Leak Fir from the a hydrogen flange in a synthetic adhesives production plant

Event

Event ID: 633
Quality: 3
Description: This accident occurred at the unit producing synthetic adhesives by adding hydrogen to petroleum resin under high temperature and pressure. Hydrogen was added to the reaction via a supply pipe at the bottom of the reactor.
Hydrogen leaked from a flange of the check valve attached to the hydrogen supply pipe and ignited due to static electricity. The leak was due to the deformation of the flange gasket, made of aluminium. The aluminium had deformed due to the high temperature, reducing the tightness of the flange.
Event Initiating system: Hydrogen System Initiating Event
Classification of the physical effects: Hydrogen Release and Ignition
Nature of the consequences: Fire (No additional details provided)
Macro-region: Asia
Country: Japan
Date: 07/07/1986
Main component involved?: Flange (Bolts)
How was it involved?: Leak & Formation Of A Flammable H2-Air Mixture
Initiating cause: Loss Of Tightness (Thermal Stress/Cycling)
Root causes: Material/ Manufacturing Error
Root CAUSE analysis: The INITIATING CAUSE was the deformation of the gasket of a flange on the hydrogen supply pipe.
The KHK report attributes the ROOT CAUSE to the wrong choice of the gasket material. The report does not specify if this was due to a wrong installation (human error) or a lack of clarity of procedures.

Reference & weblink: High Pressure Gas Accident Cases Database of the KHK (High Pressure Gas Safety Association): <br />
https://www.khk.or.jp/public_information/incident_investigation/hpg_inc… />
(accessed May 2025)