U.S. CHEMICAL SAFETY AND HAZARD INVESTIGATION BOARD

INVESTIGATION REPORT

DUST EXPLOSION

(6 Killed, 38 Injured)

WEST PHARMACEUTICAL

SERVICES, INC.

KINSTON, NORTH CAROLINA

JANUARY 29, 2003

REPORT NO. 2003-07-I-NC

SEPTEMBER 2004

KEY ISSUES:

 HAZARD RECOGNITION AND COMMUNICATION

 GOOD ENGINEERING PRACTICE

 LOCAL AMENDMENTS TO FIRE CODES
1

INVESTIGATION REPORT

REPORT NO. 2003-07-I-NC

SEPTEMBER 2004

(6 Killed, 38 Injured)

WEST PHARMACEUTICAL SERVICES, INC.

KINSTON, NORTH CAROLINA

JANUARY 29, 2003

KEY ISSUES

HAZARD RECOGNITION AND COMMUNICATION

GOOD ENGINEERING PRACTICE

LOCAL AMENDMENTS TO FIRE CODES

DUST EXPLOSION

U.S. CHEMICAL SAFETY AND HAZARD INVESTIGATION BOARD
2
3

Abstract

This investigation report examines a dust explosion at West

Pharmaceuticals, Inc., in Kinston, North Carolina. Six

workers were killed and 38 others were injured, including two

firefighters. The Kinston plant manufactured rubber drugdelivery components. This report identifies the root and

contributing causes of the incident and makes recommendations

on hazard recognition and communication, good engineering

practice, and local amendments to fire codes.

The U.S. Chemical Safety and Hazard Investigation Board (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, hazard investigations, safety recommendations, case studies, safety bulletins, incident digests, special

technical publications, and statistical reviews. More information

about CSB may be found at www.csb.gov.

CSB publications may be

downloaded at www.csb.gov

or obtained by contacting: or 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 investigation reports

may be purchased from: 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.

For this report, refer to NTIS

number PB2005-100005
4
5

Contents

EXECUTIVE SUMMARY .......................................................... 11

1.0 INTRODUCTION .......................................................... 13

1.1 Background .................................................................. 13

1.2 Investigative Process .................................................... 13

1.3 West Corporate Profile ................................................. 14

1.4 Kinston Facility............................................................. 15

1.5 Facility Overview .......................................................... 15

1.6 Rubber Compounding Process ..................................... 17

1.6.1 Overview ....................................................... 17

1.6.2 Kitchen .......................................................... 18

1.6.3 Mixing............................................................ 20

1.6.4 Milling ........................................................... 20

1.6.5 Cooling, Coating, and Folding ....................... 21

1.6.6 Heating, Ventilating, and Air Conditioning.... 22

1.6.7 Dust Control.................................................. 24

1.7 Description of Incident................................................. 24

1.8 Emergency Response and Facility Damage................... 26

1.8.1 Emergency Response .................................... 26

1.8.2 Facility Damage ............................................. 27

1.8.3 Facility Relocation ......................................... 29

2.0 ANALYSIS OF INCIDENT ............................................ 31

2.1 Fuel for Explosion ........................................................ 31

2.1.1 Polyethylene Dust: The Only Credible

Fuel for Explosion ......................................... 32

2.1.2 Other Fuel Sources Considered..................... 34

2.2 Center of Explosion...................................................... 35

2.3 Acceleration of Fire...................................................... 39

2.4 Initiating Event ............................................................. 39

2.5 Engineering .................................................................. 41

2.6 New Material Safety Review ......................................... 43

2.7 Previous Incidents ........................................................ 46

3.0 REGULATORY ANALYSIS ........................................... 47

3.1 State Fire Safety Regulations........................................ 47

3.1.1 Combustible Dusts ........................................ 47

3.1.2 Combustible Liquids ..................................... 48

3.1.3 Fire Inspectors .............................................. 49

3.2 Federal and State Occupational Safety and Health

Regulations ................................................................... 50

3.2.1 Combustible Dusts ........................................ 50

3.2.2 OSHA Hazard Communication Standard...... 51

3.3 Guidance Documents ................................................... 52

3.4 Combustible Dust: A Hazard Not Readily Apparent ... 53
6

Contents (cont’d)

4.0 RECENT DUST EXPLOSIONS IN UNITED STATES.... 55

5.0 COMBUSTIBLE DUST HAZARD STUDY .................... 57

6.0 ROOT AND CONTRIBUTING CAUSES....................... 59

6.1 Root Causes ................................................................ 59

6.2 Contributing Cause ..................................................... 59

7.0 RECOMMENDATIONS ................................................ 61

8.0 REFERENCES ............................................................. 65

APPENDIX A: Test Results ..................................................... 67

A.1 Explosivity ................................................................... 67

A.2 Minimum Ignition Energy ........................................... 68

A.3 Dust Layer Ignition...................................................... 69

APPENDIX B: Blast Damage Observations ............................. 71

APPENDIX C: Initiating Events .............................................. 73

C.1 Deflagration of Vapors Emitted by

Decomposing Rubber .................................................. 73

C.2 Ignition of Dust by Overheated Electrical Ballast

or Fixture .................................................................... 75

C.3 Ignition of Dust by Electrical Spark ............................ 75

C.4 Ignition of Dust in Motor Cooling Duct ....................... 76

APPENDIX D: Logic Diagrams ............................................... 77

APPENDIX E: Timeline .......................................................... 85
7

Figures and Table

1 Layout of West Pharmaceutical Services

Kinston Facility ...........................................................16

2 Simplified Two-Story Rubber Compounding

Process Diagram .........................................................18

3 Plan Sketch of Kitchen Layout ...................................19

4 Rubber Compounding Process Plan View Layout ...... 22

5 Comfort Air System for Milling and Batchoff Area ... 23

6 Roof of Facility, With Two-Story Compounding

Section in Background............................................... 28

7 Remains of ACS Warehouse Viewed From

Compounding Area ................................................... 28

8 Dust Explosion Pentagon ........................................... 33

9 Estimated Zone of Maximum Explosive Force ...........37

10 Location of Maximum Explosive Force ..................... 38

11 Extensive Damage and Debris Near Mill and

Batchoff Machine #1.................................................. 40

B-1 Beam and Cross Bracing Deflected Southeastward

Toward Warehouse .....................................................71

B-2 Uplifted Concrete Floor in Mixer Area ...................... 72

B-3 Southwest Wall of Compounding Area Deflected

Outward..................................................................... 72

Figures

Table

A-1 Explosion Severity Test Results ................................. 68
8

Acronyms and Abbreviations

AC Alternating current

ACS Automated rubber compounding system

ASTM American Society for Testing and Materials

ATF Bureau of Alcohol, Tobacco, Firearms and

Explosives

ATSDR Agency for Toxic Substances and Disease Registry

bar-m/sec Bar-meter per second

CFD Computational fluid dynamics

CFR Code of Federal Regulations

CMU Concrete masonry unit

CSB U.S. Chemical Safety and Hazard Investigation

Board

EMS Emergency Medical Services Division, Lenoir

County Department of Emergency Services

EPA U.S. Environmental Protection Agency

ERM Environmental Resources Management

oF Degrees Fahrenheit

FDA U.S. Food and Drug Administration

FMEA Failure modes and effects analysis

HazCom Hazard Communication Standard (OSHA)

HSE Health and Safety Executive, United Kingdom

HVAC Heating, ventilating, and air conditioning

ICC International Code Council

IFC International Fire Code

LEV Local exhaust ventilation

LTA Less than adequate

m3 Cubic meter

mJ Millijoule

MIE Minimum ignition energy
9

MOU Memorandum of understanding

Namico National Milling & Chemical Co., Inc.

NCDENR North Carolina Department of Environment and

Natural Resources

NCDOL North Carolina Department of Labor

NCOSHA Occupational Safety and Health Division (NCDOL)

NEC National Electric Code

NFPA National Fire Protection Association

NMR New materials review

OSHA Occupational Safety and Health Administration

psi Pounds per square inch

psig Pounds per square inch gage

SCE Safety Consulting Engineers, Inc.
10
11

AJanuary 29, 2003, dust explosion at the West

Pharmaceutical Services, Inc., plant in Kinston, North

Carolina, killed six workers and injured 38 others, including

two firefighters.

The Kinston facility manufactured rubber drug-delivery

components such as syringe plungers, septums, and vial seals.

Production operations included rubber compounding, molding,

and extrusion. The rubber compounding process consisted of two

separate production lines, each with a mixer, a mill, and batchoff

equipment. Raw materials were prepared in another area of the

plant.

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

determined that accumulated polyethylene dust above a suspended ceiling fueled the explosion. Because of the extent of

damage to the Kinston facility, it was not possible to definitively

determine the event that dispersed the dust or what ignited it.

CSB determined the following root causes of the January 29

incident:

 West did not perform adequate engineering assessment of

the use of powdered zinc stearate and polyethylene as

antitack agents in the rubber batchoff process.

 West engineering management systems did not ensure that

relevant industrial fire safety standards were consulted.

 West management systems for reviewing material safety

data sheets did not identify combustible dust hazards.

 The Kinston plant’s hazard communication program did not

identify combustible dust hazards or make the workforce

aware of such.

CSB makes substantive recommendations to West Pharmaceutical

Services, Inc., to:

 Develop/revise policies and procedures for new material

safety reviews, and safety reviews of engineering projects.

 Ensure that its manufacturing facilities that generate

combustible dusts meet the requirements of National Fire

Protection Association (NFPA) Standard 654.

 Improve hazard communication programs.

Executive Summary
12

CSB recommends to the North Carolina Building Code Council

that the State fire code be amended to require compliance with

NFPA 654. Additionally, recommendations are made to the North

Carolina Department of Labor, Occupational Safety and Health

Division; North Carolina Code Officials Qualification Board; and

Crystal, Inc.–PMC.
13

1.1 Background

On Wednesday, January 29, 2003, at 1:28 pm, an explosion

and fire at the West Pharmaceutical Services, Inc., plant in

Kinston, North Carolina, killed six workers and injured at least

38 others, including two responding firefighters. Much of the

facility—which manufactured small rubber parts for pharmaceutical delivery devices—was severely damaged.

One student was injured when windows were broken at a school

0.7 mile away. Businesses located in the same industrial park as

West were damaged, and windborne burning debris ignited fires in

wooded areas as far as 2 miles away. One home located nearby

was damaged slightly, and at least two families were evacuated as

a precautionary measure.

Because of the number of deaths and injuries, the U.S. Chemical

Safety and Hazard Investigation Board (CSB) launched an investigation to determine the root and contributing causes of the

explosion and to make recommendations to prevent similar

occurrences.

1.2 Investigative Process

The Lenoir County Department of Emergency Services1

commanded the incident response. Officers of the Lenoir

County Sheriff’s Department controlled site access and security.

CSB investigators arrived at the site on the evening of January 29.

CSB investigators and agents from the Bureau of Alcohol,

Tobacco, Firearms and Explosives (ATF) worked under the terms

of an existing Memorandum of Understanding (MOU) and entered

the site jointly after unstable portions of the plant were secured

and made safe for entry. CSB also worked under MOUs with the

U.S. Environmental Protection Agency (EPA) and the Agency for

Toxic Substances and Disease Registry (ATSDR).

EPA and the North Carolina Department of Environment and

Natural Resources (NCDENR) performed air monitoring and

screening of water runoff from the firefighting effort. West

1.0 Introduction

1

This County department includes an Emergency Management Division and an

Emergency Medical Services (EMS) Division, among others.

. . . An explosion

and fire . . . killed six

workers and injured at least workers and injured at least

38 others, including two

responding firefighters. responding firefighters.
14

contracted with HEPACO, Inc., an environmental cleanup company, and with Environmental Resources Management (ERM) to

set up a water treatment and filtration system to reduce the

discharge of potential chemical contaminants into the environment.

The North Carolina State Bureau of Investigation assisted ATF

with interviews. Intentional criminal activity was ruled out, and

ATF concluded that the explosion was accidental. In such circumstances, the MOU calls for ATF to forgo further analysis and for

CSB to continue the investigation. In addition, inspectors from

the North Carolina Department of Labor (NCDOL), Occupational

Safety and Health Division (NCOSHA), and the U.S. Occupational

Safety and Health Administration (OSHA) remained on scene to

conduct a separate investigation.

CSB began interviewing hourly and contract workers, as well as

plant management personnel, on the morning after the incident.

