First Name
Andy
Last Name
Piatt
Severity
Incident
Was Hydrogen Released?
Yes
Was There Ignition?
Yes
Ignition Source
Sparks from angle grinder
Incident Date
May 27, 2008
Equipment
  • Hand Tools
  • Angle Grinder
  • Hydrogen Storage Equipment
  • Atmospheric Storage Tank
Damage and Injuries
When Incident Was Discovered
Lessons Learned

Many accidents reported from paper mills have much in common with this incident. Microorganisms in the process water with pulp produce hydrogen gas that mixes with air to form an explosive atmosphere. The ignition source is typically sparks produced by hot work, but ignition by electrostatic discharges in a cloud of mist in a storage tower has also been reported (see Explosion Caused by Microbial Hydrogen Formation).

Provided the hazard posed by bacterial hydrogen production has been recognized, there are several preventive and/or mitigating measures that can be considered for reducing the risk:

It is advantageous to avoid anaerobic and stagnant conditions in the solution by providing sufficient circulation and/or aeration (bubbling air through the solution), but this requires monitoring and could result in foaming or generation of biogas.
The formation of an explosive atmosphere may be avoided by providing sufficient natural or forced ventilation to keep the hydrogen concentration below the lower flammability limit (LFL), or by using an open-top floating roof tank to remove the space where an explosive mixture could form.
Forced ventilation can be used, but this solution requires monitoring, and care must be taken to avoid introducing a potential ignition source.
The free space above the liquid level can be blanketed with an inert gas to prevent the formation of an explosive mixture, but this is a relatively expensive solution that requires monitoring, and the inert atmosphere will promote anaerobic conditions that favor bacterial hydrogen production.
Strict enforcement of hot work procedures, including gas measurements and the use of non-sparking tools, may prevent certain ignition sources, and especially those that are directly associated with personnel risk.
Technical solutions such as grounding to prevent build-up of electrostatic charges and installation of flame arresters on all openings in the tank to prevent ignition by lightning, etc. can also reduce the risk, but the possibility of having an explosive atmosphere inside the tank should still be regarded as a severe hazard.
Risk management strategies should include a continuous focus on preventive maintenance, mandatory safety training for all workers, regular reviews of risk assessments, and learning from previous accidents in related industries.

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