Fire in a Pharmaceutical Plant
The accident occurred in a plant producing synthesized active ingredients for the pharmaceutical industry. An explosion and a fire occurred in one of the workshops of the plant. The chemical reaction is the reduction of an imide compound to an amine compound in anhydrous medium in presence of (AlCl3) activated sodium tetrahydroborate. The reaction is performed in an ether solution and the reactor is nitrogen inerted. - The imide compound is introduced in the reactor via a flexible pipe connected with a mobile pneumatic dosing pump. - The operating procedure specifies that the reaction has to be performed for at least 8 hours and that the temperature of the reaction medium must not exceed 65C. The following substances were used in the process: aluminum trichloride anhydrous (R44) (C.A.S. No: 7446-70-0) sodium tetrahydroborate (aka sodium borohydride, C.A.S. No: 13762-51-1) imide, dimethylether triethylene glycol (R10) The reaction products were - diborane which can spontaneously ignite in air at 25C (C.A.S. No: 19287-45-7) - hydrogen (C.A.S. No: 1333-74-0) - amine .Chronology of the event: - 6:30 h: the operation started - 30 min before shift end. - 6:45 h: the temperature threshold was reached - the operators started to cool the reactor in order to maintain the temperature around 65C - the reaction ran away : the temperature and the pressure rose in the vessel. - The operator nearest to the reactor smelled an unpleasant odor. Through the sight glass he saw a glow preceding the explosion. Employees at 15 m distance perceive a blow. A flame projected through the workshop, other flames shot out from a joint and other damaged connections of the reactor. Employees outside the building perceived a blow just before the explosion. A flame several meters high was visible for some seconds at the exit of a chimney connected with the reactor rupture disk (calibrated at 0.5 bar) that burst, allowing the decompression of the reactor.
Event Date
September 1, 1993
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Causes
Cause Comments
When the accident occurred significant quantities of hydrogen were formed by the runaway reaction and were not absorbed by the reaction medium. The ignition of the gas may have been caused by static electricity in the reactor, a hot spot or the presence of diborane and water traces. The process instructions did not consider the flow regulations to be performed during transfer operations. These flow regulations were left to the know-how of the operators. The workers who were working at the reactor when the accident occurred were experienced with the exception of the worker who performed the imide compound transfer for the first time. The unit worked discontinuously and was essentially operated manually. Considering the hazards related to the reaction, the equipment has to be absolutely reliable and there has to be enough personnel to control the functioning of the equipment in completely safe conditions. These conditions were not guaranteed the day of the accident because: - 2 pumps with different flow capacity could be used for transfer operation, but no flow control meter was provided. - there were no safety or devices to alert the operators in case of a drift of the operating parameters (high flow, high pressure in the reactor,) - the unit was not equipped with remote control valves allowing the reactors to be isolated rapidly. The reactors could not be discharged rapidly, a "neutralization of the reacting medium was impossible. - the installation was brittle due to glass components.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
pump, reactor
Storage/Process Medium
Location Type
Location description
Industrial Area
Operational Condition
Pre-event Summary
Workshop in a plant producing synthesized active ingredients for the pharmaceutical industry. The chemical reaction is the reduction of an imide compound to an amine compound in anhydrous medium in presence of (AlCl3) activated sodium tetrahydroborate. The reaction is performed in an ether solution and the reactor is nitrogen inerted. - The imide compound is introduced in the reactor via a flexible pipe connected with a mobile pneumatic dosing pump. - The operating procedure specifies that the reaction has to be performed for at least 8 hours and that the temperature of the reaction medium must not exceed 65C. The synthesis operation had already been performed several times over 2 years.
Number of Fatalities
2
Currency
Property Loss (onsite)
237000
Lessons Learned
Lessons Learned
The following technical improvements have been made in the workshop: - measures on the parameters directly influencing he synthesis (substitution, automatic memorization of the data, automatons with precise calibration) - check of all rupture disks - computerization of the process control system (particularly of the alarm system) - installation of mobile dosing pumps with calibrated flows for specific use - control of the stirring speed - back-fitting of the electrical system - identification of the substances by means of color codes - updating of the operating procedures and instructions - validating the equipment for every specific synthesis process. - upgrading of personnel training ( realization of individual files, permanent training program)
Event Nature
Emergency Action
The emergency services evacuated the casualties
Ignition Source
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
References
From public part of MARS database