| Case Name |
Ink varnish leakage from trench piping of a lorry station |
| Pictograph |
|
| Date |
December 15, 1994 |
| Place |
Kawasaki, Kanagawa, Japan |
| Location |
Chemical factory |
| Overview |
At the trench piping of the lorry shipping line of resin varnish for gravure ink, leakage occurred due to improper use of the gasket; its material and unbalanced tightening torque. Early detection was not possible for the steel plate trench cover, and the varnish leaked into the sea. Although this accident is not a simple behavioral accident, it comes under the category of human error. |
| Incident |
Varnish for gravure ink leaked from a flange of piping laid in a trench at a lorry station of a hydrocarbon resin factory. A part of the leaked oil passed through buried drainage piping, and escaped from the drainage channel into the sea. The accident occurred 10 years later after laying the piping. Varnish for gravure ink is a mixture of 58% Hydrocarbon resin dissolved into 42% toluene. |
| Processing |
Manufacture |
| Individual Process |
Transfer |
| Substance |
Varnish for printing ink |
| Type of Accident |
Leakage, environmental pollution |
| Sequence |
At about 06:00 on December 15th, 1994, there was no abnormality when the shift leader patrolled at the fixed time, and checked the sea. From 07:30, operators started preparations for shipping by lorries on that day, steam heating of varnish circulation and loading piping were carried out, and circulation of the tank -> pump -> tank started with the loading pump.
At about 08:00, loading work into lorries started.
At about 09:30, the loading was completed and the loading pump was stopped.
At about 09:40. The City Ports and Harbors Bureau staff member discovered resin material floating near the drainage channel of the company at Shiohama canal. The staff member visited the company, and required confirmation.
At about 09:50, it was confirmed that the floating material was the same as a product of the resin company from its composition and the location of the drainage channel.
At about 10:00, it was confirmed that the leakage was from the gravure ink varnish loading line in the lorry station, and recovery of oil started at the location of the leak. |
| Cause |
The leak occurred through a flange on 3-inch piping which was traced with steam. Although the correct gasket to be used at the flange was a vortex gasket with an outer ring, the gasket actually used was inappropriate, and was not suitable for this type of oil. In addition, as the tightening torque of the flange was imbalanced, it is thought that deterioration of the gasket occurred gradually over a long period from the part with weak tightening torque. In spite of trench piping, the cover was a steel plate instead of expanded metal, which makes it very easy to check the inside of the trench. Therefore, discovery was delayed, and material leaked into the sea. |
| Response |
The leakage of oil on the ground was recovered by factory members, and the sea oil spill was recovered with a workboat of the marine cooperation disaster prevention organization. |
| Countermeasures |
1. All flanges of the piping were checked, and the correct new gasket was used.
2. The insulation of the flange was removed to facilitate inspection of the flange.
3. Part of the trench cover was changed to expanded metal with a network structure, and a daily check was facilitated.
4. The piping construction method was changed. It was changed to a method with which all of the piping is lifted and bolting is conducted, and then all of the piping is lifted down into the trench. Unbalanced tightening torque is difficult to occur in this way.
5. Thorough field management is performed at a turnaround shutdown; the clearance in the flange is confirmed over the whole circumference using calipers and a clearance gauge to prevent reuse of a gasket and confirm proper use of a suitable gasket. |
| Knowledge Comment |
1 Safety can be maintained by assuming standards are obeyed. The material of the gasket is given by a standard.
2. Although not a standard, some methods are used for some reason. Without clearly understanding the reason, management might be faulty and improper facilities might be used.
3. It is very difficult to judge whether something is correct or not from the appearance. (Material and unbalanced tightening torque of the gasket in this case). Correct selection and correct work, etc., provide the meaning for the final assurance test. |
| Background |
1. In an airtight test of this piping in 1984, a temporary gasket was used at the flange where a blind plate was inserted. The temporary gasket was mistakenly not changed and was used for a long time instead of the correct gasket.
2. Unbalanced tightening force of the gasket is considered to be a factor. Measurement of distribution of thickness and an appearance test on the leaked gasket were carried out. Against originally 1.5 mm thick, the thickest portion was 1.5 mm and the thinnest portion was 1.35 mm. Varnish permeated ruptured pieces and adhered to its circumference. At other positions, adhesion and impregnation of varnish could not be found. It can be guessed that the organization of the gasket was spoiled due to ingress of toluene where the tightening force of the gasket was weak, and this reduced tightening torque.
3. A cause of the unbalanced tightening torque was the construction method. Bolting was carried out after the piping was lowered into the trench. The construction conditions were bad at the underside where the ruptured pieces existed, and wrenches, etc. could not be used sufficiently.
4. Why was a leak into the sea allowed without being discovered in the
factory yard? Trench piping was used to carry out inspections for leakage easily by digging a groove in the ground and laying the piping on it, unlike buried piping. However, the trench was covered with an iron plate, so leakage could not be detected easily.
The trench piping: Piping was changed from burial to lying on a groove.
This has an advantage to easily discover a leak. |
| Reason for Adding to DB |
Example of accident caused due to poor construction environment |
| Scenario |
| Primary Scenario
|
Organizational Problems, Poor Management, Slackness of Management, Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Carelessness, Insufficient Understanding, Insufficient Recognition of Risk, Planning and Design, Poor Planning, Poor Planning of Repair, Failure, Fracture/Damage, Damage of Gasket, Secondary Damage, Damage to Environment, Flow out to the sea
|
|
| Sources |
Kawasaki City, Fire Fighting station, Prevention division, Peace section. N resin Co., Ltd.. Leakage accident at the Lorry station of the gravure ink varnish. Material of the Kawasaki City complex safety countermeasure committee (1995)
|
| Physical Damage |
One sheet gasket was damaged. About 454 liters of gravure ink varnish leaked on land and about 89 liters into the sea. |
| Financial Cost |
¥28,000. (Material of the Kawasaki City Complex safety countermeasure committee ) |
| Consequences |
At about 9:40 on December 15, 1994, a City Ports and Harbors Bureau staff member discovered resin material floating near the N resin company's drainage channel at Shiohama canal. About 89 L of varnish had leaked into the sea. |
| Field |
Chemicals and Plants
|
| Author |
KOBAYASHI, Mitsuo (Office K)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
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