Case Studies Handouts

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Hazardous and Safety Engineering GPE 412

Case Studies 1

Case Studies

Explosions and Fires in Chemical and

Petrochemical Plants

Contents

1. Bhopal Disaster (Sherif Murad)

2. Buncefield Fire (Ahmed Habib- Mohamed El Nahas)

3. Flixborough Explosion(Mohamed Awad - Mina Zarif)

4. Guadalajara disaster (Amr Elbadry- Khaled Habib)

5. Phillips Petroleum Chemical Plant Explosion and Fire (A.Hamdy)

6. Piper Alpha Explosion (A.El-shora- M.Sherif- A.FoadA.Thabet )

7. T2 laboratory Inc. Runaway Explosion (A.Shamaa- A.Harraz)

8. Chemical Explosion in Toulouse (Omar zanana- Hazem Essam)

9. Valero Propane Fire (Mina George- Josephine Ezzat)

10. Waste Fuel Oxidizer (Ehab Gamal- Mahmoud Abdel-Fatah)


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Case Studies 2

1.Bhopal Disaster During the night of December 23, 1984, large

amounts of water entered tank 610,

containing 42 tonnes of methyl isocyanate.

The resulting exothermic reaction increased

the temperature inside the tank to over 200 C

(392 F), raising the pressure to a level the

tank was not designed to withstand The

reaction sped up because of the presence of

iron in corroding non-stainless steel pipelines.

Factors leading to this huge gas leak include:

1-The use of hazardous chemicals (MIC) instead ofless dangerous ones

2-Failure of several safety systems (due to poormaintenance and regulations).

3-Safety systems being switched off to save money.The flare tower and the vent gas scrubber hadbeen out of service for 5 months before thedisaster.

4-Possible corroding material in pipelines.


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Case Studies 3

Handling of the disaster

Police are alerted. Residents of the area evacuate.

Isolation of the explosion took place but however

this was not efficient because it was so large.

Getting all the workers out and sending the

impaired ones to hospital . The first people

reached Hamidia hospital. Symptoms include

visual impairment and blindness, respiratory

difficulties, frothing at the mouth, and vomiting.

Precaution

Four manual back up system must beimplemented in all factories dealing with toxic

substance. The prevention of using corroding materials

must be diminished in pipe lines.

High maintenance and regulations arerequired for safety systems.

The prevention of using corroding materialsmust be diminished in pipe lines


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Case Studies 4

After treatment

Within weeks, the State Government establisheda number of hospitals, clinics and mobile units inthe gas-affected area.

When the factory was closed in 19851986,pipes, drums and tanks were cleaned and sold

The area around the plant was used as a dumping

area for hazardous chemicals. In order to provide safe drinking water to the

population around the UCC factory, there is ascheme for improvement of water supply.

Company Overview

The terminal was the fifth largest oil-products storage depot in the

United Kingdom.

Capacity of about 60,000,000 imperial gallons (272,765,400 l) of

fuel.

The terminal is owned by TOTAL UK Limited (60%) and Texaco 40%.

The HOSL is a major hub on the UK's oil pipeline network (UKOP)

with pipelines to Humberside and Merseyside .

2.Buncefield Fire


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Case Studies 5

Accident & Explosion Overview

Date : December 11th , 2005

Time : 06:01 UTC

Location : Hemel Hempstead,

Hertfordshire, England.

Casualties : 43 injuries & 2 serious injuries

In the early hours of Sunday 11th December 2005, there were a number of

explosions heard at the Buncefield Storage Depot.

The first and largest explosion occurred at 06:01 UTC near container

912. Further explosions followed which eventually overwhelmed 20 large

storage tanks.

Causes

Unleaded motor fuel was being pumped into storage tank 912, in the north west

corner of the site.

Safeguards on the tank failed and none of the staff on duty realized its capacity

had been reached.

An automatic high level safety switch should trigger an alarm if the tank reaches

its maximum capacity.

Automatic shutdown did not happen and when fuel continued to be pumped in,

it overflowed through roof vents.

