1. Office of Safety & Health Consultation presents
Combustible Dust
Notes:
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2. Goal
To improve the safety of workers in environments where combustible dusts may be encountered by increasing employee awareness of this hazard and by demonstrating how the hazard can be recognized and addressed in their workplace.
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3. Objectives Identify the elements necessary for dust to explode.
Explain how to prevent dust from reaching combustible levels.
Describe the difference between primary and secondary dust explosions.
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4. Introduction A Chemical Safety Board Study Shows:
From 1996 to 2005, a total of 106 explosions resulted in 16 fatalities and 126 injuries, at an estimated cost of $162.8 million in damages to the facilities.
In 2005, there were 13 grain dust explosions reported in the US.
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5. Organic Dust Fires & Explosions
Organic Dust Fires and Explosions:
Massachusetts
(3 killed, 9 injured)
North Carolina
(6 killed, 38 injured)
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6. Massachusetts Incident
Fire in a foundry shell molding machine
Caused a primary explosion in ducts containing heavy deposits of Phenol formaldehyde resin dust.
Resulted in a dust cloud from ledge dust deposits outside the ducts and an explosion in the plant area.
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7. North Carolina Incident
Combustible polyethylene dust accumulated above suspended ceilings at pharmaceutical plant
A fire at the plant caused dust to be dispersed and explode in the ceiling space
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8. Grain Handling Industry Experience
In the late 1970s, grain dust explosions
left 59 people dead and 49 injured.
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9. Grain Handling Industry Experience
In 1987, OSHA promulgated the Grain Handling Facilities standard (29 CFR ) still in effect
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10. Combustible Dust Explosions
Imperial Sugar 2008
Malden Mills 2004
Dust
Kansas 2011
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11. What’s so bad about a little dust?
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12. It’s Only Dust
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13. It’s Only Sugar!
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14. A Chronology of Past Events
February 7, 2008 – Imperial Sugar Plant explodes
February 11, 2008 – Fire still burning in parts of plant
February 24,2008 – 11th worker dies from injuries
July 2008 – OSHA fines Imperial Sugar Co. $8.8 million For violations in Georgia and Louisiana
August 2008 – 14th worker dies from injuries
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15. What’s so bad.
For the employer the millions of dollars in OSHA fines and insurance payments not to mention the cost of rebuilding the plant .
For the workers and their families – the cost, heartbreak and pain – That 14th worker spent 6 months in a burn unit fighting for his life. A total of 40 other workers were injured with severe burns.
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16. That averages to more than 10 explosions per year
Between 1980 and 2005 the Chemical Safety Board has knowledge of over 280 dust explosions resulting in 119 deaths and 718 injuries
That averages to more than 10 explosions per year
Despite the time since the Port Wentworth explosion brought this issue to the national forefront the explosions continue.
10/30/ killed, 2 injured Kansas
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17. Important Points Regarding the CSB Data
According to the CSB, “The combustible dust incidents the CSB lists…from 1980 to 2005 are likely only a small sampling, as no federal or state agency keeps specific statistics on combustible dust incidents, nor does any single data source provide a comprehensive collection of these incidents.
Information about small combustible dust incidents and near-misses is also generally unavailable.
Incidents that cause no fatalities, significant injuries or major fires may not be recorded in the OSHA and fire incident databases
The true extent of the problem is likely understated.
Due to these limitations, the CSB does not represent the incident data as complete or error free and other compilations of dust explosion data are available.”
