Safety alert issued after three hot work incidents occur in one month

In October 2022, a worker suffered serious burns to his upper body after being engulfed by a fire at an engineering workplace. Early investigations revealed he was welding a metal plate to repair a leak to a tank, when an explosion occurred that resulted in a fire. In a second incident in October, a worker suffered facial injuries when the lid of a 44-gallon drum struck him. Investigations revealed he was preparing to remove the drum lid with a range of cutting tools, when an explosion occurred. The majority of the lid separated from the drum, causing him injury. A third fire and explosion incident also occurred in October, which resulted in one worker receiving fatal burns and two other workers sustaining serious burns. Initial enquiries indicated one worker was using an electric grinder at the time to cut a drum.

‘Hot work’ is any process involving grinding, welding, brazing, oxycutting, heat treatment or any other similar process that generates heat or continuous streams of sparks. Undertaking hot work in areas where flammable or combustible chemicals or materials are present could create a risk of fire or explosion. Conducting hot work on containers such as drums, tanks and pipes that have not been properly decontaminated is a common cause of serious incidents. Even if a drum or container is considered to be empty and has been empty for some time, flammable vapours can still remain and be a risk of explosion when heat is applied. Rinsing drums or containers is not a fail-safe way to remove oily residues or flammable vapours.

Small quantities of flammable or combustible substances within a closed drum or fuel tank on which hot work is conducted can have catastrophic impacts; incidents have occurred where bungs are left in steel drums and containers are sealed/closed off, effectively creating a bomb. Heated residues expand and can pressurise the container to the point of failure, leading to a significant release of energy that can cause harm to people or property. Fuel containers are not the only containers of concern; some chemical formulations such as agricultural chemicals may also include flammable or combustible solvents presenting similar fire or explosion risks with their containers.

Taking steps to manage risks is a condition of doing business in Queensland. If an incident occurs, business owners will need to show the regulator that they have used an effective risk management process — this responsibility is covered by the primary duty of care in the Work Health and Safety Act 2011. Employers are advised to use the ‘hierarchy’ of controls to determine how to eliminate and reduce risks in their place of work. The hierarchy of controls ranks types of control methods from the highest level of protection and reliability to the lowest. It’s a step-by-step approach to eliminating or reducing risks.

The Work Health and Safety Regulation 2011 requires specific controls for preventing fire and explosion risks associated with hazardous chemicals. These include S51, in which a person conducting a business or undertaking (PCBU) must manage risks to health and safety associated with a hazardous atmosphere in the workplace; and S52, in which a PCBU must manage risks to health and safety associated with an ignition source in a hazardous atmosphere at the workplace.

If there is a possibility of fire or explosion in a hazardous area being caused by an ignition source, PCBUs must ensure the ignition source is not introduced into the area. PCBUs must also manage risks to health and safety associated with a hazardous atmosphere — this includes identifying all sources of ignition — such as welding, hot-cutting, and grinding — which generate heat, flames and sparks that could cause an ignition. In relation to hazardous chemicals, a hazardous atmosphere is when the atmosphere has a concentration of flammable vapour that exceeds 5% of the lower flammable explosive limit (LEL) for the vapour. PCBUs must ensure that the flammable or combustible substances are kept in the lowest practicable quantities. This includes waste liquids in containers and gas cylinders, whether empty or full.

Effective controls for fire and explosion risks associated with hot work are often made up of a combination of controls, including avoiding the reuse of fuel containers and ensuring they are properly disposed of; and isolating fuel sources from ignition sources.

A safe system of work should be implemented to manage the fire and explosion risks associated with hot work activities. This can include having a hot work permit system designed to control when and how hot work is undertaken, and obtaining a current safety data sheet (SDS) from the manufacturer, importer or supplier of the chemical and making the SDS readily available to workers. PCBUs are advised to keep a hazardous chemicals register for use by workers; a hazardous chemicals register is a list of hazardous chemicals stored, handled or used at a workplace — the current SDS for each of the hazardous chemicals listed must be included with the register.

Employers should also check what has previously been stored in the empty drum or container by reading the label and reviewing the SDS for the hazardous chemical and assessing the information provided on safe storage and handling. If it has been found to contain flammable or combustible substances, employers should dispose of the container and avoid any hot work on it. Employers are advised to be wary of any container that is not correctly labelled or has an unknown history; the best approach is to properly dispose of such containers, otherwise it will have to undergo appropriate cleaning or testing to ensure that there is no fire or explosion risk resulting from historical contents.

If there is no alternative but to perform hot work on the container, employers should remove all traces of flammable or combustible materials from the container to ensure it is properly cleaned of residues and vapours and certified as vapour-free by a competent person. Fire-resistant barriers should also be used to prevent other non-related hot work sparks from accidentally reaching flammable and combustible materials including nominally empty containers. Drums should not be used as welding or work platforms, and empty drums should be stored with bungs removed, in a well-ventilated place away from other work areas. Removing the bung will not guarantee all hazardous residues and vapours have been naturally vented. Fire-fighting equipment must be maintained and kept nearby.

Workers — including inexperienced workers — should receive instruction, training and supervision on the fire and explosion hazards, and safe work procedures. Training should be provided to workers by a competent person with information, training and instruction provided in an easy-to-understand manner. Employers must ensure worker training, experience and competency aligns with the requirements of the task; this includes keeping records of training completed and ensuring training is always fit-for-purpose.

A PCBU must prepare an emergency plan to reduce the effects of an emergency involving hazardous chemicals at their place of work. When preparing an emergency plan, a PCBU must consider all relevant matters, including the nature of the work being carried out, the nature of the hazards at the workplace, the size and location of the workplace, and the number and composition of the workers and other persons at the workplace.

PCBUs must also ensure the workplace is equipped with fire protection and firefighting equipment that is designed for the types of hazardous chemicals at the workplace. The workplace should consider the hazardous chemicals from the perspectives of the quantities in which they are used, handled, generated or stored. In Queensland, fire protection and firefighting equipment must be compatible with equipment used by the Queensland Fire and Rescue Service. It must also be properly installed, tested and maintained with a dated record kept of the latest testing results and maintenance until the next test is conducted. The control measures put in place must be reviewed regularly to ensure they are still effective.

Image credit: iStock.com/Kittisak Kaewchalun