Virginia, USA-based crane rental company W.O.Grubb used a Manitowoc MLC300 lattice boom crawler crane to replace an industrial lime kiln at a plant in Wilmington, North Carolina.
The plant was located near a river in a coastal region, so the job site’s terrain was soft and wet. The lift called for a crane that could fit into a tight space and lift the 215 US ton (190 tonnes) kiln, but could still handle the tricky terrain.
A feature of the crane that proved especially useful for this job, the company said, was the Variable Position Counterweight (VPC) and its ability to reduce the ground bearing pressure of the crane as less counterweight is needed.
Jeff Collins, vice president of engineering and administration at W.O. Grubb, said that he chose the 330 US ton (approximately 300 tonnes) MLC300 because of its capacity, small footprint and low ground bearing pressure.
“We had to erect the crane in an alleyway and only had an allowable ground bearing value of 2,000 pounds per square foot (psf) to work with. Without the VPC, we couldn’t have made the crane light enough to safely complete the job,” he said. “Also, the MLC300 was a good choice for this job because it gave us the size and load capacity on a compact footprint.”
The crane’s primary job was to lift the lime kiln that measured 25 feet (7.6 m) in diameter through a 35 ft by 75 ft (10.6 m x 22.8 m) opening in the roof of a 45 ft (13.7 m) tall structure. The kiln was then placed on storage stands and hauled to a remote laydown area. The MLC300 then lowered a replacement kiln through the same opening so that an engineering team could weld the new unit into place.
Collins continued, “We were working in a very tight spot. The crane had to be positioned within inches of a building wall at one end, with only a three inch (76.2 mm) vertical clearance between the top of the counterweight stack and the bottom of a pipe rack under which the counterweights were forced to swing. It was a complex series of lifts, but even working in such tight quarters, the MLC300 performed flawlessly. We were able to finish the turnaround in 36 hours.”