| Case Name |
Explosion of residual gas during digging up and dismantling of an underground tank at a gas station |
| Pictograph |
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| Date |
May 27, 1991 |
| Place |
Kamakura, Kanagawa, Japan |
| Location |
Service station |
| Overview |
An explosion happened during gas-cutting work for dismantling an underground tank in a disused gas station after it was dug out. The inside of the tank had an explosive atmosphere with flammable vapor mixed with air, because purging was insufficient. The flammable mixture ignited and exploded on gas-cutting. As a result, the end plate of the tank blew off, and the wall enclosing the construction site was blown down. In addition, a door of a private house on the other side of the road was seriously damaged, and a concrete wall of a neighboring house was destroyed.
When a tank is dismantled, it is necessary to adopt either of the following methods. After it is washed with an emulsifying agent, 1) water is filled. 2) It is confirmed that there is no combustible mixture inside. |
| Incident |
For the whole repair of a gas station, a 10 kL underground tank for gas oil was dismantled. Gas-cutting started after purging. Flammable vapor in the tank ignited and exploded, and the end plate of the tank blew off. The door of a nearby private house was seriously damaged. |
| Processing |
Waste and disposal |
| Substance |
Gasoline |
| Type of Accident |
Explosion |
| Sequence |
On May 7th, 1991. Oil was drained from several tanks.
On May 14th-24th. One tank was dismantled after concrete dismantling.
On May 25th. Two tanks were dug out and one tank was dismantled.
In the morning on May 27th. Two tanks were dug out including the tank that exploded.
Afternoon. It was attempted to remove the end plate using heavy machinery as well as other tanks, but it did not go well. Gas-cutting started during injecting of 3 kg of dry chemicals into the tank through oil piping. An explosion occurred after 1-2 minutes. |
| Cause |
The atmosphere in the tank was explosive because flammable vapor mixed with air. It ignited and exploded on gas-cutting. |
| Countermeasures |
When an abandoned tank is dismantled, water is filled or it is confirmed that the inside does not have a combustible mixture after it is washed with an emulsifying agent. |
| Knowledge Comment |
Even if an oil tank is filled with water, the space might be filled with a combustible mixture if water is drained. |
| Background |
It is thought that inconsistent purging work and insufficient safety management were the most important causes. The reasons are as follows. It is difficult to remove hazardous materials completely from a hazardous materials vessel such as an underground tank. It is difficult to remove liquid that infiltrates into the space of flanges or inside the rust. Even if it seems that purging is completed, the liquid evaporates again and flammable vapor is generated. With understanding this, substitution operation and attention for hot work must be performed. |
| Sequel |
Notice on safety management guidance for abolished tanks was notified to administrative divisions from Fire and Disaster Management Agency. |
| Reason for Adding to DB |
Example of explosion caused due to difficulty in complete purging of tank contents |
| Scenario |
| Primary Scenario
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Misjudgment, Misunderstanding, Understanding Premise of the Work, Poor Value Perception, Poor Safety Awareness, Insufficient Safety Measure, Planning and Design, Poor Planning, Poor Planning of Repair, Usage, Maintenance/Repair, Dismantle, Malicious Act, Rule Violation, Safety Rule Violation, Secondary Damage, External Damage, Explosion, Bodily Harm, Death, Bodily Harm, Injury
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| Sources |
Fire and Disaster Management Agency, Explosion during disassembly of underground storage, Accident cases of dangerous materials, 1991, pp.170-173.
Osamu Yoshimura, Safety management guidance concerning disused underground storage tanks. Monthly fire fighting, No.145, pp.30-34(1991).
National dangerous object safety association, Explosion during disassembly of the gasoline tank, One hundred cases of accidents at dangerous facilities -No.2- pp.65-66(1994).
Dangerous materials safety research association of the Kawasaki City, Explosion during disassembly of underground storage at oil supply station, Examples of accidents at dangerous facilities that are useful at present wiyh FTA, pp.176-178(1997).
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| Number of Deaths |
1 |
| Number of Injuries |
1 |
| Physical Damage |
Debris was scattered as far as a bus garage 44.1 m away on the other side of the road. Passenger cars, light trucks, and a fence of a garage were damaged. |
| Financial Cost |
¥ 100,000. (Fire and Disaster Management Agency). |
| Field |
Chemicals and Plants
|
| Author |
OGAWA, Terushige (Graduate School of Environment and Information Sciences, Yokohama National University)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
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