The overflow from the tank led to the rapid formation of a rich fuel and air vapor


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Case Studies 6

How fire was spread

Fuel cascaded down the tank and formed a rich fuel/air mix, which

collected in the area surrounding the tank bounded by a low wall

designed to prevent leaked liquid spreading.

Between 5.45 am and 6 am the rate at which fuel was being pumped

into tank 912 gradually increased from 550 cubic meters (1,805 cubic

feet) an hour to around 890 cubic meters (2,920 cubic feet) an hour

At 6.15 am, with the vapor cloud cloaked over a large area and reaching

buildings next to the site, the first explosion occurred.

Fire Handling Artificial pool with water pumped from nearby lake used to create foam and

water mix.

Fire engines, foam cannon and fixed fire-fighting units already at depot used to

pump mixture onto blaze.

Fire brigade water curtain protected intact tanks on eastern part of site.

The bunds around each tank fail to contain all the contaminated liquid run-off - a

mix of firefighting water and escaped fuel.

Investigations find "large amounts" of run-off escaped from the site,

contaminating ground and surface water.


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Case Studies 7

Recommendations

Tank operating practices, staffing levels and systems, must provide effective

safety margins to prevent a release.

Joints in bunds must be capable of resisting fire. Existing bunds should be

modified to meet this requirement.

Tertiary containment measures must be capable of preventing the

uncontrolled escape of firewater and other products to the environment.

Effective shift/crew handover communication arrangements must be in place

to ensure the safe continuation of operations.

Event The Flixborough disaster was an explosion at a chemical plant

used for production of Nylon on 1st June 1974.

It killed 28 people and seriously injured 26. 8 of the Dead

Bodies were never Found

A temporary by-pass pipe Jack-knifed and failed under

thermal expansion stress.

Due to Failure,40 of 120 ton of cyclohexane(raw material)

escaped from the reactors forming a vapor cloud.

Within two minutes, the vapor cloud ignited and Vapor Cloud

Explosion (VCE) took place (35 tons TNT equiv).

3.Flixborough


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Case Studies 8

causes Two months before the incident, R-5 was found to be leaking. A 6

ft. long crack had developed

A water stream was directed to the crack to cool and quench the

small cyclohexane leak. The cooling water contained nitrates which encourage stress

corrosion of certain carbon steels.

The Reactor was Removed for Maintenance & To Keep The Process

Operating, a Dog-leg bypass Pipe Was Used

Thy bypass Pipe was Poorly designed and it Caused The Leakage

that led to Explosion


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Case Studies 9

Handling Controlling (&not Extinguishing) fire lasted 3 days and 250 firemen

were employed at the height of operations on the1st of June.

The last fires in some storage vessels were allowed to burn under

controlled conditions and were extinguished on the 13th of June

Plant was declared safe 13 days after the accident and it was a

mound of ash and fused metal (i.e Totally destroyed)

.

After Explosion


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Case Studies 10

Future prevention1. The storage of hazardous material to be kept to aminimum

2. Better Plant Layout(To avoid the domino effect)

3. Ensure they employment of qualified and experienced

staff to make critical decisions.

4. Modifications to be designed, constructed, tested and

maintained to the same standards

5. Sufficient inerting material on site. ( Using N2 for Putting

Out Fires )

Location ,problem identification & humaninvestigation prior to the explosion

Mexicos historic 475-year-old Guadalajara, the capital of Jalisco state, islocated on a dry and arid mile-high plain 300 miles west of Mexico City.

The heart of downtown Guadalajara began to notice a persistent odor

reminiscent of gasoline and other chemical odors emanating from their

toilets and drains

Official members of the state measured explosivity in the separating

tank and discharge reading area, but found nothing [unusual]. [Explosivity

readings are based on the proportion of gaseous vapor in the air trapped

in the sewer pipes.] SIAPA took samples of water at the Pemex plant

outlets and made no mention of having found any irregularities

4.Guadalajara disaster


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Case Studies 11

Samples took from in between Rio Atotonilco and Tototlan avenues.

On Doctor R. Michel Avenue ,concentrations were measured up to

100% explosivity were found. The suspected solvent appeared to be

coming from the La Central S.A. oil processing plantIt was reported

that hexane was stored at this plant.

