The sensing diaphragm of a pressure transducer (PT), as supplied on an outdoor hydrogen compressor, unexpectedly ruptured and released approximately 0.1 kilograms hydrogen to atmosphere from the compressor discharge line. At time of incident, personnel nearby were alerted by a loud 'pop' and dust disturbance. Simultaneously, the facility monitoring system detected loss of the PT signal and initiated equipment shutdown. Facility personnel then closed isolation hand valves to stop the leak, locked and tagged out the equipment, and restricted the area. The failed component, a cigar type PT rated to 20,000 psi, originally supplied and installed by the manufacturer as part of the compressor package, was removed and inspected. Inspection revealed severed wires, a separated wire housing, view more
While performing hydrogen gas release experimentation by thermally reacting a slurry of ammonia borane powder in silicone oil in a plug flow reactor, a discharge port on the test reactor became loose. A foaming white product was leaking from the fitting and discharging in the direction of the heat tape and insulation (back over the reactor). As a result, hot, reacting slurry flowed out of the port and was exposed to air. In the presence of oxygen, the slurry ignited, producing a green flame. A small green flame was noticed at the leak site and flaming product dripped onto the hood deck surface. The flame at the end of the reactor was ~10-12 inches tall at the highest point. The flame on the deck was ~4-6 inches in height.
The incident occurred behind the lowered sashes in the view more
A petroleum refinery experienced a catastrophic rupture at one bank of three heat exchangers in a catalytic reformer/naphtha hydrotreater unit because of high temperature hydrogen attack (HTHA). Hydrogen and naphtha at more than 500F were released from the ruptured heat exchanger and ignited, causing an explosion and an intense fire burned for more than three hours.
The rupture fatally injured seven employees working in the immediate vicinity of heat exchanger at the time of the incident. The workers were in the final stages of a start-up activity to put a parallel bank of three heat exchangers back in service following cleaning. Such start-up activities had resulted in frequent leaks and occasional fires in the past and should have been considered as hazardous and nonroutine. view more
A chemical plant experienced a valve failure during a planned shutdown for maintenance that caused hydrogen to leak from a valve and catch fire. Four chemical reactor chambers in series were being emptied of liquid using hydrogen gas as part of a maintenance procedure. Two heater valves were opened allowing 3000 psi hydrogen to flow in reverse direction to purge the reactor system for approximately 25 minutes. At completion of the purging process, a "light" thud was heard as the reactor empty-out valves are being closed. Smoky vapor was observed coming out of one of the reactor empty-out valves and the valve closing was stopped by the operator. The operator summoned a second operator for help at which time a second "loud" thud was heard with a much larger light and view more
An alarm sounded at a recently inaugurated hydrogen fueling station in a major metropolitan area. One out of a total of 120 high-pressure hydrogen cylinders, located on the roof of the fueling station, failed in service. Gaseous hydrogen was leaking from a screw fitting of the cylinder, but the hydrogen was not ignited. Three hydrogen gas sensors detected the leakage and triggered an alarm that resulted in an immediate emergency shutdown, isolating the leaking high-pressure cylinder bank from the other three banks and notifying the local fire department. No personnel were allowed to enter the roof area, approximately 7-9 meters above ground level.
The police isolated the area around the fueling station within a radius of 200 meters. The maximum content of the leaking cylinder view more
A pressure relief device (PRD) valve failed on a high-pressure storage tube at a hydrogen fueling station, causing the release of approximately 300 kilograms of hydrogen gas. The gas ignited at the exit of the vent pipe and burned for 2-1/2 hours until technicians were permitted by the local fire department to enter the station and stop the flow of gas. During this incident the fire department evacuated nearby businesses and an elementary school, closed adjacent streets, and ordered a high school to shelter in place.
There were no injuries and very little property damage. The corrugated roof on an adjacent canopy over a fueling dispenser was slightly singed by the escaping hydrogen flame, causing less than $300 in damage.
The station's operating systems worked as view more
A single-stage regulator "failed" while flowing hydrogen gas from a standard 200 cu.ft. gas bottle. The regulator had functioned properly prior to the event through several on-off cycles. During the event, a solenoid valve was opened to allow hydrogen to flow, when a rather loud noise was noted and gas began flowing out of the pressure relief valve on the side of the regulator. It was noted that the low-pressure gauge on the regulator was "pegged" at the high side (>200 psi). The valve on the bottle was shut off, and hydrogen flow was immediately stopped. Hydrogen flowing out of the relief valve did not ignite. With the bottle shut off, the regulator was removed and replaced with another regulator of the same type, and activities continued.
The failed view more
A hydrogen leak at the flange of a 6-inch synthesis turbocharger valve in an ammonia production plant ignited and exploded. Hydrogen detectors and the fire alarm alerted the control room, which immediately shut down the plant, and the fire was then extinguished rapidly. There were no injuries caused by the accident, since the operator heard a wheezing sound and was able to run away just before the explosion occurred. The leaking gas was composed of 70% hydrogen at a flow rate of 15,000 cubic meters per hour. Property damages in the turbocharger included electrical cabling, melted siding, and heavily damaged pipes. The ammonia plant was shut down for more than a month.Five days before the incident, a problem with the CO2 absorber column led operators to open the vent downstream of the view more
During restart of an ammonia production plant, syngas (50% hydrogen mixed with methane, ammonia, and nitrogen) leaking from a flange directly downstream of the synthesis reactor ignited. The plant had been shut down for about 90 minutes due to a technical problem. Alerted by the plant fire alarm, the operator activated the emergency shutdown, which isolated and depressurized the synthesis loop. Steam was sprayed onto the leak site to dampen the fire, which was brought under control 55 minutes later. Property damages included pipe insulation, the reactor's protective shutters, concrete fireproofing of the reactor structure, and instrumentation cables within 3 meters of the leak site. The flames did not affect the synthesis reactor itself, which was protected by a deflector. The view more
Operators in a powdered metals production facility heard a hissing noise near one of the plant furnaces and determined that it was a gas leak in the trench below the furnaces. The trench carried hydrogen, nitrogen, and cooling water runoff pipes as well as a vent pipe for the furnaces.
Maintenance personnel presumed that the leak was nonflammable nitrogen because there had recently been a nitrogen piping leak elsewhere in the plant. Using the plant's overhead crane, they removed some of the heavy trench covers. They determined that the leak was in an area that the crane could not reach, so they brought in a forklift with a chain to remove the trench covers in that area.
Eyewitnesses stated that as the first trench cover was wrenched from its position by the forklift view more
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