In addition, CSB:

 Examined damage to the facility and reviewed design plans

and documents.

 Commissioned testing of product ingredients and other

materials found throughout the plant.

 Reviewed pertinent codes, standards, technical guidelines,

management practices, and regulations.

West is one of the world’s largest manufacturers of closures and

components for sealing drug vials and prefilled syringes. Headquartered in Lionville, Pennsylvania, the company has approximately 4,000 employees working in eight facilities in North

America and 10 in Europe and Asia. West was founded in 1923

and is publicly traded. In 2003, sales exceeded $490 million

(West, 2004).

1.3 West Corporate

Profile

West is one of t t is one of the world’s

largest manufacturers of largest manufacturers of

closures and components

for sealing drug vials and

prefilled syringes. prefilled syringes.
15

1.4 Kinston Facility

West’s Kinston facility has manufactured drug-delivery

components—such as syringe plungers, septums, and vial seals—

since 1975. The rubber compounding process in use at the time

of the incident started up in 1987, following a major expansion

and automation project. At the time of the incident, 264 West

employees and 35 full-time contract workers were employed at

the plant.

The rubber compounding process at the Kinston plant was generally similar to other rubber manufacturing processes, such as tire

production. It was semicontinuous, producing sequential batches

and operating 24 hours per day, 5 or 6 days per week.

1.5 Facility Overview

The West plant was located in a light industrial business park

adjacent to the regional airport. Two private residences and the

local Humane Society shelter were each located about 1,000 feet

from the facility. The plant was approximately 150,000 square

feet in area and primarily single story; however, some of the

rubber compounding equipment was located on a 60.5-foot-high

second floor area (Figure 1). The plant housed two operations—

rubber compounding and finishing, in which the compounded

rubber was molded and pressed into stoppers and plungers.

The plant housed

two operations—rubber

compounding and

finishing . . . finishing . . .
16

Figure 1. Layout of West Pharmaceutical Services Kinston facility.

Warehouse

Rubber

compounding

"Kitchen"

Admin.

offices

Visitor entrance

Employee entrance

Product finishing

Shipping

Offices, labs, and shops

Tote elevator

Two-story area
17

1.6.1 Overview

The automated rubber compounding system (ACS) consisted of

two separate production lines, each with a mixer, a mill, and

batchoff2 equipment. Raw materials were prepared in the

“kitchen”—a separate section of the plant. Solid materials were

weighed in the kitchen and loaded into totes. A roller conveyor

transported the totes to an elevator, where they were lifted to the

second floor of the compounding structure. A conveyor then

carried the totes to the mixers, where the ingredients were compounded. Other solid ingredients used in large quantities, such

as clay, were pneumatically conveyed through pipes to the secondfloor mixers. Liquid mineral oil used as a plasticizer3 for the

rubber blends was piped directly to the mixers.

Once compounded in the mixers, the rubber dropped through

chutes to the ground floor, where roller mills smoothed it into

strips. The strips of rubber were trimmed, dipped into a vat

containing a slurry of very fine polyethylene powder and water,

and then air dried and stacked for shipment or molding in the

finishing area of the plant.

A suspended acoustic tile ceiling hung 10.5 feet above floor level.

The ceiling covered the entire room where the rubber was rolled,

dipped, cooled, and folded (Figure 2).

2

“Batchoff” is a term of art used in the rubber processing industry. Rubber is

compounded in batches. The batchoff machine cools, coats, and folds the

strips of rubber from a compounded batch.

3A plasticizer is a substance that—when blended with plastic or rubber—

increases the flexibility of the material.

1.6 Rubber

Compounding

Process

Once compounded in the mixers, Once compounded in the mixers,

the rubber dropped through

chutes to the ground floor,

where roller mills

smoothed it into strips. smoothed it into strips.

A suspended acoustic

tile ceiling hung 10.5 feet

above floor level. The ceiling

covered the entire room

where the rubber was rolled, where the rubber was rolled,

dipped, cooled, and folded. dipped, cooled, and folded.
18

1.6.2 Kitchen

The kitchen was a process area located east of the rubber

compounding area and separated from it by a concrete masonry

firewall. Bulk materials, such as raw rubber or synthetic polymers, were cut and weighed on one side of the kitchen; employees

used the other side for measuring powders. An automatic carousel dispensed smaller-portion ingredients. Roller conveyors along

each side of the kitchen moved the totes with premeasured

components to an elevator in the northwest corner of the room

Figure 2. Simplified two-story rubber compounding process diagram.

Mill

Suspended ceiling

Concrete upper level floor

Batchoff

machine

Mixer

Rubber drops from mixer 

chute into traveling bucket 

and is then dropped onto 

mill rollers

Rubber is milled into 

strips and trimmed

Rubber strips are 

folded and packed into 

containers

Rubber strips are 

dipped into antitack 

slurry, air-cooled, and 

dried on rollers

Fans

Antitack 

slurry dip 

tank

Bulk materials, such as raw

rubber or synthetic polymers, rubber or synthetic polymers,

were cut and weighed on one

side of the kitchen; employees

used the other side for

measuring powders. measuring powders.
19

Figure 3. Plan sketch (view from above) of kitchen layout.

(Figure 3); the totes were then sent to either of two mixers

located on the second floor.

As a quality control procedure, each tote was individually

barcoded—as was each separately bagged component in the tote.

The mixer operator checked the barcodes to verify components

before loading the contents into the mixer.

Carousel

Heavy materials conveyor

Light materials conveyor

Bulk

materials

handling

Tote elevator

(to mixer level)
20

1.6.3 Mixing

The rubber mixers4 were located in recessed areas on the upper

level of the compounding structure. Ingredients were generally

loaded into the mixers through an open hatch on the side.

However, bulk powders used in large portions—such as calcined

clay—were pneumatically transferred to weigh hoppers and

automatically dropped into the mixers. After the batch was

loaded, the operator closed the feed door and engaged the automatic controls.

The kneading action of the mixer causes frictional heating of the

rubber. Although chilled cooling water flows through the

machine’s kneading rotors, the varying speed of the rotors and

the duration of the mixing phase largely control the temperature

of the rubber. Automatic controls hold the process temperature

below the onset for vulcanization.5 The rubber is vulcanized later

during the forming process, when the finished products are

molded.

When the batch reaches a predefined temperature or time limit,

the automatic controls open a door on the bottom of the mixer to

allow the rubber to drop through a chute into a bucket located in

the mill area on the ground floor.

1.6.4 Milling

The rubber is dumped from the bucket onto the milling machine,

where steel rollers cool, flatten, and smooth it into a sheet of

roughly uniform thickness. The flattened rubber is cut into a

strip, which then enters another machine—referred to as the

“batchoff”—where it is cooled, coated, and folded.

4

Each mixer has two opposing rotors that mesh, pull, and shear the rubber

components to create a uniform mix; the process is aided by the frictional heat

generated by the mixer.

5

“Vulcanization” refers to the process of heating rubber in the presence of

sulfur or other agents to form crosslinks between the rubber molecules, which

gives the rubber greater elasticity and strength.

Automatic controls hold the

process temperature below the

onset for vulcanization. onset for vulcanization.

When the batch reaches a

predefined temperature or time

limit . . . the rubber [drops]

through a chute into a bucket through a chute into a bucket

located in the mill area

on the ground floor.

The flattened rubber is cut int ubber is cut into

a strip, which then enters

another machine—referred to

as the “batchoff”—where it is

cooled, coated, and folded. cooled, coated, and folded.
21

1.6.5 Cooling, Coating, and Folding

In the batchoff machine, the rubber strip first passes through a

dip tank containing a slurry of polyethylene powder and water.6

The powder is very fine, with an average particle size of 12

microns, and acts as an antitack agent.7 The water slurry further

cools the rubber so that retained heat does not promote premature vulcanization.

After leaving the dip tank, the rubber is passed in front of a series

of air fans. The fans draw air from the room and blow it across

the rubber strip, drying it as water evaporates from the surface.

At the exit of the batchoff, the rubber is folded and packed in

containers. It is then stored prior to use in the molding section

of the plant or shipped to another West facility.

Almost all of the powdered antitack ingredient in the slurry

coating adheres to the folded rubber; however, small amounts

of dried powder that do not remain on the surface may become

airborne. The Kinston plant used Namicote,8 a slurry containing

a zinc stearate antitack agent, until 1996. A slurry containing

Acumist9 —a finely powdered grade of polyethylene—was used in

place of zinc stearate from 1996 until the time of the incident.

Figure 4 shows a plan view layout of the rubber compounding

process.

6

The slurry is referred to in the rubber industry as a “slab dip.”

7

Antitack agents are materials designed to reduce adhesion between surfaces.

8

Namicote is a trade name of Namico, the National Milling & Chemical Co., Inc.

9

Honeywell International, Inc. (formerly AlliedSignal Inc.), manufactures

Acumist.

In the batchoff machine, the

rubber strip first passes through

a dip t a dip tank cont ank containing a slurry of

polyethylene powder and water.

Almost all of the powdered

antitack ingredient in t edient in the slurry

coating adheres to the folded

rubber; however, small amounts

of dried powder that do not of dried powder that do not

remain on the surface may

become airborne. become airborne.

A slurry containing Acumist —

a finely powdered grade of a finely powdered grade of

polyethylene—was used in place

of zinc stearate from 1996 until 996 until

the time of the incident. the time of the incident.
22

Figure 4. Rubber compounding process plan view layout.

1.6.6 Heating, Ventilating, and

Air Conditioning

Air handlers located on the building roof provided comfort air for

the milling and batchoff area (Figure 5). They drew air from the

room, filtered and heated or cooled it (mixing it with some fresh

air), and then returned it. Air from the room generally flowed

to the air handlers through ducts (equipped with diffusers)

connected directly to the suspended ceiling; however, some ducts

Mill 2

Batchoff 2

Batchoff 1

Mill 1

Lower level Upper level

Offices

Office

Mixer 2

Mixer 1

Tote Conveyor

Mixer Pits

Offices

Offices

Tote 

elevator 

from 

kitchen

Mixer 2

Mixer 1

Tote conveyor

Mixer pits
23

were not so connected and instead drew air from the area above

the ceiling. Because the zone above the suspended ceiling had a

slightly lower pressure than the room it covered, a portion of the

room air was drafted through the ceiling into the open space

above.

Figure 5. Comfort air system for milling and batchoff area.

Ceiling space

(Compounding area)

(Milling and batchoff area)

Roof-mounted

comfort air handlers

Exhaust

Exhaust airflow Supply airflow

Supply air

Mixer pit Mixer pit

Negative

pressure

source

Negative

pressure

source

Suspended

ceiling
24

The comfort air system for the upper level of the building, where

the mixers were located, was not in use. Large exhaust fans on

the upper level were sufficient to cool that area of the facility.

1.6.7 Dust Control

West was aware that the compounding process could create dusty

conditions. Local exhaust ventilation (LEV) ducts were installed

at the mixers and in certain areas of the kitchen, primarily to

limit employee exposure to airborne nuisance dusts. The LEV

ducts transported dust to outdoor collectors.

West also relied on continuous housekeeping to prevent dust

accumulation in work areas. A cleaning staff worked around the

clock vacuuming and wiping up dust to minimize visible accumulation on exposed surfaces.

Because West manufactured products for pharmaceutical use, the

cleanliness of the facility was a high priority. Management focused on the extent and effectiveness of housekeeping in working

areas, and the effort was a matter of facility pride.

Partition walls partially enclosed the batchoff machines to separate them from other areas. Regular housekeeping was conducted around the machines; dehumidifiers/filters associated

with the enclosures removed some dust from the air.

Interviews conducted by CSB investigators indicate that operations on the day of the incident were typical. No one recalled any

sights, sounds, or odors that would have indicated a problem.

The explosion occurred abruptly at 1:28 pm on January 29, 2003.

Employees throughout the plant heard the explosion, which some

described as sounding like “rolling thunder.” After seeing the

exterior siding blow off the second story of the compounding

structure, witnesses outside saw a fireball and a rising smoke

cloud.

1.7 Description of

Incident

Local exhaust ventilation ducts

were installed at the mixers and

in certain areas of the kitchen, in certain areas of the kitchen,

primarily to limit employee

exposure to airborne nuisance

dusts.

Because West manuf t manufactured

products for pharmaceutical products for pharmaceutical

use, the cleanliness of the

facility was a high priority.

. . . Operations on the day of . . . Operations on the day of

the incident were typical. No

one recalled any sights, sounds, one recalled any sights, sounds,

or odors that would have

indicated a problem. indicated a problem.

