Event
- Event ID
- 325
- Quality
- Description
An explosion occurred in a Dewar used for metals tensile testing at liquefied hydrogen temperatures. The container consisted of vacuum insulated bottom and of cylindrical shaped polyurethane foam top. The venting of hydrogen was through a 2 inch diameter hole in the side of the foam insulation. The boil-off of liquid hydrogen was being accelerated by the use of two electric heaters on the bottom of the Dewar. Explosion was evaluated equivalent to about 0.25 lb TNT. This was followed by the dispersion of hydrogen which resulted in further hydrogen-air explosions.
- Event Initiating system
- Classification of the physical effects
- Hydrogen Release and Ignition
- Nature of the consequences
- Macro-region
- North America
- Country
- United States
- Date
- -
- Component involved
- cryogenic vessel
- Failure mode
- internal explosion
- Initiating cause
- inadequate or no purge
- Root CAUSE analysis
The INITIATING CAUSE was the formation of a air-hydrogen mixture inside the Dewar.
Air is believed to have backed into it through the vent hole in the polyurethane top. It was possible that air could have been cryo-pumped into it due to the high porosity of the foam.
Ignition is believed to be caused by high surface temperature of heaters.The ROOT CAUSE was inadequate design of the system.
- Root causes
- Date entry in HIAD
- 30/10/2025
Facility
- Application
- Laboratory / R&D
- Sub-application
- Aerospace
- Hydrogen supply chain stage
- All components affected
dewar
- Process temperature range [C]
- cryogenic temperature (below -50°C)
- Location type
- Unknown
- Location
- unknown
- Operational condition
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
In-depth data
- Release type
- liquid
- Involved substances (% vol)
- H2 100%
- Probable IGNITION SOURCE
- Explosion type
References
- Sources categories
- ORDIN
- Reference & weblink
Mishap no 35 in
P. L. Ordin, Review of hydrogen accidents and incidents in NASA operations, 1974, NASA TM X-71565
https://ntrs.nasa.gov/citations/19740020344Hankinson and Lowesmith, Qualitative Risk Assessment of Hydrogen Liquefaction, Storage and Transportation, FCH JU project IDEALHY, Deliverable 3.10 (2013)
confidential
(accessed October 2025)Lowesmith 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
