Combustible Dust Hazards and Controls Paul Schlumper Georgia Tech Research Institute 404-407-6797.

Combustible Combustible DustDust

Hazards and ControlsHazards and Controls

Paul SchlumperGeorgia Tech Research Institute404-407-6797

““Combustible Dust in Combustible Dust in Industry:Industry:

Preventing and mitigating the effects of Preventing and mitigating the effects of fires and explosions”fires and explosions”

OSHAOSHA Safety and Health Information Bulletin 07-31-Safety and Health Information Bulletin 07-31-20052005

Acknowledgement – Ben Ross – OSHA Region IVAcknowledgement – Ben Ross – OSHA Region IV

Adapted from

Deadly dust

This presentation describes:This presentation describes:• Hazards of combustible dust• Work practices• Guidelines• Training to protect employees• OSHA’s National Emphasis Program• Potential Citations

BackgroundBackgroundOrganic Dust Fires

and Explosions:– North Carolina

(6 killed, 38 injured)

– Kentucky (7 killed, 37 injured

Organic Dust Fire and Explosion: Organic Dust Fire and Explosion: North CarolinaNorth Carolina

• A fire at the plant caused dust to be dispersed and explode in the ceiling space

• 6 were killed, 38 injured

• Plant and nearby buildings were severely damaged

• Combustible polyethylene dust accumulated above suspended ceilings at pharmaceutical plant

Organic Dust Fire and Explosion: Organic Dust Fire and Explosion: KentuckyKentucky

A fire at an unattended oven ignited a dust cloud created by cleaning operations at a facility making fiberglass insulation for the automotive industry.

• The explosion was fueled by resin dust accumulated in a production area,

• The resin involved was a phenolic binder used in producing fiberglass mats.

Oxygen

Confinement

IgnitionFuel

Dispersion

Dust Explosion Requirements

Adapted from CSB

Some event disturbs the settled dust into a cloud

Dust cloud is ignited and explodes

Dust explosion in a work area

Dust settles on flat surfaces

Dust

Adapted from CSB

Dust explosionsDust explosionsAn initial (primary) explosion in• processing equipment or in an

area where fugitive dust has accumulated – may shake loose more accumulated

dust, or– damage a containment system (such

as a duct, vessel, or collector). • The additional dust dispersed into the air

may cause one or more secondary explosions.

• These can be far more destructive than a primary explosion

Facility Dust Hazard AssessmentFacility Dust Hazard Assessment

• dyes, • coal,• metals (e.g.,

aluminum, chromium, iron, magnesium, and zinc), and

• fossil fuel power generation.

Combustible dust explosion hazard may exist in a variety of industries

• food (e.g., candy, starch, flour, feed),

• plastics, • wood, • rubber, • furniture,• textiles, • pesticides, • pharmaceuticals,

Particles and Powders*Particles and Powders*Size

– Pellets > 2mm diameter

– Granules 0.42mm and 2mm, and

– dust particles < 0.42mm (420μm)

Hazard increases as particle size decreases – larger surface area for

combustion – Fine particle may have a larger

role in dust cloud ignition and explosion propagation.

Particles and Powders*Particles and Powders*

Dusts may occur in the process stream and cause a hazard, regardless of starting particle size of the material

may break into

or

Facility Analysis ComponentsFacility Analysis ComponentsCarefully identify:• Materials that can be

combustible when finely divided;

• Processes which use, consume, or produce combustible dusts;

• Open areas where combustible dusts may build up;

• Hidden areas where combustible dusts may accumulate;

• Means by which dust may be dispersed in the air; and

• Potential ignition sources.

See Explosives

regulations

Dust CombustibilityDust CombustibilityThe primary factor in an

assessment of these hazards is whether the dust is in fact combustible.

*Determine if a dust cloud will:– Detonate– Deflagrate– Present a fire hazard– Or will Not burn or

ignite

Testing may be necessary

Dust CombustibilityDust Combustibility

Combustible dust per NFPA 654• Prior to 2006 - “Any finely divided solid material

that is 420 microns or smaller in diameter (material passing a U.S. No. 40 Standard Sieve) and presents a fire or explosion hazard when dispersed and ignited in air.”

• *2006 Edition – 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.

Dust CombustibilityDust Combustibility• *OSHA work site health Limits (PELs) 2.5

ug/m3 (.0000025g/m3) through 15 mg/m3 (.015 g/m3)

• Explosive range for combustible dusts 15 g/m3 through (Approx.) 1200 g/m3

0 250 500 750 1000 g/m3

Dust cloud concentration

*25 watt light bulb probably can not be seen through ten feet of a combustible dust mixture

Dust CombustibilityDust Combustibility

What bulb?

25 watts

2 meters

Glass Glass

40 g/m3 concentration of comb. dust suspended in air

What is wrong here?

