| Case Name |
Fire occurred on opening to the atmosphere of a soil-covered underground oil tank of the Self-Defense Force |
| Pictograph |
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| Date |
July 13, 1992 |
| Place |
Asahikawa, Hokkaido, Japan |
| Location |
Self-defense force establishment |
| Overview |
On opening to the atmosphere of a soil-covered tank of the Self-Defense Force, a fire occurred when the workers began to enter the tank for cleaning. Mistakes were made, and gasoline vapor still remained in the tank. Although safety management of work environment was a duty of the facility manager, it might have been omitted. |
| Incident |
Some workers intended to clean a soil-covered tank of the Self-Defense Force. A fire occurred when they opened the manhole to get into the tank after they purged the vapor in the tank. Four persons were injured. |
| Processing |
Storage |
| Substance |
Gasoline |
| Type of Accident |
Fire |
| Sequence |
On July 1st, 1972; gasoline in the tank was transferred to an adjacent tank.
In the morning on July 13th; the upper manhole of the tank was opened, and removal of gasoline vapor started.
In the afternoon of July 13th; four workers went to the entrance to the tunnel of the tank to clear sludge in the tank, during at the same time purging vapor. Then, they opened the manhole at a side wall of the tank.
At that time, they tried to evacuate because they smelled an intense gasoline odor from the tank. However, it was too late, and four workers suffered burns. |
| Cause |
There was a fire of spouting gasoline vapor remaining in a tank due to insufficient purging. As a fire source, damage to a socket of a cable reel or a plug was considered. From the report, the manhole was opened to clean sludge on purging gasoline vapor, but such parallel work is never permitted. Moreover, the approach to the side wall manhole is possible by only through a tunnel because it was a soil-covered tank. Therefore, there was only one escape route, so all of the workers were injured by the fire. |
| Response |
Actions by facility fire fighters and public fire fighters. |
| Countermeasures |
At an opening to the atmosphere, the manhole should be opened after completely removing inflammable liquid and vapor. Completion of purging should have been confirmed by a gas detector. A subcontractor may executes work at the site, but the managers of facilities has to provide safety management with sufficient care because they have responsibility to maintain safe working conditions. Safety education for workers is also very important. |
| Knowledge Comment |
Many fires occurred during hot work. There is a big possibility of improper safety management during repair work at Self-Defense Force facilities. The owner and the user of the facilities was the Self-Defense Force, management of repairs was the duty of Defense Facilities Administration Agency, and repair work was done by a private company. In addition, actual work at the site was left to a subcontractor of the private company. During gas purging, it is necessary to confirm the vapor concentration using a gas detector. It is important to understand the difficulty perfectly cleaning out liquid from an underground tank. |
| Background |
Doing vapor removal and other work in a tank at the same time is forbidden, as described in the "Cause" column. Moreover, electrical devices were not explosion-proof. Doing vapor removal work means that liquid that generates vapor or vapor itself still remains in the tank. It cannot be generally thought that such work would be decided only by a subcontractor. It is considered that the manager of the facilities confirmed safety, and instructed work to begin. The main cause of the accident seems to have been a judgment by the manager of the facilities.
From a technical viewpoint, the problem was not insufficient vapor-purging, but lack of understanding of impossibility of perfect liquid draw-off from a tank. Liquid remains in the lower part of the drain valve, clearances of flanges, and dead-end piping. It is very difficult to completely remove such residual liquid. |
| Incidental Discussion |
Although a soil-covered tank is believed to be safer, an accident can happen during maintenance work. Gas purging might be easily omitted. |
| Reason for Adding to DB |
Example of fire of a soil-covered underground oil tank caused due to difficulty completely displacing combustibles |
| Scenario |
| Primary Scenario
|
Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Ignorance, Insufficient Knowledge, Insufficient Study, Planning and Design, Poor Planning, Poor Purge Planning, Malicious Act, Rule Violation, Safety Rule Violation, Secondary Damage, External Damage, Fire, Bodily Harm, Injury, 4 person injured
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| Sources |
Fire and Disaster Management Agency, Fire at tunnel of soil-covered tank when cleaning the tank. Accident cases of dangerous materials. pp.152-154 (1992)
|
| Number of Injuries |
4 |
| Financial Cost |
¥ 500,000 (Fire and Disaster Management Agency). |
| 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)
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