Combustible Dust Presentation

8/4/2019 Combustible Dust Presentation

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J Howicz 2008

Combustible Dust

Hazards and Controls

Benjamin RossAssistant Regional AdministratorOffice of Enforcement Programs(404) 562-2300


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Combustible Dust inIndustry:

Preventing and mitigating theeffects of fires and explosions

OSHA Safety and HealthInformation Bulletin 07-31-2005

Adapted from

Deadly dust

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This presentation describes: Hazards of combustible dust Work practices Guidelines Training to protect employees


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Background

Organic Dust Fires andExplosions:

North Carolina

(6 killed, 38 injured)

Kentucky

(7 killed, 37 injured

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Organic Dust Fire and Explosion:

North Carolina

A fire at the plantcaused dust to bedispersed and explodein the ceiling space

6 were killed, 38injured

Plant and nearbybuildings wereseverely damaged

Combustible polyethylene dust accumulatedabove suspended ceilings at pharmaceutical plant


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North Carolina

The causes of the incident cited by the ChemicalSafety Board (CSB) included inadequacies in:

Hazardassessment;

Hazardcommunication;and

Engineeringmanagement.

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Kentucky

A fire at an unattended ovenignited a dust cloudcreated by cleaning

operations at a facility makingfiberglass insulation for theautomotive industry.

The explosion was fueled byresin dust accumulated in a

production area, The resin involved was a

phenolic binder used in producing

fiberglass mats.


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Kentucky

The CSB identified ineffective dust control and explosion prevention /mitigation

Both of these causes involvedproblems relating to

Hazard assessment; Hazard communication; Maintenance procedures; Building design; and, Investigation of previous fires.

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Oxygen

Confinement

IgnitionFuel

Dispersion

Dust Explosion Requirements

Adapted from CSB


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Some eventdisturbs the

settled dustinto a cloud

Dust cloud isignited andexplodes

Dust explosion in a work area

Dust settles on flatsurfaces

Dust

Adapted from CSB

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Dust 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 secondaryexplosions.

These can be far more destructive than aprimary explosion


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Facility Dust Hazard Assessment

dyes,

coal, metals (e.g.,

aluminum,chromium, iron,magnesium, andzinc), and

fossil fuel powergeneration.

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,

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Facility Dust Hazard Assessment. . .any industrial process that reduces a combustible

material and some normally noncombustiblematerials to a finely divided state presents a potential for a serious fire or

explosion. (NFPAs Industrial Fire Hazards Handbook)


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Particles and Powders*

Size Pellets > 2mm diameter Granules 0.42mm and 2mm,

and dust particles < 0.42mm

(420m)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.

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Particles and Powders*

Dusts may occur in the process streamand cause a hazard, regardless of

starting particle size of the material

maybreakinto

or


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Facility Analysis Components

Carefully 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 mayaccumulate;

Means by which dust may bedispersed in the air; and

Potential ignition sources.

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Facility Analysis Components

Identify and follow the applicablefederal, state, and local lawsand regulations. Somecommonly applicable mandatoryrequirements

OSHA General Duty Clause andStandards

The International Code Councils

International Fire Code NFPAs Uniform Fire Code.

29 CFR 1910

Local building codes frequently adopt NFPAdust standards by reference


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See

Explosivesregulations

Dust Combustibility

The primary factorin anassessment of thesehazards is whether thedust is in factcombustible.

*Determine if a dust cloudwill:DetonateDeflagrate Present a fire hazard

Or will Not burn orignite

Testing may be necessary

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Dust Combustibility

Combustible dust per NFPA 654

Prior to 2006 - Any finely divided solid materialthat is 420 microns or smaller in diameter(material passing a U.S. No. 40 Standard Sieve)and presents a fire or explosion hazard whendispersed and ignited in air.

*2006 Edition A combustible particulate solid thatpresents a fire or deflagration hazard whensuspended in air or some other oxidizing mediumover a range of concentrations, regardless ofparticle size or shape.


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Dust 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

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*25 watt light bulbprobably can not be seenthrough ten feet of acombustible dust mixture

Dust Combustibility

Whatbulb?

25 watts

2 meters

Glass Glass

40 g/m3 concentration ofcomb. dust suspended in air


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What is wrong here?

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Dust 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 processequipment.

Many others


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Electrical classification

OSHA Electrical standard(29 CFR Part 1910 Subpart S)

NFPA 70, the NationalElectrical Code.

NFPA 499, . . . Classificationof Combustible Dusts and of

Hazardous (classified)

Locations for Electrical

Installations in ChemicalProcess Areas.

