Fire in a chemicals plant

Following the breakdown of a piston rod, a mixture of hydrogen and light hydrocarbons was released from the fresh hydrogen compressor of an oil refinery.
The rod broke down because of stress corrosion. The stress exerted on the rod was significantly inc

The INITIATING CAUSE was a leak from a hydrogen pipe, due to corrosion.

The IGNITION SOURCE could have been electrostatically charged particles provided by the snowfall occurred earlier that day.

ROOT CAUSE was an organisational cause: shortcomings in service and maintenance allowed corrosion progress to the moment when the pipe could bear no more the internal pressure. A additional root cause component could regards an inadequate risk assessment, not considering the consequence of a hydrogen leak near the control room.

Hydrogen pipe in a sodium chlorate plant

3 production lines were shut down.

1. The on-duty field technician noticed the flame, located in the space above the plant control room right above the exit door.
2. The technician signalled an alarm to the plant control room: field operator, shift supervisor and the regional emergency response centre were notified.
3. Staff on the site tried to extinguish the fire by means of fire extinguishers, unsuccessfully.
4. The affected unit was then shut down using the emergency stop function.
5. The other two production plants were similarly shut down.
6. Fire fighters used a fire hose up onto the landing and fully extinguished the fire, which was already dying down due to the shutdown.

The existence of hydrogen leak could be detected because environmental condition (snowfall) provided an ignition source to ignite the hydrogen. It is unknown how long the hydrogen had leaked undetected before it became ‘visible’.
Its location, just above the door to the control room of the plant, was increasing its hazard. It is plausible to assume that with just slightly modified accidental scenario, for example a higher leaking rate directed downwards, had a potential for more damage and escalation. If, on top of that, the exit door of the control room was the only emergency escape door, the accidental scenario would have even worse.
Hydrogen sensors could have been able to detect earlier the leaking hydrogen. It is unknown if the pipe environment was allowing for the placements of a detection system it. The incident showed that the possibility of a hydrogen diffusion into the control room, cumulation and explosion was not negligible, and should have been considered in a risk assessment.