Event
- Event ID
- 765
- Quality
- Description
A leak occurred on a line connecting the hot separator to the cold separator of a refinery diesel desulphurization.
The alert was given by the activation of the fixed H2S detector.
The 30 bar pressure line contained essentially hydrogen with a high concentration of H2S. The operators stopped the unit and isolated the leak in about ten minutes. The line was pierced at a bend at an angle of 135, following a bend at an angle of 90 degrees. The accident investigation showed that the presence of the elbows resulted in turbulence which created a localized depression: this configuration favoured the formation of deposits (in particular during the stops of the water wash pump).- Event Initiating system
- Classification of the physical effects
- Unignited Hydrogen Release
- Nature of the consequences
- leak no ignition
- Macro-region
- Europe
- Country
- France
- Date
- Component involved
- pipe (bend)
- Failure mode
- leak, no ignition
- Initiating cause
- material degradation (internal corrosion / erosion)
- Root CAUSE analysis
The INITIATING CAUSE was puncturing of the H2 pipe due to deposition of corrosive substance at the pipe bends.
An inspection of the 90-degree elbow was performed by the site inspection department, but not the one with the 135-degree elbow.
The ROOT CAUSE could be a combination of shortcoming in design (favouring local corrosion) and of a lack of thorough inspection.- Root causes
- Date entry in HIAD
- 01/01/2020
Facility
- Application
- Petrochemical industry
- Sub-application
- Hydrodesulphurisation process
- Hydrogen supply chain stage
- All components affected
process gas pipe
- Process temperature range [C]
- Above ambient temperature (50°C to 100°C)
- Process pressure range [MPa]
- medium pressure (2 to 10 MPa)
- Location type
- Unknown
- Location
- industrial area
- Operational condition
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Post-event summary
The operators stopped the unit and isolated the leak in about ten minutes.
- Emergency action
The alert was given by the activation of the fixed H2S detector.
The operators stopped the unit and isolated the leak in about ten minutes.
In-depth data
- Release type
- gas mixture
- Involved substances (% vol)
- H2,
H2S - Release temperature [°C]
- 25
- Release pressure [MPa]
- 3
- Probable IGNITION SOURCE
References
- Sources categories
- ARIA
- Reference & weblink
ARIA data base
event no. 23175:
https://www.aria.developpement-durable.gouv.fr/accident/23175/
(accessed July 2024)
