|Health and Safety Executive - Safety Alert|
|Department Name:||Construction Sector|
|Bulletin No:||FOD 4-2010|
|Issue Date:||24 June 2010|
|Target Audience:||Owners and users of Manitowoc Potain Tower Cranes & Thorough examination bodies. Industries - Construction, Engineering, Metals and Minerals processing and production, Manufacturing (general), Off Shore, Nuclear, Docks, Ceramics, Chemical processing and production, Entertainment and Leisure.|
|Key Issues:||A manufacturing defect has been identified in spigots used on K600 and K800 mast sections used in Manitowoc Cranes, Potain MD, MDT and MR Tower Cranes. There have been two known mast section failures from this cause. Action is needed to identify any other potentially affected mast sections and ensure they are taken out of service immediately then quarantined for further investigation.|
We are aware of two crane mast failures in which faulty mast section spigots were implicated. The first of these incidents was in Chicago in February 2009. The most recent incident involved a crane in London in April 2010. Metallurgical tests undertaken on the London crane showed that the spigot failed catastrophically in brittle fracture from a small fatigue crack. The tests have shown that the failed spigot did not meet the performance characteristics specified for the component. It is believed that there was a flaw in the heat treatment process during the manufacture of the spigot. Whilst investigations continue to isolate the cause of the problem, as a precaution all spigots manufactured between 1 November 2006 and 28 Feb 2007 are suspected of being substandard and subject to the remedial action outlined in this document.
Figure 1 shows an example of a spigot with the batch number visible on centre right of the photograph.
If a tower crane mast fails and collapses there is potential for multiple fatalities. Tower crane masts or towers are constructed from a number of individual sections which are located one on top of another to achieve the required height. For the type of cranes covered by this safety notice, spigots provide a means of connecting individual mast sections together. Their condition is crucial to the integrity of the mast. Each mast section has 4 spigots. They locate within female housings on the mast section fitted above. Once assembled the batch numbers of the spigots are hidden by the female housing and cannot be read. There is no non-destructive testing which can be undertaken to check the current condition of the spigots. The only effective means of preventing mast collapse is to identify and remove all potentially affected spigots from service or weld additional reinforcement in accordance with the specification provided by Manitowoc Cranes.
We have been informed by Manitowoc Cranes that the K600 and K800 series mast sections are only used on MD,MDT and MR series cranes.
K600 and K800 series mast sections manufactured between 1 November 2006 and June 2007 (when spigot stocks were exhausted) are in scope. Each mast section has a unique identification number known as a PIN number. See figure 2 for details of where to find the number. The numbers for mast sections produced in this time period are in the range 80323 - 103784.
Figure 1 gives an example of the spigot number. The potentially affected spigots are in the ranges 3086* to 3496* and 0037* to 0577* - the letter on the end of the reference number is irrelevant for identification.
For general advice on tower cranes work see
Contact Manitowoc Cranes for advice on welding solution:
Steve Bradby B.Eng., C.Eng.M.I.Mech.E.
UK After Sales Manager (Tower Crane Product),
Direct Dial: +441280818856
Post: Manitowoc Crane Group (UK) Ltd
Manitowoc House, Network 421,
Radclive Road, Gawcott, Buckingham. MK18 4FD.
Please pass this information to a colleague who may have this equipment.