Event
- Event ID
- 322
- Quality
- Description
- A large hydrogen gas leak from a dewar resulted when bolts holding fitting the top of the tank was loosened. The fitting contained instruments. On loosening the third bolt, hydrogen gas excaped from the opening around seal. The Viton or neoprene 0-ring was blown out of its groove and was immediately frozen, making it impossible to reseal the fitting cover. The area was evacuated, dewar vented and gasket replaced. The ullage space was not purged with helium gas during the gasket replacement which may have been responsible for small leaks which developed during the transfer.
[Ordin, NASA (1974)] - Event Initiating system
- Classification of the physical effects
- Unignited Hydrogen Release
- Nature of the consequences
- Leak No Ignition (No additional details provided)
- Macro-region
- North America
- Country
- United States
- Date
- -
- Main component involved?
- Flange (Bolts)
- Initiating cause
- Loss Of Tightness (Wrong Operation)
- Root causes
- Root CAUSE analysis
- The INITIATING CAUSE was a release from a flange sealing.
The fitting which contained the instruments was mounted on a flange, which in turn, was secured to another flange. A set of long bolts and short bolts were used to retain the components. The bolt heads were identical and not labelled, therefore an error was made in loosening the wrong bolts. Leaks after gasket replacement probably due to condensation of moisture on related vent valve components.
The ROOT CAUSE was a human error facilitated by lack of clear guidelines/procedures.
Facility
- Application
- Non-Road Vehicles
- Sub-application
- Aerospace
- Hydrogen supply chain stage
- Hydrogen Storage (No additional details provided)
- All components affected
- cryogenic tank
- Location type
- Unknown
- Operational condition
Emergency & Consequences
- Number of injured persons
- 0
- Number of fatalities
- 0
- Environmental damage
- 0
Lesson Learnt
- Lesson Learnt
- H2TOOLS proposed improvement based on the need to clearly label bolts according to their function/role
Bolts could be identified by means of colour coding. Obviously, an explanation of the colour coding should be easily available at the working place.
Event Nature
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Actual pressure (MPa)
- <1.0
- Design pressure (MPa)
- <1.0
- Presumed ignition source
- No ignition
References
- Reference & weblink
Mishap no 32 in <br />
P. L. Ordin, Review of hydrogen accidents and incidents in NASA operations, 1974, NASA TM X-71565<br />
https://ntrs.nasa.gov/citations/19740020344Lowesmith et al., Safety issues of the liquefaction, storage and transportation of liquid hydrogen: An analysis of incidents and HAZIDS, Int. J. Hydrogen energy (2014) https://doi.org/10.1016/j.ijhydene.2014.08.002
Hankinson and Lowesmith, Qualitative Risk Assessment of Hydrogen Liquefaction, Storage and Transportation, FCH JU project IDEALHY, Deliverable 3.10 (2013)<br />
confidential<br />
(accessed October 2025)Hankinson and Lowesmith, HAZIDs for Hydrogen Liquefaction, Storage and Transportation , FCH JU project IDEALHY, Deliverable 3.11 (2013)<br />
https://www.idealhy.eu/uploads/documents/IDEALHY_D3-10%20HAZIDs_Liquefa… />
(Only summary publicly available, accessed October 2025)References\HIAD_322 H2TOOLS.pdf
JRC assessment
- Sources categories
- ORDIN
