Static spark caused fire and explosions at Barton Solvents Des Moines facility

27 September 2008

A fire and series of explosions at the Barton Solvents Des Moines, Iowa, chemical distribution facility on October 29, 2007, was caused by a static electrical spark resulting from inadequate electrical bonding and grounding during the filling of a portable steel tank, the U.S. Chemical Safety Board (CSB) determined.
One employee received minor injuries and one firefighter was treated for a heat-related illness in the accident, which occurred about 1 p.m.

A large plume of smoke and rocketing barrels and debris triggered an evacuation of the businesses surrounding the facility. As the CSB Case Study notes, the main warehouse structure was destroyed and Barton's business was significantly interrupted. The accident occurred about three months after a July 17, 2007, explosion and fire destroyed a Barton Solvents facility in Wichita, Kansas. The CSB attributed that accident to static sparks and lack of bonding and grounding as well in a June 2008 final report.

CSB Chairman and CEO John Bresland said, “These accidents show the need for companies to address the hazards associated with static electricity and flammable liquid transfer. They should apply good practice guidelines - outlined in our Case Study - to determine if facilities are properly designed and safety operated.”

The accident in Des Moines occurred in the packaging area of the facility as an operator was filling the 300-gallon steel tank, known as a tote, with ethyl acetate, a flammable solvent. The operator had secured the fill nozzle with a steel weight and had just walked across the room when he heard a 'popping' sound and turned to see the tote engulfed in flames. Employees tried unsuccessfully to extinguish the fire with a handheld fire extinguisher before evacuating.

CSB Lead Investigator Randy McClure said, “The CSB investigation found the nozzle and hose were not intended for use in transferring flammable liquids. Furthermore, we found the steel parts of the plastic fill nozzle and hose assembly were not bonded and grounded. Static electricity likely accumulated on these parts and sparked to the stainless steel tote body, igniting the vapour that accumulated around the opening of the tote during filling.”

The report notes that static electricity is generated as liquid flows through pipes, valves, and filters during transfer operations. Metal parts and equipment must be electrically wired to each other, known as bonding, and then electrically connected to the earth, known as grounding.

“In this case, all the conductive metal objects in the nozzle and hose, and the steel weight which was suspended from the handle by a wire, were all isolated from ground and were susceptible to static accumulation and discharge,” McClure said. “This is a set-up for disaster.”

The packaging area - where the fire started - had no automatic sprinkler system and was adjoined to the flammable storage warehouse. The investigation found the wall separating the two areas was not fire-rated. As a result, the warehouse was rapidly consumed, and although this area had an automatic sprinkler system, it was incapable of extinguishing the large blaze.

The CSB investigation determined that if Barton had implemented a comprehensive static electricity and flammable liquid safety program, in compliance with current regulatory standards and good practice guidelines, the fire likely would have been prevented. These include OSHA's Flammable and Combustible Liquids standard and codes and recommended practices of the National Fire Protection Association.