Case Ditails

Case Name Fire of a floating roof tank of crude oil caused due to a large earthquake and full face fire of another floating roof tank two days later
Date September 26, 2003
Place Tomakomai, Hokkaido, Japan
Location Refinery
Overview At a 33,000 kL crude oil floating roof tank, a fire occurred in oil that leaked due to sloshing from an earthquake with a seismic intensity of the 6th grade. In addition, a larger fire occurred at a different tank two days later. During the earthquake, naphtha rose above the floating roof. A fire occurred during preparation for covering the surface of the naphtha with foam. At new regulation tanks, only an oil leak has occurred. The two tanks that caused large leakages were built under old regulations.
Incident A fire occurred at a 33,000 kL crude oil floating roof tank and attached piping at a refinery. There was an earthquake with a seismic intensity of a little under the 6th grade and a magnitude of eight. The fire was extinguished after about seven hours. Two days after the earthquake, a fire occurred at a 33,000 kL floating roof storage tank containing naphtha, which was damaged by the earthquake. Due to the earthquake, the floating roof sank and naphtha floated above the roof and ignited. This was the first fire of its type at a floating roof tank in Japan. It took 44 hours to extinguish the fire. There was insufficient foam available, and it had to be collected from the whole country.
Processing Storage
Substance Naphtha
Crude oil
Type of Accident Fire
Sequence About 04:50 on September 26th, 2003, an earthquake occurred, and the first fire occurred almost simultaneously.
12:09, the fire was extinguished. Naphtha rose above the floating roof of the tank. To prevent evaporation of naphtha, sealing with fire extinguishing foam was prepared.
About 10:49 on September 28th, naphtha on the roof of the naphtha tank caught fire.
11:07, Transfer of naphtha in the tank to another tank started. Transfer was subsequently carried out intermittently.
11:41, a fixed foam extinguishing system started operation.
12:15, at the same time, four foam fire engines started operation. Then, fire extinguishing work by fire engines using foam and spraying cooling water was carried out.
About 03:50 on September 30th, the fire was brought under control.
06:55, the fire was confirmed to have been extinguished.
Cause A description of the direct cause was not found. The cause of the first fire was considered to be a spark caused by an impact and friction from sloshing. Ignition causes of the two fires are also not known.
Response There is no description of emergency measures taken by the company. Although the plant was shut down, it is a general measure against a large earthquake. The private fire brigade also participated in fire extinguishing activities along with the public fire brigade.
Countermeasures Officially, a new study has been made on floating roof tanks including construction of the tank. As an immediate countermeasure, there were "remodeling of the old regulation tank into a tank that met the new regulation" and "lowering the storage volume to a safe level." Actually, the execution of these countermeasures seems very difficult because it is expensive.
Knowledge Comment Early remodeling is better when a structure is required to follow new safety rules. A major earthquake can occur anywhere and anytime in Japan.
Background It is considered that a weak point of a floating roof tank was exposed. Being subjected to vibration during an earthquake, the floating roof sloshed and crude oil leaked out. The floating roof sank at the second fire. This was also influenced by earthquake vibrations. There was only a base plate to hold the tank wall. With a fixed roof tank, the tank wall is held by the roof.
There is some indication that the movement of a liquid during long period earthquake vibrations is lager than assumption.
A large number of floating roof tanks are located in the same district other than the refinery. In a so-called new regulation method tank, there has been no damage except for a slight leak at a floating roof. It has also been indicated that the damaged tank with a big leak was a tank built under the old regulation.
Sequel Under the current fire protection law, a fire at a floating roof tank is considered as a ring fire (small leakage by sloshing and burning only along the wall). "A fire after a floating roof sinks" was not expected before, The fire fighting disaster prevention countermeasures against such a fire has been discussed.
Incidental Discussion 1. A large amount of foam was required, and there was an insufficient quantity in Hokkaido, so it was collected from the whole country. It was difficult to cover the large tank's upper surface with foam. It was not effectively covered due to wind and flames. It might be important to study how to cover the whole surface with foam.
2. Before the cause of the accident had been determined, the president of the company said that it must be due to a natural disaster. However, the managing director in charge of technology said that the engineers did not think it was the result of a natural disaster.
Reason for Adding to DB Example of tank fire caused due to sloshing from an earthquake and necessity for reconstruction of a tank by new regulations
Primary Scenario Poor Value Perception, Poor Organizational Culture, No Sincerity Reception against Unfavorable, Unknown Cause, Occurrence of Abnormal Phenomenon, Out of Thought about Floating-roof Sinking by Sloshing, Misjudgment, Misjudgment of Situation, Usage, Transport/Storage, Storage, Non-Regular Action, Emergency Action, Reaction for the Out-of-Thought Event, Failure, Fracture/Damage, Floating Roof Sinking, Secondary Damage, External Damage, Fire, Loss to Organization, Economic Loss, Manetary Damage for Restoration, etc. 10 billion yen, Loss to Organization, Social Loss, Trust Damage
Sources Accident prevention technical center, Urgent report, Outline of factory fires that occurred recently. Safety & Tomorrow, No.92, pp.17-27 (2003)
Hokkaido agency. 2003 Tokachi-Oki Earthquake countermeasures and status of damage. Response after I petroleum H refinery disaster and safety field headquarters. Home page of Hokkaido agency. (2003)
Takeshi Morita, Details of disaster. Field study. I petroleum H refinery fire, Modern fire fighting. No.511, pp.23-25 (2003).
Naphtha tank fire in I petroleum H refinery. Industry and safety Vol.19, No.41, pp.9-12 (2003)
Large-scale fire in August September, 2003. Fire, No.266, pp.5-7 (2003)
Physical Damage A crude oil storage tank and piping burned. A naphtha storage tank collapsed.
Financial Cost Claims for damages till October 8th; Due to the second fire at I Co., Tomakomai west harbor shut for 43 hours, and about 20 ferry sailings were cancelled, so four ferry owners; Pacific Ocean ferry (Nagoya), Kawasaki adjacent waters steamer (Tokyo), Shosen-Mitsui ferry (Tokyo), Eastern Japan ferry (Sapporo) demanded compensation. The total amount was ¥ 1-2 hundred million.
Costs of the fire accident at I Petroleum H Refinery rose to about ¥ 10 billion for tank restoration, etc. (A newspaper account on November 19th)
Consequences A smell of oil, soot, and a fire extinguishing agent was detected at Tomakomai City. Large numbers of inhabitants and school children complained of physical discomfort. Environmental concentration of formaldehyde, xylene, toluene, and benzene was measured at three locations about 3 km away from the tank for two hours from 22:30 on September 29th. As a result, the value of benzene temporarily reached the maximum of 8.2 micrograms per 1 cubic meter, which surpassed the environmental standard of 3 microgram.
Field Chemicals and Plants
Author KOBAYASHI, Mitsuo (Office K)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)