14.06.2008

Safe or not?

The two Sun tower cranes shut down in Seattle two weeks ago have now been inspected by an independent engineer who claims that neither meets safety standards, according to a statement from the state Department of Labor & Industries yesterday.

A third Sun crane working in Renton which was also shut down has now been certified safe and is back at work. All three were stopped due to claims that their electrical systems were not certified as safe, while the two Seattle units used structural components from different manufacturers.

The electrics on all three are now fully certified, however there is now a debate going on regarding the Seattle cranes. It seems that Lewis Equipment, the importer of the Yongmao cranes which it markets under the Sun brand in North America, has built these two cranes using a mix of Sun/Yongmao tower sections while at least some other parts, possibly the superstructure, are built by Terex Comedil.

The state is maintaining that its rules require that the tower cranes be used in accordance with the manufacturer's specifications. While SunCrane has approved the mix, Terex/Comedil’s manuals clearly prohibit the use of its components with those of other manufacturers.
There is also some confusion due to the allowed wind speeds from the two manufacturers, with one allowing 25 mph for one crane and the other 33 mph for components employed.

Dallas-based Lewis Equipment says that it believes the cranes are safe and that the mixed parts are compatible. The cranes have been submitted to all the relevant safety and overload tests which they have passed.
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Vertikal Comment

Due to the sensitive nature of this incident, we have not yet been able to obtain the full details of this ongoing situation. From what we understand Lewis has simply used a Yongmao tower under a Comedil top, something which is not unheard of. Such an application clearly requires the proper calculations to have been carried out and the manufacturer’s approval obtained. While a purpose built and certified transition section needs to be used between the tower and the superstructure.

The state and the crane inspector are naturally being cautious given recent accidents and media coverage involving tower cranes. The ball most likely is in Terex’s lap, whose standard statement is that components must not be mixed.

Given the litigious atmosphere in the USA and the fact that in many respects Lewis is a competitor, there cannot be much of an incentive for Terex to approve this application?

Most manufacturers are very clear with their views regarding the use of non original components and parts, considering it to be highly dangerous. However a number of them will approve the use of a different tower with their superstructures, in the case where it is as strong as or stronger than the original and an approved and fully certified transition component is used.

In fact we are aware of at least one reputable manufacturer that will check and approve a competitor’s tower for its cranes, while at least one will even fabricate the transition section. We would be pleased to hear your views. [email protected]