Because the zone above the

suspended ceiling had a slightly

lower pressure than the room

it covered, a portion of the

room air was drafted

through the ceiling

into the open space above. into the open space above.
25

Inside the facility, employees had varying observations. Those

most distant from the compounding area saw lights flickering,

and ceiling tiles and debris being blown about. Some workers saw

a bright flash and felt either a pressure wave or a vacuum effect

that knocked them off their feet. The entire facility was affected

to some extent, though explosion damage was most severe in the

rubber compounding and milling areas.

A Kinston police officer on patrol less than 1 mile south of the

plant noticed smoke above the tree lines that surrounded the

facility. He immediately contacted his dispatch to inquire if a

controlled burn was taking place at the airport. Seconds later, he

observed the smoke rising into a cloud hundreds of feet into the

air, and he reported the explosion—which was heard as far as 25

miles away. He immediately proceeded to the scene and began

assisting victims out of the facility to safety.

U.S. Army reservists from a quartermaster battalion located next

to West in the same business park estimated that they entered the

burning building within 3 minutes of the blast and helped at least

five employees to safety. National Guard personnel from a

nearby armory arrived shortly thereafter; they assisted firefighters and other responders by providing additional first aid and

stabilizing the injured.

The six people who were killed were working on the ground level

of the plant. Three were working near the southeast mill and

batchoff machine. The fourth, who died several weeks after the

incident, was working at the northeast batchoff. The force of the

blast pushed the fifth victim east into the kitchen, and objects on

the finishing side of the plant fell onto the sixth person.

The majority of the fatal injuries were either thermal burns or

blunt force trauma caused by falling objects or collapsing walls.

When police officers entered the facility, one of the victims was

pinned under a fallen girder near the end of the batchoff machine.

Because of the advancing fire, however, the officers and West

employees had to abandon their efforts to rescue this person, who

died at the scene.

Immediately after the explosion, many employees were dazed or

buried under debris. Responders and other employees equipped

with flashlights assisted them out of the plant to triage areas. A

The entire facility was affected

to some extent, though

explosion damage was most explosion damage was most

severe in the rubber

compounding and milling areas. compounding and milling areas.

The six people who were killed

were working on the ground

level of the plant. level of the plant.

The majority of the fatal injuries

were either thermal burns or

blunt force trauma caused

by falling objects or

collapsing walls. collapsing walls.

The explosion occurred abruptly

at 1:28 pm on January 29.

The explosion broke feeder

lines to the fire sprinkler

system, disabling it. system, disabling it.
26

few workers clung to the exposed frame of the building’s second

story and were rescued by firefighters.

Fires developed throughout the facility. The explosion broke

feeder lines to the fire sprinkler system, disabling it. The largest

and most persistent fire—which burned for 2 days—developed in

the warehouse (Figure 1) and involved the large volume of stored

baled and strip rubber. Some of the rubber continued to smolder

and flare up for about a week.

1.8.1 Emergency Response

Lenoir County Emergency Management dispatch (9-1-1) received

more than 650 radio transmissions and phone calls in the first

2 hours following the explosion. Because early reports suggested

that a plane might have crashed, emergency responders immediately went to a level three response, the maximum alert level.

The Kinston City Fire Department responded to what it thought

was an accident at the airport, and a mass casualty event was

declared.10 After the true nature of the emergency was determined, Kinston immediately lent mutual aid assistance to the

primary responder, the North Lenoir Volunteer Fire Department.

The County Emergency Management Division established incident

command, while the Kinston fire chief handled fire suppression

efforts.

Injured victims were moved to the northwest side of the site and

assessed before being transported to local hospitals. A landing

zone on a grassy area of the grounds was used for air evacuation

of the most severely injured victims to burn trauma centers.

10At this declaration, Emergency Management officials call out additional

rescue equipment and implement other emergency response procedures, which

include staging response trucks, establishing triage and treatment areas, and

arranging for reinforcement personnel.

1.8 Emergency

Response and Facility

Damage

The largest and most persistent The largest and most persistent

fire—which burned for 2 days—

developed in the warehouse and

involved the large volume of involved the large volume of

stored baled and strip rubber.
27

Other responding parties included:

 Eight Lenoir County volunteer fire departments.

 Fourteen other fire departments (rendering mutual aid).

 Ten EMS providers.

 Medevac helicopters (used to airlift burn victims to trauma

centers in Chapel Hill, Raleigh, and Durham).

 Lenoir County Hospital (implementing its disaster plan).

 Kinston Police Department.

 Lenoir County Sheriff’s Office (providing communication

and site security).

 North Carolina State Highway Patrol (using a helicopter for

aerial spotting of fires spreading beyond the facility and

aerial reconnaissance for emergency responders).

 North Carolina State Forestry Service units located in

Kinston (attacking the grass and woods fires, starting

downwind and working back toward the facility).

Local authorities estimated that equipment and supplies valued at

more than $250,000 were consumed or damaged during the

firefighting efforts.

1.8.2 Facility Damage

The explosion and ensuing fire heavily damaged the compounding

section of the Kinston facility. Photographs below and in the

remaining sections of this report show the extent of damage. All

exterior sheathing on the compounding structure was destroyed.

Masonry block walls were knocked down, the warehouse collapsed, and the building was rendered mostly unusable (Figures 6

and 7).

All exterior sheathing on

the compounding structure was

destroyed. Masonry block walls

were knocked down, the

warehouse collapsed, and

the building was rendered

mostly unusable. mostly unusable.
28

Figure 6. Roof of facility, with two-story compounding section

in background.

Figure 7. Remains of ACS warehouse viewed

from compounding area.
29

1.8.3 Facility Relocation

Fourteen months after the explosion, West relocated to an available industrial facility several miles south of the destroyed plant.

Some equipment that was not used in the compounding process

was salvaged from the original plant and is in use at the new

location, and much of the workforce was rehired. At present,

however, the destroyed facility and the compounding machinery

are not in use.

West is not compounding rubber at the new facility. Rubber

strips are being produced by contract manufacturers or at other

West facilities and are shipped to Kinston for molding. Fourteen mont een months after the

explosion, West relocated to an

available industrial facility

several miles south of the

destroyed plant. destroyed plant.
30
31

2.1 Fuel for Explosion

Witness statements and photographs submitted by West

indicate that the visible accumulation of dust in the milling

area was minimal—even around the batchoff machines. Although

the cleaning crew continuously cleaned the areas around the

equipment, several employees told CSB investigators of a layer of

dust on top of the suspended ceiling, above the room where the

rolling mills and batchoff machines were located. Accumulation

was reported to be widespread but heaviest in the areas directly

above these machines.

Accounts from individual witnesses varied. Employee references

to dust accumulations of 0.25 inch were common, but other

witnesses described heavier accumulations—such as 0.5 inch or

more. One individual who had performed a maintenance job

above the ceiling in the months prior to the incident recalled

seeing as much as 2 inches of powder in some areas. Another

person, who had been above the ceiling 2 weeks before the explosion, estimated an accumulation of up to 0.5 inch across 90

percent of the ceiling area. The company investigation concluded

that the overall dust accumulation ranged from 0.125 to 0.25 inch

in depth.

The area above the ceiling also contained pneumatic conveying

lines for the calcined clay and other high-volume noncombustible

powders used in the mixers. Because these lines were reported by

employees to have leaked on at least one occasion, it is possible

that some of the dust accumulation above the ceiling was noncombustible material.

The batchoff machine was a source of fugitive emissions11 of

combustible dust.12 Fans blew air across the rubber strip to cool

and dry it as it passed through the machine. Some portion of the

antitack agent was carried on air currents into the room, where it

tended to settle on surfaces. The cleaning crew continuously

2.0 Analysis of Incident

11Fugitive emissions are those released to the air other than from stacks or

vents. Examples include equipment leaks, evaporative processes, and windblown disturbances.

12The National Fire Protection Association (NFPA) Standard 654 defines

combustible dust as any finely divided solid material 420 microns or less in

diameter that presents a fire or explosion hazard when dispersed and ignited in

air.

Although the cleaning crew

continuously cleaned the areas

around the equipment, around the equipment,

several employees told CSB

investigators of a layer of investigators of a layer of

dust on top of the

suspended ceiling . . . suspended ceiling . . .

Fans blew air across the rubber

strip to cool and dry it as it y it as it

passed through the [batchoff]

machine. Some portion of the

antitack agent was carried on air

currents into the room, where it currents into the room, where it

tended to settle on surfaces. tended to settle on surfaces.
32

wiped and vacuumed the dust from surfaces so that the area was

generally free of visible accumulation.

The comfort air system created a slight negative pressure above

the suspended ceiling, and room air was pulled into this zone,

where conditions were favorable for the settling of dust. West

changed out large areas of ceiling tiles from time to time—

primarily for aesthetic reasons because they tended to discolor.

However, the frequency of replacement was insufficient to address dust accumulation. There was no organized cleaning

program for surfaces of beams, conduits, and other features

above the ceiling.

CSB investigators recovered a sample of the antitack slurry agent

from the dip tank of one of the batchoff machines. It was sent to

Safety Consulting Engineers, Inc. (SCE), in Schaumburg, Illinois,

where it was dried to a powder under vacuum and tested for

combustibility in accordance with American Society for Testing

and Materials (ASTM) guidelines. Dispersions of the powder in

air were confirmed to be combustible. (See Appendix A for test

results.)

Because no other material capable of producing such a large

explosion was present or used at the plant, CSB concludes that

accumulated polyethylene dust above the ceiling tiles fueled the

explosion. Section 2.1.1 presents supporting data for this conclusion. Several other possibilities were investigated and determined

to be not credible, as described in Section 2.1.2.

2.1.1 Polyethylene Dust: The Only Credible

Fuel for Explosion

There is general agreement in the scientific literature that a dust

explosion requires the following five simultaneous conditions:

 Combustible dust (of sufficiently small particle size)

 An oxidizer (such as air)

 Dispersion of the dust (into air)

There was no organized

cleaning program for surfaces

of beams, conduits, and other

features above the ceiling. features above the ceiling.

Dispersions of the [antitack

slurry agent] powder in air

were confirmed to be

combustible. combustible.

. . . CSB concludes that . . . CSB concludes that

accumulated polyethylene dust accumulated polyethylene dust

above the ceiling tiles fueled

the explosion. the explosion.
33

 A confined environment (such as a building)

 An ignition source.

These requirements are sometimes represented as a pentagon

(Figure 8), similar in concept to the well-known fire triangle.

Eckoff (1997) explains that the concentrations of dust in air

required to create an explosive mixture are so high that a

combustible cloud will appear opaque to an observer at close

range. The minimum explosive concentration is typically a

thousand or more times higher than that which would cause

employee discomfort or hygiene concerns.

During interviews, West employees described no such visible

dispersions of dust in the air. Thus, it is not a realistic possibility

that explosive concentrations of dust were normally present in

production areas of the plant, including the area around the

batchoff machines. It is apparent that accumulated polyethylene

dust above the ceiling tiles was the only fuel source available for

such a large explosion. CSB investigators were unable to conclusively determine what dispersed the dust to create an explosive

cloud.

Figure 8. Dust explosion pentagon.

During int ing interviews, West

employees described no . . . employees described no . . .

visible dispersions of dust in the

air. Thus, it is not a realistic

possibility that explosive

concentrations of dust were

normally present in production

areas of the plant . . . areas of the plant . . .

Fuel Ignition

Dispersion Confinement

Oxidizing substance

(such as air)
34

Resting accumulations of combustible dusts are known to be

hazardous:

 NFPA Standard 654, Standard for the Prevention of Fire and

Dust Explosions From the Manufacturing, Processing, and

Handling of Combustible Particulate Solids (2000), explains

that a 1/32-inch dust accumulation over the floor area of a

room, if uniformly suspended, can create a 10-foot-high

cloud of optimal explosive concentration. It warns that

accumulations may be hazardous when they exceed just 5

percent of the floor area (e.g., on exposed beams and joists).

 The Health and Safety Executive of the United Kingdom

warns (HSE, 2003):

The most important mitigation measure is

maintaining the process building in a clean

condition . . . Do not neglect the highest parts of

buildings as these are the areas where the finest

and most hazardous dust can be found.13

2.1.2 Other Fuel Sources Considered

The following potential fuel sources were considered by CSB but

determined to be not credible for the reasons given:

 Flammable liquid: No flammable liquids were stored in

the compounding area, other than a water-alcohol solution

used for cleaning that was dispensed from small-volume

containers.

