Event
- Event ID
- 306
- Quality
- Description
The accident occurred when a welder of a sub-contractor company was working on a tank roof. The zeolite crystallisation tank was being cleaned out with approx. 20% sulphuric acid. It was not pressurised and was vented to atmosphere. The worker had been asked to cut a larger inspection hole in tank top. He had not yet begun to cut, but possibly had already lit up the oxy-acetylene equipment, when a loud explosion was heard by many.
Hydrogen evolution due to acid action on steel vessel walls was suspected to be the cause of the accident.
- Event Initiating system
- Classification of the physical effects
- Hydrogen Release and Ignition
- Nature of the consequences
- Macro-region
- Europe
- Country
- United Kingdom
- Date
- Component involved
- chemical storage tank (H2SO4)
- Failure mode
- internal explosion
- Initiating cause
- accidental hydrogen formation
- Root CAUSE analysis
The HSE communication does not give indications useful for drawing a root cause.
- Root causes
- Date entry in HIAD
- 28/02/2009
Facility
- Application
- Chemical industry
- Sub-application
- Chemical storage
- Hydrogen supply chain stage
- All components affected
zeolite crystallisation tank, H2SO4, welding gear
- Process temperature range [C]
- ambient temperature (-50°C to +50°C)
- Location type
- Unknown
- Location
- industrial area
- Operational condition
- Pre-event occurrences
The accident occurred when the tank was being cleaned. An additional intervention was planned, consisting in cutting a large inspection hole on the tank top. .
Emergency & Consequences
- Number of fatalities
- 1
- Number of injured persons
- 0
- Investigation comments
1. Oxy acetylene equipment and sample from tank taken for analysis.
2. FCG contacted.
3. Hydrogen evolution due to acid action on steel vessel walls
suspected to be the cause of the accident.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 (probably)
- Release temperature [°C]
- 25
- Probable IGNITION SOURCE
- Explosion type
References
- Sources categories
- HSE
- Reference & weblink
Event description provided by HSE, original source confidential
