1

FIRE AND EXPLOSION:

HAZARDS OF BENZOYL PEROXIDE

CATALYST SYSTEMS, INC.

Gnadenhutten, Ohio

January 2, 2003

Introduction

This Case Study

describes a benzoyl

peroxide (BPO)

explosion and fire that

occurred at the Catalyst

Systems, Inc., production facility in

Gnadenhutten, Ohio. At

11:55 am on January 2,

2003, a vacuum dryer

holding nearly 200

pounds of BPO

exploded. Employees

were drying granular 75

percent BPO to make

98 percent BPO when

the material explosively

decomposed. One

employee was slightly

injured, and the BPO

processing building was

significantly damaged. KEY ISSUES:

 Hazards of Benzoyl Peroxide

 Reactive Chemical Hazards

 Process Safety Management

Systems

NO. 2003-03-C-OH

October 2003

Case Study

U.S. CHEMICAL SAFETY AND HAZARD INVESTIGATION BOARD

INSIDE . . .

BPO Properties 2

Catalyst Systems Operations 5

Incident 8

Initiating Scenarios 11

Standards and Guidance 13

Chemical Process Safety 14

Regulatory Analysis 19

Conclusion 20

Annotated References 21
2

CSB Case Studies summarize

incident investigation data and

present conclusions based on

CSB analyses. They do not

discuss root and contributing

causes or make safety

recommendations—unlike the

more comprehensive CSB

Investigation Reports.

U.S. Chemical Safety and

Hazard Investigation

Board

Office of Investigations and

Safety Programs

2175 K Street NW

Suite 400

Washington, DC 20037-1848

202-261-7600

www.csb.gov

Organic peroxides may be

thermally unstable and

sensitive to shock, impact, and

friction. A peroxide is any compound with an oxygen-to-oxygen

bond1 (-O-O-) in its chemical

structure. An organic peroxide has

an organic (or carbon-containing)

molecule attached to at least one

side of the oxygen-to-oxygen bond.

The thermal instability of organic

peroxides is caused by the weak

oxygen-to-oxygen bond, leading to a

tendency for spontaneous change

toward more stable substances.

Although their potential energy is

low compared to that of conventional explosives, these compounds

can be very destructive when stored

energy is released. The degree of

hazard is reduced by dilution, either

in a suitable solvent or in water.

The National Fire Protection Association (NFPA)2 divides organic

peroxides and their solutions into

hazard classes based on reactivity

and destructive effects. Table 1

lists the NFPA hazard classifications for selected concentrations of

BPO.

1.0

Benzoyl Peroxide Properties and

Applications

BPO—also known as “dibenzoyl

peroxide”—is represented by the

chemical formula (C6H5CO)2O2. Its

chemical structural formula shows

the unstable oxygen-to-oxygen

bond:

1

The oxygen-to-oxygen bond is also referred

to as a peroxy bond.

2

NFPA Standard 432, Code for the Storage

of Organic Peroxide Formulations, 2002.

Table 2 lists the characteristic

properties of BPO, which is available in several forms. Dry BPO is

a granular solid and usually contains less than 5 percent water. Wet

BPO is also a granular solid; common formulations contain between

66 to 85 percent BPO and 34 to 15

percent water. BPO pastes usually

contain 50 percent BPO, with the

remainder being water and some

type of plasticizer.

Ninety-eight percent granular BPO

is classified as a strong oxidizer

susceptible to explosive decomposition3 by excessive heat, friction, or

sudden shock; NFPA lists it as a

Class I organic peroxide. In contrast, 50 percent BPO paste is

listed as a Class IV organic

peroxide.

3

Decomposition is a chemical reaction that

leads to the breakdown of a chemical into

smaller molecules or elements, often with

liberation of energy and gases.
3

Table 1

NFPA Peroxide Classifications

Peroxide BPO

Hazard Class Characteristics Concentrations

I Capable of deflagration but not 98% granular

detonation (a)

II Burns very rapidly, presents a 78% granular

moderate reactivity hazard

III Burns in the same manner 75% granular

as ordinary combustibles,

presents a minimal reactivity hazard

IV Burns with less intensity 50% paste

than ordinary combustibles or

does not sustain combustion,

presents no reactivity hazard

(a) A deflagration is a reaction that propagates at less than the speed of sound and, with

confinement, can result in an explosion. By comparison, a detonation is a reaction that

propagates at greater than the speed of sound and results in an explosion regardless

of confinement. Detonations have a much greater destructive potential than

deflagrations.

Table 2

Characteristic Properties of 98 Percent Granular BPO

SOURCE: NIOSH, 1977.

Appearance White rhombic crystalline solid

Stability Becomes unstable and may spontaneously decompose if

exposed to temperatures of 75 to 80 degrees Celsius (°C)

for prolonged periods; decomposes explosively if

subjected to friction or sudden shock

Decomposition Dense white smoke consisting of benzoic acid, phenyl

products benzoate, terphenyls, biphenyls, benzene, and carbon

dioxide

Reactivity Reacts violently with various organic and inorganic acids,

amines, alcohols, metallic naphthanates, polymerization

accelerators, and other chemicals that are easily oxidized
4

At Catalyst Systems, BPO is manufactured by reacting benzoyl

chloride, sodium hydroxide, and

hydrogen peroxide. Because the

reactions between these chemicals

are exothermic (i.e., generating

heat), crushed ice is added for cooling. A centrifuge removes excess

water to obtain the desired concentration, normally 50 to 78 percent

BPO.

