Transcript ONLINE SELF-STUDY - Environment, Health and Safety

ONLINE SELF-STUDY
Combustible Dust Health and Safety Awareness
Training
Course Objectives
1)
Gain an understanding of the hazards
associated with Combustible Dust.
2)
Understand the UNC industrial workplace
requirements to help improve workplace
safety.
Introduction

Introduction
Introduction

Accidents in Industry caused by Combustible Dusts
 In industry, dust is generated as a by-product of several
processes that include material conveying, crushing, and
screening, sanding, and trimming of excess material. The
creation of dust does not necessarily pose a safety and
health risk. However, where combustible dust is produced
and allowed to accumulate, it can lead to catastrophic
consequences.

In recent years, combustible dust explosions have resulted in
loss of life, multiple injuries, and substantial property
damage.

The force from such an explosion can cause employee
deaths, injuries, and destruction of entire buildings. Such
incidents have killed scores of employees and injured
hundreds over the past few decades.
Introduction

Accidents in Industry caused by Combustible Dusts

For example, combustible sugar dust was the fuel for a
massive explosion and fire that occurred Feb. 7, 2008, at the
Imperial Sugar Co. plant in Port Wentworth, GA., resulting in
13 deaths and hospitalization of 40 more workers, some of
whom received severe burns. Below is an illustration of the
facility after the explosion.
Introduction

Accidents in North Carolina caused by Combustible
Dusts
 An explosion and fire occurred on Jan 29, 2003, at
West Pharmaceutical Services plant in Kinston, N.C.. This
catastrophe resulted in the deaths of six workers, injury
to dozens of employees, and job losses to hundreds due
to destruction of the plant. The facility produced rubber
stoppers and other products for medical use. The fuel
for the explosion was a fine plastic powder that had
accumulated unnoticed above a suspended ceiling over
the manufacturing area.

Between April 1988 and February 2006, 17 employers
in North Carolina had combustible dust explosions in
which 76 employees were injured, nine of whom died.
Introduction

Accidents in North Carolina caused by Combustible Dusts
Above: Courtesy U.S. Chemical Safety Investigation Board
Above: Aerial View of explosion and fire that occurred on Jan 29, 2003, at
West Pharmaceutical Services plant in Kinston, N.C
Introduction

What Materials Can Form a Combustible Dust?

Materials that may form a combustible dust include:

Metals (such as aluminum and magnesium)
Wood
Coal
Plastics
Biosolids
Sugar
Paper,
Soap
Dried blood,
Certain textiles.









In many accidents, employers and employees were unaware that a
hazard even existed.
Introduction


What Materials Can Form a Combustible Dust?
 A combustible dust explosion hazard may exist in a variety
of industries, including: food (e.g., candy, sugar, spice,
starch, flour, feed), grain, tobacco, plastics, wood, paper,
pulp, rubber, furniture, textiles, pesticides, pharmaceuticals,
dyes, coal, metals (e.g., aluminum, chromium, iron,
magnesium, and zinc), and fossil fuel power generation.
Above: Courtesy U.S. Chemical Safety Investigation Board, November 2003, fatal accident at an automotive parts
plant explosion in the U.S. that involved aluminum dust that originated near an aluminum chip melting furnace.
Introduction

What Materials Can Form a Combustible Dust?

Most organic materials, many metals (such as aluminum), and
some nonmetallic inorganic materials can burn or explode if:

Finely divided

Dispersed in sufficient concentration
Definitions

Definitions
What is Combustible Dust?

Any combustible material (and some materials normally
considered noncombustible) can burn rapidly when in a finely
divided form. If such a dust is suspended in air in the right
concentration, it can become explosive.
What is Combustible Dust?

National Fire Protection Association (NFPA 654):

“any finely divided solid material that is 420 microns or
smaller in diameter (material passing through a No. 40
Standard Sieve) and presents a fire or explosion hazard
when dispersed and ignited in air.”
What is Combustible Dust?

