DSS227: Safety Share - Flash Fire During Furnace Blowdown

In today’s episode, we’re discussing a flash fire that occurred during furnace blowdown activity. This information came from a Manufacturing Safety Alert recently released by the BC Forest Safety Council and Manufacturing Advisory Group in British Columbia. They regularly share safety incidents with the industry, including lock-out/tag-out failures, falls, forklift accidents, heavy object drops, and occasionally, combustible dust fire and explosion incidents.

This anonymous reporting system is commendable as it helps the community, workers, and sites to prevent similar incidents. We encourage signing up for Manufacturing Safety Alerts on BCForestSafe.org.

The alert we cover today contains photos of the furnace, fuel metering bin, and ledges being cleaned during the activity. The incident occurred the day after after the furnace was burned out, but it’s unclear if this indicates an issue with the furnace or an ongoing fire that required cleaning or if this was just normal shutdown and running of the furnace site itself. We do know that during the clean-out process, there was smouldering inside the furnace located approximately eight feet away from the access hatch and the ledge where the employee was cleaning.

According to the Manufacturing Safety Alert, an employee was cleaning ledges in a fuel metering bin overflow door. Although there were no sparks, the material at the bottom was smouldering. The employee used an air wand to clean the ledges, resulting in a flash ignition that caused superficial burns to the face, ears, neck, and hair. Their protective gear was not damaged.

Luckily, the flash fire on top of the bin did not result in any major injuries. The employee was examined at the hospital and cleared to return to work without any restrictions. However, this incident highlights the potential for much more severe harm.

After describing the incident, the document (which includes a few pictures that depict the bin overflow hatch, the ledge covered in hog fuel, and the area after the flash fire) proposes several recommendations. Their suggestions included:

Developing a cleaning procedure for the ledges
Utilizing a scraper tool instead of an air wand and ensuring that it has a long handle so employees can keep a safe distance when working near the hatch.
Requiring a face shield not only when cleaning the hatch but also in the surrounding areas.
Waiting until the furnace has cooled down or until the material in the screw has been cleared before performing the cleaning job.
Using a water hose to moisten the area before starting.

The Safety Share emphasizes that flash fires are dangerous and all employees should be trained on how to minimize their potential. Although the suggestions are a good starting point, there may be additional factors to consider in this situation.

It is unclear whether this was an upset condition or a typical procedure when the furnace is shut off. If it is a frequent procedure, tools such as scrapers may be appropriate. If it is done infrequently or done due to an urgent furnace issue, a comprehensive assessment of the situation is necessary before an employee performs any cleaning task.

While the suggested actions in the Safety Share are helpful, it may be necessary to come up with a more nuanced approach to handle emergency situations, as using a scraper tool in such situations could still pose significant risks.

Conclusion

To summarize, we have examined an incident involving a flash ignition in a fuel metering bin above a furnace’s overflow hatch. It is worth noting that according to NFPA 652, section 8.4.2.6, compressed air blowdown should not be used for cleaning anything on, inside, or near a furnace situation unless the furnace has no smouldering or active fire activity, and three requirements are met:

Using other cleaning methods first
Ensuring dust is below the MEX threshold
Removing all ignition sources and hot surfaces prior to using air blowdown.

For this type of operation, compressed air blowdown would not be in compliance with NFPA 652, which is also mentioned. It is important to consider compliant activities and not use compressed air blowdown in, around, or near an active furnace or furnace with smouldering combustion.

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