Event
- Event ID
- 492
- Quality
- Description
An empty tanker was returning to the home terminal after delivery to a customer. However, the drivers had failed to properly stabilize the residue pressure in the tank before departing from the customer site. This caused a pressure increase during the journey back. The drivers noticed the pressure increase and stopped in a remote area at an exit ramp service road, There they manually released the tank pressure by venting part of the residual hydrogen succeeding in stabilising the pressure. They continued on to their home terminal without further incident (approximately 6 hr driving).
- 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
- LH2 tank (road tanker)
- Failure mode
- manual venting
- Initiating cause
- over-pressurisation (wrong operation)
- Root CAUSE analysis
The INITIAL CAUSE was over-pressurisation of the LH2 tank, which caused an intervention of the drivers to reduce pressure.
The ROOT CAUSE was the failure in stabilising tank pressure after having performed the LH2 transfer.- Root causes
- Date entry in HIAD
- 01/01/2025
Facility
- Application
- Hydrogen transport and distribution
- Sub-application
- LH2 tanker
- Hydrogen supply chain stage
- All components affected
vacuum thermal insulation
- 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
The tanker was almost empty, after delivery.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Currency
- US$
- Property loss (onsite)
- 20
- Post-event summary
3.3 kg hydrogen were released.
- Emergency action
The drivers stopped in a remote area at an exit ramp service road. There they manually released the tank pressure by venting part of the residual hydrogen succeeding in stabilising the pressure.
Lesson Learnt
- Corrective Measures
The drivers received remedial training regarding the procedure for trailer pressure stabilisation.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Released amount (kg)
- 3.35
- Probable IGNITION SOURCE
References
- Sources categories
- PHMSA
- Reference & weblink
Incident I-1997040263 of the US Pipeline and Hazardous Materials Safety Administration PHMSA:
https://portal.phmsa.dot.gov/analytics/saw.dll?Portalpages&PortalPath=%…
(accessed September 2024)
