External Webinar - What to Know Before Completing a Dust ......equipment explosion, dust explosion within equipment, primary dust explosion, etc.) o Resulting blast and air motion

What to Know Before Completing a Dust Hazard Assessment

Principal Engineer – BakerRisk, San Antonio Has performed over 200 dust hazard analyses as well as numerous incident investigations across a

wide range of industries all over the world. Committee member of:

NFPA 652 “Standard on the Fundamentals of Combustible Dust.” NFPA 654 “Standard for Prevention of Fire and Dust Explosions from the Manufacturing,

Processing, and Handling of Combustible Particulate Solids,” NFPA 61 “Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food

Processing Facilities”www.BakerRisk.com

Presenter: Phil Parsons

Copyright BakerRisk. All rights reserved.

Dust Hazard Assessment Webinar, February 2021 2

Presenter: Phil ParsonsPrincipal Engineer, BakerRisk

What to Know Before Completinga Dust Hazard Assessment

February 9, 2021Copyright BakerRisk. All rights reserved.

[email protected]

Dust Hazard Assessment Webinar, February 2021

Notable Losses

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Housekeeping

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How Dust Explosions Occur

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Codes and Standards

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Common Deficiencies

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Dust Hazard Analysis

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Overview

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Imperial Sugar Company

Port Wentworth, GA

14 fatalities

Numerous injuries

Imperial Sugar (2008)


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Didion Milling (2017)

Didion Milling

Cambria, WI

5 fatalities

14 injuries


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Slow Combustion Faster Combustion

Deflagration(Explosion if Contained)

Source: Dust Explosions in the Process Industries, Second Edition, Rolf K Eckhoff

How Dust Explosions Occur (1 of 5)

• If it can burn, its dust is probably a combustible dust

• Combustion rate increases with subdivision of material


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• Damage generally limited to enclosure in which explosion occurs, with potential for heavy damage to adjoined structures

• High potential for burn injuries in vicinity of dust explosion


Testing Completed by BakerRisk


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• Catastrophic dust explosions are generally secondary dust explosionso Primary explosion occurs (e.g., gas fired

equipment explosion, dust explosion within equipment, primary dust explosion, etc.)

o Resulting blast and air motion suspends dust that had accumulated in area (primarily on elevated horizontal surfaces)

o Suspended dust ignites and explosion propagates until dust is consumed throughout enclosed area



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• Significant dust explosions can also occur from “primary” explosionso Deflagrations within individual or connected equipment can result in significant consequence

unless appropriately protected

o Major focus of dust hazards analysis (DHA)



Firefighter Caught in a Vented Dust Deflagration Fireball (Photo courtesy of OSHA.gov)

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• Good housekeeping eliminates secondary explosion potential

Importance of Housekeeping (1 of 3)

o NFPA 654: manage dust accumulations <1/32-inch (0.8 mm, paper clip) over < 5% of building footprint 5% typically equivalent to surface area of

elevated horizontal surfaces Can scale allowable thickness for different

bulk densities (1/32-in based on 75 lb/ft3) BakerRisk recommends using “accumulation

obscures color of underlying paint” as criteria for cleaning


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Examples of problematic dust accumulations


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Examples of good housekeeping


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NFPA 652Standard on the Fundamentals of Combustible Dust

NFPA 61Agricultural and Food Processing Facilities

NFPA 654Manufacturing, Processing and

Handling of Combustible Particulate

Solids

NFPA 664Wood Processing and

Woodworking Facilities

NFPA 655Sulfur Fires and

Explosions

NFPA 484Combustible Metals

NFPA 499 Recommended PracticeClassification of Combustible Dusts and of Hazardous

(Classified) Locations for Electrical Installations in Chemical Process Areas

NFPA Standards


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• On October 18, 2007, OSHA published the “Combustible Dust National Emphasis Program” (NEP)o NEP describes OSHA expectations regarding owner / operator compliance with U.S. Safety

Standards

o OSHA references NFPA relevant standards for guidance on identifying and mitigating combustible dust hazards

• NEP activity has lagged over last few years due to lack of qualified inspectors

• OSHA still issuing dust-related citations based on plant inspections

• OSHA will issue dust-related citations in event of incident

US Regulatory Environment (1 of 2)


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US Regulatory Environment (2 of 2)

