Event
- Event ID
- 738
- Quality
- Description
A vehicle fill was initiated by the operator. During the hose pressurisation step, a leak was observed at the breakaway fitting. The operator pressed the emergency stop to terminate the fill.
- 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
- dispenser (hose)
- Failure mode
- leak, no ignition
- Initiating cause
- loss of tightness
- Root CAUSE analysis
The INITIATING CAUSE was the loosening of the treaded breakaway joint, probably due to torques applied to the refuelling hose.
A probable ROOT CAUSE was a shortcoming of the hose assembly design.- Root causes
- Date entry in HIAD
- 15/04/2026
Facility
- Application
- Hydrogen refuelling station
- Sub-application
- Dispenser
- Hydrogen supply chain stage
- All components affected
breakaway
- Process temperature range [C]
- ambient temperature (-50°C to +50°C)
- Process pressure range [MPa]
- high pressure (above 50 MPa)
- Location type
- Open
- Location
- unknown
- Operational condition
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Environmental damage
- 0
- Property loss (onsite)
- 0
- Post-event summary
A negligible quantity of hydrogen leaked.
Lesson Learnt
- Corrective Measures
The breakaway joint was a straight SAE, easy to be loosened by applying a torque to the whole hose. Following the leak, additional means were adopted to restrict joint loosening.
Moreover, a cover was installed to deflect leakage.
Finally, by using a different type of nozzle, the torque applied to the hose when operating the nozzle was reduced. (The H2TOOLS does not provide the technical details of the loosening-limiting means and nozzle new type)
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Release pressure [MPa]
- 70
- Probable IGNITION SOURCE
References
- Sources categories
- H2TOOLS
- Reference & weblink
Event of the US database H2TOOLS
https://h2tools.org/lessons/leak-breakaway-fitting
(accessed April 2026)