BPO is used in a number of

industrial processes, particularly

in manufacturing plastics. Some

common applications are dental

resin cement, automobile body

putty, mine roof bolt systems,

flour and cheese bleaches, acne

medication, and silicone rubber

and polyvinyl chloride (PVC)

manufacturing.

What is a reactive incident? What is a reactive incident?

A reactive incident is a sudden event involving an uncontrolled

chemical reaction—with significant increases in temperature, pressure, or gas evolution—that has caused, or has the potential to cause,

serious harm to people, property, or the environment. The January

2003 incident at Catalyst Systems was a reactive incident.

In September 2002, CSB completed its major hazard investigation,

entitled Improving Reactive Hazard Management. This investigation concluded that better management of reactive hazards is

necessary to prevent reactive incidents.
5

Catalyst Systems is a wholly

owned subsidiary of U.S.

Chemical and Plastics, Inc., a

privately owned corporation headquartered in Massillon, Ohio, which

is a subsidiary company of Alco

Industries. U.S. Chemical and Plastics formulates and manufactures

repair, appearance, and maintenance products for the marine and

aviation industries and the automobile aftermarket. These products

include a variety of putties, fillers,

waxes, compounds, paints, coatings,

catalysts, and adhesives.

Twenty-five people are employed at

the facility in Gnadenhutten, Ohio.

A portion of this staff supports

Catalyst Systems operations, while

the remainder is dedicated to other

activities of U.S. Chemicals and

Plastics.

The plant site has two buildings

(Figure 1). Building 1 contains

offices, a quality control laboratory,

a shop, storage areas, and a paste

filling and packaging area. Building

2 was constructed in 1977 and is

used solely for BPO production. It

is divided into a manufacturing area

and a paste room.

In the manufacturing area, raw

materials are added to a reactor to

produce 20 percent BPO—which

is then sent through a centrifuge,

where water is removed. The

resulting product is 78 percent

granular BPO. Some of this

material is packaged in drums for

2.0

Catalyst Systems Operations

sale or further processing. In the

paste room, the 78 percent BPO, a

plasticizer, water, pigments, and

surfactants are mixed to create 50

percent BPO paste.

A 98 percent granular BPO product is also made in the paste room

by drying batches of purchased 75

percent granular BPO using a

spherical rotating vacuum dryer.

The 98 percent product is packaged

into 1-pound bags.

Catalyst Systems began producing

98 percent granular BPO 5 years

ago for the rubber, marine, and

printed circuit board industries.

This product was initially manufactured by air-drying 75 or 78 percent BPO granular products in

open metal pans in an oven over

several days. Because the process

Figure 1

Catalyst Systems, Inc., plant site

Building 2 Building 1

Catalyst Systems

began producing

98 percent

granular BPO

5 years ago for

the rubber, marine,

and printed circuit

board industries.


6

was both time consuming and subject to quality problems (i.e., the

metal pans rusted and contaminated

the finished product), Catalyst

Systems determined that vacuum

drying was more economical and

maintained the required quality

control.4

In June 2001, Catalyst Systems

purchased a used double-cone

vacuum dryer, which was jacketed

and glass-lined (Figure 2). Maintenance personnel installed the

equipment and placed it in the

northwest corner of the paste room

(Figure 3).

The vacuum dryer was loaded

through a feed port with 200 pounds

of 75 percent BPO. Hot water (approximately 82°C) was circulated

through the dryer’s jacket to indirectly heat the BPO. The dryer

rotated slowly, causing the BPO to

tumble and evenly heat, minimizing

the production of hot spots.

The atmosphere in the dryer was

placed under vacuum. As the BPO

was heated, the vacuum system

pulled air and water vapor from inside the dryer through a polypropylene bag filter, then a separator, and

4

When a system is dried under vacuum, the

temperature at which water evaporates is

lower—which allows the material to be dried

at a lower and usually safer temperature.

Figure 2

Catalyst Systems vacuum drying system

(8.7-ft3 working capacity dryer and associated piping/equipment)

Separator

Vacuum line

Hot water

In Out

V3

V1 V2

V1 = fail closed

V2 = fail closed

V3 = fail open

Drain Vacuum

pump

Polypropylene

bag filter

Temperature probe

Unloading port with

butterfly valve

Automatic

Valves

Feed port

Temperature

controller

In June 2001,

Catalyst Systems

purchased a used

double-cone

vacuum dryer,

which was

jacketed and

glass-lined.


7

finally to a water suction vacuum

pump.

Hot water from the building’s heating system circulated through the

dryer’s jacket. As shown in Figure

2, there were three automatic

valves in the hot water piping.

When operating normally, valves V1

and V2 are open and V3 is closed.

A temperature control system used

a probe located inside the vacuum

dryer to determine when to open

and close the hot water valves.

When the thermocouple reached

42°C,5 the inlet and outlet valves on

the jacket lines closed and the bypass line opened, which stopped hot

water from circulating through the

jacket.

A typical batch took 2 to 2.5 working days to dry from 75 to 98 percent BPO. The drying system was

started in the morning and ran until

about 2:00 pm, when the hot water

was shut off; however, the dryer

continued to rotate under vacuum

until 3:30 pm, when the entire system was shut down for the evening.