At least one radio station had deployed personnel to the area

endangered by the gasoline spill hours prior to the explosion.

The Red Cross treated a police officer, a fireman, and a worker from

[Pemex] for gasoline inhalation

Cause(s) of the sewer explosion

New water pipes, made of zinc-coated iron, were built too close to anexisting steel gasoline pipeline. The underground humidity caused thesemetals to create an electrolytic reaction, which eventually caused themetal to corrode, creating a hole in the pipelines that caused gasoline toleak into the ground and into the main sewer pipe.

The sewer pipe had been recently rebuilt into a U-shape so that the citycould expand their underground railway system. Usually sewers are builtin a slope so that gravity helps move waste along. In order to get the U-shape to work, an inverted siphon was placed so that fluids could bepushed against gravity. The design was flawed, however. While liquidswere successfully pumped through, gases were not, and gasoline fumeswould build up.

A small spark was all that was needed to ignite the dangerous gases


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Case Studies 12

Lessons to be taught

Any industrial waste (specially that from a petrochemical or oil industry)should be pipelined away in a private sewage away from that of domesticones

Sewage line should be away from the city, incase of any explosions, nohuman sole loss will occur

Parts of pipes(specially u tubes)should be bought from a trusted company

Any activity in a company or factory should be stopped immediately incaseof feeling of any leakage

Official regulations should be respected

The hole in pipe that leaked


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Case Studies 13

Explosion map

The IncidentTime 1:42pm 23th of October, 1989.

A small explosion occurred in Gas plant No. 1, followed a short while later by a series

of 3 large explosions and a major fire.

Two employees were killed and several received serious injuries.

Because of the risk of further explosions, the entire site was shut down and people

living within 5 kilometers of the plant were evacuated.

Site fire teams, a local air force fire crew, and the public fire brigade fought the fire for

2 days before it was finally brought under control.

5.Phillips Petroleum

Explosion and Fire


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Case Studies 14

The cause

The immediate cause of the first explosion was the catastrophic failure of a heat

exchanger in the absorption oil circuit.

Adsorption oil is a light hydrocarbon oil, chilled to -20 C which is used to remove

ethane, propane and butane from the natural gas to produce LPG.

The adsorption oil and natural gas were contacted in an absorber tower, then the oil,

rich with absorbed gases, was fed to a de-ethaniser columnand a fractionationcolumn to flash of the gases.

Why did it happen ?

A Royal Commission of Inquiry was established to investigate the incident, and after 8

months produced the following findings.

No HAZOP study had ever been carried out on Gas Plant No. 1. If it had been, the

hazards associated with a loss of absorption oil flow could have been identified,

and appropriate operating procedures developed.

The personnel charged with responsibility for operating the plant did not have the

necessary knowledge to deal with the situation, and steps taken to resolve the

problem were inappropriate.


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Case Studies 15

25 hours after the initial explosion

Lessons Learned

Having good Risk Management systems and procedures is important.

Making sure that they are being used correctly is even more important.

Training of employees in understanding the hazards of the processes they are

operating is a critical element of running a safe business.

Application of effective Hazard Analysis techniques could have averted the disaster

and prevented unnecessary loss of life.


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Case Studies 16

INTRODUCTIONThe Piper Alpha was a North Sea Oil Production platform operated by

Occidental Petroleum(Caledonia)Ltd.

The platform began production in 1976,first as an oil platform and

then later converted to gas production.

An explosion and resulting fire destroyed it on July 6,1988, killing 167

men.

To date it is the worlds worst offshore oil disaster in terms of lives lost

and impact to industry.

6.Piper Alpha ACCIDENT

Timeline of the incident

Two pumps on the platform, A and B, displaced the condensate

for transport to the coast

On the morning of July 6, Pump A's pressure safety valve was

removed for routine maintenance and The open Condensate

pipe was temporarily sealed with a blind flange(flat metal disc).

The on-duty engineer filled out a permit which stated that Pump

A was not ready and must not be switched on under any

circumstances.


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Case Studies 17

As he found the on-duty custodian busy, the engineer neglectedto inform him of the condition of Pump A.

