Event
- Event ID
- 288
- Quality
- Description
A tube trailer carrying compressed hydrogen was travelling along a city road, when the drivers heard an abnormal sound from behind. They stopped and discovered that hydrogen was leaking from the threaded joint of a pipe connecting all the tubes to the manifold. They tightened the joint, but the leak did not stop, therefore it was decided to transfer hydrogen to another tube trailer.
The reason of the leak was the O-ring of the joint, which did not fit properly. All tube trailers of the same type were modified by installing a valve to each of the tubes.- Event Initiating system
- Classification of the physical effects
- Unignited Hydrogen Release
- Nature of the consequences
- leak no ignition
- Macro-region
- Asia
- Country
- Japan
- Date
- Component involved
- joint/connection (gasket)
- Failure mode
- leak, no ignition
- Initiating cause
- wrong component
- Root CAUSE analysis
The INITIATING CAUSE was a defective O-ring causing a leak on a joint.
According to the KHK report, the was an inspection failure, which had not been able to identify the wrong O-ring and the ensure tightness the joint before departure. Since the leak was heard only when travelling, road vibration could have been a contributing factor. Since there was no possibility to isolate the tubes from the general manifold, the fundamental ROOT CAUSE is a shortcoming in design, which did not take into account all possible accidental scenarios.- Root causes
- Date entry in HIAD
- 30/08/2025
Facility
- Application
- Hydrogen transport and distribution
- Sub-application
- CGH2 tube trailer
- Hydrogen supply chain stage
- All components affected
O-ring, threaded joint
- Process temperature range [C]
- ambient temperature (-50°C to +50°C)
- Process pressure range [MPa]
- medium to high pressure (10 to 50 MPa)
- Location type
- Open
- Location
- populated area
- Operational condition
- Pre-event occurrences
There were 22 long tubes on the trailer
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Post-event summary
Since the O-ring was defective and therewas no possibility to isolate the tubes from the common manifold, it was decided to transfer hydrogen to another tube trailer.
- Emergency action
The drivers tightened the joint, but the leak did not stop, therefore it was decided to transfer hydrogen to another tube trailer.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Release temperature [°C]
- 25
- Probable IGNITION SOURCE
References
- Sources categories
- KHK
- Reference & weblink
High Pressure Gas Accident Cases Database of the KHK (High Pressure Gas Safety Association):
https://www.khk.or.jp/public_information/incident_investigation/hpg_inc…
(accessed May 2025)