The same procedure was followed

on the second day. On the morning

of the third day, the cover was

removed and a sample taken for

analysis. If the concentration was

at 98 percent, the dryer was unloaded; otherwise, the BPO was

subjected to additional heating

cycles.

5

Employees interviewed stated that the temperature was 42°C. CSB was unable to independently verify this temperature because of

damage following the explosion.

 Building 2 layout

Figure 3

The 98 percent BPO was emptied

through the bottom butterfly valve

discharge opening into fiber drums.

BPO from the drums was then

packaged in 1-pound plastic bags—

20 bags to a box—for shipping.

The dryer was cleaned after every

second batch by rinsing with water

and allowing it to air-dry with the

doors open.

BPO

Manufacturing

Overhead

door

Lunch table

BPO

dryer

Exit

Exit

Exit

Overhead

door

Paste

equipment

Paste

Room

120 ft

60 ft

N
8

3.1

Pre-Incident Activities

On Friday morning, December 27—6 days before the

incident—Catalyst Systems employees began normal procedures to

prepare a batch of 98 percent BPO.

The vacuum dryer was loaded with

200 pounds of granular 75 percent

BPO and started. As per practice,

hot water to the dryer was shut off

at about 2:00 pm to allow the material to cool. At approximately

3:30 pm, the entire drying system

was shut down for the day. Because

the plant did not operate over the

weekend, the drying system remained off and sealed on Saturday

and Sunday.

On Monday morning, December 30,

operators followed normal procedure to restart the drying system.

The drying process described above

was repeated. On the following 2

days—plant holidays—the drying

system was not operated, and the

dryer remained sealed.

Plant personnel returned to work on

January 2, 2003. Because it typically took 2.5 days to dry 75 percent

material to 98 percent, operators

anticipated that the batch would be

ready after completing one drying

cycle in the morning. The dryer

was opened and sampled at approximately 8:00 am. The plant laboratory determined the concentration

3.0

Incident Description

to be 97 percent BPO, which was

within the range expected. The

drying system was started.

At about 8:50 am, operators heard

the hot water valve close, indicating

that the temperature inside the

dryer had reached 42°C. They

then closed a manual valve on the

hot water line to ensure that the

hot water did not automatically restart. The dryer continued to

rotate under vacuum to allow the

material to cool. Operators

planned to resample the material

after lunch to determine if it had

reached the desired concentration

of 98 percent.

3.2

The Explosion

At 11:30 am on January 2, the

operators took their lunch break at

a table located in the Building 2

paste room (Figure 3). One of the

operators noted an unusual noise

coming from the vacuum pump,

which he planned to check after

lunch. At 11:55 am, the vacuum

dryer suddenly exploded while the

operators were still seated at the

lunch table.

The employees described thick

black smoke with rolling flames and

a loud boom. They quickly exited

the building and went to the

designated evacuation area. One

Because it

typically took

2.5 days to dry

75 percent

material to

98 percent,

operators

anticipated that the

batch would be

ready after

completing one

drying cycle [on]

the morning [of

January 2].

At 11:55 am, the

vacuum dryer

suddenly

exploded . . .




9

The dryer was

propelled

through the

corrugated steel

dividing wall . . .

and through

several pallets

of filled fiber

drums.



of the employees received a minor

puncture wound on his shoulder,

possibly from flying debris.

The automatic building sprinkler

system activated. The Gnadenhutten Police and Fire Departments

responded immediately; they extinguished a small fire in the southwest

corner of the paste room. The

Tuscarawas County Hazardous

Materials Team and several other

nearby fire departments were

called to assist.

Following the advice on the material

safety data sheet (MSDS) for BPO,

the fire department continued to

put water on the building and its

contents. Runoff water leaving the

property was tested at several

locations and determined to be nonhazardous.6

Figures 4, 5, and 6 show some of the

damage caused by the explosion.

The dryer was propelled through

the corrugated steel dividing wall,

shown in Figure 4, and through several pallets of filled fiber drums

(Figure 5). It landed approximately

35 feet from its original location.

The siding and siding supports on

the south side of the building, as

well as the dividing wall, were extensively damaged (Figure 6). The

building’s primary structural

frames were intact, though the roof

decking and supports in the southwest corner were badly damaged.

6

Tests were performed to determine pH as

well as the presence of oxidizers, fluoride,

petroleum products, organic solvents, iodine,

bromine, and chlorine.

Figure 4

Damage to Catalyst Systems BPO production building

BPO dryer base
10

Filled fiber drums damaged by dryer

Figure 5

BPO dryer vessel

Figure 6

Building damage, southwest side
11

BPO may

decompose

violently when

exposed to

excessive heat,

shock, or friction.



The Catalyst Systems BPO

drying system had no indicators or recording devices for

temperature or pressure; it was

primarily manually controlled.

Because the drying system was

extensively damaged and there

was little recorded information,

it was not possible to determine

exactly what initiated the explosion. However, CSB identified

several potential scenarios by

examining and testing physical

evidence, interviewing employees, and reviewing system

documentation.

BPO may decompose violently

when exposed to excessive heat,

shock, or friction. Contaminants

may initiate the decomposition

reaction, which produces a large

volume of gas. Each of these

hazardous conditions was potentially present in the BPO drying

system.

