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Four workers injured in gas explosion

In June 2023, four workers were injured in a workplace gas explosion and fire.

Early enquiries indicate they were clearing a gas line by purging a liquefied petroleum gas (LPG) boiler line, creating a flammable atmosphere in the room. For reasons not yet known, a brazing torch ignited the atmosphere, resulting in an explosion and fire.

Safety issues

LPG is a highly flammable gas stored in tanks and cylinders under pressure in a liquefied state. It’s used as a gaseous fuel for a wide range of purposes. The main potential dangers of gases in cylinders or tanks are:

  • damage to a valve or regulator may cause a failure and rapid release of the gas
  • heating of the cylinder from a heat source including fire or an impact to the pressure vessel may lead to a catastrophic rupture resulting in a rapid and large release of gas and flying shrapnel
  • an uncontrolled release of a flammable gas may lead to a fire or explosion, particularly in a confined area where potential ignition sources are present.

LPG is heavier than air which means that on release, it will tend to collect in adjacent low-lying areas such as pits, depressions and basements. People working in low-lying areas where LPG is present may then be exposed to the risk of fire, explosion or asphyxiation.

LPG can be readily ignited by a range of ignition sources, including hot work. Hot work is any process involving heat treatment, grinding, welding or any other similar process that involves high-energy such as heat, sparks or naked flames. Hot work may also involve the use of portable power tools and energised equipment. Hot work in areas where flammable or combustible chemicals are present creates a significant risk of fire or explosion.

Ways to manage health and safety

Effective risk management starts with a commitment to health and safety from those who manage the business. If an incident occurs, you'll need to show the regulator that you’ve used an effective risk management process. This responsibility is covered by your primary duty of care in the Work Health and Safety Act 2011.

Use the hierarchy of controls to help decide how to eliminate and reduce risks in your 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. You must work through the hierarchy of controls when managing risks, with the aim of eliminating the hazard, which is the most effective control.

Possible control measures to prevent similar incidents

The Work Health and Safety Regulation 2011 requires specific controls for prevention of fire and explosion risks associated with hazardous chemicals. These include:

  • s51 - A PCBU a workplace must manage risks to health and safety associated with a hazardous atmosphere at the workplace
  • s52 - A PCBU a workplace must manage risks to health and safety associated with an ignition source in a hazardous atmosphere at the workplace
  • S355 - A PCBU must ensure that the ignition source is not introduced into a hazardous area (from outside or within the space).

A hazardous area must be identifiable from a hazardous area classification process that has been undertaken by the designer of a system involving flammable gas, otherwise a classification is to be undertaken by the person conducting a business or undertaking (PCBU) who has management control of the system. This will help ensure that potential ignition sources are controlled in this defined area.

The classification process will account for the potential release points of gas and the extent of the ventilation available to disperse flammable gas. Identification of a hazardous area also provides for installation of appropriately rated electrical equipment where required in that area. Further, operational activities can be established for the area to exclude ignition sources.

PCBUs must also manage risks to health and safety associated with a hazardous atmosphere that may be generated by a flammable gas. In relation to hazardous chemicals, a hazardous atmosphere is when the atmosphere has a concentration of flammable gas that exceeds five per cent of the lower flammable explosive limit (LEL) for the vapour. The LEL for LPG is typically quoted in the range of 1.8–2.4 per cent by volume in product safety data sheets (SDS).

Managing the risks includes identifying and managing all sources of ignition, such as welding, hot-cutting and grinding, which generate heat, flames and sparks that could cause an ignition. You must ensure that flammable or combustible substances in the workplace are kept in the lowest practicable quantities.

PCBUs must consider implementing higher order risk controls when installing, operating, maintaining, repairing, removing or decommissioning an LPG gas tank and associated pipe work and fittings. This includes a safe system of work. Petroleum and gas legislation in Queensland requires that LPG gas work is only undertaken by authorised people.

When installing and commissioning a flammable gas-fuelled boiler or LPG tank:

  • have work procedures for the safe installation and commissioning of the system accounting for fire and explosion risks associated with the flammable gas
  • account for the hazardous areas that have been identified for the system
  • keep a hazardous chemicals register to list hazardous chemicals stored, handled or used at the workplace – the current SDS for each of the hazardous chemicals listed must be included with the register
  • refer to the SDS for the flammable gas for information on the flammability hazards and associated risk control measures including first aid, firefighting measures, release measures, ventilation requirements to prevent the accumulation of flammable gas in enclosed areas, safe handling and storage practices and personal protection equipment to be used
  • ensure safe work procedures account for any hot work to be performed and implement appropriate safe work procedures such as a hot work permit system. More information on hot work permit systems is available in the following Australian Standards:
  • consider the use of calibrated flammable gas detectors by a competent person to monitor the atmosphere in the work area and have action trigger levels identified for when gas is detected
  • consider that although reduced-sparking tools or non-sparking tools made of metals such as brass or bronze have a lower risk of generating sparks, they still generate cold sparks which can cause flammable vapours to ignite due to their relatively low ignition energy (ignition energy for LPG is typically 20 milli Joules)
  • use fire-resistant barriers to prevent other non-related hot work (e.g. welding or grinding) sparks accidentally reaching flammable and combustible materials including nominally empty containers
  • ensure worker training, experience and competency aligns with the requirements and complexity of the task (workers must be trained by a competent person and have the appropriate skills to carry out a particular task safely).
    • Keep records of completed training and ensure training is always fit-for-purpose. Some examples might include:
      • how to work safely in hazardous environments, such as confined spaces, hazardous atmospheres, and hazardous areas
      • how to safely control any fire and explosion hazards if performing hot-work on storage and handling systems containers that have contained chemicals
      • how to access safety data sheets (SDS) for hazardous chemicals and be able to understand key information in the SDS and container labels
      • proper use, storage and maintenance of personal protective equipment
      • what the emergency response actions are
      • where the gas isolation points are located and how to operate them.

Under the Work Health and Safety Regulation 2011, 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 at the workplace
  • the nature of the hazards at the workplace
  • the size and location of the workplace
  • the number and composition of the workers and other persons at the workplace.

A PCBU must also ensure the workplace is provided with fire protection and firefighting equipment that is designed and built for the system having regard to the fire load and must be compatible with Queensland Fire and Emergency Services equipment. Ensure such equipment is properly installed, tested and maintained, and dated records kept of the testing and maintenance.

More information

Have you been affected by a workplace fatality, illness or serious injury?

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