Explosion on the pressure release device of a hydrogen supply unit

Event

Event ID: 142
Quality: 3
Description: The explosion followed a hydrogen leak on a unit conditioning hydrogen.
The accident was caused by the mechanical rupture of a pressure regulator diaphragm on a section of a hydrogen line that included the dual-stage regulator, shut-off valves, and connecting flanges.This section of the hydrogen line had the purpose to reduce the hydrogen pressure from 220 to 50 bars and further to 3 bar and to supply it to an area for the conditioning of semi-trailers.
The fire was extinguished by powder-based fire estiguishers and by stopping the supply of hydrogen. FInally, the nitrogen was injected in the system..
Event Initiating system: Hydrogen System Initiating Event
Classification of the physical effects: Hydrogen Release and Ignition
Nature of the consequences: Explosion Followed By A Fire
Macro-region: Europe
Country: France
Date: 09/09/2004
Main component involved?: Pressure Regulator
How was it involved?: Rupture & Formation Of A Flammable H2-Air Mixture
Initiating cause: Material Degradation (Generic)
Root causes: Unknown (No additional details provided)
Root CAUSE analysis: The INITIATING CAUSE was the mechanical failure of a pressure reduction device.
The ROOT CAUSE is unknown.

Application: Hydrogen Production
Sub-application: Production of industrial gases
Hydrogen supply chain stage: Hydrogen Production
All components affected: hydrogen supply line, pressure reducer, hydrogen conditioning unit
Location type: Open
Location description: Industrial Area
Operational condition: Normal

Number of injured persons: 0
Number of fatalities: 0
Environmental damage: 0
Property loss (onsite): 0
Property loss (offsite): 0
Post-event summary: The damage was confined to the pressure reduction unit of the hydrogen line, on a ground surface of 4 m².

Reference & weblink: Event description in the French database ARIA<br />
https://www.aria.developpement-durable.gouv.fr/accident/28007/<br />
(accessed October 2020)