Severity
Near-Miss
Leak
No
Ignition
No

Fitting Failures for Fueling Equipment

Two fitting failures were experienced for fueling equipment filling systems. Both fittings were installed in the system thermal chamber experiencing ambient temperatures of -40C to +50C. They were connected in high-pressure lines used for 70MPa hydrogen fueling.

The first fitting, a 0.25-inch NPT hose connection, was in service for approximately one year with no signs of leakage. The failure was noticed when the system was pressurized during a filling sequence. The failure was discovered by an audible hissing noise during leak checking. The system was depressurized and the fitting removed and replaced. The system was re-pressurized with no further leakage.

When attempting to reconnect a second fitting, a double-ferrule high-pressure connection, the fitting in question would not re-seal. The nut would not spin freely on the tubing and had created gouge marks. The fitting was replaced and no further leakage occurred.

Incident Date
Sep 19, 2007
Setting
Equipment
  • Vehicle & Fueling Systems
  • Fueling Dispenser
  • Piping/Fittings/Valves
  • Piping
Damage and Injuries
Probable Cause
Characteristics
When Incident Discovered
Lessons Learned

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 discussion of best practices for fittings and joints can be found in the Hydrogen Safety Best Practices Manual.

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