9:45 p.m. Pump B stopped suddenly and could not be restarted.pump A was activated.

9:55 p.m. an overpressure was produced which the metal discdid not withstand, Gas audibly leaked out at high pressure. andbefore anyone could act, the gas ignited and exploded, firewallswere set to withstand fire not explosions, so it was easilybroken.

10:04 p.m. The control room was abandoned. Shut down wasn'tactivated

10:20 p.m. Tartan's gas line melted and burst. releasing 15-30

tones of gas every second, which immediately ignited. A massivefireball 150 meters in diameter engulfed Piper Alpha

12:45 a.m., July 7 The entire platform had gone. Module (A) wasall that remained of Piper Alpha.

AftermathThe main problem was that most of the personnel who had the

authority to order evacuation had been killed when the first explosion

destroyed the control room.

Another contributing factor was that the nearby platforms Tartan and

Claymore continued to pump gas and oil to Piper Alpha until itspipeline ruptured in the heat in the second explosion.

By the time civil and military rescue helicopters reached the scene,

flames over one hundred meters in height and visible as far as one

hundred km away prevented safe approach

Total insured loss was about 1.7 billion (US$ 3.4 billion). To date it is

the world's worst offshore oil disaster in terms both of lives lost and

impact to industry167 men were killed , with only 59 survivors


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Case Studies 18

The term runaway reaction is often improperly used to refer to any uncontrolled chemical

reaction.

As properly used, it refers to loss of control of a kinetically limited, exothermic reaction that

proceeds at a stable, controlled rate under normal conditions and that includes adequate

removal of the heat of reaction.

Methylcyclopentadienyl manganese tricarbonyl (MCMT) is used as an octane-increasing

gasoline additive.

T2 manufactured MCMT in three steps sequentially within a single process batch reactor. The

first step of the reaction required heating to initiate the reaction. After that, all three steps

were exothermic (heat-producing) and required cooling.

Heating and Cooling system

A heating system circulated hot oil through 3-inch piping installed around the inside of the

reactor.

A cooling jacket covered the lower of the reactor. A pipe from the city water system

connected to the bottom of the jacket. Water was injected into the jacket and allowed to

boil steam from the boiling water vented to atmosphere.

7.T2 Laboratories Inc.

Runaway Explosion

Process Description

First, reactants are charged through the top of the

reactor, Then the operators began to adjust the

conditions of the reactor at 50 psig and hot oil

temperature control at 360oF.

At a reaction temperature of about 300F, theprocess operator turned off the hot oil system; heat

generated by the metalation reaction continued to

raise the mixture temperature.

At a temperature of about 360F, the process

operator initiated the control system cooling

program.

The operating procedures used at the time of the

incident included no emergency instructions for

loss of cooling.


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Case Studies 19

Incident Description

On December 19, T2 was producing its 175th batch of (MCMT). At 1:23 pm,

the process operator had an outside operator call the owners to report a

cooling problem and request they return to the site. Upon their return, one

of the two owners went to the control room to assist.

A few minutes later, the reactor burst and its contents exploded, killing the

owner and process operator who were in the control room and two outside

operators who were exiting the reactor area.

The energy release of this explosion to be equivalent to 1,400 pounds of

TNT. The blast was felt 15 miles away in downtown Jacksonville (FL).

The blast occurred due to a runaway chemical reaction that generated hightemperature and pressure in the reactor.

Emergency Responses

Within 10 minutes of the incident, two hazardous

materials stations dispatched.

The Jacksonville Fire and Rescue Department completeda hazard analysis using (MSDSs) from the T2 website.

The incident commander (IC) ordered a half-mile

evacuation radius, The IC ordered full personal protective

equipment.

The Jacksonville Planning and Development Department

surveyed surrounding buildings and condemned unsafe

structures, including the four businesses closest to T2.


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Case Studies 20

Causes

The CSB found that a runaway exothermic reaction occurred during thefirst (metalation) step of the MCMT process.

1. The route cause was that T2 did not recognize the runaway reactionhazard associated with the MCMT it was producing.

2. The cooling system employed by T2 was susceptible to single-pointfailures due to a lack of design redundancy (during scale-up).Water supply valve failing closed or partially closed.