The drying system was designed

to use 82°C water to heat the

material in the dryer to approximately 42°C, at which point the

water was shut off by closing the

valve that supplied the dryer’s

jacket. However, the jacket was

not designed to be drained; the

water remained in the jacket at

82°C until it was cooled by heat

losses to the surrounding

environment.

4.0

Potential Initiating Scenarios

The self-accelerating decomposition

temperature (SADT)7

 for a 1-pound

bag of 98 percent BPO is 68°C.8

Because SADT is dependent on the

size and type of package, it would

be lower for the 200-pound batch

that was being processed in the

dryer.

Half-life data suggest that half of

the 98 percent BPO in the dryer

would have decomposed in about 3

hours at 82°C.9

 To maintain an

appropriate factor of safety below

SADT, another manufacturer’s

literature suggests that 1-pound

bags of 98 percent BPO should not

be stored at temperatures higher

than 38°C.10 Clearly, the BPO drying system at Catalyst Systems was

running very close to the thermal

decomposition temperature for 98

percent BPO, which was the likely

cause of the explosion.

7

SADT is the temperature at which a peroxide undergoes a rapid and violent decomposition, and may self ignite.

8

The SADT for a 1-pound bag of 98 percent

BPO is listed in various manufacturers’

MSDSs.

9

Degussa Corporation general technical information. Half-life indicates the time in

which half of the original quantity of peroxide will decompose at a given temperature.

Under adiabatic conditions, where no heat is

lost from the vessel, the half-life time is decreased.

10Atofina, Organic Peroxides—Their Safe

Handling and Use, 2001.

Clearly, the BPO

drying system . . .

was running

very close to

the thermal

decomposition

temperature for

98 percent BPO,

which was the

likely cause of the

explosion.


12

. . . The

probable and

possible events

. . . all point to

inadequacies in

system design

due to

insufficient

management

systems.



CSB identified several probable/

possible initiating events and other

factors that could have led to a thermal decomposition, as listed in

Table 3.

Although CSB was unable to conclusively determine the initiating event

that led to the January 2 incident,

the probable and possible events

listed below all point to inadequacies

in system design due to insufficient

management systems.

Table 3

Potential Initiating Scenarios Leading to Thermal Decomposition

Probable Initiating Events Possible Initiating Events

Failure of the temperature Contamination in the dryer

probe from foreign material

Hot spot in the dryer Contamination in the dryer

from exposure to metal surface

BPO remaining in the dryer Generation of heat energy

too long from friction

Failure of the vacuum pump, Generation of a spark

loss of evaporative cooling due to static electricity
13

Numerous standards and

guidance documents describe

the hazards of organic peroxides

and recommended practices for

storage and handling. Some of

these documents also contain

specifics on BPO. In addition, a

number of trade groups, insurance

companies, and government agencies have published books, research

reports, and technical papers, as

listed in Section 9.0, Annotated

References.

A review of standards and guidance

suggests that several commonly

accepted practices would have significantly reduced the likelihood of

the explosion at Catalyst Systems,

as noted below:

 Safeguards should be in place to

avoid overheating BPO. The

SADT is reported as 68°C for

1-pound plastic bags. Manufacturers and users should recognize that these data are specific

to the package size and characteristics, which are determined

by testing. It is not possible to

suggest an exact temperature at

which BPO will decompose; however, at higher temperatures, the

decomposition reaction takes less

time to start and proceeds more

rapidly. Safe temperatures

should be chosen for specific

systems, and temperature controls and alarms should be installed accordingly.

5.0

Standards and Guidance

 Equipment used to heat organic

peroxides should be isolated from

storage areas, other equipment,

and work areas. Buildings that

house manufacturing equipment

should be built with fire- and

explosion-resistant walls with

adequate capabilities to vent

pressure.

 Safeguards should be in place to

protect against the possibility of

exposing BPO to ignition sources,

friction, and shock. Electrical

equipment in areas with open

containers of BPO should be

classified according to Class I,

Division 1, of Article 500 of the

National Electric Code; and all

equipment should be adequately

grounded.

 BPO generates large volumes of

gases during decomposition and

should not be confined. Additionally, precautions should be taken

to avoid contamination, which

may initiate the decomposition

reaction.

These good practices—discussed

throughout the standards and guidance documents—do not represent a

complete set of practices for BPO

handling. However, if they had been

in place, they may have reduced the

potential for the explosion.

It is not possible

to suggest an

exact temperature

at which BPO will

decompose;

however, at higher

temperatures, the

decomposition

reaction takes less

time to start and

proceeds more

rapidly.



BPO generates

large volumes of

gases during

decomposition

and should not be

confined.


14

 . . . The

development,

understanding,

and application of

process safety

information during

process design

was inadequate

for managing

the explosive

decomposition

hazard of

98 percent BPO.

Process safety management is

the application of management

systems to control hazards to

ensure the safety of a process and

prevent catastrophic incidents. It

is considered to be good practice in

operations that handle and process

hazardous materials. In Guidelines

for Technical Management of

Chemical Process Safety, the

American Institute of Chemical

Engineers (AIChE) Center for

Chemical Process Safety (CCPS)

describes 12 core elements of a

good process safety management

system.

Catalyst Systems did not have a

process safety management program in place, nor were employees

trained in the use of these management systems. Deficiencies in

certain elements, as discussed

below, significantly contributed to

the January 2 incident.

6.1

Process Knowledge

and Documentation

A process safety management

system for chemical manufacturing

is only as good as the foundation

upon which it is built—the actual

research, development, design,

construction, and operational data.

