Event
- Event ID
- 103
- Quality
- Description
An explosion, followed by a fire, happened in an oven part of a hydro-treatment unit. Following a shutdown, the tube, which contained only gaseous products and hydrogen, had been affected by instable flows. Under heating and with abnormally low gas flows, the tube temperature raised reaching its mechanical resistance limit.
The tube failed due internal pressure, with a longitudinal crack of ca. 750 mm. The unit was shut down and the fire extinguished by itself.
- 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
- rupture
- Initiating cause
- over-heating (wrong operation)
- Root CAUSE analysis
The INITIATING CAUSE was the failure of a tube of the oven due to overheating.
The low flows and the excessive temperature were due to difficulties in controlling the operative parameters, also due to lack of effective diagnostics by means of measuring gauges.
- Root causes
- Date entry in HIAD
- 28/02/2009
Facility
- Application
- Petrochemical industry
- Sub-application
- Hydrodesulphurisation process
- Hydrogen supply chain stage
- All components affected
heat exchanger
- 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
- Pre-event occurrences
The oven used for hydrotreatment of complex oils had been shut down 3 hours before.
- Description of the facility/unit/process/substances
Nothing is known on the function of the oven which failed. Similar failures occurred to heat exchanger tubes used to pre-heat hydrogen and other process gases before entering he hydro-treatment reactor.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Official legal action
The unit could not restart before the conclusions of investigation and the subsequent updating of safety measures. Anyhow, a maintenance was planned in one month after the incident.
- Emergency action
The Internal Operation Plan was launched. The unit was secured by using extinguishing means, isolatiing it, depressurising it and placing it under nitrogen. The integrity of all equipment surrounding the oven was checked.
Lesson Learnt
- Corrective Measures
The plant operator:
- verified the soundness of the range of allowed operative conditions,
- ensured the correct functioning of the thermocouples measuring the temperature of the tubes,
- improved the operative procedures, in particular those regulating the transitory phases.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 (mainly)
- Probable IGNITION SOURCE
- Explosion type
- Flame type
References
- Sources categories
- ARIA
- Reference & weblink
Event no. 52706 of the French database ARIA (accessed December 2020)
