Event
- Event ID
- 106
- Quality
- Description
The event took place at the metal sheet pre-heating oven of a galvanisation unit. This was using a mixture of hydrogen and nitrogen to form a reducing atmosphere and avoid oxidation of the metallic sheets. The zinc crucible’s draining operations was completed and the hydrogen purge operation was underway since 6 hours when an explosion happened, due to failing to cut off completely the hydrogen supply.
- Event Initiating system
- Classification of the physical effects
- Hydrogen Release and Ignition
- Nature of the consequences
- Macro-region
- Europe
- Country
- France
- Date
- Component involved
- reactor / oven / furnace / test chamber
- Failure mode
- internal explosion
- Initiating cause
- wrong operation
- Root CAUSE analysis
The INITIATING CAUSE was due to the fact that the valve on the backup hydrogen tank and the by-pass on the furnace’s supply line were not closed. A hot spot in the oven probably ignited the explosive atmosphere.
No information is available on the ROOT CAUSE, but probably related to shortcomings in the procedures and/or in the inadequate overview and control of the process parameters. This is confirmed by the corrective measures adopted.
- Root causes
- Date entry in HIAD
- 28/02/2009
Facility
- Application
- Steel and metals industry
- Sub-application
- generic metal processing
- Hydrogen supply chain stage
- All components affected
metals processing unit
- Process temperature range [C]
- High temperature (100°C to 500°C)
- Process pressure range [MPa]
- ambient pressure (around 0.1 MPa)
- Location type
- Unknown
- Location
- industrial area
- Operational condition
- Pre-event occurrences
The oven had been shut down the previous evening for annual maintenance work.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Property loss (offsite)
- 0
- Post-event summary
The four employees present were not injured. No impact outside the site was reported.
- Emergency action
probably none,due to the velocity of the event.
Lesson Learnt
- Corrective Measures
Following the accident, the operator modified the procedures concerning these operations by:
- Blinding of the by-pass and leak test.
- Modifying the valve of the back-up H2 circuit to allow lock-out capability.
In-depth data
- Release type
- gas mixture
- Involved substances (% vol)
- H2, N2
- Probable IGNITION SOURCE
- Explosion type
References
- Sources categories
- ARIA
- Reference & weblink
Event No, 30365 of the French database ARIA https://www.aria.developpement-durable.gouv.fr/accident/30365/ (accessed December 2020)
