Event
- Event ID
- 75
- Quality
- Description
The driver of a liquid hydrogen tanker noticed a small vapour plume in his mirror while driving. The driver stopped and found the packing nut had loosened on the vapour recovery valve causing the valve to crack open. The driver closed the valve and tightened the packing nut. The vapour stopped and the driver continued on to complete trip without further incident.
- 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
- flange (bolts)
- Failure mode
- rupture, no ignition
- Initiating cause
- loss of tightness (road vibrations)
- Root CAUSE analysis
The INITIATING cause of the hydrogen release was the loosening of valve packing nut.
The ROOT CAUSE was identified by the PHMSA report with over pressurisation. However, the loosening of the packing nut could more plausibly be attributed to road vibrations.
- Root causes
- Unknown
- Date entry in HIAD
- 31/12/2024
Facility
- Application
- Hydrogen transport and distribution
- Sub-application
- LH2 tanker
- Hydrogen supply chain stage
- All components affected
packing nut, 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
Unknown if the tanker was containing liquid hydrogen or only cold hydrogen vapour.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Currency
- US$
- Property loss (onsite)
- 3
- Post-event summary
PHMSA reports a minimal loss of hydrogen of 60 GCF, which probably correspond to 0.2 kg
- Emergency action
The driver closed the valve and tightened the packing nut.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Probable IGNITION SOURCE
References
- Sources categories
- PHMSA
- Reference & weblink
Event incident ID I-1991110674 of the PHMSA database (Pipeline and Hazardous Materials Safety Administration, 1996),
https://portal.phmsa.dot.gov/analytics/saw.dll?Portalpages
(accessed September 2024)
