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Press Release

Overview of the Fire and Explosion at Chiba Refinery,
the Cause of the Accident and the Action Plan
to Prevent Recurrence

August 2, 2011
Cosmo Oil Co., Ltd.
Corporate Communication Dept.
Public Relations Office

Cosmo Oil Co., Ltd. (Headquarters: Minato-ku, Tokyo, Paid-in Capital: \107.2 billion, President and Representative Director: Yaichi Kimura) offers its sincere apologies for the immense inconvenience and unease caused to the neighboring residents and many other parties affected by the fire and explosion that broke out within Chiba Refinery.

This report was prepared by the Accident Investigation Committee, summarizing the overview of the accident, its cause and the action plan to prevent any similar occurrence in the future.

  1. Overview of the Accident
    1) The events, including the fire and explosion, that occurred on March 11, 2011 are described below (in chronological order):
    • At 14: 46, an earthquake of the fifth degree on the seismic scale occurred in the Pacific Ocean off the coast of the Tohoku region.
    • Many of the braces that were diagonally supporting the legs holding Tank No. 364*2filled with water on that day, (normally filled with liquefied petroleum gas (LPG)) *1 fractured.*3
    • At 15:15, another earthquake of the fourth degree on the seismic scale occurred off the coast of Ibaraki Prefecture.
    • Several legs holding up LPG tank No. 364 bent and the tank collapsed. The collapse lead to the damage of several pipes near the tank which caused LPG leakage.
    • Leaking LPG spread out and caught fire near Tank No. LPG364.*4
    • Due to the fire, the LPG tank adjacent to Tank No. LPG364 exploded, spreading fire from one tank to another.
    • Due to the spreading fire, a number of neighboring LPG tanks exploded, further expanding the fire.
    • Efforts to extinguish the fire began immediately after the outbreak of the fire and fully extinguished on March 21 at 10:10.

    *1. At the time of the earthquake, LPG tank No. 364 was under regulatory inspection and was filled with water, instead of LPG, in order to remove air from inside the tank.

    2) Major Damages :
    1) Human damage:
    6 people injured (1 major injury and 5 minor injuries)
    2) Material damage:
    All 17 LPG tanks installed in the area, the surrounding pipelines and the roads were damaged.
    Asphalt tanks adjacent to the affected area were damaged and asphalt leaked out of the tanks (the collection of the leakage was completed on May 10).
    Due to blasts and debris by the explosion, fire broke out at the sites of Maruzen Petrochemical Co., Ltd. and Chisso Petrochemical Corporation, respectively, staining or damaging glass, vehicles, marine vessels and other structures.
    In the nearby residential and other areas, the blasts damaged window glasses, shutters, slate roofs and others, and blown heat insulators and other light-weighed materials stained or damaged vehicles.
    3) Environmental Damage:
    All LPG stored in the area affected has burned by the fire and explosion and the leaked asphalt has been completely collected. As a result, no impact on air, waters nor soil by the accident has been observed.

    *2. Layout of the LPG tank area at the refinery
    Braces broke that supported the legs holding the LPG tank
    *4. Leaked LPG caught fire. (Please refer the point where the fire broke out in the image shown in the layout of the tank area*2 on the previous page.)

  2. Cause of the Event and Action Plan to Prevent Recurrence
    (1) Many braces supporting the legs holding the LPG tank broke, which caused the legs to bend,leading to the collapse of the tank.

    Damaged LPG Tank No. 364 met all the earthquake-proof structural requirements. However, since at the time of the earthquake, Tank No. 364 was filled with water, instead of lighter LPG, for a regular inspection, the initial earthquake off the coast of the Tohoku region put such a heavy load on the braces that some of them collapsed . This coincided with the second earthquake off the coast of the Ibaraki Prefecture, which led to the tank falling down. It was a temporary measure to fill the tank with water for regular inspection and we recognize that we were insufficiently prepared to deal with an earthquake of this magnitude at that time.

    For future regular inspections, we will minimize the period of time for filling up the tank with water . When we build new LPG tanks, we will incorporate safety measures into the tank installation design to withstand even during the period when it is filled with water. We will also assess the durability of the existing LPG tanks and provide enhancements, if necessary. Furthermore, when we fill up a tank with water for inspection in the future, we will protect, isolate, or separate the pipelines and other facilities adjacent to the tank preventing any harms should there be any major damages to the tanks.

