Dust Explosions Spark Safety Alert

Friday, November 9, 2018 @ 02:11 PM gHale

Aftermath of a deadly dust explosion at the Didion Milling Co. plant in Cambria, WI. Things appeared normal just before an air filter blew off a corn-grinding device shortly before the blast demolished the plant May 31 last year.

By Gregory Hale
Dust accumulation, be it in one specific location or throughout a manufacturing enterprise, can create a very explosive and lethal environment for workers and the community.

While the dust issue continues to be a problem, it is also something that is very preventable.

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Take the May 2017 Didion Mill blast that left five dead and 14 others injured.

“Our investigation of the Didion incident continues and we are analyzing evidence to understand the specifics leading up to the tragic event,” said Chemical Safety Board (CSB) Investigator Cheryl MacKenzie. “However, this investigation reinforces what we are seeing across many industries — that there needs to be a more inclusive approach to creating and maintaining a safe work environment amid processes that inherently produce dust.”

Recent Incidents
Dust incidents have been in the news as there was a dust explosion and fire at Archer Daniels Midland Co.’s (ADM) North American headquarters in Decatur, IL, Nov 3. There was an explosion in the grain elevator that serves corn and soybean plants in the Decatur complex, Jackie Anderson, a spokesperson with ADM said right after the 1 a.m. incident.

In addition, dust was the culprit for a fire and explosion at a business Nov. 1 in Lynchburg, VA, after a welding arc set off the blast. Workers were conducting maintenance on top of an oven at Hanwha Azdel, welding a new rod, when the welding arc set off a dust explosion fire in the roof system in the insulation, activating the sprinkler system, fire officials said.

Hanwha Azdel Inc. manufactures high-performance thermoplastic composites designed for interior and exterior applications across many different industries, according to its website. Major segments served include automotive, heavy truck, recreational vehicles, industrial, and other transportation applications.

All employees were accounted for and there were no injuries after an Oct. 18 dust explosion at Big V Feeds in McAlester, OK, officials said. Witnesses said they saw a tall flame and heard a big boom before black smoke billowed out of a grain bin. Big V Feeds officials said: “Just wanted to let everyone know that we had a flash dust explosion at the mill a little while ago.”

Conditions
In essence, there are five necessary conditions for a dust explosion:
• A combustible dust
• The dust is suspended in the air at a sufficiently high concentration
• There is an oxidant (typically atmospheric oxygen)
• There is an ignition source
• The area is confined—a building can be considered an enclosure

Common materials known to burn can generate a dust explosion, such as coal and sawdust. In addition, many otherwise mundane organic materials can also be dispersed into a dangerous dust cloud, such as grain, flour, starch, sugar, powdered milk, cocoa, coffee, and pollen. Powdered metals (such as aluminum, magnesium, and titanium) can form explosive suspensions in air, if finely divided.

That is why dust incidents continue to have an impact on multiple industries.

That is also why the CSB is continuing its call to action to gather comments on the management of combustible dust from companies, regulators, inspectors, safety training providers, researchers, unions, and the workers affected by dust-related hazards.

Hazard Information
The call to action lists 11 “very fundamental” questions, the answers to which the CSB said will add to its understanding of issues such as a “safe level” of dust; improving worker recognition of dust hazards; how to measure a “clean” facility; the frequency of fires that do not result in explosions; and the best way stakeholders can share information about dust hazards and measures to prevent incidents.

The CSB said it will review all responses submitted by November 26; comments can be emailed directly to the CSB.

In 2006, the CSB identified 281 combustible dust incidents between 1980 and 2005. In terms of incidents, 119 workers were fatally injured, 718 more were hurt, and industrial facilities were extensively damaged. The incidents occurred in 44 states, in many different industries, and involved a variety of different materials.

Since the publication of the study in 2006, the CSB has confirmed an additional 105 combustible dust incidents and conducted in-depth investigations of five, including the Didion Milling dust explosion in Cambria, Wisconsin.

The CSB has issued four recommendations to OSHA calling for the issuance of a comprehensive general industry standard for combustible dust, and combustible dust safety is on the agency’s Drivers of Critical Chemical Safety Change list. To date, there is no general industry standard.

Dust Update
In keeping with making sure the industry stays on top of this issue, the CSB released its Dust Update 2018 data as a collection of 105 incidents compiled by its incident screening department over an 11-year period from 2006 through 2017.

The CSB verified each incident through at least one of the following sources: Occupational Safety and Health Administration (OSHA) investigation, inspection and Integrated Management Information System reports; emergency response/fire department records; and facility documentation obtained through CSB records requests. An incident was included in the final count if the CSB obtained a record identifying that dust was involved in the explosion or fire event. Furthermore, because the CSB did not review other publicly available datasets, the incidents identified in their list do not represent all dust incidents that occurred during the same timeframe.

CSB data was then categorized into one of several broad industry types.

Click here for a complete list of dust incidents.



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