Dust CombustibilityDust CombustibilityInformation sources (some better

than others)– “As used” test data– Chemical supplier test data– MSDS sheets – Published tables Variables

• Particle size,• Shape• Moisture content. • Changes in the material

produced by process equipment.

• Many others

Electrical classificationElectrical classification

• OSHA Electrical standard (29 CFR Part 1910 Subpart S)

• NFPA 70, the National Electrical Code®.

• NFPA 499, . . . Classification of Combustible Dusts and of Hazardous (classified) Locations for Electrical Installations in Chemical Process Areas.

ElectricalEquipmentClass IIDivision 1Division 2Group A

B C

Other Hazard Analysis Other Hazard Analysis Considerations Considerations

Some subjective (and not always accurate) rules of thumb

*Begin cleaning when dust reaches – When you can write in it– When it obscures the color of the surface – 1/64th inch thick– 1/32nd inch thick– 1/16th inch thick– 1/8th inch thick– Really no need to clean - if it hasn’t exploded

by now, it won’t

CPL 03-00-008 – National CPL 03-00-008 – National Emphasis ProgramEmphasis Program

“immediate cleaning is warranted whenever a dust layer of 1/32-inch thickness accumulates over a surface area of at least 5% of the floor area of the facility or any given room. The 5% factor should not be used if the floor area exceeds 20,000 ft2, in which case a 1,000 ft2 layer of dust is the upper limit. Accumulations on overhead beams, joists, ducts, the tops of equipment, and other surfaces should be included when determining the dust coverage area. Even vertical surfaces should be included if the dust is adhering to them. Rough calculations show that the available surface area of bar joists is approximately 5 % of the floor area and the equivalent surface area for steel beams can be as high as 10%.”

Dust ControlDust ControlNFPA 654 - contains

comprehensive guidance

Some of its recommendations:

• 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;

Spots are not raindrops

?

NFPA 654 – guidance

• 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;

Dust ControlDust Control

Dust ControlDust Control

NFPA 654 – guidance

• Use cleaning methods that do not generate dust clouds, if ignition sources are present;

• Only use vacuum cleaners approved for dust collection;

HAZ LOC

Ignition ControlIgnition ControlNFPA 654, identifies

comprehensive guidance

• Use appropriate electrical equipment and wiring methods;

• Control static electricity, including bonding of equipment to ground;

• Control smoking, open flames, sparks;

No!

Ignition ControlIgnition ControlNFPA 654 - guidance • Control mechanical sparks

and friction;• Use separator devices to

remove foreign materials capable of igniting combustibles from process materials;

• Separate heated surfaces from dusts;

Magnetic Core

Non - Magnetic rotating drum

Ignition ControlIgnition ControlNFPA 654 -

guidance • Separate heating

systems from dusts;• Proper use and

type of industrial trucks;

• Proper use of cartridge activated tools; and

• Adequately maintain equipment.

Hot work permit____________________________________

Grinder

Kaboom!

Ignition ControlIgnition ControlOther ignition

sourcesUse appropriate Class II

Electrical equipment and wiring methods where required

OSHA 29 CFR 1910.178 (c) regulates powered industrial trucks in dust areas

Coal handling operations must comply with OSHA 29 CFR 1910.269

Class I & IIGroup D & G

Hazardous vertical surface accumulation

Employees need to be trained

• To recognize and prevent hazards associated with combustible dust

• In taking preventative action, and/or

• How to alert management.

TrainingTraining

TrainingTrainingThey need to know • The safe work practices

applicable to their job tasks, • The overall plant programs for

dust control and ignition source control.

Training must be• Before they start work• Periodically to refresh their

knowledge• When reassigned • When hazards or processes

change

TrainingTraining Management Responsibility• Comply with the Hazard Communication

Standard

• Have a qualified team conduct a facility analysis (or have one done by qualified outside persons) prior to the introduction of a hazard and

• Develop a prevention and protection scheme tailored to the operation. List of

Chemicals

Training Training Supervisors and managers

should be aware of and support the plant dust and ignition control programs.

Their training should include identifying how they can encourage the reporting of unsafe practices and facilitate abatement actions.

