Fires, Explosions and Related Incidents at Work 1992 1993

7/21/2019 Fires, Explosions and Related Incidents at Work 1992 1993

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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



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



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



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.



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



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



Fires, explosions and related incidents at work in 7992-7993: K. A. Owens and J. A. Hazeldean 297

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

Documents

Fires, Explosions and Related Incidents at Work 1992 1993