The first flash fire occurred at the Hoeganaes Corp. Gallatin, Tenn. plant Jan. 31, where one worker was killed and another was seriously burned. The plant experienced a second, similar fire March 29, which caused one injury. The Hoeganaes plant manufactures “atomized” iron powder that is sold to the automotive and other industries for the production of metal parts using powder metallurgy.

Preliminary test results have so far confirmed CSB’s conclusion that the fires involved combustible iron dust. In the first, fatal incident, a dust collector was reported to have been out of service for the 2 days leading to the incident. In the second fire, a plant engineer apparently dislodged accumulated iron dust during his work replacing igniters on a furnace; the dust combusted and subsequently injured the engineer.

“Tests conducted on samples of metal powder – collected from the plant – determined that this material is combustible,” said CSB Investigator-in-Charge Johnnie Banks. “The team observed significant quantities of metal dust on surfaces within close proximity to the incident locations.”

In addition to visible dust particles in the air, 2- to 3-inch layers of dust were observed on flat surfaces, rafters and railings throughout the facility.

Banks added that after reviewing company documents, CSB determined that the “presence of combustible dust was known by Hoeganaes at the times of the accidents; it appears the risks were not adequately addressed by the company.”

CSB’s investigation will examine the company’s dust prevention efforts at the facility and its compliance with the National Fire Protection Association Standard 484, which details requirements for dust collection systems, dust cleaning frequency and building construction and egress provisions.