| Case Name |
Steam explosion due to molten iron flow during operation of a melting furnace |
| Pictograph |
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| Date |
July 31, 1989 |
| Place |
Funabashi, Chiba, Japan |
| Location |
Steel mill |
| Overview |
On operating a melting furnace in a steel mill, the level of molten iron rose above the fire brick lining. The molten iron melted the steel shell and flowed out, and it came into contact with cooling water and caused a steam explosion. The cause seemed to be that temperature control of the melting furnace was inadequate, the inside of the furnace cooled, the molten iron solidified, and the internal capacity decreased. |
| Incident |
A steam explosion occurred at a melting furnace where scrap iron was melted during preparation of molten iron outflow. The level of molten iron rose above lined firebrick. The molten iron melted the steel shell by its high temperature and flowed out. It flowed into the cooling water receiver outside the melting furnace bottom and a steam explosion occurred. An operator who was working by the furnace was seriously injured. Refer to Fig2. |
| Processing |
Manufacture |
| Individual Process |
Other |
| Substance |
Iron, Fig3 |
| Type of Accident |
Explosion |
| Sequence |
20:10 on July 31st, 1989; supply of raw materials started.
21:15; raw materials supply finished.
21:39: sending air to the furnace started.
22:20; molten iron outflow from the melting furnace was prepared.
22:25; the volume of air was reduced (580 -> 400 Nm3/min), an iron run-out hole was open.
22:45; molten iron flowed out from the steel shell of the upper part of the melting furnace. |
| Cause |
When the operation started, a capacity inside the furnace decreased as the molten iron solidified at the bottom of the melting furnace and this accident started from that. The cause of a capacity decreasing may be the following.
1. The temperature at the bottom of the furnace where the molten iron was stored was low.
2. The temperature of dropping melted iron was low and then it solidified while dropping. Due to a capacity decrease, the molten iron spread to the steel shell which was not lined with insulating fire bricks. |
| Response |
Water was sprayed into the furnace. |
| Countermeasures |
Blast control was standardized to make sure the correct timing of iron flow out.
To control the level of molten iron, a temperature recorder was installed.
A safety valve was installed. However, It is not clear where and how the safety valve was installed, although it is written in an information source. |
| Knowledge Comment |
It is important to determine the operation procedure for maintaining basic safety, and to enforce it on operators. In this case, keeping the correct temperature inside the furnace during operation was very important. |
| Background |
Temperature control was inadequate. It is doubtful whether operators predicted that the capacity inside the furnace would decrease. From the viewpoint of design, it was not sufficiently considered that the temperature dropping of molten iron at the start of operation should be prevented. |
| Reason for Adding to DB |
Example of accident caused due to a double error of design and operation management |
| Scenario |
| Primary Scenario
|
Insufficient Analysis or Research, Insufficient Practice, Lack of Imagination, Organizational Problems, Poor Management, Poor operation Management, Carelessness, Insufficient Precaution, Mannerism, Planning and Design, Poor Planning, Poor Design, Failure, Large-Scale Damage, Melting/Leakage, Secondary Damage, External Damage, Explosion, Bodily Harm, Injury, 1 person injued, Loss to Organization, Economic Loss, Direct Monetary Damage 11million yen
|
|
| Sources |
Fire and Disaster Management Agency, "Major accident case, Steam explosion during melting furnace operation as molten iron flowed out due to partial damage to furnace steel shell," Accident cases of dangerous materials. pp.33, 230-231
|
| Number of Injuries |
1 |
| Physical Damage |
Scattering materials (molten iron, slag) flew within the area of four square meters. A water cover was damaged and a melting furnace became unusable. 18.67 tons of molten iron was damaged. |
| Financial Cost |
¥ 11.35 million. (Accident cases of dangerous materials) |
| Multimedia Files |
Fig2.Schematic drawing of furnace
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Fig3.Chemical formula
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| Notes |
Design error, inadequate operation control |
| Field |
Chemicals and Plants
|
| Author |
WADA, Yuji (National Institute of Advanced Industrial Science and Technology)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
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