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18. Dust Incidents, Injuries & Fatalities 1980 - 2005
(Not even close to being a complete summary of incidents)
Fatalities
Injuries
Incidents
Injuries / Fatalities
Incidents
Figure 11. Dust incidents, injuries & fatalities,
Source: Chemical Safety Board
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19. Types of Industries Involved in Dust Incidents
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20. Types of Dust Involved in incidents
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21. Combustible Dust Explosions History
Malden Mills
Methuen, MA
December 11, 1995
37 Injured
Nylon Fiber
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22. Combustible Dust Explosions History
Jahn Foundry
Springfield, MA
February 26, 1999
3 dead 9 Injured
Phenolic resin dust
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23. Combustible Dust Explosions History
Ford River Rouge:
Secondary
Coal Dust Explosion
February 1, 1999
Killed six workers and injured 36
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24. Combustible Dust Explosions History
May 16, 2002
Rouse Polymerics
Vicksburg, MS
5 dead, 7 injured
Rubber Dust
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25. Combustible Dust Explosions History
January 29, West Pharmaceutical Services, Kinston, NC
Six deaths, dozens of injuries
Facility produced rubber stoppers and other products for medical use
Plastic powder accumulated above suspended ceiling ignited
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26. West Pharmaceutical facility destroyed by polyethylene dust
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27. Combustible Dust Explosions History
February 20, 2003 – CTA Acoustics Corbin, KY
Seven Workers died
Facility produced fiberglass insulation for automotive industry
Resin accumulated in production area and was ignited
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28. Combustible Dust Explosions History
October 29, 2003
Hayes Lemmerz Manufacturing Plant
Two severely burned (one of the victims died)
Accumulated aluminum dust
Facility manufactured cast aluminum automotive wheels
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29. Combustible Dust Explosions History
October 30, 2011
Bartlett Grain Elevator
Atchison Kansas
- 6 Workers killed
- 2 Workers injured
Workers were loading
corn onto a train
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30. The Dust Explosion Pentagon
Ignition Source
Ignition Source
Dispersion
Confinement
Deflagration
Explosion
FIRE
Combustible Dust
Oxygen in Air/Oxidizers
To prevent an explosion – remove one corner of the pentagon
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31. The primary explosion is rarely the end of the story.
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32. Secondary Explosions
Occur when the blast wave from the initial explosion causes accumulated dust in other areas (which may be remote and unrelated to original explosion) to become airborne and explode
Anecdotally many investigators discover that “puffs” (small unreported explosions) had been observed for some time prior to the reported incident.
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33. So How Do I Prevent a Dust Explosion?
If one of the five elements of the Pentagon is missing a catastrophic explosion cannot occur.
= No Explosion
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34. Oxygen in Air/Oxidizers FIRE I
Ignition Source
Ignition Source
Dispersion
Confinement
Deflagration
Explosion
FIRE
Combustible Dust
Oxygen in Air/Oxidizers
FIRE I
FIRE
Two elements are difficult to eliminate:
Oxygen in Air
Confinement within processes or buildings
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35. Oxygen in Air/Oxidizers
Ignition Source
Ignition Source
Dispersion
Confinement
Deflagration
Explosion
FIRE
Combustible Dust
Oxygen in Air/Oxidizers
FIRE I
But my process doesn’t include dust!
Are you sure?
If you work with any solid combustible material, ingredients or intermediate products or by-products, handling, conveying, or otherwise manipulating these materials can create combustible dust.
Even materials typically handled and stored wet can become dry.
FIRE
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36. Definitions and Terminology What is Combustible Dust?
NFPA 654 (2006) Definitions
Combustible dust. 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.
Combustible Particulate Solid. Any combustible solid material composed of distinct particles or pieces, regardless of size, shape, or chemical composition.
Hybrid Mixture. A mixture of a flammable gas with either a combustible dust or a combustible mist.
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37. Definitions and Terminology What is Combustible Dust?
NFPA 69 (2002), and 499 (2004) Definitions
Combustible Dust. Any finely divided solid material 420 microns or less in diameter (i.e., material passing through a U.S. No 40 Standard Sieve) that presents a fire or explosion hazard when dispersed
1 micron (µ) = 1.0 x 10-6 m  = 1.0 x 10-4 cm = 1.0 x 10-3 mm 
 420 µ = 420 x 10-4 cm = .042 cm = 0.4mm
A typical paper thickness is approximately 0.1mm
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38. Good housekeeping might seem like an easy answer.
Different dusts of the same chemical material may have different ignitability and explosibility characteristics depending on variables of particle size, shape, and moisture content.
Good housekeeping might seem like an easy answer.
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39. But housekeeping is only part of the answer!
As much as is practical, containment and dust collection systems are important.
But they must be installed and maintained in a manner that keeps them from becoming an ignition source
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40. NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing of Combustible Particulate Solids
Recommends:
Minimize the escape of dust from process equipment or ventilation systems:
Use dust collection systems and filters;
Utilize surfaces that minimize dust accumulation and facilitate cleaning;
Provide access to all hidden areas to permit inspection;
Inspect for dust residues in open and hidden areas (at regular intervals);
Clean dust residues (at regular intervals);
Only use vacuum cleaners approved for dust collection;
Locate relief valves away from dust hazard areas; and
9. Develop and implement a hazardous dust inspection, testing, housekeeping, and control program.
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41. Use dust collection systems and filters
Dust Control
Design of facility & process
equipment
Contain combustible dust
Clean fugitive dust
Regular program
Access to hidden areas
Safe cleaning methods
Maintenance
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42. Inspect for dust residues in open and hidden areas (at regular intervals);
Like most pharmaceutical manufacturers this was a “clean” facility.