 Natural gas: The natural gas piping for the facility did not

traverse the area of the explosion; the zone through which it

passed was essentially undamaged during the event. The

surviving witnesses did not report the smell of natural gas

odorant prior to the explosion.

13HSE also specifies a dust accumulation layer that is considered to be

hazardous (i.e., 1/84 inch over 100 percent of an area). Although such an

accumulation is thinner than the NFPA limit, this amount of dust over an entire

floor represents greater total dust mass than the NFPA limit of 1/32 inch over

5 percent of the floor area.

NFPA 654 . . . warns that

[a 1/32-inch dust [a 1/32-inch dust

accumulation] may be

hazardous when [it exceeds]

just 5 percent of t cent of the floor area

(e.g., on exposed beams and

joists). joists).

[HSE warns]: “Do not neglect [HSE warns]: “Do not neglect

the highest parts of buildings as

these are the areas where the

finest and most hazardous dust finest and most hazardous dust

can be f can be found.”

The natural gas piping for the

facility did not traverse the area

of the explosion . . . of the explosion . . .
35

 Propane cylinders: Propane in small-volume cylinders was

used as a fuel for lift trucks and floor sweepers within all

production areas of the West facility. Investigators searched

the rubber compounding area in which the explosion occurred, but found no evidence of a failed or leaking cylinder.

The warehouse fire following the explosion eventually

affected the propane fuel cylinders, causing at least one to

explode. However, witnesses reported this explosion to have

occurred well after the initial blast, and it was not close to

the primary explosion.

 Other combustible dust: The majority of the powders used

in the West plant were not combustible, such as silicon

dioxide, barium sulfate, calcined clay, and titanium

dioxide—which were added to the rubber mixers in large

quantities. Small quantities of combustible powders, such

as sulfur, were added to certain rubber batches. Local

exhaust ventilation drew dust emissions from the kitchen

and second-floor mixing areas to exterior dust collectors.

CSB investigators recovered samples from the dust collectors for

combustibility testing. The samples are very likely representative

of general dust in the facility, excluding dust generated at the

batchoff process. Although the samples contained fractional

amounts of combustible materials, they were determined to be

noncombustible in aggregate.

2.2 Center of Explosion

Dust explosions are infrequently a single event; they often

comprise sequential explosions that quickly follow each other.

The subsequent events—known as secondary explosions—typically

occur when the initial pressure wave disperses dust into the air,

and the resulting mixture is ignited by the advancing flame front

from the earlier event. Because of this phenomenon, it can be

difficult to determine the quantity and sequence of explosions.

CSB investigators determined that the January 29 explosion

occurred in the compounding section of the plant. Moreover, the

location of the highest pressure was determined to be just east of

The majority of the powders

used in t used in the West plant were not

combustible . . . Small combustible . . . Small

quantities of combustible

powders, such as sulfur, were

added to certain rubber batches. added to certain rubber batches.

CSB investigators recovered

[representative] samples from

the dust collectors for

combustibility testing . . . they

were determined to be

noncombustible in aggregate. noncombustible in aggregate.

. . . The location of the highest . . . The location of the highest

pressure was determined to be

just east of mill #1.
36

mill #1 (Figure 9). Force vectors derived from observed damage

to the building and surrounding equipment indicate that the

largest pressure developed in the compounding section and

emanated spherically outward (Figure 10). Appendix B describes

the damage patterns CSB used to estimate the directions and

magnitude of explosive force.

CSB investigators also recovered ceiling tiles from debris in the

plant and from surrounding areas.

 Nearly all of the tiles appeared to be burnt and splattered on

the top—but not on the bottom, which had faced the room

below.

 Some of the fluorescent light fixture pans recovered from

the mill #1 area were flattened from above, as if they had

been forcefully driven downward to the concrete floor.

These two items of evidence further support the theory that

the explosion occurred within the confined space above the

suspended ceiling.

Some of t Some of the fluorescent light escent light

fixture pans . . . were flattened

from above, as if they had been

forcefully driven downward to

the concrete floor.

Nearly all of the [ceiling] tiles

appeared to be burnt and

splattered on the top. splattered on the top.
37

Figure 9. Estimated zone of maximum explosive force.

Warehouse

Shops

Finishing

Batchoff 2

Batchoff 1

shoved

westward

Mill 1

Mill 2

Kitchen

Corridor

Zone of

maximum

explosive force
38

Figure 10. Location of maximum explosive force.

A consultant to CSB used a computational fluid dynamics (CFD)

model together with building design details and damage patterns

in an attempt to visualize the Kinston accident. However, because

such modeling cannot completely account for the complex

dynamics of a dust explosion, the CFD model was used only

qualitatively, to verify that:

 The explosion occurred on the first floor of the rubber

compounding area.

 The explosion pressure from this area was the source of

blast damage throughout the facility.

The explosion pressure

from . . . [the rubber

compounding] area was the

source of blast damage

throughout t oughout the facility.
39

2.3 Acceleration of Fire

The sprinkler system—designed to mitigate incipient fires within

the plant—was rendered inoperable from the outset of the incident because the explosion broke feeder lines to the system.

Emergency responders reported hearing water freely flowing into

the structure.

Rubber and other raw materials were stored in a warehouse

southeast of the kitchen and compounding area (Figure 1). The

thermal effect from the explosion likely reached this area, igniting

incipient fires. Eventually, the entire warehouse was fully engulfed in flames. Heat from the fire caused most of the steel

framing to yield and collapse.

West stored mineral oil14 in two 7,500-gallon plastic tanks located

between the kitchen and the warehouse. These tanks failed,

spilled their contents, and burned to the ground. The release of

combustible liquid further fueled the fire in the warehouse. Two

additional but smaller plastic tanks containing mineral oil were

located near the warehouse; they, too, failed and contributed fuel

for the fire. The concrete masonry retention walls around the

tanks failed and did not prevent the burning oil from spreading.

2.4 Initiating Event

CSB believes that the accumulation of combustible dust above the

suspended ceiling is the most important safety issue in the West

incident. Because it is virtually impossible to eliminate all

ignition sources from an industrial setting, preventing the accumulation of fuel provides the best protection against fires and

explosions.

The extent of damage to the Kinston facility made it extremely

difficult to definitively determine the event that dispersed the

dust or what ignited it (Figure 11). Investigators focused on the

most pertinent hazard—the accumulation of combustible dust—

and considered the initiating event as a matter of secondary

14The mineral oil had a flash point greater than 200 degrees Fahrenheit (oF).

NFPA 30, Flammable and Combustible Liquids Code (1996), classifies such

materials as Class IIIB liquids, which do not ignite below the flash point;

however, once ignited, they burn vigorously.

The sprinkler system . . . was

rendered inoperable from the

outset of the incident because

the explosion broke feeder

lines to the system. lines to the system.

West stored mineral oil in two

7,500-gallon plastic tanks . . . s . . .

These tanks failed, spilled their

contents, and burned to the

ground. The release of ground. The release of

combustible liquid further

fueled the fire in the warehouse. fueled the fire in the warehouse.

. . . The accumulation of . . . The accumulation of

combustible dust above the

suspended ceiling is the most suspended ceiling is the most

important safety issue in the

West incident. t incident.
40

importance. CSB was unable to determine whether any of the

following theories may have been the actual initiating event:

 Overheating of a batch of rubber and subsequent ignition of

the vapors produced by thermal decomposition.

 Ignition of the dust layer by an overheated electrical ballast

or light fixture.

 Ignition of the dust layer by an electrical spark from an

unidentified electrical fault.

 Unsettling of dust in a cooling air duct for an electric motor

and subsequent ignition of the dust by the motor.

Appendix C further discusses these theories.

Batchoff area

Figure 11. Extensive damage and debris near mill

and batchoff machine #1.

Batchoff area

CSB was unable to determine

whether any of the following

theories may have been the

actual initiating event: actual initiating event:

 Overheating of a batch of Overheating of a batch of

rubber and subsequent rubber and subsequent

ignition of the vapors . . . ignition of the vapors . . .

 Ignition of the dust layer

by an overheated electrical by an overheated electrical

ballast or light fixture. ballast or light fixture.

 Ignition of the dust layer

by an electrical spark . . . by an electrical spark . . .

 Unsettling [and ignition]

of dust in a cooling air duct of dust in a cooling air duct

for an electric motor . . . for an electric motor . . .

The extent of damage . . . The extent of damage . . .

made it extremely difficult to

definitively determine the event definitively determine the event

that dispersed the dust or what that dispersed the dust or what

ignited it. ignited it.
41

2.5 Engineering

The construction of a new production facility may involve the

integration of product and process development with building

design. The West corporate engineering department focused on

product development. Outside firms conducted detailed process

and facility design for the Kinston compounding project, as well

as construction.

The West corporate engineering group developed the concept for

the new compounding process to be built at Kinston. However,

West relied on several engineering contractors for design, planning, and implementation. For example, one firm designed the

material handling and mixing systems, while another designed the

building and overall facility. The batchoff machines were a

common design used in various industries. West purchased the

batchoff machines directly from the manufacturers.

West corporate chemists developed the formulations for the

rubber and specified the powders to be used in antitack solutions.

Zinc stearate is used as an antitack agent in the rubber industry,

and West had used it in dry powder form for other purposes—well

before the automated rubber compounding system (ACS) was

built. However, when West purchased the batchoff machine

(which used blown air for drying and cooling), the hazardous

properties of zinc stearate with respect to its use in the manufacturing process and building were not fully evaluated.

NFPA 499, Recommended Practice for the Classification of

Combustible Dusts and of Hazardous (Classified) Locations for

Electrical Installations in Chemical Process Areas (1997), identifies zinc stearate as a combustible dust. However, the material

safety data sheet (MSDS) for zinc stearate slurry—used by West

corporate personnel to evaluate the material as an antitack

agent—did not include combustible dust warnings.

Any building that contains a process that produces or uses a

material classified as a combustible dust should be designed in

accordance with relevant codes and standards. In this case, the

1982 version of NFPA 654, Standard for the Prevention of Fire

and Dust Explosions in the Chemical, Dye, Pharmaceutical, and

Plastics Industries—available when the process was designed—

The West corporate engineering

group developed the concept group developed the concept

for the new compounding

process . . . However, West

relied on several engineering

contractors for design, planning, contractors for design, planning,

and implementation. and implementation.

. . . When West purchased t hased the

batchoff machine (which used

blown air f wn air for drying and

cooling), the hazardous

properties of zinc stearate with

respect to its use in the

manufacturing process and

building were not fully

evaluated. evaluated.

. . . [The] MSDS for zinc

stearate slurry—used by West

corporate personnel to evaluate

the material as an antitack

agent—did not include

combustible dust warnings. combustible dust warnings.
42

contained comprehensive guidance on measures to control the

hazards of combustible dusts.

Although there was no fire code in force in North Carolina in

1985—when the ACS was built—best engineering practice calls for

reference to available codes and standards regardless of whether

they are adopted by local regulation. West managers relied on the

engineering design firms to ensure that the work met all applicable codes and standards, though West itself was positioned to

most fully understand the materials and their use in the manufacturing process.

There is no evidence that West engineers were involved in reviewing the potential hazards posed by replacing zinc stearate with

polyethylene as the antitack agent. A comprehensive engineering

review following development of the new formulation could have

served as an opportunity to identify the associated combustible

dust hazard and to implement the precautionary measures

described in available codes and standards.

West did not conduct a formal project safety review of the ACS

process at the time of design. Although formal project safety

reviews are widely accepted in industry today, they were not

common practice in general manufacturing in 1985—nor were the

concepts of process safety as widely known outside the chemical

industry as they are today.

For example, West currently makes occasional use of failure

modes and effects analysis (FMEA)15 as a tool for evaluating

some processes. Likewise, many manufacturing companies make

project management responsible for adhering to internal hazard

assessment policies as well as external codes and standards.

Today, formal safety reviews are increasingly common during the

design, engineering, and construction of processes. Such reviews

can help identify the hazards of materials such as combustible

dust and alert project management to the need to avoid inappropriate design features for dusty areas (e.g., unsealed suspended

ceilings). West was not required by statute or regulation to

15FMEA is one of the systematic analysis methods recognized by OSHA for

process hazard analysis in the chemical process industry (20 CFR 1910.119

(e)).

