Case Ditails

Scenario
Case Name Explosion and fire due to use of an electric spray during painting work inside a pontoon of a floating roof tank
Pictograph
Date June 24, 1994
Place Ichihara, Chiba, Japan
Location Refinery
Overview On June 24th, 1994, painting work was being carried out in the sealed place during remodeling of a tank in a refinery. The work instruction indicated that the work should be done by hand. However, workers used an electric spray-gun to increase work efficiency with neglecting the instruction. Furthermore, the sealed place was badly ventilated. Toluene vapor from a paint solvent exploded.
Incident An explosion occurred when painting work was being done in a pontoon of a floating roof tank. It occurred while a floating roof was being changed into an inner floating roof tank. One worker died and another was injured. The pontoon was deformed, the seal of the floating roof was burned by ignited paint, and paint on the side wall came off.
Pontoon: a steel float for floating roof. A small chamber installed around the floating roof.
Processing Maintenance
Individual Process Other (Painting)
Substance Toluene, Fig2
Type of Accident Explosion, Fire
Sequence On June 24th, 1994; tank remodeling work was being carried out in a refinery. Two workers and a watchman started painting work inside the pontoon.
In the instructions given at the morning meeting and by a work procedure guide, they were demanded to use brushes or rollers for painting work. However, they used an electric spray gun, disregarding the procedures. Paint diluted with a large amount of thinner which consisted mainly of toluene was used.
They finished painting of the inside of the first pontoon.
The paint was refilled while they were painting the second one.
Shortly after that, an explosion occurred due to sparks when the electric spray gun was switched on.
One worker died by the blast. The other received a burn and a bruise.
The paint in the fallen paint can was ignited and a fire occurred.
A part of the sealing material of the floating roof burned and paint on a small part of the side wall peeled off.
Cause A combustible gas-air mixture was formed in the pontoon, which was almost completely sealed, although the manhole was open. This combustible mixture was generated by the paint diluted with a large amount of thinner and the absence of an effective ventilation system. The ignition source was possibly sparks from the electric spray gun without explosion-proof switching. This was the worst case of "an accident waiting to happen". An instruction, which required ventilation of the inside of the pontoon, was given but it was probably not carried out.
Response Fire extinguishing activities inside the tank. Rescued the injured and sent them to the hospital.
Countermeasures Use of a spray painting machine should be prohibited in sealed structures.
Thorough ventilation should be provided in the sealed structures.
Establishment of the management of facilities and the working method, and a safety management system. Thorough safety education is conducted.
Knowledge Comment In very dangerous work such as in a tank, the owner is accountable not only for giving instructions on safety measures but also checking whether the safety measure and work procedures are followed by workers.
Background Basically, the accident was caused due to disregarding of the work procedure. In other words:
1. The workers used the electric spray gun even though they were instructed to use a brush or rollers in work procedures and the morning meeting.
2. They were instructed to ventilate the pontoon, but this was possibly not done properly.
3. The paint was diluted with thinner which was ten times as much as the regulation amount.
If workers are told only that an action is prohibited, they may not really follow instructions as they want to save time and energy. The owners and contractors should give instructions with specific reasons, and also be responsible for advising and supervising the workers to follow safety procedures. The workers know what they are doing, but are not always be able to judge whether it is dangerous or not. They should not be allowed to judge safety or danger by themselves when working in a factory where dangerous materials are handled. Violating instructions is considered to be the biggest factor. Moreover, the managers were irresponsible.
Incidental Discussion Workers do not always have good knowledge of dangers. They sometimes focus more on work efficiency than safety measures and work procedures. The owners and contractors are accountable for securing the safety of work, especially for maintaining safe conditions of facilities.
Reason for Adding to DB Example of explosion accident caused due to neglect of a work plan for efficiency
Scenario
Primary Scenario Organizational Problems, Poor Management, Poor Working Management, Ignorance, Insufficient Knowledge, Convincement, Misjudgment, Misperception, Selfish Judgment, Usage, Maintenance/Repair, Painting, Malicious Act, Rule Violation, Safety Rule Violation, Bad Event, Chemical Phenomenon, Burning, Secondary Damage, External Damage, Fire/Explosion, Bodily Harm, Death, Bodily Harm, Injury
Sources Ichihara City Fire Department and Explosion and fire accident during painting work for outdoor storage tank, pp.125-132(2002) Edited by Japan Society for Safety Engineering
Fire and Disaster Management Agency. Major accident cases - An explosion during painting work in a floating roof pontoon of outdoor tank, Accident cases of dangerous material, pp.29, 128-129
Ichihara City Fire Department, K. Ozuna, Explosion and fire during painting work in refinery, Accident cases of dangerous materials seminar, pp.23-39(1995)
Number of Deaths 1
Number of Injuries 1
Physical Damage A floating roof pontoon was deformed. A delta seal partially burned. Painting of the sidewall partially came off. Epoxide resin and 18 L of solvents (thinner) were damaged.
Financial Cost ¥ 10 million. (Accident cases of dangerous materials)
Multimedia Files Fig2.Chemical formula
Notes Disregard for safety measures, generation of combustible gaseous mixture.
Field Chemicals and Plants
Author WADA, Yuji (National Institute of Advanced Industrial Science and Technology)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
Scenario