Fire of a Mixture of Hydrogen and Hydrocarbons in a Refinery
The fire occurred on the tube plate gaskets of 3 of the 4 exchangers loaded with catalytic reforming effluent. The fuel (500C and p=30 bar) was a mixture of 30% hydrocarbons and 70% hydrogen. After depressurisation of the unit and nitrogen flushing (some problems to access the valves), the exchangers being cooled (overall flow 600 m/h on 3 units), the fire was controlled until extinction by nitrogen injection. The accident was apparently due to incorrect tightening of the threaded rods; only 1/5 were correctly tightened on one of the heat exchangers involved. Three threaded rods break and the gasket surfaces were poorly prepared.
Event Date
October 14, 1971
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Causes
Cause Comments
The immediate cause was the release of hydrogen at a flangeThe root (or interm4ediate) cause was the wrong execution of the flange joint (incorrect tightening, bad quality of the gasket surface)
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
heat exchanger of the catalytic reforming unit
Storage/Process Medium
Location Type
Location description
Industrial Area
Lessons Learned
Lessons Learned
The flange tightening process was reviewed and improved.
Event Nature
Emergency Action
The unit was depressurised, nitrogen flushed (with some problems to access the valves), the exchangers being cooled (overall flow 600 m/h on 3 units), the fire was controlled until extinction by nitrogen injection.
Release Type
Release Substance
Hydrogen Release Concentration (%)
70.00
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
References
Event description in the French database ARIA
https://www.aria.developpement-durable.gouv.fr/accident/26616/
(accessed September 2020)