Event
- Event ID
- 335
- Quality
- Description
An explosion occurred during tensile tests of metals in a liquid hydrogen vessel. efforts were made to prevent air from entering by using a flexible top skirt designed to allow for movement of the tensile machine. A purge was also applied at each testing cycle.
- 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 an air-hydrogen explosive mixture inside the liquid hydrogen apparatus, and the following ignition .
The most probable cause was air which had condensed in the LH2 vessels system due to leaks. This air was most likely solidified and collected in the bottom of the vessel. Purging after each test did not warm the vessel sufficiently to remove the air. Fracturing of the specimen probably provided sufficient energy for ignition.
ROOT CAUSE could be then identified in an inadequate procedure applied at the end of the test and aiming to purge completely the testing vessel. Moreover, it should be possible to identify the presence of frozen ai inside the vessel by simple visual inspection. The fact that air could leak into the vessel speaks for a shortcoming of the design.
- 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
- countryside or desert
- Operational condition
- Pre-event occurrences
It is not completely clear when exactly the explosion took place.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
In-depth data
- Release type
- liquid
- Involved substances (% vol)
- H2 100%
- Release pressure [MPa]
- <1.0
- Probable IGNITION SOURCE
- Explosion type
References
- Sources categories
- ORDIN
- Reference & weblink
Mishap no 42 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