ElectricalEquipmentClass IIDivision 1Division 2Group A

B

C

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Other Hazard Analysis

ConsiderationsSome 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

1/16

th

inch thick 1/8th inch thick

Really no need to clean - if it hasnt exploded by now,

it wont


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Dust ControlNFPA 654 - contains

comprehensive guidanceSome of its recommendations:

Minimize the escape of dust

from process equipment orventilation systems;

Use dust collection

systems and filters;

Utilize surfaces thatminimize dust

accumulation and facilitate

cleaning;

Spotsare not

raindrops

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?

NFPA 654 guidance

Provideaccess to allhidden areas topermit inspection;

Inspect for dustresidues in openand hidden areas,at regular

intervals; Clean dustresidues atregular intervals;

Dust Control


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Dust Control

NFPA 654 guidance

Use cleaning methodsthat do not generatedust clouds, if ignitionsources are present;

Only use vacuumcleaners approvedfor dust collection;

HAZ LOC

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Ignition ControlNFPA 654, identifiescomprehensiveguidance

Use appropriateelectrical equipment andwiring methods;

Control static electricity,

including bonding ofequipment to ground;

Control smoking, openflames, and sparks;

No!


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Ignition Control

NFPA 654 -guidance Control mechanical

sparks and friction;

Use separator devices

to remove foreign

materials capable ofigniting combustibles fromprocess materials;

Separate heatedsurfaces from dusts;

Magnetic

Core

Non - Magnetic

rotating drum

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Ignition Control

NFPA 654 -guidance

Separate heating

systems from dusts;

Proper use and typeof industrial trucks;

Proper use ofcartridge activated

tools; and Adequately maintain

equipment.

Hotworkpermit

_________

_________

_________

_________

Grinder

Kaboom!


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Ignition Control

Other ignitionsources

Use appropriate Class IIElectrical equipment andwiring methods whererequired

OSHA 29 CFR 1910.178(c) regulates poweredindustrial trucks in dust

areasCoal handling operations

must comply with OSHA29 CFR 1910.269

Class I & II

Group D & G

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Hazardousvertical surfaceaccumulation

Employees needto be trained

To recognize andprevent hazards

associated withcombustible dust

In takingpreventative action,

and/or

How to alertmanagement.

Training


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TrainingThey need to know

The safe work practices applicable totheir job tasks,

The overall plant programs for dustcontrol and ignition source control.

Training must be

Before they start work

Periodically to refresh their knowledge

When reassigned

When hazards or processes change

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TrainingManagement Responsibility

Comply with the Hazard CommunicationStandard

Have a qualified team conduct a facilityanalysis (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


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TrainingSupervisors and managers

should be aware of and supportthe plant dust and ignitioncontrol programs.

Their training should includeidentifying how they canencourage the reporting ofunsafe practices and facilitate

abatement actions.

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IMPERIAL SUGARIMPERIAL SUGAR

COMPANYCOMPANY

Port Wentworth, Georgia

Facility constructed in 1917; purchased by ISCin 1997

2nd largest sugar refinery (300+ acres)

Publicly traded

Largest sugar refiner in country-2001

Bankrupt in 2001, sold off most facilities

850 employees total; 400 at Port Wentworth Refines cane sugar into granulated,

confectioners (powdered) sugar, brown sugar,liquid sugar and specialty sugars


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Overview of EventOverview of Event

February 7, 2008 @7:16pm catastrophic dustexplosion

8 employees killed immediately; 40 employeesinjured

19 victims admitted to Augusta Burn Center; 5 diedfrom their injuries; 3 remain hospitalized

13 total employees killed

CEO in plant at time of event

117 employees onsite; 29 contract employees

7 total contractors; 3 contractors on site at time ofevent; 2 of the fatalities were contract employees


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Response

SAV AO arrives on-site @ 8:45pm Established contact and entered into ICS

Assistant Safety Officer

Investigation Team

Initiated Compliance Assistance support until 2/15

Police & Fire State Fire Marshall (Arson Investigation) ATF National Response Team (Criminal Inv) Chemical Safety Board

Entered site agreement with OSHA & company

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THE INVESTIGATION OSHA onsite within one and half hours Began interviews upon release from ATF February 15 Interviews of 200+ employees and managers (not

including contractors) Over 1,000 hours of interviews & depositions Collection and evaluation of physical evidence to

determine cause of explosion Collection & review of over 20,000 documents, 7

subpoenas issued Comprehensive inspection of all accessible parts of

facility Limited engineering documentation maintained OSHA camper and trailer


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Deflagration - WorkingDefinition

Propagation of a flame or combustionzone through a mixture of a fuel andoxidizer (usually air) producing a pressurefront and flame front that propagate fromthe point of ignition at a rate that is slowerthan the speed of sound in the unburnedmixture.

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Deflagration

Deflagrations liberate large quantities ofheat very rapidly. Increases the air temperature rapidly

Causes the air and combustion product gasesto expand rapidly (8X for sugar)

Rapid heating and expansion causes largepressures to develop

Large pressures cause structural failure

Heat and structural failure cause personnelinjuries


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Necessary Conditions for DustDeflagration

Four conditions must be met: Combustible particulate solid of sufficiently

small particle size to be deflagrable.

