Up go the girders (and trolleys)
20 Jun 2016
It took 55 trucks to deliver the parts for the giant crawler crane and ten days to assemble them.
Positioned above the Assembly Hall, the crane's boom holds a man-sized hook that passes through the roof. The crane, delivered from Saudi Arabia for this lifting task, is operated by personnel from the Dutch company Mammoet.
In order to lift the four girders and their corresponding trolleys into position 43 metres above the Assembly Hall basemat, the crawler crane was positioned outside the building. Its boom, high above the building, held a man-sized hook that passed through an opening in the roof and reached down to the waiting components.
Below, workers were busy adjusting cables, slings, braces and shackles in order to perfectly balance the first load to be lifted—one of the four girders, now fully equipped with 30 tonnes of gear motors, wheels, braces, and electrical equipment and weighing 186 tonnes.
Despite the spectacular setting and the size of the components, the professionals appeared unfazed. "It's a standard operation," says Roberto Lanza of the ITER Building & Civil Works Section. "We'll first lift then slightly tilt each girder in order to align it with the rails above."
The operation is a mix of brute force, high technology and worker know-how. Connected by radio to the lifting supervisor, the crane operator sitting in his cabin outside the building slowly lifts the load. Surveyors direct their laser beams to ensure that everything is proceeding nominally, and men on the ground and up in the rafters use ropes to adjust the component's position.
As with all things ITER, tolerances are stringent. "The final adjustment must be ... and will be ... perfect," says Roberto.
Two of the four girders are now in place as well as one of the four 100-tonne trolleys. Lift operations will continue and by the end of this week the Assembly Hall will be fitted out with one of the most spectacular tools required for the assembly of the machine.
The Liebherr LR 11000, with a lifting capacity of 1,000 tonnes and a maximum hoist height of 222 metres, is one of the most powerful crawler cranes available. This one was shipped to ITER from Saudi Arabia.
Gear-motors, wheels, braces, and electrical equipment —the fitting out of the girders has added some 30 tonnes. Each girder now weighs 186 tonnes.
As the girder is lifted toward the overhead rails, 43 metres above the basemat of the Assembly Hall, a bit of pushing and pulling tilts it in the right direction.
A man-sized hook is passed through an opening in the roof by the beam of the crawler crane. The crane operator, with no direct line of sight to the lifting operations, receives radio instructions from the "rigger," who oversees the whole operation.
The four girders and four trolleys will be lifted into place over a period of 10 days. The first girders were installed on 14 and 16 June, followed by first of the four 100-tonne trolleys.
On Friday 17 June, a trolley is lifted to join the two girders already in place. Operators moved the girders to the end of the building to free the opening in the roof.