| Case Name |
The 200KL kerosene tank explodes in painting construction. |
| Pictograph |
|
| Overview |
An outdoor tank of hazardous-materials site installed in a factory in B-city, A-prefecture exploded, and nearly fill the kerosene began to leak. At the top of the outdoor tank, the vent pipe had been installed in order to maintain the pressure in the tank, and the wire gauze of 40 meshes had been installed as an ignition prevention net. The coating operation of the tank external surface was carried out 2 days before the day of the accident. At the time, the professinal painter made a mistake with the wire gauze of the ignition prevention network, and the painting was direct cause of the accident. An orderer had sent instructions for a coater in order to paint the tank external surface without confirming the office regulation, for painting construction. The concerned place was not checked during patrol supervision, too. They didn't think the place would cause a terrible accident. In the meantime, the specialists painting trader's awereness for the work was "all we have to do is painting", so he didn't check prevention net unlike external surface steel plate, and it was painted.
Two days after of the coating operation, a minitanker carried out to supply to the tank.
During the supply, the air of the tank inside must be discharged from the vent pipe.
However, the discharge in proportion to the supply speed became impossible,
since the ignition prevention net of the vent pipe inside was painted,
and the rise in the internal pressure was caused, and led to the rupture. |
| Incident |
The outdoor tank of hazardous-materials site installed in some factories exploded and nearly fill kerosene began to leak. |
| Sequence |
At the top of the outdoor tank of hazard owes materials, the vent pipe had been installed, and the wire gauze of 40 meshes had been installed as an ignition prevention net in the atmosphere opposite edge division. Through the vent pipe, the air is supplied from outside during the consumption of the kerosene, and the air of the inside is discharged outside during supply of the kerosene. The vent pipe plays the important role which maintains the pressure in the tank. The coating operation of tank external surface was carried out 2 days before the accident-generation day. The , and the professional painter didn't notice the role of the vent pipe either, and the ignition prevention net was not confirmed and was painted. As the result, dangerous object outdoor tank storage area installed in the factory exploded, and nearly fill the kerosene became leak. |
| Cause |
The direct cause of the accident was the specialist painter erred in the wire gauze of the ignition prevention net during the coating operation which was carried out 2 days before the accident-generation day. The combustible steam had been formed in the tank on the oil level. In case, there is fire outside of the tank for some reason, it is fered that inflammable steam of the tank catch fire. The ignition prevention net has been installed in order to prevent fires. The outside air of the volume which corresponds to the consumption of oil content is supplied in the tank through the ignition prevention net, when the kerosene in the tank is consumed.
For the contrariety, during the supply to the tank by passing the ignition prevention net, increased inflammable steam is through the prevention net and discharged outside. The pressure in the tank was maintained of the fuel by the vent pipe during comsumption and supply. There are many "deformation from dented" which cause by a bird making the nest on the damage of the tank in the wire part generally, and the vent pipe blocking. During consumption, it need to be supply air from the outside, but the supply was prevented by nidus avis, and atmospheric pressure of the tank became negative. This accident arosed not during the fuel comsumption but 1 hour after from had finished supply by the tanker. It is guessed that the part of the ignition prevention net was left remain un-painted. The kerosene in the tank were continually consumed after the coating operation, and the hoop and consumption rate are comparatively slow. Therefore, in the consumption, the tank inside did not develop negative pressure in spite of painting the part of the wire gauze hole, and the concave deformation was not generated. The supply by the tanker occurs 1, time at the 4 - 5 day, and length of supply for 1 time is about 1.5 hours. Therefore, the air quantity which comes in the tank in passing through the vent pipe for the 4 - 5 day, will be discharged in the supply for 1.5 hours. This time, the discharge in proportion to the supply speed became impossible, and the rise in the internal pressure was caused, and led to the rupture. |
| Response |
Around 10:30 a.m., a worker who had been worikng at a yard near the tank saw that steam arose from top of the tank.
When the worker approached the tank, he found that a part of around baseplate and sideplate joint of the tank transformed, and from the crack the kerosene was spouting, so he got in touch with the department in charge.
The charge department confirmed the situation immediately, and they were reported to the responsible person who was just finished the regular meeting and been left the room.
Though the responsible person rushed to the field, and he checked it didn't catch a fire but stil dengerous stiuation, and this accident were about dangerous objects and facillities, so he called fore an ambulance in accordance with a fire fighting plan. Public establishment fire brigade was cautious about fire just in case, devased a foam extinguisher scheme by chemical fire engine, and closed to the sorrounding roads. In the other side, they asked for help based on mutual support agreement of dangerous object, and amount of 15 10t lorry cars which were suddenly prepared recovered the kerosene from top of the tank. The other, the private fire brigade recovered the kerosene, which leaking in the oil retaining wall, in manual work and the amount reached about a houndred drum can. Because of the work might be carried out under heightened security, the recovery operation was finished at 16 o'clock without be ignited. About the oil retaining wall of the tank, the part of directly under the tank was strengthen but other part had been made only by mortar. Therefore, when lower of the tank was deformation, this mortal broke and the kerosene permeated in the underground. In the examination after the recovery operation, they planed that it drilled around the oil retaining wall and the oil on the groundwater surface should be recovered. Next day, they carried out excavation and recoverd floated oil in the groundwater of 1.3m underground. In addition, this recovery floated oil was guided in large floated oil recovery tank offered from the industrial waste cleaning traders, and the moisture was run in the process round water system of the factory. |
| Countermeasures |
The orderer has participated in the maintenance of machinery for the long term, and it is a supervisor of the post.
The coating operation exterior of the tank was carried out 2 days before of the accident was happened.
From the content of the work, the orderer carried out appointment of the coating material and indication on the safety in the time, attention and indication based on the structure of the tank were not done.
The point of consideration in the tank coating operation was arranged as an office regulation including the precaution on the vent pipe, and this regulation collection was being put in the shelf in his back.
The operations which recurred every over 3 months or carried out over 3 months from last work, should be confirm the regulation. |
| Knowledge Comment |
It is necessary that the work which recurred every long term or long time has passed form last work (ex. over 3 months) to confirm regulation certainly.
Otherwise, it is possible to miss points which were just simple but can connect with serious accident.
This mistakes will bring the local community the danger, it becomes not only confusion of production and distribution systems it thorough delay in the delivery date, but also that it will bring the company to the social sanctions. |
| Reason for Adding to DB |
The work as the long time from the work which recurs in long-term interval or work in last time had passed wanted to complain of carrying out regulation, certainly and confirm. |
| Scenario |
| Primary Scenario
|
Ignorance of Procedure, Disregard of Procedure, Insufficient Analysis or Research, Insufficient Environment Study, Non-Regular Action, Change, Malicious Act, Rule Violation, Bad Event, Chemical Phenomenon, Secondary Damage, External Damage, Loss to Organization, Social Loss
|
|
| Field |
Civil Engineering
|
| Author |
WATANABE, Tsunemi (Kochi University of Technology)
|
|
