Disclaimer: The Lessons Learned Database includes the incidents that were voluntarily submitted. The database is not a comprehensive source for all incidents that have occurred.
Cause and effect can sometimes be predicted by observing abnormal behavior even when the behavior is within specifications. Operators log equipment data and inform shift management when specifications are exceeded or when unusual equipment…
Although most of the hydrogen fluoride piping system was open to the atmosphere before the elbow was cut, the lines were not purged. Two plugs of residual material on either side of the elbow remained in place, thus allowing hydrogen to be…
Upgrade the liquid hydrogen pump control system to shut down operation of the pump and protect the system when malfunctions like leaks, pump cavitation, or loss of purge gas occur.
Verify that maintenance procedures used for liquid…
The packing in the flow control valve should be replaced periodically. A planned investigation will determine the optimum time period for packing replacement.
The uncontrolled release of hydrogen occurred as a result of the rupture of the No. 6 hydrogen storage tube’s burst disc. This disc failed in response to being overloaded by mechanical stresses developed as water expanded and formed ice while in…
As demonstrated by the fire discussed above, lack of adequate maintenance, system monitoring and oversight of maintenance of these facilities can contribute to the ignition of a fire that is difficult to extinguish and poses an extreme danger to…
An important lesson to be derived from this incident is the need to carefully engineer and test all repairs and modifications to high-pressure process equipment.
This incident illustrates the danger of hydrogen being inadvertently released through blown water seals. Similar incidents have occurred in non-nuclear industrial facilities, but offgas systems present a special hazard because of the…
The investigative report noted that the explosion could have been prevented by (among other things) a continuous gas analyzer test of oxygen and hydrogen product purity. The continuous analyzer should be interlocked to shut the electrolyzer down…
All valves and connectors should be clearly labeled to minimize chances for mis-connection. All technicians must be trained on proper procedures for both taking systems offline and bringing them back online.
Valves for compressed hydrogen…
Normally hydrogen fires are not extinguished until the supply of hydrogen has been shut off due to the danger of re-ignition and explosion. During a gas leak/fire, it is important to shut off the source of the hydrogen if it is safe to do so. If…
Lessons Learned
Construction errors are difficult to detect once construction is complete. It is important to develop and use a systematic oversight process for minimizing construction errors during the construction process.
…
The uncontrolled release of hydrogen occurred as a result of the rupture of the No. 6 hydrogen storage tube’s burst disc. This disc failed in response to being overloaded by mechanical stresses developed as water expanded and formed ice while in…
Routine maintenance activities on pressurized hydrogen systems should be conducted per written design specifications. The procedures should provide detailed oversight regarding bolt, nut and fitting replacements or repairs. A formal review…
This incident emphasizes the need for proper gas detection and ventilation systems, as well as fire suppression systems, in laboratories using and storing hydrogen. This is especially true when open flame burners are in close proximity.…
Hazards should be eliminated to the extent possible rather than depending on workers to follow an operations manual.
Potassium carbonate draw-off operations should be improved, and the operations manual should be revised. The manual…
Fail-safe position of control valves in supply lines must be set correctly to prevent damage to pressure vessels.
Recommendation
Set all valves for fail safe operation (open or closed) according to needs before installation…
The packing in the flow control valve should be replaced periodically. A planned investigation will determine the optimum time period for packing replacement.
Included inspection on monthly preventive maintenance plan and evaluated alternate materials for better cold-weather performance.
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