NASHVILLE (AP) — A federal investigation into flash fires that killed five people this year at a Gallatin metal powders plant found that multiple reports of earlier small flash fires at two plants did not spur the Hoeganaes Corp. to try to mitigate the hazard, according to a report released Wednesday.

It also found that Hoeganaes gave the plant's approximately 180 workers no training to help them understand the dangers they faced on the job. They were "forced to tolerate conditions at the facility," according to the report.

And it found the Gallatin Fire Department did not recognize the iron dust accumulated on surfaces around the plant as a fire hazard when it inspected two weeks before a May accident that killed three.

The report by the U.S. Chemical Safety Board was released ahead of a public meeting in Gallatin, about 30 miles northeast of Nashville.

It concluded that airborne iron powder was the fuel source for January and March flash fires at the company. In the case of the May fire, hydrogen leaking from a corroded pipe exploded and lofted dust into the air that then created a fireball.

"Instead of utilizing engineering and administrative controls such as dust collection systems and housekeeping programs, Hoeganaes relied on FRC (fire resistant clothing) to protect workers from iron dust flash fires," the report found.

It also concluded that the company had no system in place to inspect or maintain its hydrogen pipes, which run underneath the floor. And it had no established procedures for what to do if a gas leak were suspected.

At the time of the May accident, Hoeganaes executive Mike Mattingly was in Gallatin to attend the funeral an employee who had succumbed to his burns from the January flash fire. Mattingly said at the time that the company was "devastated" by the latest accident. "Our number one concern in priority is the affected employees and their families."

More recently, he has declined to comment on the situation at the plant.

Safety Board investigators have previously said that the company documented multiple reports of flash fires during repairs on furnace belts at their facility in Cinnaminson, N.J., where Hoeganaes is headquartered. Someone was killed in a 1996 accident there and an accident in 2000 injured two others.

The Gallatin plant had also seen an injury in a 1996 fire, although, according to the new report, "Workers told CSB investigators there were multiple small dust flash fires at the Gallatin facility that did not result in any injuries."

The Safety Board investigates industrial accidents and makes recommendations, but has not power to force their implementation and it does not levy fines.

The Tennessee Occupational Safety and Health Administration fined Hoeganaes $42,900 just one week before the May accident for 12 serious violations found in investigations of the January and March accidents. TOSHA's investigation of the May flash fire is expected to be complete next week. But neither TOSHA nor its federal counterpart, OSHA, have rules regulating combustible dust in general industry.

The Hoeganaes plant's last inspection by TOSHA before this year's accidents had been in 2008, and the inspector did not look for dust hazards or even enter production areas.

In its new report, the Chemical Safety Board reiterated its call for OSHA to begin regulating combustible dust, asking that rules be put in place within a year.

The request for OSHA to create dust rules was one of the safety board's key recommendations in a 2006 report that found there were at least 281 dust explosions in the U.S. between 1980 and 2005 that killed 119 workers and injured 718.

It took OSHA three years to act on the recommendation. In 2009, OSHA began the rulemaking process, but rules are not yet in place and Labor Department officials are not able to say how long they will take to implement.