During a facility walk-through, it was noted that a combustible gas (hydrogen) monitoring system installed in a furnace room was inoperable (the system had been unplugged). This system is used to detect and warn facility employees of an explosive or flammable environment. An explosive or flammable environment can only occur if there is a leak in the system, which would not be expected to occur during normal operations. When the system was reactivated, no leaks were indicated.

The incident had the following three causes:

A procedure describing administrative controls necessary to ensure safe operations in the area should have been developed and implemented prior to disabling the hydrogen monitoring system.
The hydrogen monitor was not hard-wired, which allowed it to be unplugged and rendered inoperable.
The hydrogen monitors were disabled and the status of the monitors was not communicated to personnel that work in the area.

Incident Date
Jul 25, 1996
  • Safety Systems
  • Measurement / Sensing Device
Damage and Injuries
Contributing Factors
When Incident Discovered
Lessons Learned

Work pre-planning is essential whenever maintenance or work activities may have an adverse impact on everyday operations. When there are changes to the operational status of any critical system, especially a safety critical system, those changes must be communicated to affected personnel. Standard operating procedures (SOPs) must be fully implemented, and the implementation should be verified during facility and organizational assessments.

Additional information on planning for maintenance and start-up and inspection of equipment is available in the Hydrogen Safety Best Practices Manual.