Explosion from a venting valve

Event

Event ID: 531
Quality: 2
Description: Hydrogen escaped when a venting valve was opened for the inspection of a cap. The escaped hydrogen caught fire, resulting in the death of 4 people, injuries to others 3 and damages to the plant.
Event Initiating system: Non-Hydrogen System Initiating Event
Classification of the physical effects: Hydrogen Release and Ignition
Nature of the consequences: Fire (No additional details provided)
Macro-region: Europe
Date: 27/07/1984
Main component involved?: Valve (Generic)
Initiating cause: Inadequate Or No Purge
Root causes: Job Factors
Root CAUSE analysis: The INITIATING CAUSE was the release and ignition of hydrogen when a tank was opened for inspection.

The tank under renovation probably had not been completely degasified, hinting at a ROOT CAUSE related to inadequate procedures.

Application: Unknown
Sub-application: stationary GH2 storage
Hydrogen supply chain stage: Hydrogen Storage (No additional details provided)
All components affected: CGH2 tank
Location type: Confined
Operational condition: Maintenance
Pre-event occurrences: a venting valve in the tank was opened for the inspection of a cap.

Number of injured persons: 3
Number of fatalities: 4
Post-event summary: The result of the fire was 4 fatalities, 3 injuries and damages to the plant.

Lesson Learnt: Incidents with pressurised flammable gas systems are often caused by an inadequate purging or inertisation, with consequent flammable gas residual left inside.
Any operation on tanks having previously contained any kind of flammable liquid or gas shall be performed only after a complete degasification, the results of which have to be verified my measures.

Reference & weblink: Event nr 8761 of the UK database ICHEME in PDF format<br />
https://www.icheme.org/knowledge/safety-centre/resources/accident-data/… />
(accessed October 2020)