Severity
Incident
Leak
Yes
Ignition
Yes

A five-pound CO2 cylinder being stored in a compressed gas storage cage at a power plant failed catastrophically and became a missile. The cylinder destroyed the storage cage, then struck one of six stationary hydrogen storage cylinders used as emergency make-up for the hydrogen supply system. One of the hydrogen cylinders was broken away from its mounts and moved 10 feet from its original location. The loss of this cylinder severed the manifold tubing, creating a leak path to the atmosphere for the remaining five hydrogen cylinders. The leaking hydrogen gas apparently self-ignited, engulfing the immediate area. The site fire brigade responded and used hose lines from a distance to provide cooling until the hydrogen supply was consumed. The fire was out within seven minutes, and no off-site fire assistance was needed. All normal supplies of hydrogen were isolated and a re-flash watch was established until all damaged hydrogen cylinders were removed to an isolated "safe zone." Damage was restricted to the CO2 cylinder, the six hydrogen cylinders, associated piping (which showed flame impingement), and the compressed gas storage cage.

Preliminary results indicated that the CO2 cylinder rupture was caused by tensile strength overload caused by overpressurization. The safety disc assembly was dissembled and it was found to contain three safety discs where there should have only been one. Installation of multiple safety discs probably resulted in failure to relieve the overpressure condition prior to cylinder rupture.

Incident Date
Apr 30, 1995
Setting
Equipment
  • Pressure Relief Devices
  • Burst Disk
  • Hydrogen Storage Equipment
  • Gas cylinder
Damage and Injuries
Contributing Factors
Characteristics
When Incident Discovered
Lessons Learned

Revise fire protection operations surveillance tests to include a maximum of 110% of the agent net weight to prevent over-filled cylinders from being placed in service.
Identify cylinders currently in service that exceed the 110% maximum allowable limit, remove them from service, have them inspected and refilled to the new criteria, and then return them to service.
Purchase new compressed gas pilot control cylinders.
Revise the plant industrial safety program to enhance cylinder storage requirements by eliminating the use of ropes as restraints.
Purge the gas storage shed of all non-related storage, secure all cylinders with chain, fabricate cylinder racks for small cylinders, and eliminate storage of items next to the hydrogen system emergency manifold.
Conduct a probabilistic safety assessment of the possibility of missile hazards from compressed gas cylinders.
Change from the current CO2 vendor to another qualified service vendor.
Investigate whether a breakdown of the fire protection QA program occurred.

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