Water drain valve failing open or partially open.

Failure of the pneumatic system used to open and close the water valves.

Blockage or partial blockage in the water supply piping.

Faulty temperature indication.

Mineral scale buildup in the cooling system.

3. The MCMT reactor vessel relief system was incapable of relieving thepressure from the runaway reaction.

Future Precautions1. Frequent periodic maintenance for all equipments and utility must be scheduled, especially

for cooling systems and fire fighting units including piping systems, pumping, valves,housekeeping.etc.

2. Operating Procedures used must include emergency instructions for loss of cooling; whendealing with exothermic reactions that are ready to be exothermic runaway reactions.

3. A secondary (backup) source of water stored on site (for cooling) must be immediately

available to process operator in emergency.

4. Overpressure Relief Device and Rupture disks must be properly designed to prevent runawayreactions in their initial stages.

5. Cooling Requirements in a small-scale process do not usually accurately indicate the amountof cooling needed in full scale reactor. So take into consideration the effect of scaling on theprocess hazards as well as the yield.

6. Chemical Engineers and Chemists must be aware of Process Hazards as well as Processchemistry.


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Case Studies 21

What Happened?

On Friday, September 21. the French town of Toulouse was

rocked by a devastating chemical explosion. Two production

halls of the AZF fertilizer factory, a literally flew into the air.

Initial reports spoke of 29 dead and. A total of 2,400 were

injured,

Two chimneys collapsed and all that remained from the two

halls at the centre of the explosion was a crater 10 meters

deep and 50 meters wide. The pressure from the explosion

was sufficient to send automobiles flying into the air, causing

a nearby shopping centre to collapse

8.Chemical Explosion in Toulous

Causes: For years the AZF petrochemical factory has been regarded as a

ticking time bomb..

Reports last year emphasized the danger of an explosion

Experts for factory safety had already received alarming

information lst week of leaks in the plant, through which liquid

ammonia gas could escape.

Three thousand tons of ammonium nitrate were stored at the

plant. It is well known that ammonium nitrate can detonate

when it is overheated or brought into contact with organic

material such as oil or coal.


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Case Studies 22

How did they deal with it:

As a huge orange colored cloud of gas, smelling of ammonia,

moved towards the city centre for 3 kms. Gas masks were

distributed in the town centre and the metro system in

Toulouse was evacuated because of the spread of gas. The city

council issued a warning that people should stay indoors and

close their windowsa problem for those whose windows

had already been shattered.

The airport at Toulouse-Blagnac and the main railway station

were closed and 90 schools in the area evacuated. Over radio,

inhabitants were called upon to refrain from drinking tap

water and use as little water as possible.

Hazards of Fertilizers Industry:

The fertilizer plants, particularly those manufacturing ammonia

are amongst the most complex plants in the chemical industry.

The process involve handling of various hazardous substances

The operating conditions are also severe and affect the safety ofequipment, personnel involved and the environment.


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Case Studies 23

How to Prevent Further Accidents: Many process vessels operate under pressure or vacuum.

These vessels are to be examined regularly.

Valves are used for isolating the piece of equipment in case of

maintenance work but these are liable to leak, valves alone

should not be used as the means of isolation.

The instrumentation in the process industry is vital and a key

factor in the safe operation. The logic followed in theinstrumentation coupled with the trips and interlocks should

have the intrinsically safe features.

9.Valero Propane Fire

Fire From IceOn February 16,2007, a liquid propane

released from a cracked control stationcaused massive fire in propane

deasphalting unit (PDA) caused injuries of

three employees and constructor. The fire

caused extensive equipment damage and

shutdown and evacuation of the refinery.


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Case Studies 24

Process description:

The PDA unit recovered fuel feedstock and paving-grade asphaltfrom the heavy bottoms produced in the refinerys vacuumcrude oil fractionator. In the McKee PDA process, twoliquid/liquid extraction towers used liquid propane as a solventto extract gas oil from the pitch under approximately 500pounds per square inch (psi)pressure. The recovered gas oil wasprocessed into gasoline in another refinery unit. The asphaltproduced was sold for use in paving materials.

