Event
- Event ID
- 327
- Quality
- Description
This event occurred when dismantling the cryostat. While a hot air dryer was being used to free a coupling in a hydrogen cryostat, a flash fire occurred.
- Event Initiating system
- Classification of the physical effects
- Hydrogen Release and Ignition
- Nature of the consequences
- fire
- 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 the formation of an air-hydrogen explosive mixture in the cryostat.
The temperature at the centre of the cryostat was sufficiently low to liquefy air. The ignition of the hydrogen-air mixture was probably due to a spark from an open filament of the dryer.
The prescribed requirements for purging and bringing cryostat to room temperature was circumvented.The ROOT CAUSE a human error.
- Root causes
- Date entry in HIAD
- 30/10/2025
Facility
- Application
- Non-road vehicles
- Sub-application
- Aerospace
- Hydrogen supply chain stage
- All components affected
cryostat
- Process temperature range [C]
- cryogenic temperature (below -50°C)
- Location type
- Unknown
- Location
- unknown
- Operational condition
- Pre-event occurrences
The cryostat was being heated up and emptied (probably at the end of an experiment)
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
Lesson Learnt
- Lesson Learnt
In this event, the existing procedure for bringing back the cryostat to room temperature and to dismantle it were not followed. The report does not explain why , but it is easy to assume that the operators wished to accelerate the work and forced a quicker warming up of the coupling by using an heating equipment which clearly was not fitted for the purpose, because not being explosion proof. This suggests a lack of basic knowledge of hydrogen safety principles, and possibly also a lack of supervision or of communication.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Probable IGNITION SOURCE
References
- Sources categories
- ORDIN
- Reference & weblink
Mishap no 37 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
Also in H2TOOLS
https://h2tools.org/lessons/hydrogen-cryostat-dismantling-incident
(Accessed December 2025)