Basic process safety information

includes the following:

6.0

Management of Chemical Process Safety

 Chemical, physical, and reactive

properties of materials.

 Health and toxicity data for

reactants and products.

 Thermal and chemical stability

data for reactants and products.

 Process chemistry and technology information.

 Equipment design temperature

and pressure.

 Range of process temperature

and pressure.

 Equipment and materials of construction specifications.

 Material and energy balances of

the chemical process.

 Safety systems (e.g., interlocks,

pressure relief systems, detection or suppression systems).

 Operating procedures and training information.

 Design codes and regulatory

standards.

All of this information should be

compiled, analyzed, and updated

before beginning design and construction, and then kept up to date.

The information should be readily

available to employees.

At Catalyst Systems, the development, understanding, and application of process safety information

during process design was inadequate for managing the explosive
15

decomposition hazard of 98 percent

BPO. Although Catalyst Systems

was aware of the SADT for a

1-pound package of BPO, this information was inappropriately used to

determine the high temperature

limit for the much larger amount in

the dryer.

Further evaluation of thermal and

chemical stability would likely have

taken into account the differences

between 1 pound of BPO in a plastic shipping container and 200

pounds in a closed metal dryer.11

Such an evaluation would have

allowed Catalyst Systems to adequately design its drying system.

Test information on the resistivity

of 98 percent BPO would have

prompted the design of a drying

system to prevent static accumulation and to assess the hazard posed

by static sparks. For example:

 The vacuum dryer was set to rotate slowly enough to prevent the

buildup of static charges and

frictional heating, yet still allow

BPO to tumble (e.g., two revolutions per minute). However,

little consideration was given to

adequately grounding the dryer

to dissipate static charges that

might accumulate while the

material tumbled. Likewise,

there was no consideration of

whether the polypropylene bag

filter over the vacuum inlet

might be a source of static electricity inside the dryer.

 Although the electric motor

attached to the frame of the

dryer was grounded through its

electrical wiring, it is unknown

whether the grease in the sealed

bearings—where the dryer rotated on its frame—was conductive.12 If nonconductive grease

was used, the rotating dryer

shell might have been totally isolated from the frame, allowing

static charges to accumulate on

and inside the dryer.

The only information that Catalyst

Systems had on the vacuum dryer

was an item description on a

purchase order. There was no

wiring diagram. There were no

sketches or basic process flow diagrams, and there were no engineering drawings for major system

components. This basic system information is necessary to properly

review the design, maintain the

equipment, and manage changes.

There were no written operating

procedures for drying BPO using

the vacuum dryer; management

provided only verbal instructions

to the operators. Catalyst Systems

has written procedures for other

operations. For example, for the

previous drying process, which

used an oven, written procedures

included warnings and other information on the sensitivity and

instability of 98 percent BPO.

12Catalyst Systems had no documentation

describing the type of grease used in the

sealed bearing.

11An increase in volume changes the ability

of the substance to cool because of differences in surface area.

Although Catalyst

Systems was

aware of the

SADT for a

1-pound package

of BPO, this

information was

inappropriately

used to determine

the high temperature limit for the

much larger

amount in the

dryer.

. . . Little consideration was

given to

adequately

grounding the

dryer to dissipate

static charges . . .




16

Process flow diagrams, engineering

drawings, and detailed operating

procedures should have been a key

component of operations and maintenance training at Catalyst Systems. Operating procedures should

have been prepared for operator

tasks, instrument readings, sampling, and normal operating conditions (e.g., temperature, pressure,

concentration, reaction rate).

These procedures should have included safety precautions during

operation; safe operating limits for

critical operating parameters; and

how to handle upset conditions, such

as what to do if the vacuum pump

malfunctions.

6.2

Capital Project

Review and Design

Procedures

Capital projects add or significantly

modify processes or equipment.

Safety reviews are normally completed during the various stages of

implementation. These reviews may

include hazard reviews, reactive

hazard evaluations, siting reviews,

process design reviews, and

prestartup safety reviews.

A reactive hazard evaluation is

designed to identify, evaluate, and

control hazardous chemical

reactivity in a chemical process.

Catalyst Systems did not conduct

such an evaluation. After collecting

relevant reactive hazard data for

BPO, Catalyst Systems should have

identified process parameters for

further evaluation. Basic reactive

hazard testing and evaluation procedures should have been used to

determine the magnitude of potential hazards.

The results of this testing and

evaluation could then have been

translated into control measures

and safeguards. For example, safe

temperature limits could have been

developed based on the SADT for

the specific processing conditions;

and the testing data could have been

used to determine if pressure relief

was necessary to eliminate confinement hazards.

Catalyst Systems did not complete

any formal hazard reviews during

design and installation of the BPO

drying system. A formal process

hazard analysis (PHA) would have

systematically evaluated the

hazards of the drying process and

reviewed the following questions:

 What scenarios could cause the

temperature in the dryer to go

beyond an established safe level

(e.g., valves fail to isolate hot

water)? What warnings alert

operators to a high temperature?

What control systems are in

place to prevent the temperature

from getting too high?

 What happens if a decomposition

reaction starts in the dryer?

How fast and with what force

does it occur? Is venting

adequate to alleviate pressure

buildup?

. . . Procedures

should have

included safety

precautions during

operation . . .

and how to

handle upset

conditions . . .



