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Petroleum and gas safety alert no. 36 | 26 February 2009 | Version 2

Inappropriate modification and use of wrenches and stilsons

What happened?

Incidents continue to occur in which hand tools, particularly stilsons and other types of wrenches, are being used inappropriately. Hand tools are just that, designed to be used as hand tools. They are not designed to have attachments such as crowbars, pipe-lengths or other items welded to or bolted to them.

Petroleum and Gas Inspectors continue to find modified use of hand tools, particularly in the drilling industry, but are yet to see any manufacturer endorse its products being cut, welded or otherwise attached to a device.

Unauthorised modifications of hand tools are a serious safety breach. Unauthorised modifications can stress the hand tool beyond its design limits.

In some cases, the modified hand tools have ruptured violently, posing serious hazards and injuring people. There have been serious hand, arm and facial injuries (including a broken jaw).

Key issues

  • Hand tools are designed and manufactured to specific conditions by the manufacturer.
  • Hand tools are designed to be operated by hand only with no additional devices.
  • Modifications seriously compromise the hand tool's integrity.
  • Risk analyses need to be undertaken for any change or planned change to a hand tool. The manufacturer must be consulted and should authorise any changes.


  • Organisations should review their operational procedures and change management procedures in their safety management plans (SMP) to ensure there is no inappropriate use of hand tools.
  • Changes to equipment require an engineering design and assessment and 'formal safety assessment consisting of the systematic assessment of risk'.
  • Use of modified tools must be documented in the SMP and available for inspection by the Inspectorate upon request.

Investigations are ongoing and further information may be published as it becomes available. The information in this publication is what is known at the time of writing.

We issue Safety Notices to draw attention to the occurrence of a serious incident, raise awareness of risks, and prompt assessment of your existing controls.

Authorised by Chief Inspector, Petroleum and Gas

Contact: Chief Inspector, Petroleum and Gas

Issued by Queensland Department of Mines and Energy