Event
- Event ID
- 318
- Quality
- Description
- The incident occurred at end of a hydrogen fuel pump test, when large volume of gaseous hydrogen was vented off. An explosion occurred at or near the top of the vent stack, with damage to stack segment, vent systems, ducting, and valves. The top section of vent stack was missing (it consisted in a covering "hat" section,15 ft. length, on top of the vent stack and was housing a double reversing turning vane assembly).
[Ordin, NASA (1974)] - Event Initiating system
- Classification of the physical effects
- Hydrogen Release and Ignition
- Nature of the consequences
- Macro-region
- North America
- Country
- United States
- Date
- -
- Main component involved?
- Venting System
- How was it involved?
- Ignition Of Vented H2
- Initiating cause
- Inadequate Or Wrong Design
- Root causes
- Root CAUSE analysis
- The INITATING CAUSE was the formation and ignition of an explosive air-hydrogen mixture at the end of the venting stack, where a new ''hat" section of the vent stack had been installed. Failures of internal structures had been observed prior to this incident. Therefore, the vent system had a slightly higher than normal catch tank pressures due to partial restriction of the vent stack outlet. Ignition was by static electricity or burning gas in vicinity of stack outlet.
The ROOT CAUSE could be identified in an inadequate design (and possibly manufacturing) of the stack ‘hat’.
Facility
- Application
- Non-Road Vehicles
- Sub-application
- Aerospace
- Hydrogen supply chain stage
- All components affected
- LH2 pump, vent stack
- Location type
- Unknown
- Operational condition
Emergency & Consequences
- Number of injured persons
- 0
- Number of fatalities
- 0
- Environmental damage
- 0
- Property loss (offsite)
- 0
- Post-event summary
- Losses probably limited to the vent end.
Lesson Learnt
- Lesson Learnt
- This and similar events occurred when knowledge of hydrogen fluid-dynamic and ignition behaviour was still in its infancy. The NASA was learning-by-doing from these mishaps, which were causing only some property damage.
In the specific case of this event, it could be further considered if the vent ‘hat’ caused an overpressure due to some failed internal element, or just because of its geometry, forcing the vented hydrogen to reverse the flow direction. We do not know, unfortunately, the reason for the need to change the direction of the venting. It could have been the need to ensure better protections for neighbouring components.
Event Nature
- Release type
- liquid
- Involved substances (% vol)
- H2 100%
- Presumed ignition source
- Static electricity
References
- Reference & weblink
Mishap no 30 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)
JRC assessment
- Sources categories
- ORDIN
