas did not ignite.
Other incidents
These are incidents which are not appropriate to any of
the categor ies above. Twenty-four of these incidents
occurred as a result of people burning themselves with
cutting and welding equipment. The main lesson from
these incidents is that the use of suitable protective cloth-
ing, e.g. hand and arm protection, could reduce the num-
ber of injuries sustained by welde rs. Othe r incidents that
arose due to hot work are recorded in the most appropri-
ate material category . How ever, it is convenient to note
here that a total of 136 incidents occurr ed as a result of
hot work which either ignited other materials or caused
burns from the flame of a torch.
References
‘A Guide to the Reporting of Injuries, Diseases and Dangerous
Occurrences Regulations 1985’. HS R)23, HSE Books, Sudbury,
UK
‘Safe Handling of Combustible Dusts’, HS G)l03, HSE Books, Sud-
bury, UK, 1994
‘Electric Storage Batteries’, HSE Leaflet, IND G) 139L, HSE Books,
Sudbury, UK, 1994
The Fire at Hickson and Welch Limited’, HSE Books, Sudbury,
UK, 1994
‘The Fire at Allied Colloids Limited’, HSE Books, Sudbury, UK,
1994