Basic reactive

hazard testing and

evaluation

procedures should

have been used to

determine the

magnitude of

potential hazards.


17

 What are potential sources of

static electricity or friction?

What are potential sources of

contamination?

 Are employees adequately

protected and able to safely

evacuate?

Catalyst Systems did not complete a

prestartup safety review, as is customary prior to startup of a new

process. This safety review looks at

differences between the intended

design and the system as actually

installed to ensure that there is no

compromise on safe operation.

During its design process, Catalyst

Systems planned to include redundancy in the control of valves in the

heated water piping to protect

against the failure of a single valve;

however, this safety feature was removed due to wiring problems during installation.

A proper prestartup safety review

would have ensured that if an intended safety feature was removed,

it would be replaced with a suitable

alternative. Catalyst Systems did

not have a management system in

place that mandated these reviews.

If Catalyst Systems had completed

a formal PHA and reactive hazard

evaluation, it likely would have discovered that the drying system did

not include adequate measures to

protect against thermal decomposition or its consequences. Measures

should have been taken to prevent

the temperature from getting too

high; to eliminate potential sources

of contamination, static charges,

electrical charges, and friction; and

to avoid confinement.

6.3

Process and

Equipment Integrity

Equipment used to handle or

process hazardous materials should

be maintained to control the risk of

fires, explosions, releases, and other

accidents. Even well designed

equipment cannot ensure process

safety if it fails prematurely, or if

its components do not operate in an

emergency.

Preventive maintenance is a

program of inspections and tests

to ensure that equipment operates

satisfactorily. A preventive maintenance program consists of the following activities:

 Identification of equipment and

instrumentation critical to

process safety.

 Determination of required

inspections or tests, their frequency, and acceptable limits or

criteria for passing.

 Establishment of maintenance

procedures.

 Training of maintenance personnel.

 Documentation and analysis of

results.

Catalyst Systems had no established

preventive maintenance program

for the BPO drying system.

If Catalyst

Systems had

completed a

formal PHA and

reactive hazard

evaluation, it likely

would have

discovered that

the drying system

did not include

adequate

measures to

protect against

thermal decomposition or its

consequences.

Catalyst Systems

had no established

preventive

maintenance

program for the

BPO drying

system.




18

Because the temperature controller

was critical to safe operation of the

system, it should have been included in such a program. Catalyst

Systems should have developed test

methods to ensure that the thermocouple was working properly, and

that the high temperature set point

on the temperature controller

was accurate and functioned as

intended. The frequency of testing

should be based on known failure

history, manufacturer’s recommendations, and operating experience.

A preventive maintenance program

should also have included the glass

lining inside the vacuum dryer.

Interviews with operators revealed

that a chip had developed in the

lining. Granular BPO may have become lodged in this chip and overheated (because it was now closer to

the jacket and heated to a higher

temperature than the rest of the

batch), creating a hot spot. Moreover, the metal under the glass lining provided a potential source of

contamination. Catalyst Systems

should have developed procedures

for inspecting the glass lining and

making repairs when necessary.

6.4

Training and

Performance

To safely operate a chemical

process, operators must be trained

on its normal operation and

hazards, in addition to deviations

during abnormal situations.

At Catalyst Systems, operators

received on-the-job training only.

Although the operators appeared to

have good knowledge of normal

operation, there were no written

procedures and no structured

training. In addition, there were no

procedures for abnormal situations.

Catalyst Systems should have identified unusual scenarios and trained

operators on response actions, such

as what to do about finding a chip in

the dryer’s glass lining, hearing unusual noises from the vacuum

pump, or detecting abnormal process conditions.

Although the

operators

appeared to have

good knowledge

of normal

operation, there

were no written

procedures and no

structured training.


19

The Occupational Safety and

Health Administration (OSHA)

Process Safety Management

(PSM)13 Standard was established to

prevent or minimize the consequences to employees from

catastrophic releases of highly

hazardous chemicals (HHC) in the

workplace. It covers processes

containing individually listed

chemicals that present a range of

hazards, including reactivity.

The PSM Standard lists BPO

because of its reactivity. When the

standard does not specify a chemical concentration, the listed

chemicals are covered in pure

“chemical” or “commercial”

grades.14, 15 For BPO, this concentration is 98 percent.

For a process to be covered by the

PSM Standard, a minimum or

threshold quantity of the listed

chemical must be present. The

threshold quantity for BPO is

7,500 pounds. The Catalyst

Systems process was not covered

because the maximum amount of

98 percent BPO onsite at a given

time was 2,550 pounds.16

7.0

Regulatory Analysis

In determining the appropriate

threshold quantities for PSM-listed

chemicals that pose reactivity hazards, OSHA chose the quantity of

material that would cause a 2.3-

pound-per-square-inch (psi) overpressure at 100 meters17 based on

the following:

 Blast waves with pressures

greater than 2.3 psi cause serious

physical damage to buildings and

structures, and cause fragments

to fly at speeds that could seriously injure workers.

 An explosion that produces an

overpressure of 2.3 psi or

greater at a distance of 100

meters from the blast origination

represents a catastrophic incident rather than a local incident.

This is the same distance used by

the State of Delaware in developing its Extremely Hazardous

Substances Risk Management

Act18 prior to the PSM Standard.

One hundred meters was also

supported by public comments

received by OSHA during its

rulemaking process.