. . . The 1982 version of NFPA

654. . . available when the

process was designed—

contained comprehensive

guidance on measures to

control the hazards of control the hazards of

combustible dusts. combustible dusts.

West managers relied on t elied on the

engineering design firms to

ensure that the work met all ensure that the work met all

applicable codes and standards, applicable codes and standards,

though West itself was

positioned to most fully

understand the materials and

their use in the manufacturing

process. process.
43

perform these reviews when the ACS was constructed, nor would

it be similarly required to do so today.

Before new materials are introduced into a manufacturing

process or workplace, it is important to review them for hazards

and potential safety issues. Reviews of this type typically consider

the information contained in MSDSs and in more comprehensive

technical and scientific literature.

West has a formal management system in place for conducting

new material reviews. Corporate personnel consider potential

safety issues before new materials are introduced. Reviews are

performed by a committee and approved by the regulatory affairs

administrator, quality control chemists, and product group

manager. The focus is primarily, but not exclusively, on toxicity

issues and U.S. Food and Drug Administration (FDA) requirements.

In 1990, West corporate personnel reviewed Acumist, a fine

polyethylene powder,16 for use in limited quantities as a dusting

agent. Several years later, another review was conducted for the

use of a slurry containing Acumist in water suspension to replace

the zinc stearate slurry as the antitack agent in the batchoff

machine. Neither review identified the associated combustible

dust hazard.

To understand why the reviews did not identify combustible dust

hazards, it is useful to review the company’s use of the material

as an antitack agent.

The following chronology (pages 44–45) outlines West’s history

of assessing and using antitack agents (see Appendix E for a

timeline):

16This was a micro-fine grade of an average particle size of 12 microns,

referred to as “micronized.”

2.6 New Material

Safety Review

Before new materials are

introduced into a manufacturing

process or workplace, process or workplace,

it is important to review them

for hazards and potential for hazards and potential

safety issues. safety issues.
44

1987

The ACS is first put into operation at West’s Kinston facility. Zinc stearate, in

a preformulated aqueous slurry called Namicote, is used as the antitack agent

for the rubber strips. The MSDS for Namicote does not include dust hazard

warnings. According to currently available MSDSs and NFPA standards, zinc

stearate in dry powder form is a combustible dust.

1990

West corporate conducts a new material review of Acumist powder for use

as a directly applied dust for trials of Teflon-coated rubber stoppers at a St.

Petersburg, Florida, manufacturing facility. The 1988 MSDS for Acumist is

referenced in this review. The MSDS states:

v “Avoid conditions that create high levels of product in the air in a closed

room as a dust explosion hazard can exist.”

v “Sweep up with a minimum of dusting. Remove ignition sources. Keep

away from heat or flame.”

The MSDS does not refer readers to NFPA 654; however, the section on

“Fire and Explosion” hazards states:

v “High levels of product in the atmosphere may present a dust explosion

hazard. Appropriate precautions should be observed.”

West consults a technical data sheet included with the MSDS, “Static Electricity and Fine Particle Size Polyethylene Waxes.” The data sheet addresses

static electricity and the hazard of using the polyethylene with solvents. It

does not mention that the polyethylene powder is, itself, a combustible

material. It states that housekeeping is of prime importance but does not

explain that accumulations of the powder pose a hazard of dust explosion.

The housekeeping warning in the MSDS may be unclear because it is presented in the context of static electricity hazards.

West intends to use the polyethylene powder as a directly applied dust agent

in small quantities and in a manner that is unlikely to result in static electricity

or significant fugitive dust emissions.17

Use of Antitack Agents at Kinston Facility

17West managers told CSB investigators that they did not consider the hazards outlined in

the MSDS and technical data sheet to be relevant to their intended use of the material.
45

18Crystal, Inc.–PMC is a subsidiary of PMC Group International, Inc., based in Lansdale,

Pennsylvania. It manufactures or blends waxes, oils, soaps, and detergents.

1992

West comes into possession of a revised MSDS for Acumist, dated March

1990. The “Fire and Explosion” section advises users to consult NFPA 654.

The review committee does not refer to the revised MSDS because West is

already using the product and the material was previously reviewed. However, the MSDS is transmitted to personnel at the Kinston plant.

1994

West corporate staff directs suppliers to develop formulations to replace the

zinc stearate antitack slurry in the batchoff machines with a slurry containing

Acumist polyethylene powder. West contracts with Crystal, Inc.–PMC18 to

produce a concentrated water-based paste of polyethylene powder.

Crystal produces an MSDS for the water-based paste, describing it as a

benign substance without health or safety risks. The MSDS contains no

combustibility warnings, though Crystal understands the end use of the

material and is aware that fine polyethylene powder is combustible.

West corporate staff conducts a new material review for the polyethylene

paste produced by Crystal, referring to the Crystal MSDS. The review team

notes that the polyethylene powder ingredient—Acumist—was reviewed in

1990 and decides not to re-evaluate it. The current review excludes a

specific engineering component to consider how using this material as an

antitack agent in the batchoff machine rather than as a dusting agent may

create different conditions (i.e., the polyethylene is used in greater quantities in the batchoff machine, and there is greater potential to release it into

the air.)

1996

The Kinston facility begins using the polyethylene slurry as the antitack agent

to coat rubber strips. Kinston employees dilute the paste with water to

obtain the desired slurry consistency before adding it to the batchoff dip

tank.
46

As detailed below, the new material reviews West conducted on

Acumist as a dusting agent (in 1990) and on a paste containing

Acumist as an antitack agent (in 1994) did not identify combustible dust hazards or lead to the mitigation of dust hazards:

 The technical information available at the time the Acumist

polyethylene powder was first reviewed for use as a dusting

agent contained some hazard warnings regarding combustible dust; however, the warnings were not considered to be

relevant in the minor application envisioned.

 The second review failed to identify the dust hazard

associated with an antitack slurry containing polyethylene

powder. The committee did not review the documentation

from the earlier review and considered only the properties

of the aqueous paste and the MSDS supplied by Crystal

(which contained no combustible dust warnings). The

revised 1990 Acumist MSDS—which contained the reference

to NFPA 654—was not referred to.

2.7 Previous Incidents

CSB investigators learned that in an earlier maintenance

operation involving welding, polyethylene powder in proximity to

the batchoff machine had ignited, but the fire self-extinguished.

This event demonstrated that the powder was ignitable.

There is no documented investigation of the welding incident.

A comprehensive incident investigation, with documentation and

sharing of lessons learned, might have led to broader awareness

of combustible dust hazards. Given that West went to great

lengths to keep working areas clean and free of dust accumulation, it is likely that West also would have cleaned above the

ceiling had it understood the hazard posed by settled dust.

. . . The new material reviews

West conduct t conducted on Acumist

as a dusting agent (in 1990)

and on a paste containing

Acumist as an antitack agent Acumist as an antitack agent

(in 1994) did not identify

combustible dust hazards or

lead to the mitigation

of dust hazards. of dust hazards.

Given that West went to great

lengths to keep working areas

clean and free of dust clean and free of dust

accumulation, it is likely that accumulation, it is likely that

West also would have cleaned

above the ceiling had it above the ceiling had it

understood the hazard posed

by settled dust. by settled dust.
47

Fire codes protect the public and property by conveying basic

facility safety requirements. Two codes are commonly used

in the United States:

 National Fire Codes, published by NFPA.

 International Fire Code (IFC), published by the International Code Council (ICC).

Both sets of codes address the hazards of combustible dusts.

States, localities, and cities typically set minimum fire safety

standards by adopting a code or by incorporating one by reference into regulations or administrative requirements. In 1991,

North Carolina adopted the Standard Fire Prevention Code,

published by the Southern Building Code. In 1994, the Southern

Building Code Congress International, Inc., merged with other

code organizations to form ICC. In 2000, this council revised

IFC, which the State of North Carolina adopted in 2002.

3.1.1 Combustible Dusts

The National Fire Codes and IFC each have a distinct approach to

addressing dust hazards:

 The National Fire Codes are written in directive language

and are highly prescriptive. Several NFPA standards set out

specific minimum technical measures for managing the

hazards of agricultural dusts, powdered metals, coal dust,

sawdust, and chemical and plastic dusts.

NFPA 654, Standard for the Prevention of Fire and Dust

Explosions From the Manufacturing, Processing, and

Handling of Combustible Particulate Solids (2000), and its

predecessors are pertinent to the situation at West. They

specify engineering and construction requirements for dusttight segregation of hazardous building zones, classification

of electrical equipment in dusty areas, and special air

conditioning requirements and explosion venting—in addition to recommending management systems for fugitive

3.0 Regulatory Analysis

3.1 State Fire Safety

Regulations

. . . The State of North Carolina

adopted [the International Fire

Code] in 2002. Code] in 2002.

NFPA 654 . . . and its

predecessors are pertinent to

the situation at West.
48

dust emissions, associated housekeeping, and employee

training. The 2000 edition of NFPA 654 requires retroactive

application of the requirements for training, management of

change, and housekeeping.

 Except for very limited treatment of housekeeping and

ignition source precautions, IFC Chapter 13, “Combustible

Dust-Producing Operations,” does not include specific

engineering and management system measures to control

combustible dust hazards. Unlike the extensive hazard

coverage in various NFPA standards, IFC contains only a

single page of text on combustible dust.

Chapter 13 references various NFPA standards for combustible dust hazards. Instead of mandating compliance with

these standards, however, IFC “authorizes” the “code official” (the government authority having jurisdiction) to

enforce “applicable provisions” of NFPA standards on a caseby-case basis to prevent and control dust hazards. IFC

promotes this activity by requiring that a government

authority issue an operating permit to facilities that use or

generate combustible dust.

When North Carolina adopted IFC in 2002, it made numerous

amendments to the code—including making permits optional for

industrial facilities that use or generate combustible dusts. Although local authorities determine whether permits are required,

local fire officials are not necessarily involved in determining

what protective measures facilities may take to control dust

hazards. Some North Carolina localities require permits for

facilities that use or generate combustible dusts; however, Lenoir

County does not.

3.1.2 Combustible Liquids

IFC addresses the storage of combustible liquids inside structures

by incorporating NFPA 30, Flammable and Combustible Liquids

Code (1996). It recommends that storage tanks be made of steel

or some other noncombustible material. Tanks made from

combustible material, such as plastic, are allowed by exception

Unlike the extensive hazard

coverage in various NFPA

standards, IFC contains only

a single page of text a single page of text

on combustible dust. on combustible dust.

Some North Carolina localities

require permits for facilities

that use or generate

combustible dusts; however,

Lenoir County does not. Lenoir County does not.
49

for Class IIIB liquids only—provided that the facility owner

obtain approval from the local code enforcement authority.

For this class of liquids, the building must be equipped with an

approved automatic fire extinguishing system; however, safeguards for the control of spillage, such as diking, are not required.

West stored mineral oil—a Class IIIB combustible liquid—in two

7,000-gallon plastic tanks and two 300-gallon plastic tanks located

inside the building, near the warehouse (Figure 1). The tanks

were surrounded by dikes constructed of concrete masonry units.

However, because the tanks were installed before North Carolina

adopted IFC, there was no legal requirement for West to seek

approval of the local authority.

Although the Kinston facility had a sprinkler system, as required

by NFPA 30, it was rendered inoperable due to damage from the

explosion. As discussed earlier, the mineral oil tanks released

their combustible contents following the initial explosion and

fire—at which point, the liquid added additional fuel to the fire in

the ACS warehouse.

3.1.3 Fire Inspectors

Local authorities conduct fire safety inspections of commercial

facilities in North Carolina. Inspectors are certified according to

State standards set by the North Carolina Code Officials Qualification Board. Inspectors are trained to three levels of competency. Inspection officials told CSB investigators that their

familiarity with combustible dust hazards and control measures

was limited—even at the third level of competency. Current

training programs contain only minimal coverage of dust hazards

and control measures.

West stored mineral oil—a Class

IIIB combustible liquid—in two

7,000-gallon plastic tanks and

two 300-gallon plastic tanks

located inside the building . . . located inside the building . . .

However, because t , because the tanks

were installed before North

Carolina adopted IFC, there was

no legal requirement f ement for West

to seek approval to seek approval

of the local aut he local authority.
50

3.2.1 Combustible Dusts

OSHA promulgated a dust standard for grain-handling facilities in

1987, in response to repeated loss of life from grain elevator

explosions. Similarly, the Mine Safety and Health Administration

has issued standards for coal dust. Other than these regulations,

however, no specific Federal program provides for safety standards to prevent and control the hazards of combustible dusts in

industry.