West Pharmaceutical facility destroyed by polyethylene dust
Which accumulated above the tiles in a dropped ceiling
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43. NFPA 654, Standard for the Prevention of Fire and Dust Explosions form the Manufacturing, Processing of Combustible Particulate Solids
Contains comprehensive guidance on the control of ignition sources:
Use appropriate electrical equipment and wiring methods;
Control static electricity, including bonding of equipment to ground;
Control smoking, open flames, and sparks;
Control mechanical sparks and friction;
Use separator devices to remove foreign materials capable of igniting combustibles from process;
Separate heated surfaces from dusts;
Separate heating systems from dusts;
Proper use and type of industrial trucks;
Proper use of cartridge activated tools; and
Adequately maintain all the above equipment.
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44. Ignition Source Control
Electrical equipment
Static electricity control
Mechanical sparks & friction
Open flame control
Design of heating systems & heated surfaces
Use of tools, & vehicles
Maintenance
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45. Ignition Source Control
Electrical equipment
Class II, Division 1 and 2
Class I and Class III may also be an issue
Consider equipment both inside dust handling equipment and outside
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46. Ignition Source Control
Mechanical sparks & friction
Rotating equipment bearing failure can lead to very hot surfaces (above the MIT)
Sliding surfaces can develop charges
Steel tools dropping onto concrete or steel
A good mechanical integrity management system/vibration analysis system is needed to detect problems in advance with bearings and other surfaces
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47. Ignition Source Control
Mechanical sparks & friction
Open flame control
Use of tools & vehicles
Maintenance
All require effective control of Hot Work
Look for permit systems
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48. Ignition Source Control
Design of heating systems & heated surfaces
Know your materials
Minimum Ignition Temperature (MIT)
Maintain temperature controls
Moisture content may be critical
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49. Primary Applicable OSHA Standards
General – Housekeeping
Hazardous (Classified) Locations
Powered Industrial Trucks
Bakery Equipment
Sawmills
Grain Handling
General Duty Clause
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50. NFPA Standards – Dust Hazards
61 Agriculture
68 Deflagration Venting Systems
69 Explosion Prevention Systems
70 National Electric Code
77 Static Electricity
85 Boiler and Combustion Systems
86 Ovens and Furnaces
91 Exhaust Systems
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51. NFPA Standards Electrical & Systems
484 Combustible Metals
Includes Magnesium, Titanium, Zirconium, Aluminum, Tantalum and other reactive metals
499 Classification of Combustible Dust
654 manufacturing, Processing and Handling of Combustible Particulate Solids
655 Sulfur
664 Wood
and more
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52. Viewing NFPA Standards
Point to “Codes and Standards”
Click “Document List”
Click on standard desired, NFPA XXX
On bottom, click “Preview this Document”
Below disclaimer, click “I Agree”
Click “Open NFPA XXX”
After standard opens, the “1-2-3” button gives you the Table of Contents
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53. So What Should I Do?
Evaluate your workplace for the 5 points of the explosion Pentagon:
a) Combustible Dust
b) Ignition Source
c) Confinement
d) Dispersion
e) Oxygen in Air/Oxidizers
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54. How?
a) Combustible Dust – Do you see “dust” in your workplace that is used in your process or is a by product of your process
(i.e. At a sawmill sawdust is a by product of the cutting of logs/boards into product)
b) Ignition Source -eliminate any possible sources of ignition, from electricity to static electricity - a minimum of Class II electrical features
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55. How?
c) Confinement – This will depend on the configuration of the workplace and can be difficult to eliminate
d) Dispersion - keep dust from suspension in air
Use dust collectors
When cleaning do not re-suspend accumulated dust in air (DO NOT use air to “clean” surfaces)
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56. How? e) Oxygen in Air/Oxidizers
Oxygen in the air cannot be eliminated (unless workers are in SCBs)
Oxidizers, if present for process, should be isolated or replaced
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57. So What Should I Do? DO NOT DELAY
If you find that you do have the five elements
or you know you have four and may not be quite sure about number 5 –
DO NOT DELAY
Seek assistance
We don’t want your site
to look like this!
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58. If you have questions about this presentation call the Delaware Office
of Safety and Health Consultation at
If you have questions about our free Safety and Health Consultations
Please call us at
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59. Post Script -Five weeks later at another Imperial Sugar plant:
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66. So sometimes it’s not just a little dust
It’s a really fast way to demo a building
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