Danger of Combustible Dust

Tuesday, August 26, 2014 @ 02:08 PM gHale


By Gregory Hale
Combustible dust kills and the A.L. Solutions metal recycling facility in New Cumberland, West Virginia is one case where a lethal combination of dust and a sparking piece of equipment led to three workers dying after a fire and explosion.

That is why Rafael Moure-Eraso, chairman of the United States Chemical Safety Board (CSB) penned an op-ed piece Friday in The New York Times advocating the Occupational Safety and Health Administration (OSHA) create stronger standards that will help eliminate these often lethal accidents.

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Moure-Eraso is making the push for stronger standards after 75 people died and 185 others suffered injuries after an explosion ripped through a metal products factory in China’s eastern Jiangsu Province. The culprit, he said, in that incident was dust.

The call for action also comes on the heels of a report the CSB issued in July about the A.L. Solutions incident where an explosion ripped through the titanium plant in West Virginia December 9, 2010, fatally injuring three workers. The workers were processing titanium powder, which is highly flammable, at the time of the explosion.

The A.L. Solutions accident was one of nine serious combustible dust incidents investigated by the CSB since 2003. These explosions and fires caused 36 deaths and 128 injuries.

“Preventable combustible dust explosions continue to occur, causing worker deaths and injuries,” Moure-Eraso said. “The CSB believes it is imperative for OSHA to issue a comprehensive combustible dust standard for general industry with clear control requirements to prevent dust fires and explosions.”

A.L. Solutions experienced a history of fatal dust fires and explosions, the CSB report said.

“The CSB learned that the A.L. Solutions facility had fatal fires and explosions involving metal dust in 1995 and 2006 in addition to the 2010 explosion,” said Investigator Mark Wingard. “Also, from 1993 until the accident in 2010, there were at least seven fires that required responses from the local fire department.”

A new CSB safety video entitled “Combustible Dust: Solutions Delayed” gives a timeline of the incident and details the process of milling and blending metal powder at the facility which was then pressed into dense disk called “compacts.”

“As the metals were broken down during milling, the risk of a metal dust fire or explosion increased as the metal particles decreased in size,” said CSB Lead Investigator Johnnie Banks. “At A.L. Solutions a metal blender used to process zirconium was having mechanical problems that had not been adequately repaired. As a result, the blender was producing heat or sparks due to metal-to-metal contact.”

At 1:20 p.m. on December 9, 2010, a spark or hot-spot from the blender likely ignited the zirconium powder inside. The resulting flash fire lofted the metal dust particles in the blender, forming a burning metal dust cloud.

The cloud ignited other combustible dust within the production building, causing a secondary explosion that ripped through the plant, killing three workers and injuring a contract employee.

“The National Fire Protection Association (NFPA) Standard for Combustible Metals, called NFPA 484, recommends specific practices for controlling metal dust, but A.L. Solutions did not voluntarily follow those guidelines, and there are no federal OSHA standards to enforce similar requirements,” Wingard said. “In its 2006 Combustible Dust Hazard Study, the CSB recommended that OSHA issue a combustible dust standard for general industry based on the current NFPA guidelines.”

Tiny metal particles and metal dust are byproducts of the manufacturing process, and a cloud of them requires only a spark to explode — which in turn can loft more dust and cause more explosions. This issue is not an isolated problem as it affects quite a few industries, including those that process food, wood, rubber, plastics and pharmaceuticals, all of which are combustible in the form of tiny particles and dust, Moure-Eraso said in his editorial.

Dust explosions are readily preventable with engineering controls, ventilation, training and other measures, he said. The voluntary, industry-supported national fire codes have urged these measures for decades, but they are not enforceable.

In 1987, OSHA promulgated a set of regulations for combustible dust for the grain industry. This resulted in a significant drop in grain dust explosions and an increase in lives saved, at an acceptable financial cost.

Following a study the CSB board conducted in 2006, it recommended OSHA establish a comprehensive combustible dust regulatory standard for all industries. The following year, it developed an enhanced enforcement program, but the critical component — a national standard with clear requirements — has yet to see the light of day.

Inaction, Moure-Eraso said, could cost lives.



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