Risk of explosion from cutting, grinding or welding drums tanks and containers

Workplace Health and Safety Queensland (WHSQ) recently investigated two fatalities where fuel tanks exploded while undergoing repairs. This has prompted a warning from WHSQ reminding employers and workers of the risks when cutting, grinding or welding fuel or chemical containers. If the risks are not properly assessed, then fatal mistakes can be made.

These jobs should only be done by persons who have adequate knowledge and skills to perform the job properly. The job should only be done once risks have been properly assessed and a determination made that the task is safe.

Many incidents in the past involving cutting or welding of fuel storage tanks, truck diesel fuel tanks and 200 L drums containing combustible liquids have seen explosions that have resulted in severe injuries and burns. Investigations into explosions reveal that:

• drums were not cleaned properly;
• bungs were not removed when the drums were cleaned;
• drums were used as trestles to support other steelworks - eg, during oxyacetylene cutting work; or
• knowledge of the hazard associated with cutting drums was lacking.

Drums that contain residual flammable or combustible substances or vapours may explode when exposed to heat. Additionally, drums that have contained substances such as pesticides may release hazardous gases when exposed to heat.

The following points should be considered when deciding on how to control the risk of explosion when working with drums and containers.

• Never cut drums that have contained flammable or combustible liquids or gases. Even drums that have been empty for a very long time can contain enough residue substances to explode and/or emit hazardous gas when exposed to heat. Be aware that rinsing drums with water is not a fail-safe method for purging vapours from containers.
• Do not apply heat to drums that have held other chemicals such as pesticides, as any gas emitted may cause serious harm to health. Never weld or grind near empty drums.
• Do not use drums as a welding or work platform.
• Correctly label all drums on site.
• Have material safety data sheets (MSDS) available for all products.
• Dispose of drums appropriately.
• Store empty drums (with bungs removed) in a well-ventilated place, away from other work areas.
• If drums are to be recycled, use a specialist. There are companies that specialise in the correct cleaning, gas monitoring and cutting of drums.

Checklist

1. What has the drum been used for?
2. Was it a flammable or combustible liquid or gas?
3. Was it a chemical?
4. Is there a hazard diamond on the label?

If you answered “yes” to Questions 2, 3 or 4, or you are unsure what has been previously stored in the drum, do not apply heat to the drum. The fact is welding or cutting work on containers or tanks that contain or have contained flammable or combustible materials is dangerous when appropriate precautions are not taken. Workers carrying out welding or cutting jobs and bystanders can be placed at risk from fire or explosions.