Wings on a generator

Indian heavy lifting and transport contractor Freight Wings P. Ltd. (FWPL) specialises in the movement of heavy and oversize cargo by land and sea. It undertakes contracts both in India and abroad using equipment that includes hydraulic axle systems, cranes, four point hydraulic jacking system and barges.

FWPL recently demonstrated its abilities by installing a 300t steam turbine generator for Bechtel at the Enron Dabhol power plant on the west coast of India, south of Mumbai. The generator at Ratnagiri was positioned 14m above ground level with a Power Tower (34PT500WT) hydraulic system manufactured by Lift Systems of the USA. The Power Tower system has four telescopic lifting legs, powered by two diesel-driven power packs (one for each pair of towers). It can lift 500t to a height of approximately 11m, and according to FWPL it is particularly effective on sites where space or headroom is restricted.

How it was done The first stage of the lifting project was to put in place the vertical temporary steel structures to support the hydraulic lifting gantry system in an elevated position. The lattice structures were mounted on concrete blocks. Next, the runway tracks were bridged between the temporary steel structures and the generator foundation. A transfer girder and the associated transfer links, used for intermediate load transfer, were then placed onto the runway bridge. The gantry system was then rigged up for lifting with its accessories and other gear.

Hydraulic axle lines were used to transport the 300t steam turbine generator to the erection point and the generator was offloaded from the axles onto concrete blocks using the integrated hydraulics on the axle lines.

In the second stage of the operation the generator was lifted to a height level with the transfer girder and the links on the runway tracks. All four gantry legs were then lowered simultaneously. The lifting gear was slackened, and the entire load was shifted to the transfer girder.

After retracting the gantry the long lift links were replaced with correspondingly shorter ones. Again the generator was transferred, from transfer girder to the lifting links. The transfer girder and its links were then removed. The generator was lifted so that its base was about 300mm clear of the top of its foundations.

With the generator now elevated, the third stage of the operation was to move it into position horizontally. Push-pull hydraulic cylinders were attached to the legs of the gantry system and the generator was moved horizontally to its final position above the anchor bolts where it was then lowered onto its foundation. Rigging gear was removed from the generator and the gantry system was dismantled for the next lift.