Event
- Event ID
- 311
- Quality
- Description
An explosion occurred during calibration of engine. The equipment was covered by a shed and when the valve was operated allowing hydrogen gas to flow through the engine, the gas ignited. The explosion damaged the shed and injured the personnel. The suggested overpressure was over 10 psi.
- 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
- unknown
- Failure mode
- unknown
- Initiating cause
- unknown
- Root CAUSE analysis
The INITIATING CAUSE was the leak of a valve allowing hydrogen to build in the propellant header.
When the valve was operated, the hydrogen was propelled through engine and collected under shed. The ignition source is unknown.The ROOT CAUSE of the valve malfunctioning is unknown. Nevertheless, the escalation was caused by the shed allowing the formation of a pre-mixed flammable mixture, followed by an explosion. This suggests inadequate (safety) system design.
- Root causes
- Date entry in HIAD
- 30/10/2025
Facility
- Application
- Non-road vehicles
- Sub-application
- Aerospace
- Hydrogen supply chain stage
- All components affected
valve, engine, shed
- Process temperature range [C]
- cryogenic temperature (below -50°C)
- Location type
- Semiconfined
- Location
- industrial area
- Operational condition
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 2
- Post-event summary
The number of the workers injured is not given, but it is more than one.
Lesson Learnt
- Lesson Learnt
Unambiguous labelling of components and clear instruction for their maintenance and replacement should be in place. The workers involved should be well trained, also by making clear which would be the consequences of exchanging components or mounting them inverted.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Probable IGNITION SOURCE
- Explosion type
References
- Sources categories
- ORDIN
- Reference & weblink
Mishap no 23 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 H2TOOLS uploded from Ordin
https://h2tools.org/lessons/discharge-valve-installation-error
(accessed December 2025)