Section 18 of the Occupational Safety and Health Act of 1970

encourages states to develop and operate job safety and health

programs. OSHA approves and monitors these state plans.

North Carolina is one of 26 states that have adopted a state OSHA

plan.

In areas where OSHA does not exercise regulatory authority,

states are permitted to adopt their own regulations, with OSHA

approval. No specific combustible dust regulations exist in North

Carolina beyond those in the Federal standards. Following the

explosion, NCOSHA reached a settlement with West for a single

violation of the employer’s general duty to provide a safe workplace for employees.

NCOSHA inspected the Kinston facility in fall 2002 and cited

West for allowing employees to use compressed air hoses to blow

dust from their clothing (i.e., as an impact and eye injury

hazard). The inspectors were unaware of the existence of combustible dusts in the facility. Moreover, inspectors also told CSB

that they had limited understanding of combustible dust hazards

beyond sawdust and grain dust.

3.2 Federal and

State Occupational

Safety and Health

Regulations

. . . No specif o specific Federal program

provides for safety standards

to prevent and control the

hazards of combustible dusts

in industry.

Following the explosion, xplosion,

NCOSHA reached a settlement NCOSHA reached a settlement

with West for a single violation

of the employer’s general duty

to provide a safe workplace

for employees. for employees.

No specific combustible dust No specific combustible dust

regulations exist in North

Carolina beyond those in the

Federal st andards.
51

3.2.2 OSHA Hazard

Communication Standard

The OSHA Hazard Communication Standard (HazCom; 29 CFR

1910.1200) requires chemical manufacturers to evaluate chemicals produced or handled in their workplace and to communicate

the associated hazards—through MSDSs, labeling, and training—

to exposed employees. MSDSs should accurately reflect the basic

hazards of chemical products and contain generally applicable

precautions and control measures. Manufacturers and distributors must label their products and transmit associated MSDSs to

downstream customers.

In addition, the HazCom inspection procedures directive CPL

2-2.38, paragraph (d)(1)(a), states that the hazard determination

conducted by chemical manufacturers:

. . . must consider the potential exposures that may

occur when downstream employers use the product,

and address the hazards that may result from that use

on the label and MSDS prepared for the product.

Employers that are not chemical manufacturers must communicate hazard information to exposed employees using MSDSs,

labeling, and training. HazCom also requires any employer using

hazardous materials to make MSDSs readily accessible to exposed

employees.

Although the Kinston plant had the 1990 MSDS for Acumist, CSB

interviews of workers revealed that West’s training had not

informed them of combustible dust hazards. The system of

safety is best served by well-informed workers, who are more

likely to identify accumulations of combustible dust in less

traveled plant areas and to raise their concerns to management.

As noted above, HazCom requires chemical manufacturers like

Crystal to address the downstream hazards of their products.

CSB found that Crystal was aware of the end use of the polyethylene slurry it sold to West; and also aware that, when dry, it was a

combustible dust. However, the Crystal MSDS for the slurry

contained no combustibility warnings and addressed only the

potential hazards of the aqueous slurry itself.

Although the Kinston plant had

the 1990 MSDS f 990 MSDS for Acumist,

CSB int CSB interviews of workers

revealed t ealed that West’s training

had not informed them of had not informed them of

combustible dust hazards. combustible dust hazards.

. . . Crystal was aware of the

end use of the polyethylene

slurry it sold t y it sold to West; and also

aware that, when dry, it was a

combustible dust. However, the

Crystal MSDS f al MSDS for the slurry

contained no combustibility

warnings and addressed only

the potential hazards

of the aqueous slurry itself. y itself.
52

Beyond U.S. Bureau of Mines information, CSB found little

Federal guidance on the hazards of combustible dust. European

agencies, such as HSE in the United Kingdom, do publish guidance on combustible dust.

Following the explosion at West, NCOSHA published a brief

industry alert on combustible dust.19 This 2-page document

summarizes the hazards of combustible dust explosions; the

reader is referred to the National Fire Codes and National Electric

Code (NEC; NFPA 70 [2002]) for further information.

As discussed in Section 3.1.1, NFPA 654 (2000) lists several

measures for preventing or mitigating dust explosions. Specific

elements that apply to the circumstances at West are noted below:

 Separate areas in which combustible dusts are processed or

handled from other areas.

 In areas in which combustible dusts are processed or

handled, seal dust-tight all penetrations of floors, walls,

ceilings, or partitions.

 Seal areas inaccessible to housekeeping to prevent dust

entry.20

 Equip processes that generate dust with dust collectors.

 Classify areas where a hazardous quantity of dust accumulates or is present in suspension in air in accordance with

NEC (NFPA 70; 2002).

 Routinely conduct initial and refresher dust hazard training.

19This document is available at www.dol.state.nc.us/osha/etta/CombDust.pdf.

20Earlier versions of NFPA 654 (1982) advise: “Concealed spaces shall be

sealed to prevent dust accumulation.” The space above the suspended ceiling in

the mill/batchoff area was such a concealed space.

3.3 Guidance

Documents
53

Early in the investigation, it became apparent to CSB investigators

that it would have been difficult for an uninformed observer or

inspector to identify the combustible dust explosion hazard at the

Kinston facility. The hazardous dust had accumulated above the

suspended ceiling, out of sight. The working areas were regularly

cleaned. Even if inspectors had noticed the dust—without knowing that its source was the antitack slurry at the batchoff, and

without knowledge of the properties of the antitack component—

it was not obvious that the dust was combustible.

Several safety inspectors visited the facility but did not recognize

or identify the hazard. Among these professionals were the

following:

 An industrial hygienist hired to evaluate employee inhalation exposure to dusts, who did not include any mention of

combustible dusts in his report.

 NCOSHA officials, who inspected the facility 2 months

before the explosion but did not observe the dust accumulation.

 Risk insurance carriers, who inspected the facility and

pointed out the need to remove dust from sprinkler heads

but did not mention combustible dust hazards in their

reports.

3.4 Combustible Dust:

A Hazard Not Readily

Apparent

Early in the investigation, Early in the investigation,

it became apparent to CSB

investigators that it would have

been difficult for an uninformed

observer or inspect er or inspector to

identify the combustible dust identify the combustible dust

explosion hazard

at the Kinston facility.

Even if inspectors had noticed

the dust—without knowing that the dust—without knowing that

its source was the antitack

slurry at the batchoff, and

without knowledge of the

properties of the antitack

component—it was not obvious

that the dust was combustible. that the dust was combustible.
54
55

Accumulations of combustible dust within industrial facilities

create the potential for severe dust explosions. The most

serious hazards may actually be secondary explosions, which

occur when building vibrations or gases produced by a smaller

explosion disperse dust on surfaces into the air. The dispersed

dust cloud is subsequently ignited by the advancing flame front of

the initial explosion or by other ignition sources. Secondary

explosions can be devastating because they tend to bring large

amounts of dust into involvement.

Five recent dust explosions are briefly described below:

 Jahn Foundry, Springfield, Massachusetts: Powdered

plastic resin used as a sand binding agent had accumulated

on surfaces in the mold fabrication room of a foundry. On

February 25, 1999, the shock from an initial explosion in a

dust extraction duct dispersed the accumulated resin into

the air, setting up secondary explosions. Twelve employees

were severely burned; three of these victims later died. The

explosion blew out walls of the building and lifted the roof.

 Ford Motor Company, River Rouge Plant, Dearborn,

Michigan: On February 1, 1999, a natural gas explosion in

an idle power boiler at the River Rouge plant disturbed coal

dust that had accumulated on surfaces. The result was a

large secondary dust explosion. Six workers were killed,

and 14 were seriously injured.

 Rouse Polymerics International Inc., Vicksburg,

Mississippi: On May 16, 2002, a secondary dust explosion

occurred at a Rouse recycling facility. Five workers were

killed, and at least seven others were injured. The explosion

was fueled by accumulated rubber dust generated from the

grinding of scrap tires.

 CTA Acoustics Inc., Corbin, Kentucky:

A February 20, 2003, dust explosion at this automotive

insulation manufacturing plant killed seven workers and

injured 42 others. CSB is conducting a root cause investigation of this incident.

4.0 Recent Dust Explosions

in United States
56

 Hayes Lemmerz International, Inc., Huntington,

Indiana: An aluminum dust explosion at an automotive

wheel foundry killed one employee and burned two others.

The October 29, 2003, explosion destroyed a dust collector,

damaged the building, and ignited a fire that burned for 12

hours. CSB is conducting a root cause investigation of this

incident.
57

5.0 Combustible Dust

Hazard Study

During the course of several investigations, CSB has identified

gaps in the current understanding of dust explosion risks and

shortcomings in approaches for preventing dust explosions. As a

result, CSB is conducting a study to define the nature and scope

of dust explosion risks in industry and to identify initiatives to

prevent dust fires and explosions. Such initiatives may include

regulatory action, voluntary consensus standards, or other measures that could be taken by industry, labor, government, and

other parties.
58
59

6.1 Root Causes

1. West Pharmaceutical Services, Inc., did not perform an

adequate engineering assessment of the use of powdered zinc

stearate and polyethylene as antitack agents in the rubber

batchoff process.

2. The company’s engineering management systems did not

ensure that relevant industrial fire safety standards were

consulted.

3. The company’s management systems for reviewing MSDSs

did not identify combustible dust hazards.

4. The hazard communication program at the Kinston facility

did not identify combustible dust hazards or make the

workforce aware of such.

6.2 Contributing Cause

The MSDS for polyethylene paste developed by Crystal, Inc.–

PMC did not address the end-use hazard of the product.

6.0 Root and Contributing Causes
60
61

West Pharmaceutical Services, Inc.

1. Revise policies and procedures for new material safety

reviews. (2003-07-I-NC-R1) In particular:

 Use the most recent versions of material safety data

sheets (MSDSs) and other technical hazard information.

 Fully identify the hazardous characteristics of new

materials, including relevant physical and chemical

properties, to ensure that those characteristics are incorporated into safety practices, as appropriate.

 Include an engineering element that identifies and

addresses the potential safety implications of new

materials on manufacturing processes.

2. Develop and implement policies and procedures for safety

reviews of engineering projects. (2003-07-I-NC-R2) In

particular:

 Address the hazards of individual materials and equipment—and their effect on entire processes and facilities.

 Consider hazards during the conceptual design phase, as

well as during engineering and construction phases.

 Cover all phases of the project, including engineering and

construction performed by outside firms.

 Identify and consider applicable codes and standards in

the design.

3. Identify West manufacturing facilities that use combustible

dusts. Ensure that they incorporate applicable safety precautions described in NFPA 654, Standard for the Prevention of

Fire and Dust Explosions From the Manufacturing, Processing, and Handling of Combustible Particulate Solids.

(2003-07-I-NC-R3). In particular:

 Ensure that penetrations of partitions, floors, walls, and

ceilings are sealed dust-tight.

 Ensure that spaces inaccessible to housekeeping are sealed

to prevent dust accumulation.

7.0 Recommendations
62

4. Improve hazard communication programs so that the

hazards of combustible dust are clearly identified and communicated to the workforce. In particular, ensure that the

most current MSDSs are in use and that employees receive

training on the revised/updated information.

(2003-07-I-NC-R4)

5. Communicate the findings and recommendations of this

report to the West Pharmaceutical Services, Inc., workforce.

(2003-07-I-NC-R5)

Identify the manufacturing industries at risk for combustible dust

explosions, and develop and conduct an outreach program on

combustible dust hazards. (2003-07-I-NC-R6)

Amend Chapter 13, Section 1304, of the International Fire Code

(as adopted by the North Carolina Fire Code) to make compliance with NFPA 654, Standard for the Prevention of Fire and Dust

Explosions From the Manufacturing, Processing, and Handling of

Combustible Particulate Solids, mandatory.

(2003-07-I-NC-R7)

Incorporate the provisions of NFPA 654, Standard for the

Prevention of Fire and Dust Explosions From the Manufacturing,

Processing, and Handling of Combustible Particulate Solids, into

the training program for State and local building and fire code

officials. (2003-07-I-NC-R8)

North Carolina Department of

Labor, Occupational Safety

and Health Division

(NCOSHA)

North Carolina Building Code

Council

North Carolina Code Officials

Qualification Board
63

By the

U.S. CHEMICAL SAFETY AND HAZARD INVESTIGATION BOARD

Carolyn W. Merritt

Chair

John S. Bresland

Member

Gerald V. Poje, Ph.D.

