A large, hydrogen-cooled generator is driven by steam turbines at a power station. During maintenance shutdowns, the hydrogen cooling loop in the generator is purged with carbon dioxide. After CO2 concentrations are measured with a densitometer to verify the complete removal of hydrogen, the generator is purged with air and the maintenance is performed.

This purging procedure was used prior to the explosion. The CO2 reading was reported to be 100 percent CO2 at the top of the generator. The cooling system was then purged with air and a 1/2 inch pipe in the cooling loop was cut to install some new instrumentation. When the pipe was cut, pressurized gas was emitted at the opening. Workers assumed the gas was either carbon dioxide or air and proceeded with the new instrument 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 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

A fire occurred in a continuous-feed autoclave system (fixed-catalyst-bed tubular reactor) when the rupture disc released, discharging hot oil, oil distillates, and hydrogen gas out a vent pipe into the autoclave cell. The flammable mixture was discharged directly into the cell because there was no system in place to catch or remotely exhaust the autoclave contents. The oil and gas ignited in a fireball that, in turn, ignited nearby combustibles (cardboard and paper), causing a sustained fire. The hydrogen gas and autoclave system were shutoff immediately. However, a lecture bottle containing hydrogen sulfide was heated by the surrounding fire and ultimately ruptured with enough force to cause facility structural damage. (Lecture bottles do not have a pressure-relief device.) The view more

An explosion occurred in a 90-ton-per-day incinerator at a municipal refuse incineration facility. Three workers were seriously burned by high-temperature gas that spouted from the inspection door, and one of them died 10 days later. The accident happened during inspection and repair of the furnace ash chute damper. The workers injected water to remove some blockage, and the water reacted with incinerated aluminum ash to form hydrogen, which caused the explosion.

Workers noticed that the post-combustion zone was full of ash and the ash pusher was not working properly, so they tried to remove the ash from the inspection door with a shovel. They discovered a solid layer of "clinker", which is formed by solidification of molten material such as aluminum. The explosion view more

Unit 1 Plant power was stable at 90% following a plant startup. The Auxiliary Operator (AO) performed a pre-job brief with shift management before adding hydrogen to the main generator. While performing the addition, the AO attempted to verify open a half-inch hydrogen addition valve. The AO was unable to move the valve by hand and mistakenly assumed the valve was stuck on its closed seat. The valve is a normally open valve and the procedure step was to verify the valve was, in fact, open. The AO obtained a pipe wrench to assist in freeing the valve off of its "closed" seat. Using the pipe wrench, the valve handwheel was turned in the open direction. The AO attempted to open the valve by hand again. Unable to move the valve by hand, the pipe wrench was used to further open view more

Key:

  • = No Ignition
  • = Explosion
  • = Fire
Hydrogen Incident Summaries by Equipment and Primary Cause/Issue
Equipment / Cause Equipment Design or Selection Component Failure Operational Error Installation or Maintenance Inadequate Gas or Flame Detection Emergency Shutdown Response Other or Unknown
Hydrogen Gas Metal Cylinder or Regulator   3/31/2012
4/30/1995
2/6/2013
4/26/2010 12/31/1969     3/17/1999
11/1/2001
12/23/2003
Piping/Valves 4/4/2002
2/2/2008
5/11/1999
4/20/1987
11/4/1997
12/31/1969
8/19/1986
7/27/1991
12/19/2004
2/6/2008
10/3/2008
4/5/2006
5/1/2007
9/19/2007
10/31/1980
2/7/2009 1/24/1999
2/24/2006
6/8/1998
12/31/1969
2/7/2009

9/1/1992
10/31/1980

10/3/2008  
Tubing/Fittings/Hose   9/23/1999
8/2/2004
8/6/2008
9/19/2007
1/1/1982 9/30/2004
10/7/2005
  10/7/2005  
Compressor   10/5/2009
6/10/2007
8/21/2008
1/15/2019
    10/5/2009 8/21/2008  
Liquid Hydrogen Tank or Delivery Truck 4/27/1989 12/19/2004
1/19/2009
8/6/2004 12/31/1969   1/1/1974 12/17/2004
Pressure Relief Device 7/25/2013
5/4/2012
1/15/2002
1/08/2007
12/31/1969        
Instrument 1/15/2019 3/17/1999
12/31/1969
2/6/2013
    11/13/73    
Hydrogen Generation Equipment 7/27/1999     10/23/2001      
Vehicle or Lift Truck   7/21/2011         2/8/2011
12/9/2010
Fuel Dispenser   8/2/2004
5/1/2007
6/11/2007
9/19/2007
  2/24/2006
1/22/2009
     
Fuel Cell Stack            

5/3/2004
12/9/2010
2/8/2011

Hydrogen Cooled Generator       12/31/1969
2/7/2009
     
Other (floor drain, lab
anaerobic chamber,
heated glassware,
test chamber,
gaseous hydrogen
composite cylinder,
delivery truck)
  11/14/1994
7/21/2011
7/27/1999
6/28/2010
8/21/2008
12/31/1969
3/22/2018
    6/10/2019
  • = No Ignition
  • = Explosion
  • = Fire