| Case Name |
Explosion and fire of magnesium dust at an exterior frame production plant for mobile telephones |
| Pictograph |
|
| Date |
August 1, 2001 |
| Place |
Ohira, Miyagi, Japan |
| Location |
Electronic part factory |
| Overview |
An explosion and a fire occurred at a factory that made magnesium alloy exterior frames of mobile telephones. In the magnesium base alloy cutting and polishing process, magnesium alloy powder was dispersed and an explosion hazard was high. Magnesium alloy powder that accumulated in the collection duct reacted with moisture, and hydrogen was generated. The hydrogen ignited, and an explosion and a fire occurred. |
| Incident |
An explosion and a fire occurred at the dust collector of a surface cutting polishing process of a production plant for exterior frames made of magnesium alloy for mobile telephones. The explosion occurred in a steel pipe that connected a collection duct mouth and a wet dust collector. Flames spouted from a pipe hole for the dust collection, combustibles in the vicinity were ignited, and a fire occurred. Ten persons were injured. |
| Processing |
Manufacture |
| Individual Process |
Others |
| Substance |
Magnesium, Fig2 |
| Type of Accident |
Explosion, fire |
| Sequence |
About 05:01 on August 1st, 2001. An explosion and a fire occurred. |
| Cause |
It was considered that magnesium alloy powder accumulated in a steel pipe that was connected to the dust collector, made contact with water and spontaneously ignited. Dust dispersed in the duct exploded and there was a fire. The possibility of ignition by static electricity can also be considered. However, appropriate earth connections were made on the dust collector, cutting polishing equipment, and workers. Generally, magnesium reacts with water, and generates hydrogen. |
| Response |
Fire extinguishing was carried out with a powder fire extinguisher and a fire extinguisher for metal. The principle of the fire extinguisher for metal is extinguishing with dry sand. |
| Countermeasures |
Following methods were tried as countermeasures to prevent such an accident. The magnesium alloy powder was washed out by injecting a large amount of water during polishing with an air grinder. By using this method, dispersal of magnesium base alloy powder can be prevented. |
| Knowledge Comment |
Careful safety countermeasures are necessary in handling light metal dust that easily causes a dust explosion. In a magnesium alloy, hydrogen is generated by a reaction with moisture, and it is necessary also to sufficiently recognize that it can become an ignition source. |
| Background |
The hazards of magnesium, which reacts readily with water, might not have been understood. Cleaning inspection of unseen locations was ignored. Consciousness and guidance of managers could have been problems. |
| Reason for Adding to DB |
Example of explosion and fire caused due to the accumulation of metal powder having high reactivity |
| Scenario |
| Primary Scenario
|
Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Organizational Problems, Poor Management, Slackness of Management, Ignorance, Insufficient Knowledge, Insufficient Knowledge about the Properties of Treating Material, Planning and Design, Poor Planning, Poor Design, Usage, Maintenance/Repair, Insufficint Cleaning, Bad Event, Chemical Phenomenon, Abnormal Reaction, Secondary Damage, External Damage, Explosion/Fire, Bodily Harm, Injury, 10 person injured
|
|
| Sources |
Material of The National Research Institute of Fire and Disaster.
|
| Number of Injuries |
10 |
| Physical Damage |
Windows of a factory were damaged. There was no damage to the outside of the factory. |
| Multimedia Files |
Fig2.Chemical formula
|
| Field |
Chemicals and Plants
|
| Author |
DOBASHI, Ritsu (School of Engineering, The University of Tokyo)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
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