Case Ditails

Case Name Explosion of flammable gas released from expanded polystyrene beads stored in a warehouse, and a fire of the warehouse
Date August 23, 1982
Place Yokkaichi, Chiba, Japan
Location Warehouse
Overview Butane and pentane vapor released from expanded polystyrene beads stored in the warehouse exploded, and the warehouse was destroyed by fire. Although the warehouse company got an explanation that a temperature rise would deteriorate the products' performance and that the products must be kept at a low temperature, it was doubtful that the manufacturer gave enough information about the hazard of released gas. Moreover, the warehouse was converted from a food warehouse to a chemical warehouse, but there were problems because there were non-explosion-proof devices in the warehouse.
It was not a particular problem of this warehouse, but when flexible containers were introduced, generation of flammable gas was investigated and it was considered that if the container was kept under 5°C, there would be no problem because the release of gas could be controlled. However, expanded polystyrene beads were brought into the warehouse at a high temperature, and were not stored at the expected low temperature. There was not enough consideration about the time when generation of the flammable gas would be controlled.
Incident At a warehouse containing expanded polystyrene beads etc., a flammable gas such as butane or pentane, which was released from expanded polystyrene beads, exploded and burned in the warehouse. This warehouse was a low-temperature warehouse, which had been previously used as a general-purpose warehouse, and electric devices there were not explosion-proof.
Expanded polystyrene beads; polystyrene beads used as raw material of expanded polystyrene, and include a few percent of a foaming agent, LPG. After being produced, they diffuse gas gradually.
Processing Storage
Substance Butane, Fig2
Pentane, Fig3
Polystyrene, Fig4
Type of Accident Explosion
Sequence On August 19th and 20th, 1982; 120 tons of expanded polystyrene beads were carried in, (500 kg × 240 flexible containers) and stored in a warehouse. Thirty tons of expanded polystyrene beads (100 kg × 309 drums) were already being kept in the warehouse.
17:00 on August 21st; the warehouse was opened, and after that nobody entered.
03:21 on August 23rd; an explosion occurred at the warehouse, and a fire broke out.
13:54; The fire was extinguished. Three warehouse buildings completely collapsed, one warehouse partially collapsed, and within a range of about 955 meters, 347 buildings were damaged.
Cause It seemed that combustible vapor of butane and pentane had accumulated in the warehouse building because combustible vapor was released from expanded polystyrene beads gradually. The vapor diffused outside the flexible containers. The cause of ignition was not obvious, but it was reported that a distribution board of a refrigerator in the warehouse was not of an explosion-proof type.
Response The fire was extinguished by the public fire brigade
Knowledge Comment It is very important to convey information about the hazardous characteristics of materials.
Background The managers and the operators did not have enough knowledge about the release of flammable gas from expanded polystyrene beads. Expanded polystyrene beads have this hazardous characteristic, which is not well known generally, but the manufacturer seems to have shipped them after temporary storage at the manufacturer's own warehouse for releasing gas. Information on the hazard, and of the storage method of the product was not transmitted by the manufacturer to the warehouse company.
Sequel Facilities such gas detectors, ventilation equipment, electric equipment, and explosion-proof electric devices, must be of a type that is suitable for a warehouse of expanded polystyrene beads, according to a booklet published four months after the fire by The Fire and Disaster Agency Management Agency, "The fire prevention measures for expanded polystyrene beads."
Reason for Adding to DB Example of explosion caused due to inadequate handling of hazardous materials by warehousemen
Primary Scenario Ignorance, Insufficient Knowledge, Insufficient Study, Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Planning and Design, Poor Planning, Electric Device Secondhand Use Planning, Usage, Transport/Storage, Storage, Bad Event, Chemical Phenomenon, Flammable Gas Spouting, Secondary Damage, External Damage, Explosion/Fire, Loss to Organization, Economic Loss, Manetary Damage 1300 million yen, Damage to Society, Social Systems Failure
Sources Yokkaichi Fire station headquarters. Outline of N-warehouse, Modern fire fighting, No.242, pp.55-59(1982)
Union of National dangerous objects safety association. Fire in a synthetic resin storage warehouse. Examples of accidents in dangerous facilities. pp.8-10(1983).
Fire Information Res. Center. Warehouse fire caused by explosion.(Yokkaichi City) Regional disaster prevention data overview. p.88(1986)
Number of Injuries 24
Physical Damage Warehouses; a two-story steel-frame warehouse, a one-story steel-frame warehouse, a prefabricated office, a one-story steel-frame warehouse for dangerous materials were destroyed by fire; other attached buildings (including cars) collapsed completely or partially.
Near the site (within a range of 850 meters in the east, 750 meters south, 700 meters west, and 1000 meters north), 242 residences and storehouses, 99 non-residences, and three cars were completely or partially destroyed (announced by the headquarters of Mie Police Office).
318 nearby buildings were damaged (Chemical Fire Committee).
Financial Cost ¥ 1,300 million (Headquarters of Mie Police Office)
Economic Loss 170 telephone lines in Okoso area, Yokkaichi city, became out of order.
Multimedia Files Fig2.Chemical formula
Fig3.Chemical formula
Fig4.Chemical formula
Notes When a large amount of styrene resin or synthetic rubber burns, there is a possibility of a styrene has been generated in large quantities. The indoor environmental indicator value of a styrene monomer is prescribed by Ministry of Health, Labor and Welfare (indicator value: 220 ug/m3). The influence on human bodies is irritation of noses and eyes, and nerve toxicity. It is regarded as non-carcinogenic.
Field Chemicals and Plants
Author WADA, Yuji (National Institute of Advanced Industrial Science and Technology)
YOSHINAGA, Jun (Graduate School of New Frontier Sciences, The University of Tokyo)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)