HSE issues urgent tower crane alert

The Health and Safety Executive (HSE) has issued a warning to owners and users of tower cranes regarding the correct installation of high tensile bolts including those on masts, jibs and slew rings.

It highlights the need to correctly install and tighten these bolts saying: “Failure to do so could lead to the bolt connection failing, with catastrophic consequences.”

It said the information is supplementary guidance to that contained in BS 7121 Part 2:2003 ‘Code of practice for safe use of cranes – Inspection, testing and examination’, and “comes as a result of ongoing work with the tower crane industry”. It adds that adds that information is issued “without prejudice to any ongoing investigation”.

Key recommendations are:

• Use only high tensile bolts from the crane manufacturer or a quality assured vendor to the original manufacturer’s specification and replace the connections in accordance with the manufacturer’s recommendations. High tensile bolt connection components should not be reused unless permitted by the manufacturer and parts that have been immersed in water should be tested before reuse.
• Examine all components for wear, damage and corrosion before installation and ensure a good tolerance fit. Lubricate the components before installation and assemble in the correct sequence, tightening as specified by the crane manufacturer.
• Use a calibrated torque wrench on the nut rather than the bolt head, unless the manufacturer specifies otherwise. Re-tension as specified by the manufacturer - typically 3-6 weeks  - and ensure regular inspections by a competent person to check the pre-load has not reduced.

During this inspection, particular attention should be paid to check there is no visual movement at joints as a load is taken off and on the crane, the nuts have not worked loose and there are no rust stains indicating movement at the joint. It details subsequent checks and procedures if tension has been lost or other problems noted including taking the crane out of service if there are concerns regarding the integrity of the high tensile bolt connection.
 
For the full text go to: http://www.hse.gov.uk/construction/pdf/cranebolt.pdf