13See www.osha.gov.

14OSHA Director, Directorate of Compliance

Programs, letter re HHCs as applied to how

high the percentage of a chemical must be to

require compliance, April 14, 1993.

15OSHA Deputy Director, Directorate of

Compliance Programs, letter re HHCs as applied to threshold quantity, April 24, 1994.

16The approximate amount of 98 percent

BPO onsite on the day of the explosion was

2,140 pounds.

17The rationale for OSHA threshold quantities is discussed in a 1996 memo prepared by

Thomas H. Seymour, Directorate of Safety

Standards Programs, “Rationale for Preamble, Appendix A, Chemical List.”

18In its regulation, the State’s objective was

to protect people in the vicinity of a catastrophic release beyond a facility boundary.

The threshold

quantity for BPO is

7,500 pounds.

The Catalyst

Systems process

was not covered

because the

maximum amount

of 98 percent

BPO onsite at

a given time was

2,550 pounds.


20

 The amount of material

necessary to cause a 2.3-psi overpressure at 100 meters from the

blast origination is determined

using an empirically derived

function method based on equivalent mass of trinitrotoluene

(TNT).

Although there were no serious injuries on January 2, explosions such

as the one at Catalyst Systems can

be very hazardous to workers who

may be closer than 100 meters to

the origin. Because of the potential

hazard, good practices must be followed even when handling small

amounts of a hazardous chemical

such as BPO.

OSHA investigated the Gnadenhutten plant following the January 2

incident. For violation of the General Duty Clause (Section 5(a)(1) of

the Occupational Health and Safety

Act of 1970), OSHA issued a citation with willful violation to Catalyst

Systems for not following the good

practices outlined by the principles

of process safety management.

8.0

Conclusion

The January 2 explosion at

Catalyst Systems was most

likely caused by a thermal decomposition of 98 percent BPO. Other

possible causes or contributors include contamination, static electricity, or friction.

The hazards of BPO are well known

and documented. Catalyst Systems

should have reviewed consensus

standards and guidance documents

on the handling, storage, and manufacture of BPO, and implemented

their recommended practices.

Dry BPO is hazardous in any

quantity. Regardless of OSHA PSM

coverage, companies should implement good engineering practices

when working with BPO, such as

gathering relevant hazard information, reviewing reactive hazards,

developing a preventive maintenance program, and developing and

conducting training on operating

procedures for normal and abnormal situations.

If Catalyst Systems had reviewed

and followed industry standards

and guidance documents, and

implemented good engineering

practices to manage the hazards, it

is likely that this incident would not

have occurred.

. . . Explosions

such as the one at

Catalyst Systems

can be very

hazardous to

workers who may

be closer than

100 meters

to the origin.



 Catalyst Systems

should have

reviewed consensus standards

and guidance

documents on the

handling, storage,

and manufacture

of BPO, and

implemented their

recommended

practices.
21

Code for the Storage of Organic

Peroxide Formulations, NFPA 432

The National Fire Protection

Association (NFPA) began

developing codes for the storage

of organic peroxides in 1969;

the current standard was

published in 2002. NFPA 432

applies to storage only and

excludes manufacturing. The

standard defines hazard

classifications for organic

peroxides based on the

characteristics of available

peroxide formulations and a

limited number of full-scale fire

tests.

Fire, Explosion, and Health

Hazards of Organic Peroxides,

American Insurance Association

Research Report No. 11

discusses problems associated

with the use of concentrated

organic peroxides, classification

and evaluation, fire and

explosion hazards, and typical

fires and explosions; and

includes precautionary

recommendations. This 1966

report reviews case histories of

eight BPO explosions and fires

in transportation, laboratory,

and manufacturing

environments.

9.0

Annotated References

Guidelines for Technical

Management of Chemical Process

Safety, American Institute of

Chemical Engineers (AIChE)

Center for Chemical Process Safety

(CCPS)

The CCPS chemical process

safety management system

focuses on management systems,

along with technological

advances, as essential to prevent

catastrophic incidents. This

book, published in 1989,

describes the 12 core elements

necessary for a complete

process safety management

program. These practices are

recognized throughout the

chemical industry.

“Hazard Evaluation of

Dibenzoylperoxide (BPO),”

Proceedings, 17th International

Pyrotechnics Seminar–2nd Beijing

International Symposium on

Pyrotechnics and Explosives

In this scientific technical paper,

from Volume 2 of the 1991

proceedings (pp. 993-998),

authors Tadao Yoshida and

others describe an explosion in a

manufacturing factory in Tokyo

in 1990, including the results of

several experiments on the

hazards of dry and 75 percent

water-wetted BPO. The authors

conclude that—unlike dry

BPO—75 percent BPO diluted
22

with water is rather safe under

ordinary handling conditions but

displays some potential hazards

under confinement.

“Hazard Evaluation of Organic

Peroxides,” Journal of Hazardous

Materials, Elsevier Scientific , 

Publishing

This scientific technical paper

was authored by V. K. Mohan, K.

R. Becker, and J. E. Hay—and

published jointly by IDL

Chemicals Ltd. (India) and the

Pittsburgh Research Center,

U.S. Bureau of Mines, in 1982

(Volume 5; pp. 197-220). It

contains detonability, thermal

stability explosion, and energy

release test data for a number of

organic peroxides, including

BPO. These tests compare BPO

to results obtained with conventional explosives, such as TNT.