Top OSHA dust-related citations ………. Insufficient progress made on completing DHA by Sept 2020 Hazardous levels of dust accumulations in the workplaces due to

poor housekeeping practices Electrical equipment and Powered Industrial Trucks not approved

for locations handling combustible dusts Dust collectors located inside buildings without proper explosion

protection systems (e.g., venting or suppression) Deflagration isolation systems not provided to prevent deflagration

propagation from dust handling equipment to other parts of plant


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DHA Overview (1 of 6)

Owner/operator is responsible to ensure a DHA was completed by September 2020 (January 2022 for Ag/Food Industries)

DHA must be: Performed by a qualified person Documented, including action items / recommendations and path

forward to implement solutions. NFPA standards allow for two approaches to satisfy DHAo Prescriptive (gap analysis)o Performance based (risk)


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Prescriptive Approach (gap analysis) Comparison against relevant commodity-specific NFPA standard, along

with NFPA 652 Audit of operations, equipment, housekeeping, and procedures for

combustible dust fire & explosion hazards Comparison against prescriptive requirements from standards Should cover all requirements, not just the “highlights” Needs to be comprehensive to avoid false sense of security

Recommendations can be extensive Can pose challenge to address all recommendations in a timely fashion


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Prescriptive Approach – Example:


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Prescriptive approach (gap analysis)


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Performance-based approach (risk) Systematic approach to assess hazards and associated risk Allows for prioritization and screening of risks Can utilize same approach as in traditional PHA Employ corporate risk matrix Assess consequences and likelihood of identified scenarios Layers of Protection Analysis (LOPA) can be implemented to evaluate

integrity of associated safeguards BakerRisk uses PHA-Tool with purpose-built DHA module to conduct

performance-based studies


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Performance-based approach (risk)


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What’s wrong with this picture?

Deflagration Vent Panels

Exhaust Duct

Dust Collector


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Deflagration Vent Panels –acknowledges explosion hazard is credible

Dust Collector

No deflagration isolation device on the inlet!


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• Material specific explosibility data (e.g., Kst, Pmax) to support explosion system design basis Key parameters needed to ensure explosion protection system will function as intended

• If available, often not representative “As-received” vs. finest fines

Moisture content

Explosion Protection Design Deficiencies


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Design Basis Limitations

Example: Suppression System Design Details

“DURING SYSTEM ACTIVATION BY PRESSURE OR OPTICAL DEFLAGRATION DETECTION, A MOMENTARY PRESSURE EXCURSION WITHIN THE PROTECTED VOLUME NOT EXCEEDING 3.0 PSIG CAN BE EXPECTED.”


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Abort Gate Trigger


Abort Gate

Upstream Fan

Dust Collector


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Plant Manager’s Office!Dust Collector


Presenter

Presentation Notes

Note that the vents were only located on the visible side – the other side had none. Re-orientate the collector or relocate panels

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Product Buildup in the Duct

Fire Hazard!

• Not Achieving Minimum Flow Velocity (4,000 fpm)

• No Inspection/Clean out hatches


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Escape Route

Possible Solution - Canopy


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Roadway

Building Egress

Possible Solutions:

- Flameless Vents- Restricted Access- Canopy



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Deflagration Vent Panel

Vent Duct to Outside

Vendor should supply proof that design basis is compliant with NFPA standards!



It is the owner/operator's obligation to determine whether the particulate solids handled are combustible.

Do I Handle Combustible Dust?

NFPA Standards require owner/operators perform a DHA to ensure safe operations.

Should I Perform a Dust Hazards Analysis?

Ensure someone qualified with sufficient experience to be able to identify potential combustible dust hazards participates in the DHA process.

Not All DHAs are Equal

A well-performed DHA should be able to identify hazards that may still be present even though equipment is “protected”.

Details Matter

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Closing Thoughts

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• Hazard identification – Facilitate Explosibility Testing of Dusts

• Perform Your DHA - Evaluate and Quantify Combustible Dust Hazards

• Corporate DHA Guidance – Provide Assistance Developing DHA Strategies for Multi-Facility Organizations

• Incident Investigation – Aid with Determining Cause/Origin

How Can We Help?

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What to Know Before Completing a Dust Hazard Assessment

[email protected] 210-824-5960www.bakerrisk.com

www.BakerRisk.com

Phil Parsons


Upcoming BakerRisk Webinar:What to Know Before Completing a Building Upgrade

www.BakerRisk.com

Date: April 6th, 2021Presenter: David Wood


Documents

External Webinar - What to Know Before Completing a Dust ......equipment explosion, dust explosion within equipment, primary dust explosion, etc.) o Resulting blast and air motion