Skip to main content
Clean Hydrogen Partnership

Unplanned LH2 venting

Event

Event ID
331
Quality
Description
An unscheduled venting of a stage LH2 tank occurred, creating a hazardous condition for personnel and creating a potential explosion/ fire.
[Ordin, NASA (1974)]
Event Initiating system
Classification of the physical effects
Unignited Hydrogen Release
Nature of the consequences
Leak No Ignition (No additional details provided)
Macro-region
North America
Country
United States
Date
-
Main component involved?
Valve (Generic)
How was it involved?
Leak & Formation Of A Flammable H2-Air Mixture
Root causes
Root CAUSE analysis
The flexible hose from a gas bottle was left connected to the LH2 vent valve control valve. Seepage through the regulator probably occurred and the regulator control or gas bottle control valve may have been left inadvertently open.

ROOT CAUSE was a mistake in the execution of the pre-launch procedures, possibly enabled by lack of checks.

Facility

Application
Non-Road Vehicles
Sub-application
Aerospace
Hydrogen supply chain stage
All components affected
control valve or regulator
Location type
Unknown
Operational condition
Unknown (No additional details provided)
Pre-event occurrences
The event occurred during a pre-launch checkout

Emergency & Consequences

Number of injured persons
0
Number of fatalities
0
Environmental damage
0

Event Nature

Release type
gas
Involved substances (% vol)
H2 100%
Presumed ignition source
No ignition

References

Reference & weblink

Mishap no 40 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/19740020344

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

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