For example, in a ballistic

mortar test, BPO had a weight

strength of 15.5 percent of TNT;

the relative underwater bubble

energy for dry BPO (98 percent

pure) relative to the bubble

energy for an equivalent mass of

TNT was 42.7 percent. In

contrast, the relative bubble

energy of wet BPO (22 percent

water) was only 28.8 percent.

Hazardous Substance Fact Sheet:

Benzoyl Peroxide, New Jersey

Department of Health and Senior

Services

This fact sheet, revised in 1998,

summarizes the hazards of BPO

and includes information on

determining exposure. It

provides workplace exposure

limits as defined by OSHA,

NIOSH, and the American

Conference of Governmental

Industrial Hygienists. Guidelines on reducing exposure are

also included.

Occupational Exposure to Benzoyl

Peroxide, National Institute for

Occupational Safety and Health

NIOSH published this

recommended standard (77-

166) in 1977, recognizing that

the most significant concern

with BPO is its hazards due to

instability, flammability, and

explosive properties. The

standard includes a discussion of

BPO hazards and provides

general recommendations for

storage and handling.

“Organic Peroxides: Evaluation

and Management of Hazards,”

Organic Peroxides, Wiley- , 

Interscience

In Chapter V of Volume III,

published in 1972, author E. S.

Shanley discusses the storage

stability of organic peroxides;

hazards from rapid

decomposition, including tests

for evaluation of hazardous
23

behavior; hazard classification

schemes; health hazards; and

safe handling practices in both

the laboratory and plant

environment. The author

advocates separating organic

peroxide storage and

manufacturing areas.

Organic Peroxides, Factory Mutual

(FM) Global Property Loss

Prevention Data Sheet 7-80

FM Insurance Company

develops engineering guidelines

to help prevent property losses.

FM Data Sheet 7-80, revised in

September 2000, makes

recommendations on the safe

storage and handling of organic

peroxides. It applies to both

storage and manufacturing.

Properties and Essential

Information for Safe Handling and

Use of Benzoyl Peroxide,

Manufacturing Chemists

Association

MCA has split into several

different organizations since the

publication of this guidance in

1960. Although the new

organizations no longer support

this document, it provides a

thorough evaluation of the

hazards of BPO; and

recommends procedures for

handling, storing, and

manufacturing the product.

Safety and Handling of Organic

Peroxides: A Guide, Society of

Plastics Industry Inc

.

The Organic Peroxide

Producers Safety Division

published this guidance

(Publication AS-109) in 1999.

This document covers

characteristic properties of

organic peroxides, types of

organic peroxides, and rules for

safe handling—including

temperature control,

contamination control,

confinement control, quality

control, disposal of wastes, and

fire protection.

“Thermal Hazards: How to Identify

and Minimize Them in Your Drying

Process,” Powder and Bulk

Engineering

This technical article from the

April 1977 issue describes

potential thermal hazards

involved in drying processes and

explains how to evaluate powders

to minimize these hazards.

Authors V. Ebadat and J. C.

Mulligan discuss heating and

cooling during the drying

process, the onset temperature

for exothermic decomposition,

and how powders can self-heat.

Smoldering, charring, and other

factors that affect the selfheating rate are also explained.

For example, the authors state

that increasing residence time in

the dryer (inadvertently or

otherwise) may cause a powder

to decompose to a stage that

leads to a fire or explosion.
24

CSB Investigation Reports may

be purchased from:

National Technical Information

Service

5285 Port Royal Road

Springfield, VA 22161- 0002

(800) 553-NTIS or

(703) 487-4600

Email: info@ntis.fedworld.gov

For international orders, see:

www.ntis.gov/support/

cooperat.htm.

Salus Populi Est

Lex Suprema

People’s Safety

is the Highest Law

Information on available

publications may be obtained

by contacting:

U.S. Chemical Safety and

Hazard Investigation Board

2175 K Street NW, Suite 400

Washington, DC 20037-1848

(202) 261-7600

CSB is an independent Federal agency whose mission is to ensure the safety of workers,

the public, and the environment by investigating and preventing chemical incidents. CSB

is a scientific investigative organization; it is not an enforcement or regulatory body.

Established by the Clean Air Act Amendments of 1990, CSB is responsible for

determining the root and contributing causes of accidents, issuing safety recommendations, studying chemical safety issues, and evaluating the effectiveness of other

government agencies involved in chemical safety.

No part of the conclusions, findings, or recommendations of CSB relating to any chemical

incident may be admitted as evidence or used in any action or suit for damages arising out

of any matter mentioned in an investigation report (see 42 U.S.C. § 7412(r)(6)(G)). CSB

makes public its actions and decisions through investigation reports, summary reports,

safety bulletins, safety recommendations, case studies, incident digests, special technical

publications, and statistical reviews. More information about CSB may be found at

www.csb.gov.

The U.S. Chemical Safety and Hazard Investigation Board (CSB)

examined and tested physical evidence at the site, interviewed employees, and reviewed relevant plant documents. CSB contracted with

Hazards Research Corporation for assistance in evaluating benzoyl

peroxide (BPO) chemistry and processing. CSB also met with the

Organic Peroxide Producers Safety Division of the Society for Plastics

Industry (SPI) regarding the hazards, safe handling, and manufacture

of BPO.

Incident Investigation Process