OSHA National Emphasis Program (NEP):

“A combustible particulate solid that presents a fire or
deflagration hazard when suspended in air or some other
oxidizing medium over a range of concentrations,
regardless of particle size or shape.”
Definitions


Deflagration:
 Propagation of a combustion zone at a speed that is less
than the speed of sound in unreacted medium (vs.
detonation).
Explosion:
 The bursting or rupture of an enclosure (including a room
or building) or a container due to the development of
internal pressure from deflagration.
Definitions

Other NEP Definitions:
 Minimum Explosive Concentration (MEC):
 the
minimum concentration of dust suspended in air that
will support a deflagration.
 typically 2-3 orders of magnitude higher than “health”
based occupational exposure levels.
 Normally present only inside process equipment
(conveyers, silos, etc.)
 Accumulations of dust in working areas, when disturbed,
may result in temporary concentrations of dust greater
than the MEC.
How a Dust Explosion Occurs

How a Dust Explosion Occurs:
How a Dust Explosion Occurs

“Dust Explosion
Pentagon”
 Fuel
(combustible dust),
 Heat/Ignition (flame),
 Oxygen in air,
 Dispersion of dust
particles
 Confinement of dust
cloud
How a Dust Explosion Occurs

When all of the elements
in the Dust Explosion
Pentagon are in place,
rapid combustion known
as deflagration (a rapid
burning slower than the
speed of sound) can occur.
If this event is confined by
an enclosure, such as a
building, room, vessel or
process equipment, the
resulting pressure rise can
cause an explosion (a
rapid burning faster than
the speed of sound).

Above Illustration- Imperial Sugar Co.
plant combustible dust explosion in Port
Wentworth, GA., resulting in 13 deaths
and hospitalization of 40 more workers
How a Dust Explosion Occurs
How a Dust Explosion Occurs



Secondary Explosions Are Catastrophic
An initial (primary) explosion in processing equipment or in areas
where fugitive dust has accumulated may dislodge additional
dust or damage a collection system (such as a duct, vessel or
collector).
This dust, if ignited, caused additional explosions, which can result
in damage that is more severe than the original explosion due to
increased concentrations and quantities of dispersed combustible
dust.
Possible Ignition Sources

Possible ignition sources include:
Possible Ignition Sources

Possible ignition sources include:
 Open
flames and sparks (welding, industrial grinding
and cutting, matches, etc.)
 Hot Surfaces (dryers, bearings, heaters, etc.)
 Heat from Mechanical Impacts
 Electrical Discharges (switch and outlet activation)
 Electrostatic Discharges (static electricity)
 Smoldering or burning dust
 Smoking materials (cigarettes, lighters, cigars, etc.)
How Much Dust is Too Much Dust?

How much dust is too much dust?
How Much Dust is Too Much Dust?

NFPA 654 warns that a dust layer > 1/32 of an inch (or the
thickness of a typical paper clip) accumulated on surface
areas of at least 5 percent of a room’s floor/or above ceiling
area presents a significant explosion hazard.

Note: The U.S. Chemical Safety Investigation Board (CSB)
found that West Pharmaceutical explosion that occurred in
Kinston, NC, was caused by dust accumulations primarily
under ¼ inch.
How Much Dust is Too Much Dust?


Nearly one-fourth of all
dust explosions in the US
over the last 25 years
involve metal dusts.
*Aluminum metal
accumulation accounted
for the majority of these
events (primarily
associated with dust
collection systems, such
as industrial bag
houses).
Combustible Dust

Safety Hazards That May Contribute to the
Combustible Dust Hazard
Safety Hazards That May Contribute
to the Combustible Dust Hazard

Common Trends Related to Combustible Dust
Identified by OSHA:
1)
2)
3)
4)
5)
The Hazard was not recognized,
Ineffective housekeeping,
Inadequate engineering controls,
Ineffective process controls,
Unapproved electrical (e.g. inadequate bonding and
grounding for control of static electricity).
Combustible Dust