The relatively dense pitch entered an upper section of the extractorand flowed to the bottom of the tower. Less dense liquid washpropane entered a lower section and flowed to the top of theextractor. Internal structures in the tower promoted effectivecontact between the two streams. DeAsphalted Gas Oil (DAGO)extracted from the pitch flowed out of the top of the tower withmuch of the propane. This liquid flowed through a series of flashdrums8 to remove propane from the gas oil. The DAGO was sentelsewhere in the refinery for processing.

Incident Sequence

In this incident, water settling out of a propane streamlikely leaked through a 10 inlet block valve andaccumulated in the low point formed by a control

station. The control station was connected to theprocess, but had not been used for approximately 15years. A period of cold weather likely froze the water,fracturing the pipe elbow upstream of the controlvalve. Warmer weather then melted the ice, resultingin a release of highly pressurized liquid propanethrough the fractured elbow.


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Case Studies 25

Near-Miss Events:

Butane Sphere Heat Exposure

One-ton Chlorine Containers

CSB Recommendation:

Replace chlorine with safer

biocide for cooling water.

Improve hazard analysis in process.Establish of freeze protection.

Periodic inspection of dead legs in frequentlyused in process (if possible isolate it with blindisolator to prevent linkage).

Management of change reviews.


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Case Studies 26

Accident & immediate treatment

On March 26, 1997, at about 3 p.m. an explosion occurred within a fuel blending

tank at Chief Supply Corporation (Chief), in Haskell, Oklahoma. One worker was

killed and two others injured.

Several smaller explosions occurred as over 1,000 drums containing cleaning

solvents, assorted acids, bases, metal sludge, and four 5,000-gallon tanks

holding waste fuels became involved in the fire

A highway next to the site was closed

An area 1.5 miles north and one mile east of the facility in the path of a largesmoke plume were evacuated.

A solid stream of water should never be used to extinguish this type of fire

because it can cause the fuel to scatter, spreading the flames. The most effective

way to extinguish a liquid or gas fueled fire is by inhibiting the chemical chain

reaction of the fire, which is done by dry chemical and haloalkane extinguishing

agents.

10.Waste Fuel Oxidizer

Roots of the accident Chief instituted a practice of adding oxidizers to fuel blend mixture.

Chief blended wastes in two 1,000 gallon vertical tanks called dispersers

The disperser involved in the incident was equipped with a mixer, the mixer

was not supposed to be started until the liquid level reaches half of the tank

capacity.

The disperser was open to the atmosphere; no nitrogen or other inert gas

blanketing was used to suppress flammable vapors.


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Case Studies 27

Oxidizers were to be added to the fuel blend only after ensuring that the

disperser was 3/4 full and the mixer running, according to an unwritten

procedure used by lab personnel.

two workers were on top of the disperser starting a new batch and only four

drums of liquid had been added to the tank when a lab employee at the top of

the tank added one bucket of chlorates, one bucket of perchlorates, and one

bucket of nitrites to the disperser.

An explosion and fireball. The fireball fatally engulfed the employee who was

pouring the drums and started a large fire in the building.

Causes of the explosion

Strong oxidizers generally are considered to be incompatible with many organic

substances because of the potential for dangerous reactions( fire, explosion, or

violent reaction) .

Only four drums had been dumped into the previously empty disperser, Thisallowed the solid oxidizers to pile up at the bottom of the tank, in direct contact

with each other and with flammable solvent liquid and vapor.

Ethanol in the fuel blending mixture reacted with the perchlorate salt , explosive

ethyl perchlorate could have been formed.


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Precautions

Facilities need to conduct the necessary information searches or laboratory tests

to ensure that all reaction mechanisms are known and documented.

facilities need to ensure that process equipment, controls, and procedures are

designed, installed, and maintained to safely operate the process.

Standard Operating Procedures (SOPs) are essential to safe operations. Facilities

should establish a system to develop and maintain written SOPs.

Employees must be properly trained in the processes they work on,using theSOPs for that process or job tasks.

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