Member

Gary Lee Visscher

Member

September 23, 2004

Crystal, Inc.–PMC

Modify the material safety data sheet for manufactured polyethylene antitack agents to include hazards posed by the end-use

of the product. (2003-07-I-NC-R9)
64
65

American Society for Testing and Materials (ASTM), 2000.

Standard Test Method for Pressure and Rate of Pressure Rise

for Combustible Dusts, ASTM E1226-00.

ASTM, 1999. Standard Test Method for Minimum Ignition Energy

of a Dust Cloud in Air, ASTM E2019-99.

Babrauskas, V., 2003. Ignition Handbook, Fire Science

Publishers.

Cashdollar, K. L., 2000. “Overview of Dust Explosibility

Characteristics,” Journal of Loss Prevention in the Process

Industries, Vol. 13.

Eckoff, R. K., 1997. Dust Explosions in the Process Industries,

Second Edition, Reed Educational & Professional Publishing

Ltd.

Gummer, J., and G. A. Lunn, 2003. “Ignitions of Explosive Dust

Clouds by Smouldering and Flaming Agglomerates,” Journal

of Loss Prevention in the Process Industries, Vol. 16.

Health and Safety Executive (HSE), 2003. Safe Handling of

Combustible Dusts: Precautions Against Explosions, United

Kingdom.

Kletz, T. A., 2003. Still Going Wrong: Case Histories of Process

Plant Disasters and How They Could Have Been Avoided,

Butterworth-Heinemann.

Lebecki, K., Z. Dyduch, J. Fibich, and J. Sliz, 2003. “Ignition of a

Dust Layer by Constant Heat Flux,” Journal of Loss Prevention in the Process Industries, Vol. 16.

National Fire Protection Association (NFPA), 2002. National

Electric Code, NFPA 70.

NFPA, 2000. Standard for the Prevention of Fire and Dust

Explosions From the Manufacturing, Processing, and

Handling of Combustible Particulate Solids, NFPA 654.

8.0 References
66

NFPA, 1997. Recommended Practice for the Classification of

Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process

Areas, NFPA 499.

NFPA, 1996. Flammable and Combustible Liquids Code,

NFPA 30.

State of North Carolina, 2003. Combustible Dust Poses a

Dangerous, Explosive Threat in the Workplace, NCDOL

Industry Alert, North Carolina Department of Labor,

www.dol.state.nc.us/osha/etta/CombDust.pdf.

State of North Carolina, 2002. State Building Code, Fire

Prevention Code, North Carolina Building Code Council

and North Carolina Department of Insurance.

Streitwieser, Andrew, Jr., and Clayton H. Heathcock, 1976.

Introduction to Organic Chemistry, Macmillan, p. 547.

West Pharmaceutical Services, Inc. (West), 2004. 2003

Annual Report.
67

A.1 Explosivity

CSB contracted with Safety Consulting Engineers, Inc. (SCE),

of Schaumburg, Illinois, to perform explosivity testing of

material samples from the West Kinston facility. Lycopodium1

dust, a plant-based industry standard, was tested for comparison

purposes.

Samples of the antitack agent paste were recovered from the dip

tank on the batchoff machine and vacuum dried. The resulting

fine polyethylene powder was tested to determine its severity as a

dust explosion hazard. Explosion testing was performed according to ASTM E1226-00, Standard Test Method for Pressure and

Rate of Pressure Rise for Combustible Dusts. The test was

conducted in a U.S. Bureau of Mines 20-liter explosibility test

chamber.

Explosion severity is defined by the maximum rate of pressure

increase reached in the vessel during the deflagration for an

optimum dust concentration in air (Pmax) and by the deflagration

index, KST. This value is defined by the following equation:

KST = (dP/dt)max . V1/3

where: P = pressure (bar)

t = time (sec)

V = volume (m3)

KST = volume, normalized maximum rate of

pressure rise (bar m/sec)

As shown in Table A–1, testing clearly demonstrates that the dried

polyethylene powder is an explosion hazard. The potential explosion severity of dusts is commonly classified by the KST value.

The value of 140 bar-m/sec obtained in this test is proximate to

that of many finely powdered plastics. It falls into the same

explosion severity classification group as coal, flour, and wood

dust.

APPENDIX A: Test Results

1

Lycopodium is the spore of the club moss plant. The spores, which have a

mean diameter of about 30 microns, are spherical in overall shape but feature

a high degree of roughness and a correspondingly large surface area. Lycopodium is widely used as a standard material for comparison purposes in dust

explosion testing and research.

. . . Testing clearly

demonstrates that the dried

polyethylene powder

is an explosion hazard. is an explosion hazard.
68

Minimum ignition energy (MIE) is measured by using a calibrated

spark-generating system in a 1.2-liter clear plastic Hartmann tube

per ASTM E2019-99, Standard Test Method for Minimum Ignition

Energy of a Dust Cloud in Air. By this test method, MIE provides

a relative judgment of the ease of igniting a combustible dust

cloud. ASTM defines MIE as the amount of electrical energy

stored in a capacitor that—when released as a high-voltage spark—

is just sufficient to ignite the dust cloud at its most easily ignitable

concentration in air.

Tests of dried slab dip from both batchoff #1 and batchoff #2

resulted in an MIE of 15 millijoules (mJ)—which is roughly

equivalent to the energy released from a static discharge (spark)

when a person walks across a carpet and touches a doorknob.

Therefore, clouds of the material can be considered readily

ignitable.

Table A–1

Explosion Severity Test Results

A.2 Minimum

Ignition Energy

. . . MIE provides a relative

judgment of the ease of judgment of the ease of

igniting a combustible dust igniting a combustible dust

cloud.

Tests of dried slab dip . . . ied slab dip . . .

resulted in an MIE of resulted in an MIE of

15 milli 5 millijoules—which is

roughly equivalent to the

energy released from a static

discharge (spark) when a

person walks across a carpet person walks across a carpet

and touches a doorknob. and touches a doorknob.

Material Particle Maximum Maximum Deflagration

Tested Size Pressure Pressure Index

(mesh) Output (psig) Rise (psi/sec) KST (bar-m/sec)

Slab dip <-200 121 7,480 140

from batchoff #1

Lycopodium -200 107 8,375 157
69

A.3 Dust Layer Ignition

SCE also tested whether an electrical arc might ignite a resting

layer of dried polyethylene powder. A layer of dust was placed

between clear plexiglass panels, and a very slight airflow (not

enough to disturb the standing dust) was passed down the channel. A 120-volt alternating current (AC) spark was induced in the

dust layer at the front of the channel.

In several instances, the spark initiated a propagating dust explosion down the channel. This result suggests that a strong electric

discharge could in itself ignite and disperse enough dust to create

propagating dust from a standing dust layer. Further research is

necessary to confirm this theory.
70
71

CSB used observations of beam deflection and other blast

damage to determine where the explosion was most concentrated. Among the notable observations are the following:

 The force of the blast displaced batchoff #1—a machine that

weighs several tons—several feet to the southwest.

 To the immediate east of this area, the two masonry walls of

a hallway used to conduct tours of the facility were blown

northeastward into the kitchen. Structural steel in this area

was deflected in the same direction.

 To the southeast, masonry walls for an elevator shaft and

stairwell were blown southeastward toward the warehouse.

Structural steel and cross bracing were deflected in the

same direction (Figure B-1).

 The upper-level concrete slab flooring directly over the

mill #1 and batchoff #1 areas was heaved upward. The

floor to the northwest between the two mixers was also

heaved (Figure B-2).

 Structural steel for the wall adjacent to batchoff #1 was

deflected to the southwest (Figure B-3).

In examining the damage to structural steel and masonry block

walls, CSB determined that the most severe forces—which

emanated with a blast pattern of 360°—were on the first level of

the plant in the area southeast of mill #1.

APPENDIX B:

Blast Damage Observations

Figure B-1. Beam and cross bracing

deflected southeastward toward

warehouse.
72

Figure B-2. Uplifted concrete floor in mixer area.

Figure B-3. Southwest wall of compounding area deflected outward.
73

CSB considered four theories for ignition and dispersion

events, as described in Sections C.1 through C.4. However,

evidence was insufficient to determine exactly what ignited the

dust above the ceiling.

Limited evidence obtained during the investigation supports the

possibility that an overheated batch of rubber may have been

involved in initiating the explosion. An employee working in the

area of batchoff #1 recalls that the batch of rubber that

descended from the mixer just prior to the explosion appeared to

be evolving shimmering heat waves. The MSDS for the main

rubber component in the batch includes a warning that the

material may decompose at elevated temperatures and generate

flammable vapors. A control failure at the mixer could cause a

batch of rubber to overheat.

If the temperature of the rubber rises to the onset of vulcanization, the viscosity of the batch increases. At a constant mixing

speed, an increase in viscosity is accompanied by a corresponding

increase in mixer torque—which, in turn, is likely to further

increase the rubber temperature, accelerating the rate of vulcanization. In short, the temperature of the batch of rubber can run

away in the event of a control failure. However, it is not possible

to determine if this is what actually occurred because temperature control data for the final batches were lost in the explosion.

Witnesses testified that some batches produced at the Kinston

plant over the years exhibited signs of vulcanization and overheating, with some reports that the rubber smoldered or ignited in the

drop bucket. Witnesses also stated that sizable static discharges

were prevalent around the milling machine. A static spark could

ignite vapors if they evolved from the rubber, causing a localized

deflagration.1

 APPENDIX C: Initiating Events

1

A deflagration is an explosion that moves at a speed less than the speed of

sound. Most industrial explosions are classified as deflagrations.

C.1 Deflagration of

Vapors Emitted by

Decomposing Rubber

. . . The temperature of the

batch of rubber can run away

in the event of a control failure. in the event of a control failure.

However, it is not possible

to determine if this is what to determine if this is what

actually occurred because

temperature control data for

the final batches were lost the final batches were lost

in the explosion. in the explosion.
74

The drop bucket is mounted just below the suspended ceiling.

The turbulence created by a deflagration could disturb and ignite

the accumulated polyethylene dust above and set off secondary

explosions. However, West technical personnel state that the

particular grade of rubber being produced at the time of the

explosion had not ignited in the past. West also points out that

automatic process controls on the mixer are set to drop the

rubber to the bucket at a temperature 100oF below the typical

vulcanization temperature.

Subsequent to the explosion at West, a fire occurred on a rolling

mill at a Michelin rubber preparation facility in Star, South

Carolina. The compounding equipment Michelin uses to prepare

rubber batches is similar to the equipment at West. Mixers

compound the rubber, which is dropped to a rolling mill.

Michelin advised CSB that its investigation attributed the incident

to a faulty thermocouple measurement that caused the temperature control in the mixer to fail. The batch of rubber overheated

to the point of decomposition. When it dropped to the mill and

was exposed to oxygen in the air, evolving vapors ignited, creating

a flash fire. Employees were injured, but none of the injuries

were life threatening.

In another incident, a rubber fire occurred at a Bridgestone tire

plant in Graniteville, South Carolina. This plant also uses similar

compounding equipment. A rubber strip fell off rollers and

accumulated on the floor instead of passing through the water dip

tank on the batchoff machine. After a few moments, the rubber

ignited and there was a sizeable fire. Bridgestone advised CSB

that it attributed ignition of the rubber to the fact that the cooling

process was interrupted when the rubber failed to enter the dip

tank.

CSB investigators were unable to find any residual rubber near

mill #1 at the West facility, even though the witness reported that

a batch had been dropped just prior to the explosion. His observations may have been inaccurate (testimony was taken months

after the event and followed an extensive recovery from burn

injuries), or the rubber may have been consumed in the fire. No

other individuals working in the area of mill #1 and its batchoff

machine survived the incident.
75

Standard 2- by 4-foot fluorescent fixtures,2 similar to those

typically found in office environments, provided lighting for the

mill and batchoff area. The fixtures were not rated for use near

combustible dust. They consisted of metal pans with tubular

fluorescent bulbs and ballasts to supply the necessary voltage.

The lights were installed such that the “lens” of the fixture was

flush with the suspended ceiling face. The pan with the ballast on

top protruded into the space above the suspended ceiling.

Dust layers on the top surface of the light fixtures created an

insulating effect. The dust may have caused heat to accumulate

in the lighting ballasts. In turn, an overheated ballast may have

ignited the dust. If the event was sufficiently energetic, a small

dust cloud may have been lofted and ignited, leading to secondary

dust explosions. Alternatively, a localized fire above a light

fixture—ignited by an overheated, but not failed, ballast—may

have generated enough turbulence to set off a chain of dust

explosions.

