Combustible Dust Explosion

On 17th March 2008, there was an accident at the grains storage and milling plant somewhere in Lumut, Perak which caused four fatalities and two workers were given outpatient treatment. During forensic investigation at the plant it was found that they were doing some hot work involving electric arc welding (on the day of the accident) in the pit of the silo tower. The welding was on one of the grains transfer lines between the interconnected conveyor and the elevator located in the silo tower. On that day two elevators of the four elevators in the silo tower were put on to transfer the raw grains from the silos to the other parts of the facility.

It is strongly suspected that the explosion followed by a bright flash light which were witnessed by the workers in the plant’s control room originated from the basement floor causing widespread damages to the silo tower facility, shattering window glasses and displacing window frame structures from the main building. The interconnected underground tunnel which housed the continuous conveyors and ancillaries from the jetty to the basement floor of the silo tower also sustained extensive and serious damages. Three workers who were working in the silo pit died from serious injuries. One worker at the jetty who sustained serious head injury died and was found beside one of the horizontal leg of the grains unloader SKT.

 

1. Hazards identification, risks assessment and control (HIRARC) has to be carried out for any welding work in confined space.

 

2. According to Section 15, Occupational Safety and Health Act 1994 it is the duty of employers to provide safe system of work to ensure the health and safety of their workers and other persons who might be affected by the activities that are being carried out. References can also be made to the Occupational Safety and Health (Use and Standards of Exposure of Chemicals Hazardous to Health) Regulations 2000.

 

3. Sound and effective housekeeping program for all working areas in the plant have to be prepared and implemented to ensure that the presence of layered dusts on the elevators, conveyors, dust aspiration systems, silos and the dust clouds in the working areas are kept within the internationally accepted safe level.

4. References can be made to the Code of Practice that was issued by DOSH on the Work in Confined Space.

 

5. It is strongly advised that caution be exercised towards the conservative side in any hot work involving combustible dust to ensure the safety of all workers and personnel.

 

6. Further readings on the subject matter regarding combustible dust explosions are available in the following hyperlinks from overseas as follows: