The U.S. Chemical Safety Board (CSB) has found that the Oct. 9, 2012 flash fire that burned seven workers at a US Ink plant in East Rutherford, NJ, was the result of an accumulation of combustible dust, vapors and Gilsonite in what the CSB termed a “poorly designed” dust collection system.
 
The system had been in operation four days before the explosion. The combustible dust accumulated in the ductwork and overheated, causing the flash fire. CSB investigators said the system had not been tested properly after installation, and also reported that Sun Chemical, US Ink’s parent company, had not sought construction permits for the new equipment, believing that it was exempt due to New Jersey Uniform Construction Code law  regarding “manufacturing, production and process equipment.”
 
“Sun Chemical acknowledges the valuable work performed by the Chemical Safety Board in conducting its review of the fire that occurred at our East Rutherford facility on Oct. 9, 2012,” said Gary Andrzejewski, corporate vice president of environmental affairs for Sun Chemical, US Ink’s parent company.  “We fully cooperated with the CSB throughout its review and have actions, policies and procedures in place that address all of the CSB’s recommendations.”
 
Andrzejewski reported that all seven workers who suffered burns eventually returned to work. He added that “Sun Chemical has a long history and a strong record of providing a safe work environment for our employees, and we are committed to ensuring that all our global locations strictly follow Sun Chemical’s workplace safety standards, policies and procedures.”
 
CSB chairperson Rafael Moure-Eraso said that the investigators’ findings showed that neither U.S. Ink nor Sun Chemical performed a thorough hazard analysis, study or testing of the system before it was commissioned in early October 2012. “The original design was changed, the original company engineer retired prior to completion of the project, and no testing was done in the days before the operation of the black-ink pre-mixing room production was started up,” Moure-Eraso added.
 
“The closed system air flow was insufficient to keep dust and sludge from accumulating inside the air ducts,” investigation supervisor Johnnie Banks said. “But to make matters worse, the new dust collector design included three vacuuming hoses which were attached to the closed-system ductwork, used to pick up accumulated dust, dirt and other material from the facility’s floor and other level surfaces as a ‘housekeeping’ measure.  The addition of these contaminants to the system ductwork doomed it to be plugged within days of startup.”
 
According to the CSB report, an operator was loading powdered Gilsonite into the bag dump station when he heard what he said was a strange, squealing sound.  After checking some gauges in the control room, he saw a flash fire originating from the bag dump.  He left to notify his supervisor.  At about that same time, the report states that other workers heard a loud thump that shook the building.
 
“In response to the flash from the bag dump station and the thump, workers congregated at the entrance to the pre-mix room.  One worker spotted flames coming from one of the tanks,” the report added. “He obtained a fire extinguisher but before he could use it, he saw an orange fireball erupt and advance toward him.  He squeezed the handle on the extinguisher as he jumped from some stairs, just as the flames engulfed him and six other employees who were standing in the doorway.”
 
The CSB added that the flash fire was then followed by the ignition of accumulated sludge-like material and powdery dust mixture of Gilsonite and carbon black in the duct work above tank 306. 
 
“The dust collection system, which had not been turned off, continued to move burning material up toward the dust collector on the building’s roof, where a sharp pressure rise indicated an imminent explosion. This was contained by explosion suppression equipment, but the resulting pressure reversed the air flow, back to the pre-mix room, where a second flash fire occurred, engulfing the workers,” the CSB report added.
  
The CSB unanimously approved the findings of the investigators, and issued several recommendations. These included a national general industry combustible dust standard, which the agency has long recommended that OSHA approve.  The commissioners also recommended that OSHA broaden the industries it includes in its current National Emphasis Program on mitigating dust hazards to include printing ink manufacturers.
 
The CSB reported that there have been at least 50 fires attributed to combustible dust from 2008-12, killing 29 workers and injuring 161.  The most lethal was on Feb. 7, 2008, when an explosion of sugar dust at Imperial Sugar Company, Port Wentworth, GA, killed 14 workers and injured 38 others.
 
“In U.S. Ink’s case – and thousands of other facilities with combustible dust – an OSHA standard would likely have required compliance with National Fire Protection Association codes that speak directly to such critical factors as dust containment and collection, hazard analysis, testing, ventilation, air flow, and fire suppression,” Moure-Eraso said.