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What happened?
A worker conducted the daily operational check on a portable 100 HP diesel-fuelled boiler.
45 minutes later he heard a loud noise and saw black smoke coming from the boiler.
The boiler had combusted and shut itself down.
The worker shut off the control breaker.
No one was hurt and there were no emissions released to the environment.
The boiler had been certified 5 months before the incident.
A few weeks back, the boiler was taken out or service as it would only run on low fire. The fuel pump and pneumatic timer were replaced, and the boiler put back into service.
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Why did it happen?
Replacement pneumatic timer was incorrectly set at 1 second instead of 10-15 seconds.
- Maintenance program and manufacturer specifications didn’t indicate a timer setting. No industry standard for time delay.
- The time difference (1-15 seconds) created a high ignition point before a stable fire was able to start.
The annual inspection of the wiring didn’t detect substandard wiring from a previous repair. Only 2-3 strands were making contact which resulted in:
- Too much fuel into the burner chamber before ignition.
- An unreliable ignition spark.
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What did they learn?
Inspect and recertify boilers periodically.
Update boiler maintenance program to include pneumatic timer settings.
Develop both pre-use and ongoing operational boiler checklists for supervisors and boiler operators (company and third-party).
Consider applying tamper proof seals to components that could be adjusted by untrained workers.
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Ask yourself or your crew
What does an annual inspection of a boiler include/not include?
What checks do you do on your equipment before starting work?
What is the worst that can happen if a boiler catches fire on our site? How can we prevent it from happening?
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What happened?
A worker conducted the daily operational check on a portable 100 HP diesel-fuelled boiler.
45 minutes later he heard a loud noise and saw black smoke coming from the boiler.
The boiler had combusted and shut itself down.
The worker shut off the control breaker.
No one was hurt and there were no emissions released to the environment.
The boiler had been certified 5 months before the incident.
A few weeks back, the boiler was taken out or service as it would only run on low fire. The fuel pump and pneumatic timer were replaced, and the boiler put back into service.
Why did it happen?
Replacement pneumatic timer was incorrectly set at 1 second instead of 10-15 seconds.
- Maintenance program and manufacturer specifications didn’t indicate a timer setting. No industry standard for time delay.
- The time difference (1-15 seconds) created a high ignition point before a stable fire was able to start.
The annual inspection of the wiring didn’t detect substandard wiring from a previous repair. Only 2-3 strands were making contact which resulted in:
- Too much fuel into the burner chamber before ignition.
- An unreliable ignition spark.
What did they learn?
Inspect and recertify boilers periodically.
Update boiler maintenance program to include pneumatic timer settings.
Develop both pre-use and ongoing operational boiler checklists for supervisors and boiler operators (company and third-party).
Consider applying tamper proof seals to components that could be adjusted by untrained workers.
Ask yourself or your crew
What does an annual inspection of a boiler include/not include?
What checks do you do on your equipment before starting work?
What is the worst that can happen if a boiler catches fire on our site? How can we prevent it from happening?
A diesel-fuelled boiler combusted whilst in normal operation. The pneumatic timer was set incorrectly, and inadequate wiring allowed too much fuel into the burner chamber before ignition.
