China-based engineering service provider Penglai Jutal used four Terex crawler cranes for a synchronised lift of a 470 tonne steel framework as part of the assembly of an offshore oil platform on the coast of Penglai in China.
The company chose two Terex CC 6800 and two Terex CC 2500-1 crawler cranes to perform the lift, which not only involved hoisting the load but also to butt joint the 75 x 22 metre steel pipe framework of the platform’s central supporting structure on top of a previously positioned section prior to welding.
Following a test run, the four cranes simultaneously lifted the framework to clear the ground to a height of 8 m and then steadily crawled forward 10 m. To maintain the right angle of approach, the cranes hoisted their respective sides of the load to different heights.
The two CC 6800s were configured with a superlift mast, a 114 m main boom elevated 81 degrees at a 21 m radius, and 360 tonnes of counterweight and central ballast to lift their end up to 57 m.
On the opposite side, set up with a 74 m main boom elevated to 83 degrees at a 14 m radius, and a total counterweight and central ballast of 180 tonnes, the two CC 2500-1s lifted the load to a height of 41 m.
Once all four cranes had the frame hoisted to the required height, they crawled with the load for 75 m until the load faced the frame structure. Once in place, the crane operators co-coordinated their hydraulic movements to join both sections together on an incline. The whole process was completed in less than four hours.