| Case Name |
Fire caused due to an outflow of bottom oil on opening of a drain valve at the bottom of a column at a vacuum distillation unit |
| Pictograph |
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| Date |
April 16, 1998 |
| Place |
Chiba Prefecture, Japan |
| Location |
Refinery |
| Overview |
A performance test on a vacuum distillation unit of a refinery was being performed. As the sampling point of bottom oil of the vacuum distillation column, a drain valve at the outlet of the bottom oil pump of the column was chosen. A preliminary survey for checking whether it had been plugged or not started. As oil did not flow out at first when the drain valve was opened, discussion started with the valve left open. After a while, the blockage dissolved, oil flowed out, ignited, and there was a fire. As this prior work was not recognized as non-routine work, there was no work manual. |
| Incident |
A performance test was being done for a vacuum distillation unit at refinery. Naturally, bottom oil of the vacuum distillation column became the object of sampling, and a drain valve at the outlet of the bottom oil pump of the column was chosen as a sampling point. In a preliminary survey of the sampling point, the drain valve was opened to check whether it was plugged or not plugged. Although it was opened, nothing came out, so it was left as it was. During discussing how to handle the valve, the valve got hot after a while, the blockage dissolved, hot fuel oil flowed out, and a fire occurred. |
| Processing |
Manufacture |
| Individual Process |
Distillation |
| Substance |
Fuel oil |
| Type of Accident |
Fire |
| Sequence |
On April 16th, 1998. For checking whether a drain valve and a nozzle were plugged or not, operators opened the valve. However, any liquid did not flow out.
With the valve left open, a discussion among operators began about the following procedure.
9:22. Hot fuel oil suddenly began to flow from the opened valve.
9:25. Several minutes later, about 1000 L flowed out, and a fire occurred. The unit was stopped immediately.
One fire engine of self fire fighting, and three communal fire engines and eight fire-fighters turned out mobilized.
9:39. The fire was reported to the public fire department. 16 fire engines and 49 fire fighters turned out.
10:35. The fire was extinguished. |
| Cause |
As details of work are not clear, it is not known why the blockage dissolved. The blockage might have been generated from residue oil when the drain nozzle was cooled. When it flows a little and a passage is made, the plugged whole material would dissolve and bottom oil would flow rapidly. Leaving the valve open was the cause. |
| Response |
An emergency shutdown of the unit.
The company's large-scale chemical firefighting vehicle performed foam fire extinguishing.
The public fire brigade and self-fire-fighters cooled the area by spraying water. |
| Countermeasures |
Sampling from a valve that cannot be isolated or depressurized by other valves is forbidden henceforth.
A preliminary survey of the sampling point is also considered to be non-routine work, and a work manual should be prepared.
For the work different from usual work, safety is carefully studied in advance. |
| Knowledge Comment |
A smooth flow cannot be expected about a valve that has not been used for a long time, as it tends to produce a blockage and stick.
Once a fire occurs, it becomes impossible to shut the sampling valve because almost all sampling work is performed by hand. So, a sampling point should be chosen so that leakage can be stopped by shutting other valves.
The result of an investigation is often undesirable. Countermeasures should be studied on the assumption that an undesirable case might occur. |
| Background |
It must have been a deviation from the work procedure to have "left the valve open" as it was clogged, when high temperature oil was in the piping. Furthermore, the location was the most pressurized location through the line because of pump discharge.
It seems that they did not consider how to handle the valve when it was clogged, although they had checked whether it had plugged or not. It seemed that the work started with insufficient preparation.
It can be said that they started work without a work procedure instruction sheet or with insufficient management for non-routine work. However, the true causes might be different. |
| Incidental Discussion |
There are some principles in sampling at plants during operation. For example, choosing a point with a flow, with as low pressure as possible. Although there were some reasons, why was the point just at the outlet of the pump chosen, where pressure and temperature were highest in the line? |
| Reason for Adding to DB |
Example of fire caused due to mishandling of a closed drain valve for sampling |
| Scenario |
| Primary Scenario
|
Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Carelessness, Insufficient Precaution, Carelessness of Operator, Organizational Problems, Poor Management, Slackness of Management, Malicious Act, Rule Violation, Safety Rule Violation, Bad Event, Chemical Phenomenon, Melting, Secondary Damage, External Damage, Leakage/Fire
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| Sources |
Fire and Disaster Management Agency, Oil spill fire near waste oil pump in vacuum distillation column. Accident cases of dangerous materials. 1998, pp.56-57.
High Pressure Gas Safety Inst. of Japan, High-pressure gas protection overview. 1999 edition, pp.150 (2000).
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| Physical Damage |
Fire damage around an outlet of a bottom oil pump of a column. Fire damage to a power cable. |
| Financial Cost |
¥ 100,000. (Fire and Disaster Management Agency). |
| Field |
Chemicals and Plants
|
| Author |
ITAGAKI, Haruhiko (Japan National Institute of Occupational Safety and Health)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
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