Fire in the Desulfurization Unit of a Refinery
The accident occurred in the de-sulfurization unit, and specifically on a pipeline at 50 bar, for the recycling of the hydrogen (containing hydrogen sulfide impurities). The pipe failed due to corrosion and the released hydrogen ignited. The unit was containing 4000 kg of hydrogen, but it is not known if all of it was released. The unit was stopped, de-pressurized and put under nitrogen. Following the accidents, all other pipeline were controlled looking for anomalies.
Event Date
October 20, 1995
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Cause Comments
The immediate cause was the failure of a hydrogen pipe due to corrosion. The accident investigation discovered that the part of the 100 mm diameter pipe which failed had a residual thickness of 2 instead of the nominal 6.3 mm. The ARIA report (see references) does not mention any root cause, but judging by the deep corrosion, a lack of adequate inspection/maintenance can be postulated.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
hydrogen recycling pipeline
Storage/Process Medium
Actual Pressure
50
Location Type
Location description
Industrial Area
Operational Condition
Pre-event Summary
Due to inner corrosion of a 100mm (DIN 100) pipe the wall thickness was reduced from 6.3 mm to 2 mm.
Lessons Learned
Lessons Learned
Unknown
Event Nature
Emergency Action
The unit was stopped, de-pressurised and put under nitrogen.
Release Type
Release Substance
Hydrogen Release Concentration (%)
100.00
Release Amount (kg)
4000.00
Ignition Source
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/10347/
(accessed October 2020)