MOM Unveils Updates On Fatal Incident At Chemic Industries Pte Ltd

2.   Chemic Industries was engaged as a subcontractor by Alfa Laval Singapore Pte Ltd¹ to clean a heat exchanger.

3.   Investigations showed that the workers were pumping nitric acid (70% concentration) into the heat exchanger to remove some residual polymer at the time of the incident. Investigators noted that the heat exchanger was part of a process plant that used di-methylacetamide as part of the process to produce spandex. Preliminary findings revealed that during the cleaning process, a chemical reaction could have occurred within the heat exchanger and generated heat and gases, causing pressure to build up inside the heat exchanger. As a result, the contents of the heat exchanger, which included a mixture of nitric acid, were forced out of the heat exchanger. At the same time, a large amount of toxic fumes was emitted. The mixture splashed onto the workers, causing chemical burns. Four workers were killed and one was injured.

4.   MOM is releasing these preliminary findings to enable industry to learn from this case and prevent similar incidents. Going forward, there are three important points for companies handling hazardous chemicals to take note of.

(i) Hazardous nature of nitric acid and similar chemicals

5.   The concentrated nitric acid used in this cleaning process is highly hazardous, highly corrosive and a very strong oxidizer. Nitric acid attacks most metals, giving off large clouds of toxic nitrogen oxide fumes. It can react violently with many organic compounds and those containing cyanides, carbides and metallic powders. The acid is very toxic as a very small amount or dilute solutions can turn skin yellow while large amounts can cause severe and painful burns. Extreme care and measures must be taken when using nitric acid and other similar hazardous chemicals. These include having a controlled environment and using suitable personal protective equipment.

(ii) Regulatory controls of hazardous chemicals

6.   There are regulations in place to control the use of nitric acid and similar hazardous chemicals. The National Environment Agency (NEA) requires companies that intend to handle such chemicals to apply for a licence or a permit to store, use and sell such chemicals. These companies must be competent, obtain the necessary permits and check that they comply with the licence or permit conditions. In addition, they must also apply for a factory licence from the MOM and inform the Ministry of their works.

(iii) Safe use of nitric acid and chemicals

7.   To ensure safe use of hazardous chemicals, companies licensed to handle these chemicals must employ a competent person to take overall control in the handling of these chemicals and implement adequate risk management.

8.   The competent person must have adequate knowledge of the chemicals used. Persons involved in the handling or using of these chemicals must refer to their safety data sheets (SDS). The SDS of a chemical or substance will highlight its properties, associated dangers, how to use it safely and whether it can be mixed with other types of substances. If the chemical or substance is unknown, it is critical to seek clarification or conduct appropriate testing to ascertain the contents.

9.   Companies should also ensure that adequate risk management is in place while using nitric acid and other hazardous chemicals. They must first determine if a highly hazardous chemical like nitric acid was appropriate for the work and use alternatives where possible. Once decided, companies must identify possible hazards associated with the chemical, including compatibility of the equipment and fittings used. Besides general work instructions, workers must be well-briefed on the hazards of using the chemicals and be familiar with the safe work procedures, mitigating measures and the emergency response plan before the start of work. A copy of the SDS must also be made available and explained to persons likely to come in contact with the chemicals. The above measures will ensure proper handling, usage and avert risks of unintended reactions.

MOM cautions industry to ensure safe use of hazardous chemicals

10.   After the incident, MOM issued a full stop work order at Chemic Industries. Work has not commenced at Chemic Industries as we are still conducting checks on all its work processes. Investigations on the incident, including the areas highlighted above, are in progress.

11.   Mr Ho Siong Hin, Commissioner for Workplace Safety and Health with the Ministry of Manpower, said, “MOM cautions all users of hazardous chemicals to put into practice adequate safe work procedures. If procedures are not in place, hazardous chemicals can cause catastrophic accidents such as this one at Chemic Industries which took four lives. MOM will be inspecting workplaces using hazardous chemicals to ensure compliance with safety requirements. One such area is checks on whether companies have reviewed their risk assessments and safe work procedures to ensure that they are robust and effective. At the same time, MOM will also be working with the WSH Council in its upcoming forum on 30 March to share learning points from accidents involving flammable and hazardous chemicals.”

¹The owner of the heat exchanger is Invista Singapore Fibres Pte Ltd which had sent the heat exchanger to the manufacturer Alfa Laval Singapore Pte Ltd to perform the cleaning job.  Alfa Laval subsequently engaged Chemic Industries to carry out the job.