CSB Cites Lack of Safeguards for Solvent Vapor Explosion
DANVERS, MA -- A massive explosion and fire at the CAI/Arnel ink and paint products manufacturing facility in Nov. 2006 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 from the U.S. Chemical Safety Board (CSB) said in a final draft report made public today.

Steam heat to the mixing tank was most likely inadvertently left on by an operator before he left for the day. As the temperature increased, vapor escaped from the mixing tank, built up in the unventilated building, ignited, and exploded. 

The 105-page report is set to be considered by the four-member Board at a public meeting in Danvers this evening, beginning at 6:30 p.m. at the North Shore Ballroom of the Sheraton Ferncroft Hotel, 50 Ferncroft Road. The meeting is free and open to the public. Members of the public are encouraged to attend and comment on the draft report prior to the Board's consideration. 

Following a detailed presentation by the CSB investigators, including a new ten-minute video of the explosion and its impact on the community, local and state officials and a Danversport resident are scheduled to present testimony to the Board describing changes to oversight of manufacturing facilities following the accident.

CSB investigators said that ink manufacturer CAI did not follow regulations or appropriate good practices for the handling of flammable solvents, and the CSB report proposes changes to national fire codes and to state licensing and inspection procedures to improve the safety and oversight of facilities handling hazardous materials.

Investigators said that on the night of the accident, ink base materials -- including a volatile mixture of heptane and propyl alcohol -- continued to heat and then boil after all the employees left work late in the afternoon. The heating was controlled by a single, manual valve that needed to be closed by an operator to prevent the 3,000-gallon tank from overheating.

The building ventilation system was turned off at the end of the workday -- a routine procedure -- and vapor coming out of the unsealed tank spread throughout the production area and then ignited from an undetermined source, possibly a spark from an electrical device. The explosion occurred at approximately 2:46 a.m. on November 22, 2006.

The blast ripped through the adjacent Danversport neighborhood, waking sleeping residents as windows were blown into bedrooms and shattered, ceilings fell, and belongings and appliances flew about. The blast wave damaged scores of homes. At least 16 homes and three businesses were damaged beyond repair, and approximately 10 residents required hospital treatment for cuts and bruises. The fire department ordered the evacuation of more than 300 residents within a half-mile radius of the facility.

For more on the investigation, go to www.csb.org.