Scott Davis,Ph.D., P.E., CFEI
and
John Pagliaro, Ph.D. Gexcon US, USA
Presented at the International Symposium on Fire Investigation Science and Technology, 2018
ABSTRACT
On April 26, 2014 at the Georgia Pacific Corrigan plywood facility, a fire that originated at a plywood sander eventually propagated through the pneumatic dust conveying system and resulted in an explosion in the baghouse (dustcollector), fatally injuring two employees, and seriously injuring others who were responding to the incident. Sparks from the sander entered the extraction pipe, which was protected by an active suppression/isolation system (spark-sprinkler-abort gate) upstream of the baghouse. When the fire in the extraction pipe was discovered, the extraction blower downstream the baghouse (negative pressure system) was turned off and allowed smoldering and burning to continue within the pipe. The blower was subsequently turned back on, at which time a flame front developed that propagated into the baghouse which was not properly isolated. This incident occurred because of the improper design of a back-blast damper as an isolation device and operational errors associated with the blower being turned off and back on prior to extinguishing the burning material. More specifically, when designing handling and conveying equipment for combustible dusts, it is crucial to properly implement protective measures (e.g., deflagration venting, suppression, and isolation) capable of mitigating the potential consequences and avoiding escalation of the explosion event when the dust is ignited. This paper will analyze the root cause of the incident as well as key lessons learned related to: system design; performing a dust hazard analysis; required air stream flow rates; proper back blast designs; impeding deflagration vents; and exclusion zones in the path of a vented deflagration in the baghouse.
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