Event
- Event ID
- 1141
- Quality
- Description
The drivers of a CGH2 tube trailer-tractor was travelling to a delivery. they stopped to perform a visual walk-around inspection of the vehicle and discovered an audible leak coming from the neck threads of a tube. They notified the company, which dispatched a local emergency response team. The team proceeded to vent the hydrogen in the leaking tube. The trailer was returned to the shipping location to disable the defective tube valve.
- 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
- joint/connection (threaded)
- Failure mode
- rupture, no ignition
- Initiating cause
- material degradation (generic)
- Root CAUSE analysis
The INITIATING CAUSE was probably the loosening of a threaded connection of a valve, probably due to road travel vibrations.
The ROOT CAUSE is not provided.
- Root causes
- Unknown
- Date entry in HIAD
- 25/10/2024
Facility
- Application
- Hydrogen transport and distribution
- Sub-application
- CGH2 tube trailer
- Hydrogen supply chain stage
- All components affected
Threaded Connection
- 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
- highway or similar
- Operational condition
- Description of the facility/unit/process/substances
DESCRIPTION OF THE UNIT
The trailer consisted of ten steel tubes, with a capacity of 12000 gas cubic feet each (ca. 30.5 kg).
The pressure is not provided, but from Linde webpages it can be deduced a pressure of 180 to 250 bar for these steel cylinders.
The nominal trailer gas capacity is also the value provided by PHMSA for the released amount. However, the report states also a 'amount in package' of only 77.8 gas ft3, which would indicate an empty tube. Since it is also stated tht the trailer was travelling to a delivery, it could not have been empty. This is contradictory and illogic, and has been neglected in HAID encoding.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Currency
- US$
- Property loss (onsite)
- 0
- Emergency action
The company proceeded to vent the hydrogen of the leaking tube locally. Then the trailer was returned to the shipping location to disable the defective tube valve.
Lesson Learnt
- Lesson Learnt
The preventing/mitigating measures worked well: (i) the regular inspection by drivers along the route, and (ii) the emergency handling by depressurising the leaking tube and releasing its content to the atmosphere.
The loosening of threaded connection due to road vibration is a common glitch. It is however unclear, in this and similar events, how this could be avoided. Is the root cause related to shortcoming when installing / maintaining the connections, to unexpected road conditions during travel, or to a design unable to guarantee tightness during travelling?
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Released amount (kg)
- 30.5
- Release temperature [°C]
- 25
- Release pressure [MPa]
- 18
- Probable IGNITION SOURCE
References
- Sources categories
- PHMSA
- Reference & weblink
Incident I-2013080039 of the US Pipeline and Hazardous Materials Safety Administration PHMSA:
https://portal.phmsa.dot.gov/analytics/saw.dll?Portalpages&PortalPath=%…
(accessed September 2024)
