Manitowoc’s 21000 was the star of the show at Conexpo this year, where it made its debut. What makes it distinctive is the innovative “Octa-trac” design. Instead of two long crawler tracks, it has a pair of short tracks in each corner – eight, in total. This is to spread the load, reduce ground pressure, and so allow the crane to be more compact than a 1,000 US ton -capacity machine could otherwise expect to be.
Among the many to be impressed at Conexpo was Anthony Crane Rental, which placed an order. And in August the crane made its first ever jobsite lift, precision-placing a 349t (385 US ton) vessel in an operating chemical plant on the Gulf Coast of Texas. The load, a distillation column, was 62m long, and 4.3m wide. The column was part of an expansion to boost the output of the four-year-old plant to meet rising demand for light hydrocarbons that are used to make plastics.
According to Manitowoc, the chemical company’s construction managers selected the 21000 for the job because it provided “the ideal combination of capacity, mobility, and compactness to work in the congested site. They also selected the 21000 because extensive experience had convinced them Manitowoc cranes are utterly reliable.” Shipped to the site on tractor-trailer trucks in modules weighing 43.5t (96,000lb) or less, the 21000 was assembled in the relatively small open area where it would make its inaugural lift.
The footprint of the 21000 can be increased if required, or decreased where space is tight, by moving the crawler units away from or back towards the car body. For this lift the narrow crawler configuration was used, with the crawler base standing 9.1m wide by 14m long. In this configuration, the 21000 can pick and travel with any rated load, including its 900t (1,000 US ton) Max-er capacity. When swing is required, stabilisers attached to the sides of the lowerworks permit full 360O rotation.
Early in the assembly, components were handled with a hydraulic crane, while a 272t (300 US ton)-capacity Manitowoc 2250 Series II, also owned by Anthony, was put together nearby. Once assembled, the 2250 picked and placed the 21000’s remaining components. The 2250 also acted as tailing crane when the 21000 later uprighted the distillation column.
As the Octa-trac eight-crawler system distributes loads, the only site preparation needed was timber mats laid over crushed rock.
For the lift, the 21000 was rigged with 85.3m of boom, including its standard heavy-lift top. The tailing 2250 was rigged with its 21.3m basic boom.
As the lift began, the 21000’s upperworks sat perpendicular to its crawlers with the boom extending over the side and rigged to the column’s top. The 2250 was rigged to the column’s bottom. At this point, the 2250 held about 170t, and the 21000 held 179t at a radius of 19.8m.
As the column rose and the 21000 boomed in, the 2250 travelled 60m to tail the column. When the vessel was vertical, the 21000 took the full 349t of load and rigging, and the 2250 was cut loose. The 21000 then hoisted the 62m column to clear obstructions and swung 90O to position it over the front crawler modules. The 21000’s stabilisers were then raised and the crane crawled forward about 6m before lowering the column over anchor bolts at a radius of 13.7m. The entire lift took just 90 minutes.
Anthony’s director of specialised lifting, Mike Ricigliano, is clearly a fan of the new crane. “The 21000 gives us capabilities no other crane can match,” he said. “It combines the capacity of a 1,000 US ton crane with the easy mobilisation and space requirements of a 500 tonner. There’s nothing else like it.”