The blast occurred because the company lacked safeguards such as alarms and automatic shutoffs that would have prevented a 10,000-pound mixture of flammable solvents from overheating in an unattended building.

Investigators found that the ink manufacturer did not follow regulations or appropriate good practices for the handling of flammable solvents, resulting in the worst community damage the CSB has seen in its 10-year history of investigating industrial accidents.

Fortunately, no one died, but the blast wave damaged scores of homes, at least 16 of them, and three businesses were damaged beyond repair. Approximately 10 residents required hospital treatment, and the fire department evacuated more than 300 residents within a half-mile radius of the facility.

The blast occurred when steam heat to a mixing tank was left on inadvertently by an operator at the Danvers, MA facility before leaving for the day. As the temperature increased, vapor escaped from the mixing tank, built up in the unventilated building, ignited, and exploded.

“We found an underlying cause was a failure to conduct a hazard analysis or other systematic review to ensure flammable liquids were safely handled during the manufacturing process,” said CSB investigators. “The company did not have automated process controls, alarms, or other safeguards in place. The standard practice at the company was to shut off ventilation at night — to retain heat in the building and to allay residential complaints about fan noise. When the mixture continued to overheat — absent automatic shutoffs and proper ventilation — the vapor accumulated and filled much of the building over a period of hours. Without safeguards, it is likely that a small but foreseeable human error led to disaster.”

Existing Massachusetts fire codes, as well as federal OSHA standards, have requirements for ventilation of flammable vapors to prevent dangerous accumulations inside structures. But Massachusetts has not adopted the most current national fire codes for flammable liquids. The CSB also found that while the state requires local fire departments to periodically inspect facilities that handle flammable materials, the laws do not specify any inspection frequency or criteria for conducting those inspections.

Though the CSB does not impose fines or cite violations, the investigation report makes numerous safety recommendations, including calling on the National Fire Protection Association (NFPA) and the International Code Council (ICC) to revise national fire codes to prohibit the heating of flammable liquids inside buildings in unsealed tanks that do not vent outside and to require automatic safeguards to prevent overheating. For more on the report, go to www.csb.gov.

This incident reveals how difficult it can be to ensure the safety of a facility where hazardous materials are processed, and the important work of safety engineers and professionals, whose work and opinions we respect. That’s why we’d like to thank those who emailed us to inform us about some problems with the cover of last month’s issue. Given the professionalism of our readers, we’re sure others noticed that the two workers wearing respirator masks had facial hair, their hard hats were on backwards, and the D ring for the full body harness worn by the worker in the foreground is placed at mid back rather than between the shoulder blades.

This highlights two issues, one is the difficulty in trying to illustrate safety in action each month, the other is the challenge to safety professionals to make sure that people work safely, and use the safety equipment they’re given appropriately.

Each month we strive to improve the content of our magazine, so we apologize to our readers for this error, and promise to do our best not to make the same mistake again. Thanks and good luck.