| Case Name |
Explosion and fire at a manufacturing plant for manufacturing a RIM raw material liquid. |
| Pictograph |
|
| Date |
April 29, 1996 |
| Place |
Kurashiki, Okayama, Japan |
| Location |
Chemical factory |
| Overview |
At a manufacturing plant of RIM raw material, an explosion at a tank occurred during the fourth operation after a change of raw material liquid blending conditions. Following two points have been indicated as the main causes: 1) It was overlooked that a polymerization reaction occurred under the new conditions. 2) Employees did not act properly when operation conditions deviated from a range designed by computer. In the headquarters, behavior at high temperatures was understood, but this was not transmitted to the factory. Therefore, education on the response to a temperature rise was not given.
RIM: The abbreviation for Reaction Injection Molding. It is a method for making plastic molded products. The monomers are poured into a mold at the site, polymerized in the mold, and plastic integrated mold products are completed. DCPD (dicyclopentadiene) RIM is typically used for molding large products. |
| Incident |
At a plant for manufacturing RIM (Reaction injection molding) raw material, two kinds of raw material blending liquids were prepared, and they were mixed at the construction site to make molded products. The preparation method for the raw material blending liquids was changed in April. The 4th preparation liquid A was stored after the change. An explosion and fire occurred 85 hours after mixing. |
| Processing |
Manufacture |
| Individual Process |
Other |
| Process Flow |
Fig2.Unit process flow
|
| Substance |
Dicyclopentadiene, Fig3 |
| Diethyl aluminum chloride, Fig4 |
| 1,3-dichloro-2-propanol, Fig5 |
| Silicon tetrachloride, Fig6 |
| Type of Accident |
Explosion, fire |
| Sequence |
About 16:00 on April 25th, 1996; raw materials were charged into a catalyst preparation drum, and a raw material liquid was blended. It was scheduled to be used on April 30th. Temperature in the storage tank was controlled by a computer.
12:50 on April 26th; a temperature alarm of the bending liquid A tank was activated. The normal control temperature was 55 °C, and H alarm sounded at 60 °C. After confirming the temperature, the alarm was turned off by a board operation.
13:09 on April 26th; at 65 °C, HH alarm sounded. After confirming the temperature, the alarm was turned off.
20:47 on April 26th; tank temperature dropped to 63 °C. In addition, the temperature continued to fall to below 60 °C.
12:02 on April 27th; it reached 60 °C again, and H alarm sounded. After confirming the temperature, the alarm was turned off.
12:21 on April 27th; it reached 65 °C, and HH alarm sounded. After confirming the temperature, the alarm was turned off.
02:07 on April 29th; IOP alarm sounded at tank temperature of over 105 °C. The indication of the field thermometer was confirmed.
02:12 on April 29th; efforts were made to lower tank temperature, but the temperature did not drop, so operators decided to monitor the course. At about 02:30, one operator took a short nap. The temperature did not drop afterwards.
03:32 on April 29th; the tank exploded when the other operator was patrolling the site.
He was injured.
H alarm; A high alarm. An abnormal sign when a measured value was higher than a set value.
HH alarm: An alarm in a critical phase, exceeding H alarm. It was often connected directly to an interlock in the plant. Recently, HHH alarm was linked to starting an interlock. |
| Cause |
An accident occurred during storage of raw material blending liquids of the fourth blending after the method change. Under the new method, fresh raw material was charged into the preparation drum with a liquid remaining from the preceding batch. Under the old method, remaining liquid was not used. The following facts were proven by research after the accident; "Cationic species are generated in the reaction between remaining liquid and newly charged raw material. By repeating the new method, cationic polymerization by cationic species occurs, and the temperature of the catalyst solution rises. High temperature makes the reaction advance, and the solution's temperature rises rapidly. The volume of blending liquid increases because the solution temperature rises." In short, it was overlooked that an unusual reaction occurs frequently with a new preparation method. Therefore, temperature control by the computer was not effective because control was designed only for normal situations. In addition, as they could not take the appropriate countermeasures against the temperature rise, a runaway reaction occurred, the temperature reached over 100 °C, and contents spouted out. |
| Response |
Company's fire fighters (so-called the 3 point set) and public fire brigade extinguished the fire. |
| Countermeasures |
The new method was abolished and the old method was readopted. Optimization of a temperature alarm and a cancelled alarm. Education to employees on the importance of temperature control in a chemical reaction. |
| Knowledge Comment |
It is dangerous that the effects of a condition change are not sufficiently understood. In particular, attention to the reaction is necessary.
It is important to accurately transmit information, especially bad information. |
| Background |
Insufficient study on the condition change was a basic factor. The reason why the operators left the blending material in a high-temperature condition was that it was common knowledge among operators that old blending material deteriorates when stored at a low temperature. In the headquarters, the behavior of a catalyst at a high temperature was understood. However, this information was not transmitted to the factory, and workers in the factory did not worry about temperature rising. Therefore, a defect in the communication system was also a problem. |
| Incidental Discussion |
In the headquarters, many experiments were done to find the relation between a runaway reaction and temperature. However, the results of the experiments were not transmitted to the factory. |
| Reason for Adding to DB |
Example of explosion caused due to delay in countermeasures for operation procedures after a change of a catalyst preparation method |
| Scenario |
| Primary Scenario
|
Organizational Problems, Inflexible Management Structure, Insufficient Information and Communication, Poor Value Perception, Poor Safety Awareness, Insuficient Education/Training for Safety, Organizational Problems, Poor Management, Poor Work Management, Non-Regular Action, Change, Change of Operation Procedure, Malicious Act, Rule Violation, Safety Rule Violation, Bad Event, Chemical Phenomenon, Abnormal Reaction, Secondary Damage, External Damage, Explosion, Bodily Harm, Injury, Loss to Organization, Economic Loss, Manetary Danage 25 million yen
|
|
| Sources |
Material of the Japan Industrial Safety and Health Assoc.
Fire and Disaster Management Agency, Explosion and fire at CDX plant. Accident cases of dangerous materials. pp.114-117. (1996)
Japan Industrial Safety and Health Assoc. Safety and health information center, Cases of labor accidents. No.100127. The Japan Industrial Safety and Health Assoc. home page.
|
| Number of Injuries |
1 |
| Physical Damage |
Part of a manufacturing plant for manufacturing RIM raw material was damaged. Buildings near the plant were damaged. Debris were scattered within a radius of 50 m. Manufactured products were destroyed by fire. |
| Financial Cost |
¥ 25 million (Fire and Disaster Management Agency). |
| Multimedia Files |
Fig3.Chemical formula
|
|
Fig4.Chemical formula
|
|
Fig5.Chemical formula
|
|
Fig6.Chemical formula
|
| Field |
Chemicals and Plants
|
| Author |
KOSEKI, Hirosi (National Research Institute of Fire and Disaster)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
|
|
