Site report: tower power

Wolffkran’s strongest luffing cranes are working on the Kusile Power Plant project Kusile, Nkangala district, Mpumalanga province, South Africa

To help with energy shortages, two new power plants are being constructed in South Africa. One is based in Nkangala district, located in the north-eastern province of Mpumalanga.

The main contractor for the coal fired Kusile Power Station is Mitsubishi Hitachi Power Systems Africa (MHPSA). The power plant will consist of six 800 MW units and produce 4,800 MW of electricity a year. Once complete it will be the fourth largest coal-fired power plant in the world.

To help with the construction MHPSA has put seven Wolff tower cranes on site, including four Wolff model 1250 B and three Wolff model 355 B. Tasks for the cranes include moving steel and concrete elements weighing up to 60 tonnes. Approximately 115,000 tonnes of steel will be installed in the construction.

The 60 tonne lifting capacity 1250 B’s have Wolff Fine Positioning controls and have been erected on cross frame crane bases to a tower height of 120 metres and 60 metre jib radius. They are tied to the stair towers of the boiler plants.

Andreas Kahl, Wolffkran managing director, said, “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. The crane concept envisages that one of the 1250 B cranes will be relocated to Unit 6 as construction progresses.”

The 28 tonne capacity Wolff model 355 B cranes are on UW 260.3 undercarriage crane bases and are configured with 50 m jib radius and 9 m tower height. They have been erected on top of the 122 m high boiler plants, giving them an overall hook height of 186 m. “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,” Kahl added.

The luffers have been put on rails on the roof of the boiler plants, allowing them to have a movement radius of approximately 40 m. They are now being used on Units 2, 3 and 4.

Economical lifting

To help with the assembly technical monitoring of the work, four Wolffkran service technicians were sent to the site. Kahl explained why, “The requirements for the personnel on the construction site are very high and the safety regulations are understandably strict. 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.”

In the past, Mitsubishi Hitachi Power Systems had only used crawler and lattice-boom cranes in South Africa for power plant construction. MHPSA brought the seven Wolff cranes following the construction of coal-fired plants in Wilhelmshaven in Germany and Maasvlakte in the Netherlands.

Stanley Langkilde, MHPSA construction services manager, said, “With this investment, we are not only investing in Kusile, but also in future power plant projects. 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.”

Three further 355 B Wolff cranes owned by MHPSA are also currently in use at the Medupi Power Station in the neighbouring province of Limpopo. Working on behalf of the South African electricity generator Eskom, the two coal-fired power plants in Kusile and Medupi will provide energy for the region.

This site report was taken from the January 2016 issue of International Cranes and Specialized Transport magazine.