Hot work has caused the destruction of many buildings, structures, plant and equipment. Poor work practices have also started fires that cause loss of life and horrific burn injuries to workers around the world. This article examines what hot work is, how to perform it safely, and what are the expectations once the work has been completed to ensure no smouldering legacy is left behind when the worksite is left unattended.

Recent news reports and the graphic footage of the destruction of the Notre Dame cathedral in Paris shows how quickly fire can destroy a substantial and significant structure. For such an important
and solid building that survived two world wars and several hundred years of both man-made and natural disasters, this loss seemed to be impossible.

Early reports suggest that the initial cause of the fire may have been construction work that had been occurring to renovate and repair the cathedral. This started me thinking about some of my own safety experiences, and the use of what are commonly called ‘Hot Work Permits’ and associated forms and procedures.

What is hot work?

Typically, hot work is described as the use of tools and equipment that can generate sufficient heat or sparks that can ignite flammable, combustible or explosive materials in the work area. This can include:

• arc, plasma, laser cutting and welding equipment;
• gas cutting, heating and welding equipment;
• grinding and cutting machines; and
• other equipment that emits flames or sparks.

Commonly, this type of work is only allowed to commence once a permit has been obtained and approved. The only exemptions are work that is performed in a dedicated and controlled environment like a welding bay or boiler shop. This work is most often performed by tradespersons, welders and contractors.

What is the Hot Work Permit?

The Hot Work Permit (HWP) form is generally an authority to proceed with hot work that is approved by a person with adequate knowledge, skills and experience to ensure the worksite will be prepared in readiness for the work. It will also nominate the tasks that will be conducted and the responsibilities for these tasks to be done safely. It should also identify the need for a flame watch or spotter who observes the site after the work has been completed for a period of time.

On some worksites I have been on, this can extend to several hours due to the slow smoulder rate of some flammable and combustible materials. Extensive use of insulated sandwich panels (particularly used in the food industry) that contain a polystyrene core can smoulder for an extended period before the panel catches fire.

Clear procedures and training for the spotters is essential so that any smoke or heat can be detected. Infrared or thermal imaging equipment may also be used to look for hot spots, embers or smouldering materials. This spotter must be diligent and dedicated to the task and not distracted by performing other work during the period of fire watch.

Risk controls and treatments

In many cases, the HWP serves to provide a risk assessment and determine control measures to be implemented like any other risk assessment documentation. So not only is the approval process important to get the authority to perform the work, but also using the traditional hierarchy of controls approach to minimise any risks. Some of the risk controls that should be considered when planning the work are:

• removing all flammable and combustible liquids and materials in the local area (sparks can travel a long way so several metres of clear space may be required);
• ventilation and monitoring for any gases or dusts in the work area;
• wetting down the area before work commences and regularly as work continues;
• keeping fire extinguishers, blankets, hose reels, sprinklers and suppression equipment at the ready for use if and when required;
• substituting the type of tools to be used (e.g. shears, cutters or blades might be suitable instead of angle grinders and oxy-acetylene torches);
• using welding tarpaulins, fire-resistant screens or shields in good condition with no tears or holes (any openings or cracks in walls, floor or roof should be sealed if possible);
• isolating and locking out any energised equipment in the area (e.g. moving conveyors that could carry an ember or spark to a separate location, and draining and purging pipework if it contains flammable substances that could ignite); and
• relocating the hot work to a designated area inside a boiler shop.

Other considerations

There are many other considerations when performing hot work. First aid kits, quench buckets, rescue plans should also be considered in the planning phase. Hot work that occurs in confined spaces presents particularly difficult challenges and often a catastrophic health and safety risk. Most jurisdictions have banned hot work being performed in the outside environment on days of extreme fire risk. Permission may be required from a local fire authority before commencing and may only be allowed for specific reasons.

When developing procedures and training your staff, there are a number of good references from the welding industry trade association, Australian standards on fire precautions when welding, and other handbooks and guidance materials from the regulators. There are also accredited training packages that can be used for training staff in hot work.

Always consider this type of work to be inherently high risk, and ensure thorough processes have been put in place to reduce or eliminate these risks as far as reasonably practicable.