Management at a cement plant challenged Barnhart to solve a project they believed was impossible – the removal and replacement of a 9,600-pound. Bellowseal damper, which was buried behind steel and handrails and hidden around a corner. Slanted sidewalls wouldn’t allow for a conventional crane boom or even the ability to drop a hook from above. There were numerous overhead obstructions and over 40 feet of 8-foot. diameter double wall stainless ductwork, which could not be removed.
Removal required an approach that could bend around a corner 180 degrees, safely lift the damper, remove and replace. Barnhart’s engineers settled on a unique solution – a double cantilever approach. A multi-pick beam was attached to the primary beam. Counterweights were attached to this secondary cantilever. The unit was lifted by a GMK 275-ton all-terrain crane.
All components were outfitted with swivels to allow the damper to move in any direction and bend completely around a corner for both extraction and installation. Barnhart’s crew carefully guided the double cantilever system into position using remote controls, tag lines, and radios. They navigated the system between two buildings, under a slanted wall, over the ductwork, and around the corner to hook onto the damper.
The old damper was removed and lifted above the existing ductwork avoiding all obstacles and was safely brought to the ground. The process was reversed to install the new damper. Barnhart’s work on the complex project was awarded a Specialized Carriers and Rigging Association (SC&RA) 2020 Rigging Job of the Year under $150,000.