A plume of hydrogen gas escaped from the offloading valve of a liquid hydrogen delivery truck while transporting hydrogen to a commercial facility. The plume ignited, resulting in a flash and concussion loud enough to be heard inside the nearby building and to set off the building’s seismic event detectors. A small amount of hydrogen gas continued to escape from the trailer tank and burn until a company specialist arrived to manually shut off a critical valve almost eight hours later.

An employee of an incubator company that was working in a university-owned laboratory facility was checking the hydrogen pressure through the main valve on a hydrogen cylinder. The regulator on this cylinder had not been properly closed. Hydrogen escaped through the regulator and was ignited. The fire was contained in the laboratory and extinguished by the building's fire sprinkler system before fire crews arrived. There were no injuries, and damage estimates were not available.

An individual inadvertently connected a pure hydrogen gas bottle to a chamber/glove box as opposed to a 10% hydrogen (in nitrogen) bottle that should have been used. [The wrong bottle had mistakenly been delivered, and the inexperienced individual did not know the difference.] The hydrogen concentration increased within the chamber to about 9%. Since there was insufficient oxygen in the chamber to support combustion, the hydrogen did not burn, and was quickly diluted with nitrogen.

A facility manager was notified that an authorization basis requirement, associated with roofing contractor work, had not been met. The requirement was that an unused hydrogen gas cylinder adjacent to the building and not connected to a manifold be removed prior to the use of propane tanks for the hot tar portion of the work.

The project manager failed to remove the extra gas bottle as required because he did not recognize from the bottle color and lack of stencil that the bottle contained hydrogen.

A hydrogen monitor leak detector (HMLD) was out of service because of a failed membrane. The HMLD heater circuit and the ion pump and its associated controller were de-energized and red-tagged to ensure the system remained shut down. The ion pump and controller were later found energized. The ion pump circuit is a low-power (120-V, 1 amp) circuit and the pump operates in the micro-amp range. There was no damage to equipment from this inadvertent energization.

A laboratory research technician entered a lab to begin preparing samples that were to ultimately be purged in an anaerobic chamber (glove box) located in that room. As the technician walked into the lab, she looked at the chamber to see if it was adequately inflated. This chamber is equipped with a gas concentration meter, capable of simultaneously displaying the oxygen and hydrogen concentrations of the chamber atmosphere.

The interior of a small high-temperature furnace, approximately 24 inches high by 18 inches wide, became contaminated with an unknown material later identified as magnesium. The furnace was disassembled to clean the unknown material from the interior surfaces, and while attempting to clean the bottom of the furnace, the technician tapped the upper lip of the furnace with a spatula and the magnesium flashed. The technician was stepping back from the furnace when the magnesium flashed. He received minor eye irritation and his eyebrows were singed.

A person working in a hydrogen lab unknowingly closed the wrong hydrogen valve and proceeded to loosen a fitting in one of the hydrogen gas lines. The pressure in the 1/4"-diameter hydrogen line was approximately 110 psig. Hydrogen escaped from the loosened fitting and the pressure release resulted in the tubing completely detaching and falling to the floor. The person noted seeing a white stream around the hydrogen jet leak. The person noted a color change and noise change as the leak ignited (this happened in a matter seconds and he did not have a chance to react).

A facility experienced a major fire in its Resid Hydrotreater Unit (RHU) that caused millions of dollars in property damage. One employee sustained a minor injury during the emergency unit shutdown and there were no fatalities.

The RHU incident investigation determined that an 8-inch diameter carbon steel elbow inadvertently installed in a high-pressure, high-temperature hydrogen line ruptured after operating for only 3 months. The escaping hydrogen gas from the ruptured elbow quickly ignited.

Incident Synopsis
At an offsite liquid H2 fill station, a liquid hydrogen trailer hit a gaseous H2 purge shut off valve handle. Tubing attached to the purge valve was bent on both ends but did not leak.

Cause
The driver was not sufficiently careful in approaching the liquid H2 system fill point.