| Case Name |
Explosion of DMTP caused due to improper temperature control at a manufacturing plant of pesticide intermediates |
| Pictograph |
|
| Date |
April 19, 1977 |
| Place |
Osaka, Osaka, Japan |
| Location |
Pesticide factory |
| Overview |
In 1977, an explosion occurred at a pesticide factory in Nishiyodogawa, Osaka, Flammable gas was generated from thermal decomposition of DMTP during the production process of a pesticide intermediate, and the gas exploded on ignited by a spark. The overheating resulted from a reaction temperature control failure due to the use of a shorter thermometer that indicated a lower temperature than actual one. |
| Incident |
A gas explosion occurred at a pesticide intermediate manufacturing plant. The gas was produced by overheating of a melting drum. |
| Processing |
Manufacture |
| Individual Process |
Dissolution |
| Process Flow |
Fig2.Unit process flow
|
| Substance |
DMTP (o, o'-dimethyl-S-[5-methyl-1,3,4-thiadiazole-2(3H)only-(3)-methyl]dithiophosphate), Fig3 |
| Type of Accident |
Explosion |
| Sequence |
At a pesticide intermediate TP-22 manufacturing plant, DMTP and other chemicals were charged into a melting drum, agitated, and heated with steam. Use of an improper thermometer resulted in overheating and generated combustible gas. The gas was ignited by a spark from an electric motor and exploded. |
| Cause |
A thermometer shorter than the required length for monitoring the reaction temperature indicated a lower temperature than actual one. Therefore, an operator conducted warming too much, DMTP decomposed and generated flammable gas. The gas was thought to have been ignited by a spark from an electric motor. |
| Knowledge Comment |
When temperature control is important for safety, attention should be paid to redundancy of measuring instruments and a heating medium, not only depending on human power. |
| Background |
1. Use of a shorter thermometer (30 cm) than the required length (50 cm) resulted in failure in monitoring temperature accurately. This was human error, but a bigger problem was insufficient education on the importance of the thermometer itself and its management.
2. There was a reactor design error. Because of a potential hazard of a raised temperature, safeguards should be provided, such as use of a suitable heating medium or equipment with more than two thermometers.
3. An explosion-proof motor should have been used. |
| Incidental Discussion |
Temperature measurement in a drum or a tank is complicated because there can be a temperature gradient from the center of the tank to the wall and from the upper part to the bottom. Moreover, there are some influences from ambient temperature and heat release from the thermowell, etc. A thermometer with an adequate length is required. |
| Reason for Adding to DB |
Example of explosion caused due to overheating on using an improper thermometer |
| Scenario |
| Primary Scenario
|
Ignorance, Insufficient Knowledge, Insufficient Study of Heat Stability, Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Malicious Act, Rule Violation, Heating without Temperature Measurment, Planning and Design, Poor Planning, Only One Thermometer for Important Temperature Control, Bad Event, Chemical Phenomenon, Abnormal Reaction, Secondary Damage, External Damage, Explosion
|
|
| Sources |
Masamitsu Tamura. Masahide Wakakura. DMTP explosion. Reaction danger-accidents cases and analysis - p.156(1995)
|
| Multimedia Files |
Fig3.Chemical formula
|
| Field |
Chemicals and Plants
|
| Author |
YOSHINAGA, Jun (Graduate School of New Frontier Sciences, The University of Tokyo)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
|
|
