| Case Name |
Fire at a quenching oil bath caused due to short circuit at a spring manufacturing factory |
| Pictograph |
|
| Date |
October 25, 1989 |
| Place |
Koto, Tokyo, Japan |
| Location |
Manufacturer of automobile parts |
| Overview |
At a quench hardening factory for springs, abnormally high flame was generated when a heated coiled spring for an automobile was charged into the quenching oil bath by a conveyor. The flames were extinguished using a fire extinguisher. However, the flame damaged electrical wiring of the conveyor, nearly caused a short circuit, but operation restarted without sufficient checks of the facilities and the damage was overlooked. In the first batch of re-operation, the spring stopped before being immersed in the oil 8 cm above the surface due to a short circuit in the conveyor. Quenching oil was heated by the high temperature of the coiled spring, and vapor was generated. The vapor from the quenching oil ignited, and a fire occurred. |
| Incident |
At quench hardening facilities for springs, when a heated coiled spring for an automobile was supplied into a quenching oil bath by a conveyor, the abnormally high flame was generated, and was extinguished using a fire extinguisher. In normal operation, flames extend about 1 m and die down when the spring is completely immersed. The flames were not automatically extinguished this time. Then next batch started as usual without any effort to find the effect of the large flame. Before the coiled spring was completely immersed in the bath, the conveyor stopped by a short circuit. The surface of the quenching oil was heated by the high temperature of the spring, vapor from the quenching oil ignited, and a fire occurred. Refer to Fig2. |
| Processing |
Consumption and Usage |
| Substance |
Quenching oil |
| Type of Accident |
Fire |
| Sequence |
A flame that was larger than usual rose when a treated material was charged into a quenching oil bath at a quench hardening factory for coiled springs. The flames were extinguished by a fire extinguisher. Next time, when a treated material was charged, it stopped 8 cm above the surface of the quenching oil. Flames rose in the same way,, but were not extinguished. |
| Cause |
The electrical wiring of the conveyor was damaged when the fire was extinguished using a fire extinguisher. As the next batch started as usual, an electric fault was caused, and transfer of the treated material stopped on the way to the bath. Sufficient inspection was not carried out when the abnormal phenomenon with big flames occurred. It seems that the operators hurried to start the next run without sufficient inspection because they worried about work delay more than safety. |
| Countermeasures |
When using quenching oil, the danger of quenching oil is often not recognized. Safety education for dangerous materials should be provided thoroughly. Fire prevention management, arrangement, and cleaning are important. |
| Knowledge Comment |
When an abnormality occurs, there is a cause. Moreover, there is a possibility of more unusual phenomena occurring. It is more important to confirm the cause and the effect of abnormal phenomenon for preventing a more dangerous situation from occurring, rather than to restart operation in a hurry. |
| Background |
Quenching oil has a high ignition point and is safe. However, if heated, it generates the vapor and ignites.
When the equipment trouble happened, the operators did not inspect the reason sufficiently, and overlooked damage to the equipment. Operation management and facility management seem to be inadequate. |
| Reason for Adding to DB |
Example of fire caused due to restarting operation without recognizing the cause of an abnormal event |
| Scenario |
| Primary Scenario
|
Organizational Problems, Poor Management, Slackness of Management, Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Carelessness, Insufficient Precaution, Carelessness of Operator, Usage, Operation/Use, Usage of Equipment/Material, Incorrect Reaction, Poor Communication, Malfunction, Poor Hardware, Machine Not Move, Bad Event, Chemical Phenomenon, Burning, Secondary Damage, External Damage, Fire, Loss to Organization, Economic Loss, Direct Manetary Damage 12million yen
|
|
| Sources |
Fire and Disaster Management Agency, Major accident case. Fire in spring factory. Accident cases of dangerous materials. pp.35, 252-253.
|
| Physical Damage |
An attic of 40 square meters was destroyed by fire. Quenching oil equipment and 200 L of quenching oil were destroyed by fire. |
| Financial Cost |
¥12 million. (Accident case of dangerous material) |
| Multimedia Files |
Fig2.Introduction to hardening system figure
|
| 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)
|
|
