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Nippon Steel & Sumitomo Metal update on Oita Works plate mill fire¡ªThe 18th China(Guangzhou)Int¡¯l Heat Treatment, Industrial Furnace Exhibition
5/24/2017 heat treatment expo-furnace expo |
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On January 5, 2017, the plate mill on the premises of the Oita Works of Nippon Steel & Sumitomo Metal Corporation caught fire. On January 19, 2017, NSSMC established the Oita Works Plate Mill Fire Accident Response Committee including outside experts in order to investigate the cause of the fire and consider preventive measures and have been engaged in deliberation. As the Committee has completed review, NSSMC has reported the cause of the fire and the preventive measures by NSSMC.
On 5th January warning alarm in the trouble monitoring system went off and smoke was seen form first floor of the electrical room in plate mill ie Thyristor room for the auxiliary rolling equipment. After the electricity was cut, workers attempted to enter the thyristor room for auxiliary rolling equipment to inspect the situation, but without success as the smoke prevented entry. Fire fighters arrived at site and the fire was extinguished on January 6th.
Almost all control panels and cables in the electrical room burned. The building of the electrical room was damaged, and parts of its floor-supporting steel frames were damaged. The rolling line of the plate mill became inoperable.
Presumed cause of ignition - A control panel that orders a contactor inside the MC panel to open or close output abnormal control signal, and the contactor repeatedly alternated between open and closed while carrying electric current. As a result, arcs occurred continuously from the contactor and ignited flammable components of the panel (acrylic board for prevention of electric shocks, etc).
Presumed cause of the spread of fire Flames spread to adjacent panels and cables, and then spread across the entire electrical room from the 1st floor to the 2nd floor, and then to the basement.
The following measures are being implemented against the presumed cause of the fire (that is, an abnormal control signal from control panel to the contactor and the resultant occurrence of arcs).
1. Installation of circuits that shut off electric current in case of the occurrence of abnormal control signal
2. ¡°Triple Actions¡± are being implemented to prevent recurrence of the presumed cause of the outbreak of fire and address all conceivable factors.
3. Install smoke detectors to detect the occurrence of smoke inside control panel more promptly.
4. Install heat detectors on the cable racks in the electrical room and the tunnel to continuously monitor the temperature.
5. Install monitoring cameras to promptly identify the abnormal point and inspect the place where trouble is detected.
6. Install additional fire extinguishers beyond legal requirement.
7. Install halon injection equipment for extinguishing fire inside the panels.
8. Install additional fire hydrants within the building.
9. Install overall electricity shutdown device in the operation room so that an operator can shut off electricity more promptly.
10. Enlarge smoke-exhaust windows to facilitate smoke release.
11. Replace acrylic boards that caught fire with flame-retardant materials (vinyl chloride)
Currently, NSSMC is aiming at resuming operation in early August 2017 (originally, the expected timing of resuming operation was September 2017).
¡ªThe
18th China(Guangzhou)Int¡¯l Heat Treatment, Industrial Furnace Exhibition
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