A Terex AC 1000 was recently utilized by Austrian crane service provider Felbermayr to lift gigantic pipes inside the cooling tower of a unit at the Šoštanj power plant in Slovenia.
The conditions that awaited project team at the site were anything but normal. In order to install two pipes, the Terex AC 1000 all-terrain crane would have to work together with a 551-ton assist crane inside a cooling tower of a lignite-fired power plant.
Setting up the AC 1000
One side of the cooling tower had been left open so that the cranes could drive in, but that was the only concession that was given regarding space, the rest had to take place within an extremely limited space. A tight schedule was set for the project. The crane had to be inside the tower and ready to start working at 8:00 a.m., September 26, 2012.
“A total of five days–that was all we had to go in, set up, perform the lifts, tear down, and take away the crane,” reports Michal Lehner.
On September 24, 2012, the AC 1000 travelled 242 miles with its main boom on from Felbermayr’s Linz location to the site, accompanied by 11 transport vehicles carrying additional components. The project’s first big challenge came during set up. Due to tight space conditions and the fact that construction work was still being done at the power plant, the team at Felbermayr had to follow a precise plan.
The first step was to place the AC 1000 inside the tower at exactly the right spot. The crane was then moved into position to an accuracy of 10 cm so that it would be able to reach the working radii required for the two lifts. Once the crane was in position, the necessary components were brought in with trucks. Only one truck could go into the cooling tower at a time, it had to be fully unloaded and then driven out of the tower before the next truck could move in.
“Mounting the 138-ft.long luffing jib was one thing that really required laser-like precision from all those involved,” reports Heiko Stichler. The team managed to get the crane ready to go, with the boom extended as necessary, in just one day. “We configured the AC 1000 with a 138-ft. luffing jib, 42.6-ft. outriggers, and a counterweight of 119 tons for the lifts, which is where the AC 1000’s ease of setup became invaluable,” explains Michael Lehner.
The main boom was set up with a length of 138 ft. Telescopic segments one through three were extended 90% each, while segment four was extended 45%. This set up provided the AC 1000 with a total boom length of 269 ft.
Tandem and Single lifts
On September 26, the Felbermayr team was ready to perform the two lifts, a tandem lift and a single lift. The team performed the tandem lift first: A 13-ft. long plastic pipe with a diameter of about eight meters and a weight of approximately 40.7 tons (including rigging gear) had to be lifted to a height of 211.6 ft. over a protruding edge of a height of 183.7 ft.. Working at a radius of 93.8 ft., the AC 1000 picked up the load in tandem with the 500 t Liebherr assist crane. During the lift, the radius was reduced to 75 ft. and the pipe was rotated 45° at a hook height of 211.6 ft., then it was set down on a concrete pipe at the center of the cooling tower.
The AC 1000 took on the second lift by itself: This time, the crane had to lift a 39-ft. long plastic pipe with a diameter of 26 ft. and a weight of 27.6 tons. Once this pipe was attached to the spreader, crane operator Robert Gruber lifted the load at a radius of 255 ft. Once lifted to a height of 256 ft., the AC 1000 was able to set down the second pipe on top of the first one.
The particular challenge was that crane had to hold the pipe in position for five hours until the special adhesive required to join the two pipes was fully cured. “That was easy to do with the AC 1000 as well. The crane had already proven to be an outstanding machine during the two lifts,” reports Robert Gruber, who not only found the crane performance on the road and the cab comfort impressive, but the short setup times as well – especially the time saved by the ease with which the outriggers were mounted and the fact that the main boom could be left on when traveling on the road.