The mega power plant will consist of six 800 megawatt units and produce 4,800 megawatts of electricity a year making it the fourth-largest coal-fired power plant in the world. It goes without saying that the dimensions on the site are correspondingly big: Almost 60-ton heavy steel and concrete elements have to be moved, and a total of approximately 115,000 tons of steel will be installed in the construction. A job for the strongest WOLFFs in the pack. Therefore, no less than four BIG WOLFF 1250 B luffing cranes are in use in South Africa since this year. At the power plant site they really earn their place with their impressive lifting capacity of up to 60 tons. But by the same token, they also convince with the standard WOLFF Fine Positioning controls allowing for a centimeter accurate positioning of loads, which is of major importance in the cramped conditions on the construction site.
Despite having a tower height of 120 meters, the WOLFF 1250 B cranes with their 60-meter-long jibs are only tied to the stair towers of the boiler plants once. "Working together with MHPSA, our technical support department developed special collar frames for the stair towers to enable simple and yet stable anchoring of the crane to the structure", explains Andreas Kahl, Managing Director at WOLFFKRAN. "The crane concept envisages that one of the 1250 B cranes will be relocated to Unit 6 as construction progresses," says Kahl.
Economical – luffing crane on top of boiler plant
The four red giants are supported by three WOLFF 355 B luffing cranes with 50-meter jibs, which were erected directly on top of the 122-meter high boiler plants. In this way, an overall hook height of 186 meters was achieved with the use of just one tower segment. "This saves on space on the ground as well as costs for the customer, because fewer tower elements are required and the assembly, using a mobile crane, is much faster," says Andreas Kahl. Mounted on the mobile WOLFF undercarriage UW 260.3, the luffers can move back and forth along rails on the roof of the boiler plants and thus have a movement radius of approximately 40 meters. They were already used from 2011 to 2013 on first three of the six boiler plants and are now being used on Units 2, 3 and 4.
Four WOLFFKRAN service technicians were sent to South Africa for the assembly and technical monitoring of the work. "The requirements for the personnel on the construction site are very high and the safety regulations are understandably strict," says Andreas Kahl. "The space on the site is not only very restricted, but it also appears quite chaotic to the untrained eye. In addition to the seven WOLFFs, numerous crawler and lattice-boom cranes are also in use to move very heavy and large components. That is why safety has top priority at the site," says Kahl.
Proven concept convinces customer
To date, Mitsubishi Hitachi Power Systems has only used crawler and lattice-boom cranes in South Africa for power plant construction. The successful combination of WOLFF 355 B and WOLFF 1250 B cranes in the construction of the coal-fired plants in Wilhelmshaven (Germany) and Maasvlakte (Netherlands) convinced MHPSA of the more economical tower crane concept. After the European construction projects were successfully completed with rental cranes, MHPSA successively bought the seven WOLFFs for the mega-project in South Africa. "With this investment, we are not only investing in Kusile, but also in future power plant projects," says Stanley Langkilde, Construction Services Manager at MHPSA. "The concept suits our needs perfectly. Together with WOLFFKRAN’s technical services and the long-lasting, modular cranes, we are very well set-up in the power plant supply and construction market," says Langkilde.
Three further 355 B WOLFF cranes owned MHPSA are also currently in use at the Medupi Power Station in the neighboring province of Limpopo. Working on behalf of the South African electricity generator Eskom, the two modern coal-fired power plants in Kusile and Medupi will bring a reliable supply of energy into the resource-rich region for decades to come.
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