Hot workSafety Alert | 02/03/2018
This safety alert reminds people of the precautions required when carrying out hot work in the workplace, for example grinding, welding, oxy cutting or other processes which produce a flame or other ignition source.
In February 2018, a serious fire developed on a building demolition site when plastic mesh screening ignited whilst hot work was being undertaken. The demolition work involved the cutting of a metal beam using an oxy acetylene torch. The fire engulfed the site and approximately 20 people were treated on site for smoke inhalation.
The incident demonstrates one of the hazards associated with hot work, a fire caused by heat, sparks, molten metal or direct contact with the flame. Others include:
- explosion when cutting up, repairing or working on or in the vicinity of drums, tanks, pipes or vessels which contain or have contained flammable liquids, gases or materials
- fire/explosion caused by a gas leak, or flammable liquids or materials backfire or flashback
- burns from contact with the flame, sparks, molten metal or hot metal
- crush or impact injuries resulting from an explosion
- exposure to toxic fumes
- depletion of oxygen levels in the atmosphere causing suffocation.
Many materials and substances found in workplaces are flammable or combustible. They can be solids, liquids or gases.
The risks associated with a certain material or substance may not be immediately obvious. For example, flammable substances can give off enough vapour at room temperatures to form burnable mixtures with air or generate toxic fumes. However the vapours are usually invisible and often have no odour, and are therefore difficult to detect without the use of special instruments.
Any hot work process can be a potential ignition source for a flammable or combustible material.
Serious or fatal injuries can occur when hot works are undertaken on or in close proximity to flammable or combustible materials/ substances without appropriate control measures. Such injuries may occur as a result of the primary ignition, or secondary effects such as smoke, toxic fumes, oxygen depletion, or structural collapse.
Prior to carrying out any hot work on site it is essential to implement a hot work permit system, which includes a detailed review, to identify all potential hazards associated with the proposed hot work activity and to eliminate the hazards or, where this is not reasonably practicable, control the resulting risks.
Typical key measures to be considered include:
- identify any possible flammable or combustible materials in the area, including rubbish, paper or dust that could be potential fuel sources or produce dust explosions
- ensure it is not a confined space
- remove, so far as reasonably practicable, any flammable or combustible material found, or otherwise provide non-flammable covers or screens to control sparks and flash
- locate and protect, and if reasonably practicable isolate, all services
- ensure the area is adequately ventilated
- ensure gas cylinders are not damaged and fitted with flash back arresters. When not in use ensure valves are closed and cylinders are secured and stored in an upright position
- ensure adequate firefighting equipment is ready for use
- limit personnel and vehicle traffic in the area
- utilise a fire watch person to monitor the hot work environment
- isolate and secure the area to prevent unauthorised access and erect appropriate signage
- establish emergency and evacuation procedures and train all personnel
- ensure relevant workers are wearing appropriate non-flammable personal protective equipment
- conduct a post work check for smouldering material before leaving the area, e.g. for a break, end of shift or completion of work
The hot work permit system should incorporate a check list to address all hazards and controls and should be reviewed and signed off by the persons in control of the site and involved in the hot work activity. A copy of the hot work permit should be kept in the site file as well as being displayed at the site.
The hot work permit should also address housekeeping and other measures such as inspection of work site and identification and handling of hot products subsequent to the hot work activity.
Training and awareness should be provided to all site personnel and contractors covering:
- the hazards associated with hot work
- use of the hot work permit system
- use of firefighting equipment
- emergency and evacuation procedures
The Australian Standard AS 1674.1 Safety in Welding and Allied Processes Part 1: Fire Precautions provides guidelines with regards to hot work activities and an example of a typical hot work permit.
This video safety alert below highlights the dangers of cutting used drums for storage, feed trays etc. Flammable substances can still be present in old drums. Even if they have been cleaned and rinsed, the introduction of an ignition source can create a disastrous explosion.