| Case Name |
Leakage and fire caused due to corrosion of bypass piping for recirculation gas at a fuel oil desulphurization unit |
| Pictograph |
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| Date |
April 15, 2002 |
| Place |
Tomakomai, Hokkaido, Japan |
| Location |
Refinery |
| Overview |
An oval opening of 130 × 90 mm was caused in by-pass piping of the hydrogen sulfide absorption tower for re-circulation gas at the atmospheric fuel oil hydro-desulphurization unit. Internal fluid spouted, and a fire occurred. Ammonium hydro sulfide was formed by a reaction of ammonia in the crude oil with hydrogen sulfide in the by-pass. The flow of internal fluid was unique due to piping in a cold district, no heat insulation for the flange, and a vertical dead end, etc. The environment with active corrosion by ammonium hydro sulfide was partially created by drops of water. It is presumed that corrosion progressed very fast and the opening was generated. It is considered that the ignition source was static electricity or impact of metal. |
| Incident |
An oval opening of 130 × 90 mm was caused in the by-pass piping of the hydrogen sulfide absorption tower for re-circulation gas at an atmospheric fuel oil hydro-desulphurization unit. Internal fluid spouted, ignited, and a fire occurred. The by-pass piping had a nominal diameter of 10 inches, wall thickness of 28.6 mm, and the material was STS480-S. |
| Processing |
Manufacture |
| Individual Process |
Reaction |
| Process Flow |
Fig2.Unit process flow
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| Chemical Reaction |
Hydro-desulphurization |
| Substance |
Hydrogen, Fig3 |
| Hydrogen sulfide, Fig4 |
| Ammonium hydrosulfide, Fig5 |
| Type of Accident |
Leakage, fire |
| Sequence |
A fire occurred at an atmospheric fuel oil direct desulphurization unit at about 19:15 on April 15th. A private fire brigade, a district disaster prevention organization, the public fire fighting brigade, and the petroleum reserve station disaster prevention organization were engaged in fire fighting activities at once. The fire was extinguished at 5:30 on the next day, the 16th. |
| Cause |
The opening was at the dead end of piping arranged vertically. Ammonia formed by the reaction of nitrogen contained in crude oil reacted with hydrogen. Then, ammonium hydro sulfide generated by a reaction of ammonia with hydrogen sulfide accumulated in the by-pass. Water dropped between the by-pass piping due to environmental conditions such as vertical arrangement and dead-end piping, flow characteristics of internal fluid in a cold region and lack of heat insulation at the flange. Therefore, corrosion due to ammonium hydro sulfide became active. As a result, it is presumed the corrosion progressed very rapidly and caused the opening. The ignition source is thought to be static electricity or impact of metal. There is no flow in the by-pass piping, so it is called dead-end piping. Its maintenance is different from piping with a flow. |
| Response |
A private fire brigade, the fire-fighting authorities, and others were engaged in fire fighting activities. |
| Countermeasures |
Removal of bypass piping. Check on similar piping in the factory. |
| Knowledge Comment |
An environment in which corrosion progresses partially very high seems to be created by the distribution and the history of temperature in piping and the movement of internal fluid, etc. The estimation and analysis of phenomena in piping with a dead end are difficult. |
| Background |
A written report of the company states that it was impossible to foresee this accident because it was a special case. It is a unique accident with condensation at dead-end piping combined with the behavior of the flow in vertical piping. However, in general, crude oil processed at a refinery in Japan is not all the same. As a result, the corrosion medium also differs for each crude oil. Moreover, the equipment is not completely the same in terms of the pipe shape and others. It is thought, therefore, that the problem was unique to the company. |
| Incidental Discussion |
There are many accidents caused by dead-end piping. Each device differs even though the process is the same and a device is based on the same process and technology. The phenomenon might be foreseen if both the engineer and the manager consider carefully. |
| Reason for Adding to DB |
Example of fire caused due to an opening of piping from rapid corrosion under special conditions |
| Scenario |
| Primary Scenario
|
Unknown Cause, Occurrence of Abnormal Phenomenon, Insufficient Analysis or Research, Insufficient Practice, Effect of the Dead-end Piping, Planning and Design, Poor Planning, Poor Design, Failure, Abrasion, Corrosion, Secondary Damage, External Damage, Fire, Loss to Organization, Economic Loss, Total Manetary Damage over 7000 million yen
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| Sources |
Ministry of Economy, Trade and Industry, Investigation of dead-end piping of dead-end piping in fuel oil hydro-desulfurization units, Industry and protection, No.31, Vol.1, pp.2-5(2002).
I petroleum, Company home page, cause and countermeasure of H refinery fuel oil direct desulfurization unit fire accident, (2002).
Fire accident at fuel oil direct desulfurization unit, The accident investigation committee, summary, Industry and protection, Vol.18, No.17, pp.7-8(2002).
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| Physical Damage |
Radius of 30 m from a fin-fan cooler of the desulphurization unit burned in a plant set up on a site of about 15000 square meters. (Asahi Shimbun). |
| Financial Cost |
Total damage is of about ¥ 7 billion - 8 billion. (According to I petroleum report dated June 6th). |
| Consequences |
On April 15th, 2002, 20:00: The Tomakomai police station recommended the evacuation of employees of 10 companies around the refinery, such as Hokkaido Electric Power Co., Inc., and forbade people enter the area within 1 km. |
| Multimedia Files |
Fig3.Chemical formula
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Fig4.Chemical formula
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Fig5.Chemical formula
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| Field |
Chemicals and Plants
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| Author |
OGAWA, Terushige (Graduate School of Environment and Information Sciences, Yokohama National University)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
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