    (2) LPG Leaks

    It is conceivable that the earthquake jolted the LPG tank and pipes and that the collapse of the tank damaged the pipes, causing the LPG to leak. This led us to infer that LPG might have continued to leak through three cracks in the pipes, and one of these damaged parts was found on the pipe connected to an emergency shut-off valve*5 that was set as open in a fixed position.

    Before the earthquake, we had confirmed a tiny amount of air leaking from the pipe to which air was supplied in order to activate the emergency shut-off valve, which was fixed open until we fix the pipe. This was a temporary measure taken to keep the emergency shut-off valve from closing if air pressure was reduced in the pipe. The operation procedure was to manually close the valve at the time of emergency, but on March 11 we could not gain access to close the valve due to LPG leaks.

    When we have an opportunity to design a new pipe around the LPG tanks, we will ensure that an appropriate level of flexuosity*6 will be incorporated into the structure of the new pipes.

    We will not set the emergency shut-off valve to open in any situation in the future.


    *5. The emergency shut-off valve refers to the valve installed in the pipe to ensure that it will be closed, and safely and quickly shut off the LPG flow, if LPG should leak from the pipe.

    *6. A structure with flexuosity refers to a structure in which pipes are made flexible and bendable enough to absorb any displacements caused by deflection, etc.

    (3) Source of Fire, Explosion and Spreading

    We carefully investigated the ignition cause but was unable to identify this.

    Upon the breakout of the fire, we continued to spray water over the LPG tanks around Tank No. LPG364 to cool them down but we judge that the fire, which broke out near Tank No. LPG364, gathered momentum to increase the surface temperatures of the adjacent LPG tank units, which reduced their strengths, rising their internal pressure to an unsustainable amount, leading to explosions, spreading the fire from one tank to another.

  3. Safety Management System

    Our efforts to rebuild our safety management system have mainly consisted of responses to events that have happened in the past and learning lessons from our past experiences to come up with plans to prevent anomalies or deficiencies from occurring in the future. We have also ensured full compliance with regulations when filing applications for construction projects, establishing installation standards and reporting to the police in case of an emergency. However, we realize that our conventional efforts are not enough to respond to contingencies and problems caused by disasters, as seen in the recent earthquake. We also realize that the conventional operating procedures, including setting the emergency shut-off valve fixed open and the work process of filling LPG tanks with water as part of the regular inspection, do not completely conform with the laws and regulations applicable to these practices and potential risks that lie in the background of these practices. The following activities have been put in place to establish a structure capable of providing solutions to these issues:

    (1) Comprehensive Safety Inspections

    We will ensure that all the employees at Chiba Refinery, through leadership by the refinery manager, are fully aware of the relevant regulations on disaster prevention in compliance with the High Pressure Safety Act, the Fire Service Act and the Act on the Prevention of Disaster in Petroleum Industrial Complexes and Other Petroleum Facilities of Japan so that they will know their roles, responsibilities, and authority and put them into practice in their daily work.

    All operators will use checklists on safety management to check their work and further checked by other members in order to better understand the laws and regulations and the in-house safety standards, as well as to recognize potential risks that may lie in the background. The managers of the refinery will also use the checklists and work with the operators as one team visiting the sites in person to confirm the points to check.

    (2) Improvement in Contingency Response Capability

    In addition to the existing activities conducted at both the Head Office and Chiba Refinery, we will continuously execute a drill program, among all group refineries, to be prepared for all possible large-scale disasters to improve the awareness of responses to contingencies in the minds of everyone concerned.

    Each time such disaster prevention drill is held, we will review the communication and cooperation among departments to improve the contingency manual by making it more practical. We will also make crisis anticipation and the process for it dynamic enough to improve our capability for risk assumption and to transfer the technologies and skills that have been inherited from the predecessors in the refinery to the younger staff.

    (3) Progress in management of Action Plan to Prevent Recurrence and In-house Horizontal Integration

    We will ensure that the initiatives mentioned above will be implemented not only by having our people at Chiba Refinery check the progress being made in their efforts on their own but also by sending people from Head Office and other group refineries to carry out audits. What is confirmed with respect to safety, security and operating management departments responsible for safe and secure operations within the Company will be audited by the Internal Auditing Office reporting to the President of the Company, to report conformity levels to the management team. If conformity levels are found insufficient, the Internal Auditing Office will advise on improvements and corrections. It will also conduct internal audits to confirm levels of progress being made on initiatives to prevent a recurrence at the respective departments.

    Points of improvement identified in the execution of the recurrence prevention initiatives at Chiba Refinery will be relayed to other refineries within the group to help improve safety levels across the Company.

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