Installation of Building Maintenance Units on existing, long-established buildings and structures always presents specific challenges. Commonly, issues are associated with the lack of construction equipment on-site for heavy lifting and the time pressures of completing work with the minimum disruption to everyday business.

As the service provider for the Alimak Group, consisting of the leading names in the vertical access industry such as CoxGomyl, Alimak Service is uniquely qualified to deliver custom service solutions for any project. This was recently demonstrated during the installation of a replacement BMU for the 200 Clarendon building (formerly known as the John Hancock Tower) in Boston.

The Building Maintenance Unit (BMU) had to be positioned in a designated parking area around the existing track in the centre of the roof. The additional complications of antennas, heating, ventilation and air conditioning (HVAC) equipment made an installation by helicopter or derrick crane unfeasible. Therefore, the BMU itself was designed to present manageable parts which could be transported to the roof via the elevators. This still left a 25-metre journey from the roof hatch to the installation site with HVAC equipment blocking a clear path, with antennas and wires also making a route around the units impractical.

A rigging scaffold was designed to facilitate direct transport of the BMU parts into position by hoisting over HVAC units. Time was a significant factor, and the rigging scaffold was therefore equipped with two beams and two motorised trollies. This allowed two crews to work simultaneously with one group lifting the BMU parts through the hatch while the second crew worked on BMU assembly in the parking area.

The BMU crossbar middle section and platform presented an additional challenge in that, at 11 metres and 20 metres respectively, they could not be transported via the elevators. The Alimak Service team, therefore, developed a solution using the old BMU to lift the crossbar under the platform area with special outriggers used to lift it into place.

To lift the platform, the new BMU had to be partially commissioned to make use of the hoist functionality. The wire ropes were lowered to ground level with tensioning weights attached to mullion guides. There, the wire ropes were connected to the platform and a weight test was performed. This allowed for operators to safely board the platform during the hoisting process to monitor the mullion guides.

Both of these complex installation procedures were each completed in a day and the installation as a whole was completed in under two weeks.

Contact Alimak Service or the project team at CoxGomyl and Manntech, to discuss the project management and installation processes for your building access project.

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