The comfort air system drew a portion of its air from above the

ceiling and returned it to the room below. None of the employees

interviewed by CSB recalled seeing or smelling smoke prior to the

explosion, this scenario would have had to progress fairly quickly

for the employees not to have noticed a fire in progress. Comfort

air pulled from the area above the ceiling and returned to the

working spaces would have retained the odor of smoke.

The fixtures, electrical wiring, and fittings in the zone above the

suspended ceiling of the mill/batchoff area were not rated for

atmospheres containing combustible dust. NFPA 499, Recommended Practice for the Classification of Combustible Dusts and

of Hazardous (Classified) Locations for Electrical Installations in

Chemical Process Areas (1997), provides guidance on electrical

classification where combustible dusts are involved.

2

Per NEC (NFPA 70), the fixtures were not suitable for use in areas with

combustible dust. NEC was in force in North Carolina when the ACS was built.

C.2 Ignition of Dust by

Overheated Electrical

Ballast or Fixture

C.3 Ignition of Dust by

Electrical Spark

Dust layers on the top surface

of the light fixtures created an

insulating effect . . . [and] dust insulating effect . . . [and] dust

may have caused heat may have caused heat

to accumulate

in the lighting ballasts. in the lighting ballasts.

Alternatively, a localized f , a localized fire

above a light fixture . . . above a light fixture . . .

may have generated enough

turbulence to set off turbulence to set off

a chain of dust explosions. a chain of dust explosions.

None of the employees

interviewed by CSB recalled

seeing or smelling smoke prior

to the explosion . . . to the explosion . . .
76

Polyethylene is an NFPA Group II, Class G, combustible dust.

Because of the accumulation of combustible dust in most areas

above the ceiling at most times, this zone would be classified

under the code.3 At a minimum, electrical equipment would be

required to be dust-tight. However, West used general-purpose

wiring, junction boxes, and fixtures. An electrical spark from a

malfunctioning lighting fixture or wiring component or an unsealed connection may have ignited the dust layer above the

ceiling.

The West internal investigation concluded that a small dust

explosion in an air duct that supplied fresh cooling air to the

electric motors for mill #2 initiated the larger explosion. This

section of duct was above the suspended ceiling. It was distended

from internal pressure and partly split open at its crimped edges.

Splatter inside the duct was consistent with the residue from dust

explosions. Splatter of combustible dust was also found inside

the electric motors to which the ducts were attached, including on

the brushes.

Other portions of the duct traversed the area above the ceiling

tiles and were under negative pressure. Although fresh air from

outdoors flowed through the duct, dust could have entered it

through a worn canvas coupling.

3

According to NEC (NFPA 70) 500.5, Class II, Division 2, locations include

those where combustible dust accumulations on, in, or in the vicinity of the

electrical equipment may be sufficient to interfere with the safe dissipation of

heat from electrical equipment or may be ignitable by abnormal operation or

failure of electrical equipment.

C.4 Ignition

of Dust in

Motor Cooling

Duct

An electrical spark from

a malfunctioning lighting

fixture or wiring component fixture or wiring component

or an unsealed connection may

have ignited the dust layer

above the ceiling. above the ceiling.

The West internal investigation

concluded that a small dust concluded that a small dust

explosion in an air duct . . . explosion in an air duct . . .

initiated the larger explosion. initiated the larger explosion.

. . . Portions of t tions of the duct he duct

traversed the area above the

ceiling tiles and were under

negative pressure. Although

fresh air from outdoors flowed

through the duct, dust could

have entered it through a worn

canvas coupling. canvas coupling.
77

APPENDIX D: Logic Diagrams

The CSB investigation team used a combination of two

analytical approaches to determine the root causes of this

incident:

 First, the available information on the case (i.e., witness

testimony, field observations, facts from records, etc.) was

placed on a timeline with causal factors.

 Second, the team organized the known causes of the event

into a cause map (i.e., a modified fault tree wherein the

known and presumed causes are shown but the unproven

potential causes are not).
78

 LOGIC TREE

6 DEAD &

MULTIPLE

INJURIES

SPREADING

UNCONTROLLABLE

FIRE

EXPLOSION

SYSTEM

DAMAGED BY

EXPLOSION

COMBUSTIBLE

LIQUID SPILLS

AND IGNITES

A

A

END

COMBUSTIBLE

MATERIAL

PRESENT

(RUBBER,

PLASTICS, OILS)

FAILURE OF

SPRINKLER

SYSTEM

EXPLOSION

END

TANKS FAIL DUE

TO FIRE

EXPOSURE

TANKS LOCATED

INSIDE

WAREHOUSE

TANKS MADE OF

PLASTIC

AUTOMATIC

SPRINKLER

SYSTEM FAILS

END

CMU

CONTAINMENT

WALLS

DAMAGED BY

EXPLOSION

END

END END

LEGEND

AND

GATE

OR

GATE
79

 LOGIC

SUB-TREE

A

EXPLOSION

SOURCE OF

IGNITION

DUST/AIR

MIXTURE

DISPERSION

COMBUSTIBLE

DUST

ACCUMULATION

BUILDING

PROVIDES

CONFINEMENT

VAPOR

DEFLAGRATION

ELECTRICAL

SPARK

ELECTRICAL

BALLAST

FAILURE

LOFTING EVENT ACCUMULATED

DUST

DEFLAGRATION

IN MILL MOTOR

COOLING AIR

DUCT

DUST LAYER

FIRE CREATED

TURBULENCE

UNCLASSIFIED

ELECTRICAL

EQUIPMENT

ELECTRICAL

FAULT

LIGHTING

BALLAST

OVERHEATED

END B

B

A

OXYGEN

PRESENT

END

FAILURE TO PREVENT

SOURCES OF IGNITION

IN COMBUSTIBLE DUST

ENVIRONMENT

LEGEND

AND

GATE

OR

GATE

C

E

DEFLAGRATION

IN MILL MOTOR

COOLING AIR

DUCT

D

D

END
80

COMBUSTIBLE

DUST

ACCUMULATION

DUST RELEASED

FROM PROCESS

HVAC PULLS

COMBUSTIBLE

DUST INTO

CEILING AREA

UNSEALED

DROP CEILING

AREAS ABOVE

CEILING NOT

CLEANED

COMBUSTIBLE

INGREDIENT

USED IN ANTITACK SLURRY

ANTITACK

POWDER

BLOWS OFF

BATCHOFF DUST

COLLECTION

SYSTEM LTA

AESTHETICALLY

PLEASING

HOUSKEEPING

ISSUES, LESS

AREA TO CLEAN

WEST DOES

NOT CONSULT

NFPA 654

END END

WEST RELIES

ON OUTSIDE

ENGINEERS &

ARCHITECTS

CORPORATE

DESIGN

FOCUSES ON

FDA

REQUIREMENTS,

PRODUCT

SAFETY, &

PERSONAL

EXPOSURE

LACK OF

AWARENESS OF

COMBUSTIBLE

DUST HAZARD

HYGIENE

STUDIES SHOW

NO EMPLOYEE

EXPOSURE

HAZARD AT

BATCHOFF

LACK OF

AWARENESS OF

COMBUSTIBLE

DUST HAZARD

END

C

NO HAZARD

REVIEW DURING

ENGINEERING

DESIGN PHASE

B

END

END

LACK OF

AWARENESS OF

COMBUSTIBLE

DUST HAZARD

C

END

 LOGIC

SUB-TREE

B

LEGEND

AND

GATE

OR

GATE

C
81

C

LACK OF

AWARENESS OF

COMBUSTIBLE

DUST HAZARD

NMR COMMITTEE DOES NOT

IDENTIFY DUST HAZARDS FOR

POLYETHYLENE ANTITACK

SLURRY

SEVERITY OF

COMBUSTIBLE

DUST HAZARD

NOT WIDELY

KNOWN

1990 MSDS

WARNINGS FOR

MICRONIZED

POLYETHYLENE

NOT FOLLOWED

NO OUTSIDE

PARTIES RAISE

DUST AS AN

ISSUE (GOVT/

INSURANCE)

NO INTERNAL

EMPLOYEE WITH

DUST HAZARD

EXPERTISE

END

CRYSTAL MSDS

DOES NOT

CONVEY DUST

HAZARD

MSDS NARROWLY

FOCUSES ON ASSHIPPED

PRODUCT, NOT

END-STATE

CRYSTAL DOES

NOT

UNDERSTAND

COMBUSTIBLE

DUST

END

END END

END END

NO PROCESS AT

PLANT TO

REVIEW MSDS &

IDENTIFY

HAZARDS

UPDATED

ACUMIST MSDS

NOT

CONNECTED TO

ANTITACK

SLURRY

NMR FOR

POLYETHYLENE

SLAB DIP RELIES

ON PRIOR

REVIEW OF

ACUMIST

PARTITIONING

AGENT

ACUMIST NMR

USES 1988

ALLIED SIGNAL

MSDS

COMBUSTIBLE

DUST

WARNINGS ON

1988 MSDS LTA

LEGEND

AND

GATE

OR

GATE

END END

END

 LOGIC

SUB-TREE

C
82

D

DUST

ACCUMULATES

IN MOTOR

COOLING DUCT

IGNITION FROM

MILL MOTOR

COIL

CANVAS SEAL

FAILS, CAUSING

AIR TO PULL

DUST INTO DUCT

DUCT PASSES

THROUGH AREA

WITH

ACCUMULATED

DUST

MILL MOTOR

NOT CLASSIFIED

OR ENCLOSED

DUST IN

COOLING DUCT

SHAKES FREE

INTO MOTOR

LEGEND

AND

GATE

OR

GATE

DEFLAGRATION

IN MILL MOTOR

COOLING AIR

DUCT

END END END END

 LOGIC

SUB-TREE

D
83

THERMAL DECOMPOSITION OF

RUBBER PRODUCES

FLAMMABLE VAPOR

DECOMPOSITION

TEMPERATURE ABOVE

AUTOIGNITION

TEMPERATURE OF VAPOR

VAPOR

DEFLAGRATION

E

LEGEND

AND

GATE

OR

GATE

RUBBER BATCH

OVERHEATS,

TEMPERATURE

CONTROLLER DOES NOT

DUMP BATCH ON

ACHIEVING DESIRED

TEMPERATURE

RUBBER BATCH

OVERHEATS, BATCH

TIME CONTROLLER DOES

NOT DUMP BATCH ON

REACHING TIME LIMIT

END

SETPOINT

ERROR

CONTROL

FAILURE

END

 LOGIC

SUB-TREE

E
84
85

1923 West company founded.

1975 Kinston facility commences production.

1984–1986 West develops concept for new automated

rubber compounding system (ACS).

Outside engineering firm performs detailed

design for ACS process and equipment.

Another outside engineering firm designs

addition to the Kinston plant structure to

accommodate ACS.

1985 West procures batchoff machines from vendor.

1987 Rubber compounding production commences

using zinc stearate slurry as antitack agent.

1988 1988 version of MSDS for Acumist is published.

1990 New version of MSDS for Acumist is published.

West uses 1988 MSDS to evaluate Acumist as

dusting agent for trial run of stoppers to be

conducted at St. Petersburg plant.

1993 West works with Namico, which develops

antitack formulation using Acumist (as specified

by West) as replacement for zinc stearate.

1994 Insurance audits note some dust on fire sprinkler heads, but do not identify type of dust or

combustible dust hazard.

West enters contract with Crystal, Inc.–PMC to

purchase water-based Acumist paste.

West uses Crystal MSDS to evaluate Acumistbased paste as replacement for zinc stearate

slurry.

West ships Acumist powder to Crystal for

preparation of test batch of water-based paste.

APPENDIX E: Timeline
86

1996 Crystal begins shipping water-based Acumist paste

to West.

Improved dust collection system is installed in

kitchen and mixer areas.

prior Spark from welding on batchoff machine contacts

dried powder from antitack slurry used in batchoff.

Powder on floor briefly ignites and produces small

flame that self-extinguishes.

2002 New fluorescent lights are installed in mill area, and

some ceiling tiles are replaced.

2003 (January) Ceiling tiles are partially replaced; dust

accumulation above ceiling is observed and later

estimated to be 0.25 inch in some areas. Dust

accumulation is observed over estimated 90 percent

of ceiling in mill/batchoff area.

Dust explosion (January 29).

to 2001
87
88