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MSHA: MNM Close Call Accident Alert Surface - Dimension Stone

December 4, 2017

MSHA: On 23 October 23, 2017, the boom of a Pellegrini stiff leg derrick failed while lifting a muck bucket. The crane operator and the foreman were in the operator’s station, or “crow’s nest,” on the edge of the high-wall. As the boom started to fail, they were able to run to safety before the operator’s station was crushed. The derrick collapsed into the quarry, but no injuries occurred.

Best Practices: 
  • Do not overload the crane.  Know the load chart and weight of the object to be lifted in order to avoid tipping or causing structural damage to the crane.
  • Periodically inspect the crane in accordance with the procedures in the operator’s manual.
  • Follow the manufacturer’s guidelines when making repairs or conducting other maintenance on the derrick.
  • Examine and test all safety devices on a regular basis and ensure that they are operating properly.
  • When using cable clips to secure a wire rope, always apply the proper torque, use the amount required based on the rope diameter, and follow the rigger’s rule of “never saddle a dead horse” when positioning the clip.
  • Never side load the boom by rapidly swinging the load or picking up a load when it is not directly under the boom tip. Side loading the boom could cause a collapse.

Source

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