| Case Name |
Rupture, explosion and fire caused due to pressure rise during cleaning operation for a distillation kettle |
| Pictograph |
|
| Date |
February 17, 1995 |
| Place |
Kyoto, Kyoto, Japan |
| Location |
Chemical factory |
| Overview |
There was an explosion at one of the distillation facilities of a factory that produced various chemicals for sale. At the facilities, simple distillation and rectification were switched by valves. After finishing production of a batch, methanol was charged into the distillation kettle, and it was heated and vaporized. First, the simple distillation system was cleaned. On starting cleaning of the rectification system next, all the valves of the generated vapor were closed. Therefore, the pressure rose, the kettle ruptured, and an explosion and a fire occurred. |
| Incident |
An explosion occurred in a factory where many kinds of chemicals were manufactured for sale. The distillation facilities, which were used for two ways, simple distillation and rectification by switching a valve, were being cleaned as the preceding batch operation had been finished. While methanol was being heated and evaporated for cleaning, all the valves for generated vapor were closed, and the pressure in the distillation kettle rose. The kettle ruptured and the spouting methanol vapor ignited, followed by an explosion and fire. |
| Processing |
Manufacture |
| Individual Process |
Distillation |
| Process Flow |
Fig2.Unit process flow
|
| Substance |
Methanol, Fig3 |
| Type of Accident |
Rupture, explosion, fire |
| Sequence |
1. A batch operation to manufacture butyl-m-toluidine had been finished. Methanol was charged into the distillation kettle to clean the distillation facilities.
2. First, to clean the simple distillation system, operators closed a vapor valve to the rectifying column and a liquid valve from the column, and opened a rundown valve for the simple distillation. Then, they began cleaning the kettle with methanol evaporated by steam heating.
3. Next, they intended to clean the rectifying column. The vapor valve to the simple distillation was closed.
4. At the time, they forgot to open the vapor valve of the rectifying column, evaporated methanol vapor accumulated in the kettle, the pressure rose, finally the kettle ruptured, and vapor spouted out. |
| Cause |
Human error with miss-judgment. The operator was sure that two valves (vapor and liquid) at the rectifying column were open during cleaning the simple distillation system. Therefore, he did not open the two valves for the rectifier during the switching operation. As a result, he heated methanol with all valves closed, internal pressure rose, and the kettle exploded. |
| Response |
Private fire fighters and the public fire brigade extinguished the fire. |
| Countermeasures |
1. Two vapor valves should be changed to one three-way valve so that all vapor valves do not close. One vapor valve is for the simple distillation kettle and the others are for the rectifying column.
2. A safety valve should be installed.
3. Improving the operation manual and providing education.
If they consider the facilities safety, they must prevent the kettle from rupturing by setting a design pressure to be equal to or more than the maximum calculated pressure based on the components at the kettle and the pressure of the steam. Otherwise, they should install a safety valve that has sufficient capacity. |
| Knowledge Comment |
The recognition that "a chemical plant is dangerous" was insufficient. It is necessary for all factory members including managers to improve safety recognition. |
| Background |
It is speculated that the accident was due to human error or an error in operation indication. In addition, there was insufficient monitoring of pressure and temperature due to manpower shortage, so the accident could not be prevented. Moreover, they had not installed a safety valve at the kettle when it ruptured, because a pressure release device was not legally required because the facilities are used under atmospheric or reduced pressure. |
| Incidental Discussion |
Perhaps, due to a lack of manpower, they did not sufficiently observe the monitor TV etc. However, this cannot be confirmed from the information sources. |
| Reason for Adding to DB |
Example of rupture caused due to closing all vapor valves |
| Scenario |
| Primary Scenario
|
Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Insufficient Analysis or Research, Insufficient Practice, Lack of Imagination, Ignorance, Insufficient Knowledge, Insuficient Study and Experience, Planning and Design, Poor Planning, Regular Operation, Erroneous Operation, Closing Valves by Mistake, Bad Event, Chemical Phenomenon, Pressure Rise, Failure, Large-Scale Damage, Rapture, Secondary Damage, External Damage, Explosion, Bodily Harm, Injury, 2 person injured, Loss to Organization, Economic Loss, Manetary Damage 14 million yen
|
|
| Sources |
Fire and Disaster Management Agency, Explosion and fire when cleaning a distillation facility manufacturing a dangerous material. Accident cases of dangerous materials. pp.68-70 (1995)
Takayuki Ishihara, Fire department of Kyoto City, Explosion in chemical plant. 43rd national fire fighting engineering conference (1995)
|
| Number of Injuries |
2 |
| Physical Damage |
A plant building and an adjacent office were damaged. Some vessels, piping, and wiring were damaged. Three polyethylene hothouses near the factory were damaged by fire. 15 windows of residences were broken by the explosion. |
| Financial Cost |
¥ 14 million (Fire and Disaster Management Agency) |
| Multimedia Files |
Fig3.Chemical formula
|
| 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)
|
|