Regulatory Standards Related to Combustible Dust
Regulatory Standards

Currently there is not a standard for combustible dust,
but OSHA violations can be cited under the General
Industry General Duty Clause and other safety
standards related to Combustible Dust as follows:
 29 CFR 1910.22 - General Requirements:
Housekeeping
 29 CFR 1910.38 - Emergency Action Plans
 29 CFR 1910.94 - Ventilation
 29 CFR 1910.107 - Spray Finishing Using Flammable
and Combustible Materials
 29 CFR 1910.146 - Permit-Required Confined
Spaces (references combustible dust)
Regulatory Standards

29 CFR 1910.178 - Powered Industrial Trucks

29 CFR 1910.269 - Electric Power Generation,
Transmission and Distribution (coal handling)

29 CFR 1910.272 - Grain Handling Facilities

29 CFR 1910.307 - Hazardous (classified) Locations
(for electric equipment)

29 CFR 1910.1200 - Hazard Communication
Combustible Dust

Combustible Dust Hazard Assessment & Mitigation
Hazard Assessment & Mitigation

NFPA 654, Standard for the Prevention of Fire and Dust
Explosions from the Manufacturing, Processing, and Handling
of Combustible Particulate Solids
 Contains comprehensive guidance on the control of dusts to
prevent explosions.
 This NFPA Std. is geared more towards engineers during
the design stage of facilities.
Hazard Assessment & Mitigation



A thorough hazard assessment is essential to identify and
eliminate factors contributing to dust fires and explosions.
National Fire Protection Association Standard 654 provides
recommendations for Dust Control, Ignition Control, and
Damage Control.
The following slides gives some examples of these
recommendations.
Hazard Assessment & Mitigation

1.
2.
3.
4.
5.
6.
7.
8.
Dust Control Recommendations (NFPA 654):
Minimize the escape of dust from process equipment or
ventilation systems.
Use dust collection systems and filters.
Use surfaces that reduce accumulation and help with cleaning.
Conduct regular inspections for dust in open and hidden areas.
Clean dust residues at regular intervals.
Use cleaning methods that do not generate dust clouds.
Develop and implement a written program for hazardous dust
inspection, housekeeping and control.
Minimize the escape of dust from process equipment or
ventilation systems.
Hazard Assessment & Mitigation

Below Illustrations: Examples of Woodworking Shop area at
UNC that is kept clean, uses engineering controls (dust
collection systems), and is kept free of dust accumulation.
Hazard Assessment & Mitigation

Below Illustrations: An example of an industrial dust collection
system connected to a woodworking shop exhaust ventilation
system to capture generated dust.
Hazard Assessment & Mitigation

Below Illustration: An example of another Woodworking
Shop area at UNC that is kept clean and free of dust
accumulation.
Hazard Assessment & Mitigation

Below Illustration: An example of an overhead exhaust
ducting at UNC Woodworking Shop area that is kept clean
and free of dust accumulation.
Hazard Assessment & Mitigation

American Industrial Hygiene Association (AIHA):
 Some
Additional Standard Practices to help reduce the
potential risks of combustible dusts:
 Keep
all sources of ignition out of hazardous areas.
 Keep areas and equipment clean and minimize the
accumulation of dust.
 Check dust collection systems to make sure all leaks are
sealed and dust is not accumulating in the ductwork.
 Check bonding and ground of all dusty system components.
 Use cleaning methods that limit dispersal of dust in the aireither utilizing wet methods or vacuum methods.
Hazard Assessment & Mitigation

American Industrial Hygiene Association (AIHA):

Some Additional Standard Practices to help reduce the
potential risks of combustible dusts:
 Implement an effective housekeeping program with
regular cleaning frequencies for floors and work areas.
 Establish a regular program to clean horizontal surfaces,
such as ducts, pipes, hoods, ledges, and beams, that are
not part of the daily or weekly cleaning activity.
 Include mission critical equipment and dust controls in a
regular inspection and maintenance program.
 Train and retrain employees in the hazards of combustible
dust, and emphasize the importance of good
housekeeping and other proper operational procedures.
Combustible Dusts

What Can You do to Minimize the Hazard of
Combustible Dusts?
Housekeeping
1) Maintain Good Housekeeping In Work Areas to
Prevent Dust Accumulation on Work Surfaces and
Overhead Structures.