Deflagrable particulate is suspended in air (orother oxidizing medium)

Deflagrable particulate suspension ofsufficiently high concentration.

A competent igniter applied to the suspensionwhere the concentration is sufficient for flamepropagation.

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Necessary Conditions for Dust

Deflagration

All four (4) conditions must be met in the sameplace and at the same time.

Deflagrable particulate.

Suspension

Sufficient Concentration.

Competent igniter applied to the suspension where

the concentration is sufficient for flame propagation. Consequently, deflagrations are rare events with

devastating consequences.


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Hazardous Particulate

Largest particles

Smallest particles

Every large compartment is a particulateseparator, separating particles by mass.

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The Typical Explosion Event

Most dust explosions occur as a series ofdeflagrations (secondary events) instages.

While a single explosion is possible it is theexception rather than the rule.

Most injuries are the result of the secondary

deflagrations rather than the initial event, inthis case - ALL of them


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The Typical ExplosionEvent

Factory

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

Process

Equipment

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The Typical Explosion

Event

ProcessEquipment

InitialInternalDeflagration

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325


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The Typical ExplosionEvent

ProcessEquipment


Shock Wave

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

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e yp ca xp os on

Event

ProcessEquipment


Elastic ReboundShock Waves

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325


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Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

ProcessEquipment


Dust clouds causedby Elastic Rebound

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ProcessEquipment

ContainmentFailure from InitialDeflagration

Dust Clouds Causedby Elastic Rebound

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325


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ProcessEquipment

Secondary DeflagrationInitiated

Dust Clouds Causedby Elastic Rebound

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

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The Typical Explosion

Event

ProcessEquipment

Secondary DeflagrationPropagates through Interior

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325


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ProcessEquipment

Secondary DeflagrationVents from Structure

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

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Secondary DeflagrationCauses Collapse and Residual Fires

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325


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Evaluation of Causal Factors Dust emissions/housekeeping Dust collection systems Ignition Sources

PITs Electrical

Mechanical

Prevention Systems Deflagration venting

Explosion suppression systems

Explosion isolation devices Life Safety Fire Protection


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WHAT HAPPENED?

Rodding of Silo 1 all day resulting inadded fuel load in tunnel

Initiating event inside East PackagingProduction Bucket Elevator

Secondary explosions in the silogallery and the tunnel

Flame front and overpressurizationadvances through packing houses andinto adjacent buildings

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PROPOSED VIOLATIONS

Egregious willful: 12 instances of housekeeping by location

(1910.22(a)(1) & (a)(2))

44 instances of electrical equipment not classified forarea (1910.307(c)(1)(i))

5 instances of powered industrial trucks not classifiedfor 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)

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PROPOSED 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


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Housekeeping & Dust

Emissions EE statements, emphasis on production Calculation for fuel load Company created MSDSs

Numerous previous fires, including week before event Explosion at Domino, November Audit Reports (Insurance, AIB, internal) LO/TO Procedure Photos depicted heavy accumulations Injury/illness reports (injury and illnesses documented accumulations) Corp Safety Manager

Stated to have no responsibility over housekeeping, considered food quality issued Emailed managers that condition of facility was bad

VP of Ops Worst facility he has ever seen Didnt know places like this still existed in America

Told facility management they would end up in body bag Placed CEO on notice, told to cool it. Also told to give a positive response to board Spoke of accumulations up to waist deep throughout packing houses

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Other Critical Evidence Electrical

EE, mgr statements Didnt classify hazardous locations, did @ Grammercy facility Training document detailing requirement Laundry list of equipment not rated for Class II, Div 1 or 2 Insurance audits, placed on notice of unapproved devices No one assigned responsibility in selection/purchase

Deflagration protection Mgr & engineer statements

Insurance Audits (Grammercy) Protective systems in place at other company facilities One bucket elevator vented & dust collectors vented

Isolation (rotary valves) used Dust Collection

Engineering audits (poor design & maintenance) Duct velocities 20-50% designed capacity-18 months


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TOTAL PENALTIES

$5,062,000

Egregious: $4,270,000

Willful: $560,000

Serious: $232,000

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Helpful Hints

Manage the scene, dont let it manage you! Establish good communication Evidence collection

Professional input/opinions Photos Interview statements

Identify & establish base of ops Establish document collection system Demolition/Evidence collection involvement Thorough interviews!! Create Timeline (interviews, 911 calls, emerg resp docs)

Manage Photos Plan, delegate, & monitor activities Plan, obtain, & use resources wisely (personnel & equipment) Keep team focused on mission! Good communication with RO and NO. NO SURPRISES!!! Careful w/ CSB

Documents

Combustible Dust Presentation