Crane failures in high winds prompt HSE warning
Three luffing jib tower cranes have collapsed recently in high winds prompting HSE to make information available to tower crane users as supplementary guidance to that contained in BS7121 Part 5:2006, Code of practice for safe use of cranes -Tower cranes.
Safety Alert: FOD 2 – 2014 states that HSE has identified that some tower crane users have not been releasing the slew brake and/or placing the jib at the correct out of service radius, when leaving cranes out of service and unattended.
In these conditions it is possible that the crane may not be able to weathervane freely in high winds resulting in very high loadings on the crane.
HSE advises users that the following action is required:
- “Ensure they have the most accurate, up to date information for the specific crane they are operating by discussions or correspondence with the supplier or manufacturer as some manufacturers have recently changed their guidance;
- Check that such information includes the correct minimum out of service radius for the specific crane they are operating with the supplier or manufacturer;
- Check both after erection and periodically in service, the function of the device that releases the slew brake and places the crane in free slew;
- Check both after erection and periodically in service, that the condition of the slew drive motors, gearboxes and slew ring bearing has not deteriorated to the extent that the crane is prevented from slewing freely;
- Check both after erection and periodically in service, the setting and function of any devices that warn the operator that the crane jib has not been left parked at the correct out of service radius and/or the slew brake has not been released;
- Ensure that operators have been provided with instructions on how the crane should be placed in free slew and the correct radius at which the jib should be positioned when leaving the crane unattended. This should include measures to routinely check that the operators understand and are following the instructions provided;
- Undertake periodic checks that the buildings under construction, other cranes or high reach plant are not preventing the crane from free slewing. Consideration needs to be given to both front jibs and rear counter jibs.”
Manufacturer declares itself “free of blame”
It has been reported by Construction Index that the manufacturer of a crane involved in such incidents has investigated the failures and declared itself free of blame.
The company state that in each case the operator failed to leave the slewing brake off when out of service, adding:
“All the structural calculations are good. We have enough safety factor in the jib if the crane is operated correctly”
However, Jost Cranes is reported to have acknowledged that it would be a good idea for crane manufacturers to adopt the use of an automatic interlock system that prevents cranes being left with the slew brake locked adding:
“We want to see this implemented on all tower cranes of all types from all manufacturers”