Barnhart's innovative engineering solutions were on display for a rigging project at a nuclear plant in Louisiana. Barnhart had to design a lift system that would span the 178' inside diameter tank to support the 600,000 lb. projected weight of the clarifier while its 16 lateral supports were removed. The project utilized both a Heavy Lift Crawler Crane and a telescoping Hydraulic Crane to assemble the lift system. The "backbone" of this lift system featured Barnhart's 8' girder sections that were connected on the ground to a total length of 180'. Once assembled, these 8' girders weighing up to 225,000 lbs. were set to the clarifier walls with tandem lifts by the aforementioned cranes.
Due to the compromised structural stability of several grey lateral supports holding the 600,000 lb. clarifier, worker safety prevailed as the facility would not allow access inside the unit. Therefore, the clarifier had to be supported from above allowing for the safe removal of the lateral supports.
Barnhart custom fabricated stability kickers for the 8' girders on the wall, deflection load spreading rockers for the girder contact points and various spreader bars to accommodate the complicated rigging design challenges. With all the rigging in place, the clarifier was lifted and held in place while the lateral supports were removed.
With the lateral supports removed, Barnhart positioned pull-up gantries and 5' girders to support the clarifier from beneath. Then, the overhead girder/lift system was disassembled and removed. Once the new lateral supports are in place and connected, the gantries and girders will be removed allowing this Clarifier Unit to go back into service.