| Case Name |
Leakage and fire of hydrogen and gas oil mist from a flange at outlet piping of a reactor due to a heavy rain at a desulphurization plant |
| Pictograph |
|
| Date |
July 30, 1998 |
| Place |
Kawasaki, Kanagawa, Japan |
| Location |
Refinery |
| Overview |
A large quantity of rainwater falling from rain holes in the upper platform soaked into the high-temperature flange due to the failure of heat insulation cover for treating rainwater. Gas leaked from the high-temperature flange due to a difference in cooling contraction between the flange and the bolts. A fire was caused by the natural phenomenon of a heavy rain. It is necessary to consider natural phenomena such as lightning and earthquake as hazardous factors in disaster prevention. Inadequate instructions, although they are minor, during the final stage of construction as well as overlooking sheet metal failure seem to be real causes of the accident.
A rain hole is a small hole opened in the floor of the second floor or above in an outdoor structure to avoid accumulation of rainwater on the floor. |
| Incident |
During a heavy rain, rainwater soaked into beneath the heat insulation near the flange at the outlet piping of a gas oil desulphurization reactor, caused leakage of hydrogen and gas oil mist, and a fire occurred at the flange. |
| Processing |
Manufacture |
| Individual Process |
Reaction |
| Chemical Reaction |
Hydro-desulphurization |
| Substance |
Hydrogen, Fig2 |
| Gas oil |
| Type of Accident |
Leakage, fire |
| Sequence |
There was a heavy rain several hours before the accident, and a large quantity of rainwater flowed in between the rain cover and the heat-insulating sheet metal. Hydrogen and gas oil leaked afterwards and ignited. |
| Cause |
The flange and bolts in a joint section were cooled and contracted by the inflow of rainwater. The bolts contracted more than the flange due to heat capacity, as well as the influence of process temperature. As a result, the flange was tightened too much, especially around the ring gasket which was deformed eventually. The sealing function of the gasket was weakened, caused leakage. |
| Response |
The fire was extinguished by company's own fire fighters. |
| Countermeasures |
1. Measures to prevent rainwater from flowing around the flange should be taken.
2. Similar parts of the plant should be checked, and countermeasures should be taken.
3. Tightening force management for the flange should be reviewed. |
| Knowledge Comment |
It is necessary to take into account weather conditions such as a rainfall and temperature, and dangerous natural phenomenon such as an earthquake and lightning when plant safety countermeasures are formulated. |
| Background |
A lack of imagination among the construction staff, in addition to overlooking sheet metal failure caused the accident. The possibility of rainwater inflowing during a heavy rain was not considered. Although the positions of weep holes on the platform were decided at the final stage of construction at the site, there was a lack of imagination as to how the rain water would move during the operation period. In addition, considering that the plant had been used for seven years, a lack of attention during operation might be also a factor. |
| Incidental Discussion |
There are many cases where sufficient attention is not paid to the position of each valve or rain holes in plant construction. It is always after trouble that we realize the inadequacy of installing a flange or a vent valve just above a high-temperature division. |
| Reason for Adding to DB |
Example of fire caused due to inadequate instructions and facility management at the final stage of construction |
| Scenario |
| Primary Scenario
|
Insufficient Analysis or Research, Insufficient Practice, Lack of Imagination, Organizational Problems, Poor Staff, Poor Experiment of Staff, Unknown Cause, Occurrence of Abnormal Phenomenon, Big Rain over Assumption, Planning and Design, Poor Planning, Poor Design, Bad Event, Thermo-Fluid Event, Thermal Schrinkage, Secondary Damage, External Damage, Leakage/Fire
|
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| Sources |
Fire and Disaster Management Agency, Fire from flange at outlet piping of No.2 reactor: Accident examples of dangerous materials. 1998, pp.66-67
Kawasaki City Fire fighting station, Prevention division, Peace section. Fire from the flange at outlet piping of No.2 Reactor. Material of the Kawasaki City Complex countermeasure committee (1998)
|
| Physical Damage |
A pressure gage and piping heat insulation were damaged by fire. |
| Financial Cost |
¥ 100,000. (Fire and Disaster Management Agency) |
| Multimedia Files |
Fig2.Chemical formula
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| Field |
Chemicals and Plants
|
| Author |
WAKAKURA, Masahide (Kanagawa Industrial Technology Research Institute)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
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