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Worker seriously injured by wood chipper disk

In September 2021, a contractor suffered multiple fractures and a severe laceration while repairing a chipper disk weighing around two tonnes. For reasons yet to be established, the unrestrained chipper disc (part of a large wood chipping machine) has fallen from an upright position striking the contractor’s leg as it fell.

Investigations are continuing.

Safety issues

Plant and machinery come in many different shapes and sizes. Wood chippers are used in tree trimming and removal work to turn tree waste into wood chip or mulch. Although the design of individual wood chippers may vary, they all use a rotating disc or drum fitted with hardened steel blades to chip the wood.

All wood chippers require access to the cutting disc or drum for maintenance, operation and

cleaning purposes.

Source: Safe Work Australia - Guide to Managing Risks of Tree Trimming and Removal Work

Machinery, including wood chippers, pose significant risks to people providing maintenance or repair services, including but not limited to;

  • exposure to machine components that process materials by cutting, grinding, crushing, breaking or pulping/pulverising
  • moving heavy parts when changing the set-up of the machine
  • changing and handling chipper knives.

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

Before carrying out plant maintenance, you need to ensure the maintenance activities will comply with any requirements under relevant work health and safety legislation in relation to the work.

Effective control measures for plant maintenance are often made up of a combination of controls. Some common risk control measures can include but are not limited to the following examples.

Develop a safe system of work for maintenance, repair or cleaning  activities. This could include, but is not limited to:

  • Ensuring the plant is inspected, maintained and repaired according to the manufacturer’s recommendations and specifications.
  • Consulting with the manufacturer, workers and others involved in the work to obtain feedback on the plant and associated work processes and safe work procedures.
  • Providing information, training, instruction and supervision to workers who use the plant that includes developing safe work procedures in accordance with the manufacturer’s instructions.
  • Developing an isolation procedure which should be followed by workers when they are required to perform maintenance, repair and cleaning of plant. Isolation procedures involve isolating potentially hazardous energy so the plant does not move or start up accidentally. Isolating plant may also ensure entry to a restricted area is controlled while the specific task is being carried out.
  • Locking out remote controls to ensure they cannot be activated when the worker is within the danger zone
  • Ensuring the plant, or part of the plant, that could move is adequately secured to prevent unexpected movement. This could include:
    • installing mechanical locks to support parts that are suspended by hydraulic systems
    • using props, blocks or chocks
    • using purpose designed and engineered support stands, jigs or cradles.
  • Ensuring there is sufficient space for safe access to the plant for maintenance, repair, or cleaning activities.
  • It is also good practice to keep records of plant in your workplace. Records on items of plant that may be kept include:
  • information on alterations
  • information on maintenance and major repairs carried out
  • manufacturer’s specifications and user manuals
  • results of tests on the plant including safety devices.
  • Determining what special skills are required for people who operate the plant or carry out inspection and maintenance, including preventative maintenance.

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

  • when handling chipper knives, it is necessary to ensure that workers are protected from the cutting edge by gloves, aprons or other means.
  • hard hats, protective footwear, eye protection, hearing protection.

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.

More information

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