A Freedom of Information request to Scottish Fire & Rescue Service found that hot works accounted for 143 (79%) of the 180 fires reported in the sector in 2018/19. 

Fifty-one fires during this period were caused by welding or cutting equipment, 22 by manufacturing equipment and 23 by kilns or other services. These fires resulted in 21 casualties.

Hot works refer to any task that requires using open flames or applying heat or friction which may generate sparks or heat.

More specifically, it is defined by the British Standards Institution (BSI) in BS 9999 as: “Any procedure that might involve or have the potential to generate sufficient heat, sparks or flame to cause a fire.”

Examples of hot works include welding, flame-cutting, soldering, brazing, grinding and the use of other equipment incorporating a flame.

Hot works poses a particular threat within the construction sector as the cause of multiple fires in buildings. 

The most common examples of hot works and those that can pose significant risks without proper safety precautions are for example:

• Brazing and soldering
• Gas/electric welding cutting apparatus
• Grinding wheels and cutting discs
• Thawing pipes
• Open flames, blow lamps and blow torches
• Bitumen and tar boilers
• Hot air blowers and lead heaters.

Gary Ellis from CE Safety, which submitted the FoI request, said: “A variety of industries, construction, in particular, may require hot work to be carried out in their premises as part of routine work activities. It is also frequently carried out as part of contractual work, which is common in construction. 

“However, no matter who does it, they must know what kind of hazards hot work presents and how to prevent it from causing harm.”

Flying sparks are the principal risk posed by hot works and they can easily get trapped in cracks, pipes, gaps, holes and other small openings, where they could potentially smolder and cause a fire to break out.

The debris and residue which hot work creates, such as flammable swarf, molten metals, slag, cinder, and filings, are often combustible.

Hot works can cause pipes to substantially heat up and easily transfer, through the process of conduction, to another flammable surface and cause a fire.

Failure to remove flammable materials or substances from a surface before commencing work means that they could easily become hot and cause a fire.

In certain environments, there may be potentially explosive vapours or gases in the air which are highly combustible and could ignite if exposed to hot works. In a similar vein, hot works could generate fumes which, in turn, create an explosive atmosphere.

Ellis added: “The consequences of these hazards can be severe and costly for any business. Injuries can result in workers taking time off work, while a serious fire could damage a building irreparably. Both of these could even lead to legal consequences under certain circumstances. Therefore, it is crucial to understand how to implement appropriate safety controls.”