The October 25, 2010 catastrophic dust explosion at the Pinskdrev chipboard facility in Pinsk, Belarus resulting in fourteen fatalities has huge implications amongst the global manufacturing sector. Key findings from the accident investigation determined that prior to the afternoon explosion in the wood pellet area of the chipboard (particleboard) facility there was a history of numerous fires.
This illustrates very graphically how non-consequential combustible dust related fires can be precursors to catastrophic secondary dust explosions. Currently combustible dust layer fires are ignored. Where instead primary attention is directed towards more newsworthy dust explosions. This is a disastrous approach in putting the cart before the horse.
In the USA, the Chemical Safety Board (CSB) has completed accident investigations on five catastrophic dust explosions. All the CSB reports note, just as in the Pinksdrev incident, a history of non-consequential combustible dust related fires prior to the catastrophic events. If your facility has a history of non-consequential combustible dust related fires then you have a serious problem analogous to the tip of the iceberg which the passenger ship Titanic struck on her maiden Atlantic crossing. After any such fire it is imperative an accident investigation is undertaken in determining root and contributing cause so as to minimize the probability of the next incident occurring.
Court proceedings discovery: "about a week before the events wall fan was turned off."Prior Combustible Dust Related Fires
At this company repeatedly (in January, February, March, May, June and July 2010) had fire and sparking in the mill site during the production of wood pellets, where always there was an increased level of dust. "According to the Prosecution," the requirements for equipment installation room automatic fire and automatic fire alarm was suppose to be made in ... 2000. In addition, "the JV" Pinskdrev-DSP "willfully, without appropriate approvals of the Medical Service and Fire Department, installed a second production line for wood pellets.
"The audit found that the fire occurred in the enterprise before. Sometimes, that is not duly registered in the departmental professional fire protection guard traveled to the extinguishing of the fire up to four times a day. In 2010, the site for the production of wood pellets fire took place on 8 and 30 June, and October 13 - 12 days before the tragedy".
"These facts were hidden from Pinsk city Department of Emergency and were not counted as fires. Information about them from the workforce and the population in the MOE also been reported. And this despite the fact the enterprise is highly explosive. For example, in May 11, 1997 because of the high concentration of dust in the room of the main building there was a dust explosion, accompanied by fire."
“Prerequisites in the incident, apparently accumulated over a long time. The same Prosecutor General Grigory Vasilevich , visiting the site of tragedy in November 2010, said that "the company revealed serious violations of process discipline and safety rules were not complied with health standards. Repeatedly fires, which are eliminated on their own. " This was the warning calls future tragedy, says Grigory Vasilevich, but the responsibility for the safety of people officers ignored them"
This is the exact same problem here in the USA with the repeated combustible dust fires which are mostly non-consequential and extinguished in the incipient stage without any follow-up investigation of root and contributing cause,. Prior non-consequential combustible dust related fires have the potential escalating into catastrophic dust explosions.
"The investigation of the accident revealed that during operation fire safety rules were violated. Above the conveyor feed hopper in front of the hammer mill and in itself is not installed iron catcher (magnets), which paved the way for the entry into the equipment of metal objects and sparks of mechanical origin, which could be a source of ignition of an explosive dust air mixture."Explosion Venting (NFPA 68)
"Nor were installed devices that provide fire and explosion hazard shedding dust and gas mixtures and gases in the event of an explosive tank valve hammer mill was prevented delivery fire and explosion hazard and gas mixtures through the safety valves and blow-off line manual bleed into the production room. Wood dust collection system placed directly in the room area."Inadequate Local Exhaust Ventilation
"In addition, due to the fact that the primary hammer mill did not provide load two pelleting presses, in October 2010, it was replaced by the more powerful. After mounting between it and discharge hopper formed unclosed space through which the room area ejected wood dust and crushed chips, leading to a dusty room"
History North America Particleboard Combustible Dust Incidents
Two Injured, Explosion and fire at particle board plant in Smithers, BC (2008)
Explosion and fire at particleboard factory kill two, injures 8, Pennsylvania (Feb. 2001)“The fire was contained in a silo that abuts the plant, McKean County emergency management director Ken Mostyn said. A dust collection system that runs along the plant's roof and feeds the silo was heavily damaged, he said. Authorities said fire spread through sawdust piles in the building and quickly overwhelmed Temple-Inland's on-site fire brigade.”
OSHA issued three willful violations, with a proposed penalty of $189,000 and 16 serious violations with a penalty of $59,400.
"The alleged willful violations address the company failure to prevent excessive accumulations of wood dust, failure to shut down a conveyor that carried sparks to other combustibles and unapproved electrical service in restricted areas," said John Stranahan, area director of the Erie OSHA office. "Wood dust is recognized as the single greatest hazard for fire and explosion in the particleboard manufacturing industry." “Dust levels throughout portions of the plant were documented in some locations between four and six inches. The National Fire Protection Association recommends that wood dust not exceed one-eight of an inch.”Conclusion
Hopefully sharing the tragic account of the Pinskdrev Belarus incident in addition to the history of prior particleboard facility incidents in North America will assist stakeholders in understanding combustible dust fires and explosions is a global hazard. Robust engineering controls incorporated into local exhaust ventilation will ensure dust layers are minimized. When processing wood it is essential magnetic separators are installed upstream so as to prevent foreign materials from providing an ignition source downstream. Addressing the combustible dust related fires(fire triangle) immediately in determining root and contributing cause will ensure the unwelcome fire triangle will never have a chance to visit a facility.