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.
Investigation determined that internal galling has caused the failure rendering the needle valve unusable. The galling was caused by a stainless steel stem acting against a stainless steel seat. This failure mode had been observed before and the…
For the use of mechanical fittings in hydrogen service, administrative controls should be in place, as in this case, to ensure that leak testing is conducted on a regular basis. It should never be assumed that every fitting is tight. Additional…
Failure of a diaphragm is not infrequent, but the seizure of the main nut threads is very rare. The manufacturer claimed this had never occurred before with this type of unit. The broken plunger is likely the result of poor instructions/…
The visiting intern had several years of experience in research projects and tasks that were similar to those in progress at this laboratory. This led to the incorrect assumption that formal introductory training for this laboratory was…
After the aforementioned incident, a rigid cage was designed to protect the reactor from external conditions, and to protect the contents of the hood and any experimenter from the reactor, in the event of a pressure burst from the reactor cell.…
High-pressure fueling hoses should be examined daily for signs of external damage, including corrosion, abrasion, cuts, and kinking. High-use fueling hoses should be replaced every six months.
An investigation team was formed to determine the cause of this anomaly. The team performed a fault tree analysis which identified the following five main paths or gates: fault in the original weld, age, component not built per design intent,…
The combination of the cold water temperature (reducing the fatigue strength of the bolt), and the abnormally high number of cyclical stresses imposed by the imbalance from the hydraulic system check valve failure resulted in the failure of the…
Proper installation of check valves and other equipment should be visually inspected prior to pressurization.
Maintenance on the low-pressure venting system was not occurring at regular intervals. Ventilation integrity is now checked before starting an experiment.
Excessive venting of hydrogen from the tank due to lower facility consumption, in combination with extreme temperature conditions, placed thermal stress on the gland nut, causing a leak. The low consumption of hydrogen resulted from the shutdown…
Disable the fueling process if the operator does not follow the proper sequence of steps in the fueling procedure. Improve the fueling procedure to make it inherently impossible for the sequence to be done improperly with the same result.
Shutoff valve location and/or redundant shutoff valves at storage vessels are important for containment to prevent escalation.
Consider design features within equipment skids to reduce the likelihood of cascading events.
Pressure-switch…
To prevent a similar flashback, the following measures have been taken:
Many accidents reported from paper mills have much in common with this incident. Microorganisms in the process water with pulp produce hydrogen gas that mixes with air to form an explosive atmosphere. The ignition source is typically sparks…
A tool is provided for removing the cylinder cap that cannot contact the valve.
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