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Four injured in workplace explosion

In November 2021, one worker was seriously injured while three other workers received minor injuries following a workplace explosion and fire.

Early enquiries indicate an “extractor” has exploded. This machine is used to extract rosin and turpentine from pine wood chips by spraying hot turpentine over the wood chips in a process known as solvent extraction. For reasons yet to be established, an explosion has occurred.

Investigations are continuing.

Safety issues

Processes that generate heat and flames are sources of ignition. When combined with fuel and oxygen, there’s a significant risk of fire and explosion. While the greatest risks are with common flammable liquids like petrol, kerosene and ethanol, combustible liquids such as diesel fuel and oils can behave like flammable liquids when they are heated. These liquids may generate vapours when heated. When confined, these vapours can also cause an explosion if ignited.

Hot work is any process involving heat treatment, grinding, welding or any other similar process that generates heat. Hot work in areas where flammable or combustible chemicals or other materials are present creates a significant risk of fire or explosion.

Ways to manage health and safety

Taking steps to manage risks is a condition of doing business in Queensland. 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 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

Wherever flammable liquids, vapours and gases are generated, used, stored and handled, you should do a hazardous area classification to determine the extent of applicable exclusion zones for potential ignition sources. Exclusion zones are divided into zone 0, 1, or 2 based on the probability of a flammable atmosphere being present.

A hazardous area is an area in which a flammable atmosphere is or may be expected to be present from time to time, and requires special precautions for the construction, installation and use of equipment, particularly electrical equipment or any other equipment that can produce hot surfaces, arcs or sparks. A common example of a hazardous area is the vapour space inside an unleaded petrol tank and the area around its vent opening. Once hazardous areas and applicable zones are identified, potential ignition sources can be identified and either eliminated or controlled to prevent a fire or explosion.

A person conducting a business or undertaking must, if there is a possibility of fire or explosion in a hazardous area being caused by an ignition source being introduced into the area, ensure the ignition source is not introduced into the area (from outside or within the space).

You can control potential sources of ignition in a hazardous area by:

  • doing a hazardous area assessment to determine the relevant hazardous area classification and extent of hazardous zones in and around equipment
  • ensuring any later changes to the operation or design of equipment associated with a hazardous area are managed with suitable processes that re-assess the hazardous area classification and zones. An example of a change in operation is opening a vent/cover which is normally required to be air-tight (closed) during use of the equipment.
  • use of suitably rated electrical equipment (intrinsically safe or flame-proof)
  • ensuring the electrical installation is maintained and electrical equipment is properly earthed
  • ensuring the auto-ignition temperature of the hazardous chemical is considered as some hazardous chemicals may ignite spontaneously above certain temperatures
  • where electrical installations or equipment need to be located or used in a hazardous area (lighting, forklift trucks, torches etc), these items must be designed and constructed so they cannot release energy within the hazardous area that is sufficient to cause an ignition. Any equipment designed and constructed to operate within a hazardous area must also be supplied with documentation stating in which zone and temperature class etc. that it is suitable to be operated (certificates of conformity from IECEx – IEC System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres).
  • ensuring only licensed electrical workers who are competent to install, service and maintain electrical equipment associated with hazardous areas are engaged. In addition, electrical installations within a hazardous area in Queensland must be inspected by an Accredited Auditor appointed under the Electrical Safety Act prior to the installation being energised
  • ensuring imported plant is assessed by a competent person to verify it complies with Australian conditions and the duties for importers of plant under the Electrical Safety Act and WHS Act prior to installation or use.

Positioning plant in the workplace to ensure:

  • risks from hot plant, for example, molten material and hot gases, can be controlled through restricted access, guarding or insulation
  • there is sufficient space for safe access to the plant for operation, cleaning, maintenance, inspection and emergency evacuation
  • the proximity to other plant does not have a negative effect on operation of the plant or work processes
  • the plant rests on a suitable foundation where required, for example on a floor or other support that ensures the plant is stable and secure
  • ventilation can deal with the nature and volume of emissions from the plant.

Engineering controls include mechanical devices that eliminate or minimise the generation of chemicals, suppress or contain chemicals, or limit the area of contamination in the event of spills and leaks. They often involve partial enclosure, use of exhaust ventilation or automation of processes. Examples include:

  • providing ventilation (mechanical extraction) to vent to a safe area. Ventilation systems should be suitable for the types of hazardous chemicals at the workplace. To ensure the effectiveness of ventilation systems:
    • they should be designed in accordance with appropriate technical standards, and installed and maintained by qualified or experienced persons, such as engineers or occupational hygienists.
    • they must be resistant to the vapours being extracted
    • exhaust gases and air should be discharged where they will not cause other hazards
    • regular checks of the system (fixed and/or portable types) should be included in planned maintenance schedules to ensure that the type of ventilation is still fit for purpose.
  • designing plant to relieve and redirect pressure and flame when an explosion occurs
  • installing systems to detect leaks of flammable gases or vapours.

Administrative controls should only be considered when other higher order control measures are not practicable, or to supplement other control measures. This can include developing a safe system of work. This could include, but is not limited to the following examples:

  • developing policies and safe work procedures for the use, handling, storage, clean up and disposal of hazardous chemicals
  • implementing safe work procedures to limit ignition sources in hazardous areas
  • determining what special skills are required for people who operate the plant or carry out inspection and maintenance
  • providing easy to understand information, training and instruction to workers
  • workers must be trained and have the appropriate skills to carry out a particular task safely. Training should be provided to workers by a competent person.
  • the arrangements in place to deal with emergencies, including evacuation procedures, containing and cleaning up spills and first aid instructions
  • the availability of SDS for all hazardous chemicals, how to access the SDS, and the information that each part of the SDS provides
  • ensuring there is sufficient space for safe access to the plant for maintenance, repair, or cleaning activities.

Any remaining risk must be minimised with suitable personal protective equipment. For example:

  • overalls, aprons, footwear, gloves, chemical resistant glasses, face shields, respirators and air-supplied respiratory equipment.

Adopting and implementing higher order controls before considering administrative or PPE controls will significantly reduce the likelihood of a similar incident occurring. The control measures you put in place should be reviewed regularly to make sure they work as planned.

Source: WorkSafe QLD