High-Pressure Hydrogen Explosion in Ammonia Synthesis Reactor
The event took place in the on one out of the seven reactors for ammonia synthesis. The day of the accident, preparation works for the decennial pneumatic test (previous pneumatic test was carried out in 1978) were started on that unit. The reactor was put out of service and a slow pressurization with process gases (hydrogen and nitrogen) was carried out at ambient temperature. It was necessary to carry out many pneumatic cycles of pressurization and depressurization because of leaks from some flanges. After any cycle, the bolts of the flanges were tightened and a purging with nitrogen at 8 bar was carried out. Eventually, a slow pressurization with process gases was in progress at ambient temperature when the explosion occurred, 20 minutes after the start, at an internal pressure of 250 bar. The explosion caused one fatality and one injury, destroyed the upper part of the column; metallic parts of the reactor were thrown in a radius of many meters around it. It also caused the complete destruction of the building where the reactor was located.
Event Date
June 9, 1988
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Causes
Cause Comments
The original investigation report is not available. According to the eMARS report (see reference), some experts suggested the possibility that accident occurred due to an internal explosion (deflagration) in the reactor.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
Ammonia synthesis reactor
Storage/Process Medium
Location Type
Location description
Industrial Area
Operational Condition
Pre-event Summary
Maintenance works were on going The steel reactor had been manufactured in 1929. It had a volumetric capacity of 8,000 liters, was 7.7 meters high and had a diameter of 850 mm, with a design pressure of 300 bar.It had been regularly tested.
Lessons Learned
Lessons Learned
Unknown
Event Nature
Emergency Action
After the accident, on-site arrived the local fire brigade and the police. The ammonia production was interrupted. The ammonia production was interrupted and the whole factory wasstopped by the authorities to establish the causes of the explosion. On June 14 the production in the other plants not involved in the explosion started again.
Release Type
Release Substance
Ignition Source
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
References
Event description in the European database eMARS
https://emars.jrc.ec.europa.eu/en/emars/accident/view/d2b442eb-a58a-f25…
(accessed September 2020)
Page of the newspaper La Stampa of the 11 June
available at the La Stampa archive:
http://www.archiviolastampa.it/component/option,com_lastampa/task,searc…
(accessed September 2020)