Event
- Event ID
- 375
- Quality
- Description
An empty liquid hydrogen tanker was returning to home terminal after having delivered at a space centre. A motorist passed by and pointed to the rear of the tanker. The driver stopped the vehicle and noticed that a small amount of hydrogen vapour was coming out of the vent stack.
The driver found that the vent valve had vibrated open and was releasing hydrogen vapour through the vent stack. The driver secured the valve and returned to the base with no further incident. No defects were found after inspection at the home terminal.- Event Initiating system
- Classification of the physical effects
- Unignited Hydrogen Release
- Nature of the consequences
- leak no ignition
- Macro-region
- North America
- Country
- United States
- Date
- Component involved
- valve (generic)
- Failure mode
- leak, no ignition
- Initiating cause
- loss of tightness (road vibrations)
- Root CAUSE analysis
The INITIAL CAUSE was the release of a small quantity of hydrogen through a partially loose vent valve.
The ROOT CAUSE is not given. Similar cases have been attributed to road vibration (shortcoming In design), but it could be as well related to a non-completely tight closure of the vent valve after operation (procedure not properly followed)- Root causes
- Unknown
- Date entry in HIAD
- 16/11/2024
Facility
- Application
- Hydrogen transport and distribution
- Sub-application
- LH2 tanker
- Hydrogen supply chain stage
- All components affected
vent valve
- Process temperature range [C]
- cryogenic temperature (below -50°C)
- Process pressure range [MPa]
- low to medium pressure (below 2 MPa)
- Location type
- Open
- Location
- highway or similar
- Operational condition
- Pre-event occurrences
Probably the tanker was not containing LH2, but only gaseous hydrogen, after having delivered hydrogen to a customer site.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Currency
- US$
- Property loss (onsite)
- 1
- Post-event summary
720 kg of hydrogen were released.
- Emergency action
The leaking valve was closed by the driver.
Lesson Learnt
- Lesson Learnt
the mitigation procedure in place was applied properly. This event could be also classified as a near-miss.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Probable IGNITION SOURCE
References
- Sources categories
- PHMSA
- Reference & weblink
Report I-1993050573 of the US Pipeline and Hazardous Materials Safety Administration PHMSA:
https://portal.phmsa.dot.gov/analytics/saw.dll?Portalpages&PortalPath=%…
(accessed September 2024)