NEP/ Industry ApplicationNEP/ Industry Application• Food products• Agriculture• Chemicals • Textiles• Forest and furniture products• Metal processing• Tire and rubber manufacturing plants• Paper products• Pharmaceuticals• Wastewater treatment• Recycling operations (metal, paper, and plastic)• Coal dust in coal handling and processing

facilities

Primary Applicable OSHA Primary Applicable OSHA StandardsStandards

1910.22 General – Housekeeping1910.307 Hazardous (Classified) Locations1910.178 Powered Industrial Trucks1910.263 Bakery Equipment1910.265 Sawmills1910.272 Grain HandlingGeneral Duty Clause

NFPA Standards – Dust HazardsNFPA Standards – Dust Hazards

61 Agriculture68 Deflagration Venting Systems69 Explosion Prevention Systems70 National Electric Code77 Static Electricity85 Boiler and CombustionSystems86 Ovens and Furnaces91 Exhaust Systems

NFPA StandardsNFPA StandardsElectrical & SystemsElectrical & Systems

484 Combustible MetalsIncludes Magnesium, Titanium, Zirconium, Aluminum, Tantalum and other reactive metals

499 Classification of Combustible Dust654 manufacturing, Processing and Handling of Combustible Particulate Solids655 Sulfur664 Woodand more

38

Database of Combustible DustDatabase of Combustible Dust

• BGIA GESTIS-DUST-EX Database of Combustion and Explosion Characteristics of Dusts

• Important characteristics of more than 4000 dust samples from virtually all sectors of industry

• Developed in Germany with the financial support of the EC

39

Database of Combustible DustDatabase of Combustible Dust• There are limits of applicability of the data

– a wide variation is possible in the nature of the dusts• e.g., composition, particle size distribution,

surface structure, moisture content, etc.– the numerical value of the characteristics

depend on the test methods

• Always be aware that the values listed only serve as a guideline for the design of preventive and protective measures.

• http://www.hvbg.de/e/bia/gestis/expl/index.html

CitationsCitations

• Typical hazards

– Accumulation of combustible dust in areas which have/may have ignition sources

– Lack of, or inadequate, explosion mitigation

– Failure to control ignition sources inside equipment

– Cleaning dust with non-explosion proof equipment (e.g., vacuums)

CitationsCitations

• Typical hazards (con’t)

– Cleaning dust with compressed air (electrostatic issue)

–PPE– Inadequate Ventilation–HazCom training

CitationsCitations

• Cite the HAZARD!!!• Where possible, use OSHA/State

OSHA standards– 1910.22(a)(1) – General Housekeeping– 1910.176(c) – Housekeeping in storage

areas– 1910.307 (See Class II Locations)

• Class III and Class I Locations may be an issue, too

– 1910.269(v)(11)(xii) – Electrical Power Generation

– State specific standards

CitationsCitations

• 5(a)(1)– See the Sample Citations File– NFPA standards are used as both

•Evidence of industry recognition•Feasible and Acceptable Abate method

– Reference Mandatory “shalls” in NFPA to ensure standard requirements

– Use “shoulds” for abatement recommendations

CitationsCitations

• Other important standards– 1910.1200 – HazCom

•Failure to train•Inadequate MSDS•Also a possible source of employer

knowledge

– 1910.132(a)•Properly assess workplace hazards &

provide•Non-static clothing•Flame retardant clothing•Footwear

CitationsCitations

• Other important standards– 1910.119

•When dust is listed in Appendix A, 1910.119 can be cited in its entirety

•Possible citations if dust explosion hazard not evaluated in Process Hazard Analysis and could affect covered processes

– May lead to additional citations such as:»Siting»Training»Operating procedures, etc.

CitationsCitations• Other important standards

– 1910.178 (Powered Industrial Trucks)– 1910.252 (Welding, Cutting and Brazing)– 1910.145(c)(3) – Warning signs– 1910.156 (or 1910.38)– 1910.263(k)(2) – Bakery Equipment– 1910.265(c)(20)(i) – Sawmills– Agriculture

• HazCom• General Duty

© J Howicz 2008

© J Howicz 2008

© J Howicz 2008

© J Howicz 2008

© J Howicz 2008

PROPOSED VIOLATIONSPROPOSED VIOLATIONS

• Egregious willful: – 12 instances of housekeeping by location (1910.22(a)(1) &

(a)(2))– 44 instances of electrical equipment not classified for area

(1910.307(c)(1)(i))– 5 instances of powered industrial trucks not classified for

the area (1910.178(c)(2)(vii))

• 8 Willful violations: – Explosion prevention systems (5a1) – Dust collection deficiencies (5a1)– Operation of “sweeper” in hazardous locations (5a1)– Fall Protection (1910.22 & 23)– Unguarded belt & pulley (1910.219(d)(1) & (e)(3)(i)

PROPOSED VIOLATIONSPROPOSED VIOLATIONS

• 51 Serious violations– Dust collection system installed improperly (5a1)– Masonry construction of exterior wall in powder room (5a1)– Conveyor belts with no sensors (5a1); – Maintenance of boilers (5a1)– Stairs & Ladders– Egress– Manlifts– Fire extinguishers– Machine Guarding– Welding– Electrical– Lead– Maritime

TOTAL PENALTIESTOTAL PENALTIES

• $5,062,000– Egregious: $4,270,000– Willful: $560,000– Serious: $232,000

QUESTIONS?QUESTIONS?