Implement a housekeeping program with regular cleaning
frequencies established for floors and horizontal surfaces,
such as ducts, pipes, hoods, ledges, and beams, to minimize
dust accumulations within operating areas of the Work
Unit.
Under the housekeeping program, dust must be removed
from floors, overhead surfaces and structures, and other
surfaces as soon as possible to prevent any accumulation
of dust.
Housekeeping




Conduct regular inspections for dust in open and
hidden areas.
Conduct regular inspections of tools and equipment
and implement a maintenance cycle to prevent dust
accumulation.
Clean dust residues at regular intervals.
Use cleaning methods that do not generate dust
clouds (e.g. do not use compressed air or blowers) if
ignition sources are present or could be present after
the cleaning.
Housekeeping

Use Supplemental dust
cleaning equipment (e.g.
HEPA vacuums) or other
dust reducing methods
when needed to clean the
work area.
Ignition Control
2) Ignition Control: Hot Work/No Smoking Precautions
Hot work is not to be performed in areas where a potential
combustible dust hazard exists (e.g. in carpentry work areas
where dust has accumulated on overhead ducting and other
surfaces which have not been cleaned). Follow all safe
welding, cutting, and brazing instructions and precautions.
 Ensure employees follow the University Smoking Policy.
Smokers are only to smoke at approved designated areas
away from UNC buildings and facilities (especially not in
work areas where dusty conditions may be present).
 We recommend posting areas where smoking is prohibited
with "No Smoking" signs, especially in work areas where
dusty conditions may exist.

Maintenance
3) Proper Maintenance
and Operation of
Dust Generating
Equipment
 Ensure
all equipment
that may produce dust
in the work area is
maintained according
to manufacture
specifications.
Maintenance

Industrial Equipment
 Some IMAC work areas use industrial equipment such
as glove box abrasive blast units (as illustrated
below) and other industrial equipment that can leak
dust if not properly maintained.
 It is critical that dust-containing systems (ducts and
dust collectors) are designed and installed in a
manner that fugitive dusts are not allowed to
accumulate in the work area.
 Ensure that a thorough inspection is performed to
ensure that the system is operating according to
manufacture instructions and to ensure that dust does
not leak into the work area.
Maintenance
 It
is also important to
ensure that all dustcollection systems are
operating properly
and collected dust is
recycled and/or
disposed according to
the manufacture
specifications for the
equipment.
Maintenance
 Check
dust collection
systems to make sure
all leaks are sealed
and dust is not
accumulating in the
ductwork. Check
bonding and ground
of all components in
accordance with the
manufacturer
instructions.
Maintenance

Industrial Glove Box
Abrasive Blast Units:
Inspect for leaks and
defects prior to and
during operation.
 Do not allow dust to
accumulate on work
surfaces and overhead
structures if a dust leak
is observed.

Maintenance

Woodworking Equipment
 Maintain
cleanliness around woodworking machinery to
prevent the build-up of dust.
 When possible use dust collection devices to capture
dust.
 Establish a cleaning schedule to ensure that collected
dust is disposed as soon as possible to minimize the
accumulation on work areas.
Maintenance

Woodworking Equipment
 Ensure
that hot work (welding, cutting, and brazing) or
other work that could cause an ignition source does not
occur in areas where wood dust is being generated or
has accumulated.
 Keep overhead ventilation ducting and equipment free
from accumulation of dust.
Conclusion

Combustive dust continues to be a very real problem in the
industrial work environment. Preventing the accumulation of dust
provides the best protection against fires and explosions. Please
make sure your work area at UNC is as safe as possible by
keeping it dust free.