22nd October, 2019

What Is Hot Work? (Definition, Risk And How To Control It)

Hot work is any activity or process that generates a source of ignition, this could be through a flame, heat or a spark. Hot work can be direct, e.g. the equipment or tool creates a flame. Other times it may be indirect, e.g. using an abrasive wheel to cut metal produces sparks.

What Is Hot Work? (Definition, Risk And How To Control It) header image

Hot work is dangerous work. It introduces new risks to your workplace that need to be managed. Hot work may be permanent, or temporary. But whenever, and wherever, it happens - it needs to be controlled.

So what is hot work? Is it work in hot weather? Work in hot temperatures? A task or activity where you work up a sweat? No, no and no. This might be work that makes you hot, but it's not the definition of hot work.

Hot work is any activity or process that generates a source of ignition, this could be through a flame, heat or a spark. Sometimes, hot work can be direct, e.g. the equipment or tool creates a flame or produces heat. Other times it may be indirect, e.g. using an abrasive wheel to cut metal produces sparks. Hot work is dangerous because it can introduce a risk of fire or explosion.

Hot work is any process that generates flames, sparks or heat. It includes welding, cutting, grinding and sawing.

Examples of hot work:

Using hot work techniques in your workplace needs careful consideration. While some of these tasks might like everyday activities, they can introduce serious, sometimes fatal, risks.

Fires and explosions caused by hot work have claimed the lives of many workers over the years. The risks have been known for many years but accidents still happen and people are still getting killed.

Hot work can be deadly. At Dusseldorf Airport in 1996, hot work caused a fire that resulted in hundreds of injuries and 17 deaths. When hot works go wrong, it can also be costly. A report by Zurich on hot work insurance claims reported handling cases with loss estimates of up to £20m.

Cutting or welding an empty tank or pipe might seem safe if you're using the equipment correctly. But what did it contain before? Was it flammable? Are there any residues? Just a teaspoon of fuel in a tank can be enough to cause an explosion when heated up and turned into vapour.

hot work fire
Hot work can start devastating fires

Controlling hot work

To manage the risks, hot work needs to be controlled. Not just during the activity, but before and after as well. Every workplace is different, and a risk assessment should be carried out to check it is safe to carry out hot work in the environment. Consider what other work is being carried out in the workplace, the presence of flammable substances, the training of the operative and the condition of the equipment.

A hot works permit should be used as a further control measure, especially in workplaces not designed for hot works. For example, when hot work is carried out during a construction project or as part of maintenance work. This will ensure a series of checks are made before authorising any hot work to start.

Find out more about permits to work and what they are used for in The Purpose Of A Permit To Work System blog post.

A careful assessment of the work area should look to identify and remove or cover any combustible materials. This could be floor coverings, fixtures or fittings. Look for gaps in the floor or walls, where sparks could escape into other areas. There should be no flammable substances (in liquid or vapour form) where hot works are taking place. Dust can also create flammable atmospheres and increase the risk when completing hot work.

After hot work is finished, the risk hasn't gone. Fires can take a while to start, and sparks can remain burning for sometime after you are done. A fire watch is an important precaution to take once hot work is completed. The fire watch is usually carried out for 60 minutes after the work is done, depending on the type of hot works. Never sign off a hot work permit until the fire watch has been carried out.

Before hot work:

During hot work:

After hot work:

hot work sparks
Sparks can remain burning after work is finished

Some work areas are especially high risk for hot works. Like confined spaces, or places where flammable substances are or have been stored. It's always worth looking at alternative options before planning hot work.

Alternatives to hot work

When hot work can be eliminated from your workplace, it should be. It might be safer (and cheaper) to replace rather than repair. Or to get pre-fabricated items manufactured off-site in a factory. Other methods like cold cutting with high powered water jets can reduce or remove heat from the process altogether.

Alternative methods like cold cutting or prefabrication might not eliminate all risks. Cold cutting can introduce other risks and still needs to be carried out safely. Prefabrication may just move the risks to another, albeit more controlled environment.

But you don't need to eliminate all risks, just reduce them as low as reasonably practicable (ALARP). So if using an alternative to hot work is an option, and a safer option that reduces the residual risk of an activity, then it's an option you should be taking.


Need to control hot work in your workplace? Use the hot work risk assessment and hot work permit to manage the work, and the hot work toolbox talk to raise awareness of the risks.

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This article was written by Emma at HASpod. Emma has over 10 years experience in health and safety and BSc (Hons) Construction Management. She is NEBOSH qualified and Tech IOSH.

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