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Molten Sulfur Tank Incident

Case Name Fire of molten sulfur due to ignition of iron sulfide on opening of a molten sulfur tank
Date  March 5, 1991
 Place  Kawasaki, Kanagawa, Japan
Overview  Receiving of molten was stopped at the storage of a refinery as its level gauge did not function. A fire started and burned when inspection of the gauge was being carried out with the calibration chamber at the upper side of the open. Flammable iron sulfide was generated in the chamber. The fire broke out when iron sulfide ignited on opening the chamber, then hydrogen sulfide generated also caught fire. In inspection, manuals should be made to explain the necessity of paying attention to air inflow and detecting gas composition, and making them known to everyone.
Incident  Inspection of a level gauge of a molten was being carried out with the calibration chamber at the upper side of the open after stopping the receiving of molten. As the inspection proceeded, iron sulfide ignited, hydrogen sulfide generated in the burned with high speed, internal pressure rose suddenly and damaged the. In addition, some burned.
 Processing  Storage
Substance  Sulfur and Iron sulfide
Type of Accident Fire
 Sequence  The level gauge had been remodeled to the current one with a closed calibration chamber about three years before.
On the day before the accident, receiving of to the was stopped as the level gauge did not function.
On the day of the accident, a fire started when the upper part of the was opened and the gauge was inspected. Flames spread rapidly and an instrumentation engineer fell. Smoke was rising from the upper part of the.
 Cause Flammable iron sulfide was generated in the chamber. A fire broke out when iron sulfide ignited on opening the chamber and hydrogen sulfide being generated also caught fire with a flame of iron sulfide.
 Response  Extinguishing with water
Countermeasures  The level gauge chamber was removed, and an open-type level gauge frame was adopted. The material was changed to stainless steel to prevent iron sulfide from generating. Periodic gas analysis in the was also carried out
Knowledge Comment  Lack of knowledge related to hazards such as ignition, combustion and generation of hydrogen sulfide in the presence of.
 Background 1. The closed chamber was installed when the level gauge was remodeled three years before. The inside of the chamber satisfied the optimum conditions for generating flammable iron sulfide, such as low oxygen concentration, sufficient moisture, steel construction, and existence of hydrogen sulfide in.
2. The chamber was carelessly opened, without noticing the existence of ignitable iron sulfide and allowed it to contact oxygen.
3. There was a lack of a thorough study at the time of remodeling. In the operations of a refinery or a basic petrochemical factory, the existence of flammable iron sulfide is a matter of common sense. This is considered to be an issue of communicating safety countermeasures and technology.
 Incidental Discussion The used before remodeling had eight non-valve vent pipes. The closed chamber would not have been adopted if the functions of these pipes had been properly understood.
Scenario Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Carelessness, Insufficient Precaution, Inadequate Handling, Planning and Design, Poor Planning, Poor Design, Usage, Transport/Storage, Storage, Bad Event, Chemical Phenomenon, Burnng/Explosion, Secondary Damage, External Damage, Leakage, Bodily Harm, Injury, 1 person injured
Sources High Pressure Gas Safety Inst. of Japan. storage. The fire in molten. Accident Examples of Petroleum refinery and Petrochemical unit. pp.87-91(1995).
National dangerous object safety association. Explosion due to exothermic reaction of iron sulfide generated in molten. One-hundred accident cases at dangerous facilities. -No.2-. pp.50-51(1994).
Kawasaki City Fire fighting station Prevention division, Peace section. Outline of fire accident at molten  storage in T petroleum Co., Ltd. K refinery. Material of the Kawasaki City Complex safety countermeasure committee.
National dangerous materials safe association. The outdoor storage area. Explosion. One-hundred accident cases at dangerous facilities p.25(1999)
 Number of Injuries  1
Financial Cost  ¥1,690,000 (Material of the Kawasaki City Complex safety countermeasure committee)
 Field Chemicals and Plants
Author WAKAKURA, Masahide (Kanagawa Industrial Technology Research Institute)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)


This is a great example of a sulfur incident in Japan and how they have done a very good job at being transparent with the Incident and their RCFA. We should do this in the states…but I doubt that will happen. The Oil industry is self reporting for the most part and very secretive. It’s good information. Refiners can look at others police themselves and go “Oh yeah, I could see that happening…or yeah, I better make sure I do this particular thing so I don’t end up having the same thing happen.

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