Flammable vapours in the drum can cause the drum to explode during welding or cutting. It is often unclear what's been in an empty drum, and flammable or toxic vapours may persist in the drum for years.  

• Even after cleaning, small amounts of vapour left in a drum can explode. 
• Overflowing drums with water is not a satisfactory way of degassing drums as this method often pushes vapour pockets to the top of the drums where they can be ignited. 
• A single spark inside an empty drum can set off a massive explosion. 

Do: 

• Correctly label all drums on site.  
• Store empty drums in a well ventilated place away from work areas.  
• Make sure these drums are properly labelled and recycled by specialist cleaning companies.  
• Have Material Safety Data Sheets available for all hazardous substances and dangerous goods used.  
• Provide information to workers about the hazard of cutting or reusing drums.  
• Choose drums which have only ever held non toxic, water based products for recycling.

Do not: 

• Cut drums that have contained flammable liquids or flammable gases. Vapours left in the drum may explode.  
• Apply heat to drums that have held chemicals. Residues may produce poisonous gas and cause serious harm to your health.  
• Cut any drum that is not labelled, as you do not know what residues may be present.  
• Weld or grind near empty drums - sparks fly.  
• Use drums as welding or cutting platforms. Construct a proper trestle. 

What has the drum been used for? 

• Was it a flammable liquid or gas?  
• Was it a chemical?  
• Is there a hazard diamond on the label? 

If you answer yes to any of these questions:

DO NOT APPLY HEAT TO THE DRUM

Keep the drum away from oxyacetylene torches, naked flames or sparks from grinding and welding equipment.

There are companies that specialise in cleaning and cutting drums. 

Before applying heat to empty drums, specialist companies thoroughly clean and test the inside of the drums with gas monitoring instruments, to ensure that there is no chemical residue or explosive vapour. 

These firms also specialise in removing dents from drums ready for re-use. Do not be tempted to remove dents using air pressure without adequate controls - the drums commonly over-fill and burst. 

Go to the specialists. 

The Occupational Safety and Health Act 1984 requires employers to provide employees with a safe and healthy work environment, and employees to take reasonable care with their own safety and health at work and the safety and health of others. 

Regulation 3.96 of the Occupational Safety and Health Regulations 1996 indicates that the employer, main contractor or self-employed person must ensure that immediately before any welding or cutting is carried out on or in any container, drum or tank, the employer shall, in accordance with section 3.3(h) of Australian Standard AS 1674.1-1997 : Safety in welding and allied processes - Fire precautions, ensure that there is no danger of fire or explosion (available from SAI Global).

• Safety alert 02/2011 - Cutting drums with an angle grinder
• Safety alert 10/2002 - Explosion danger in cutting drums
• Dangers of hot work (YouTube video 13:56 mins)​