September 25 - Vanguard has transported, offloaded and installed power generation equipment for the Dedisa Peaking power plant in Port Elizabeth.
Two sets of 191-tonne gas turbines, 231-tonne generators and 140-tonne transformers were transported from the Coega port to the project site, where the equipment will help stabilise the national electricity grid from 2015.
According to Vanguard project manager Dale Huddy, the six heavy units arrived at the Coega port in two shipments. "After directly discharging the vessels, we staged the heavy units in our port yard - in order to relocate the equipment in the required sequence for delivery," he explained.
"The turbine needed to arrive at the Dedisa site first, and was loaded onto our 16-axle, three-file Goldhofer trailer."
Each Goldhofer muti-axle combination loaded with the heavy units was powered by a push-pull combination of Mercedes Actros prime movers.
Passing under the N2 highway, the planned route for the convoy included only a couple of challenging corner turns, said Huddy. "We managed to navigate the tight corners so that there was only one road island to traverse, and the trailer's sophisticated multi-axle suspension technology handled that with ease, distributing the load evenly despite the axles having to navigate different heights."
To lift and place the heavy units into final position on their respective foundations, Vanguard had set up its 500-tonne hydraulic gantry lift system on site. "We manoeuvred the trailer in line with the foundations and between two sets of rails on which our gantry system was placed," Huddy went on.
"After detaching the turbine's transport saddle, our gantries were able to lift and travel forward with the turbine over a distance of 40 m to its final resting place - lowering the unit onto four threaded rods on either side of the turbine itself," he explained. "Alignment was achieved by the accurate placement of slings over the header beams and lifting the unit in the correct position."
The generator and transformer were then relocated, offloaded and positioned on site in a similar fashion, using a second set of Vanguard's 600-tonne gantries to lift the units onto trailers.
Elsewhere in the Eastern cape, Vanguard is providing crane services for 20 wind turbine generators at the new Grassridge wind energy facility near Port Elizabeth.
For this project, Vanguard will lift and position the 3MW Vestas V112 wind turbine generators at an average rate of two per week at the facility, which can generate up to 60MW of renewable energy - enough for about 40,000 homes.
Once the base of the turbine tower is secured on its foundation at the wind farm site, Vanguard's GTK1100 crane and support crane are then positioned to install the two top tower sections of each turbine, which weigh up to 60 tonnes and measure up to 30 m in length.
"We then lift and position the remaining components of the turbine," explained project manager Joost Heystek. "This includes the nacelle hub and the three 55 m turbine blades."
The drive train weighs some 60 tonnes, with the combined weight of the nacelle and its contents exceeding 130 tonnes. Vanguard said that the considerable size and weight of the nacelle makes it necessary to transport its components separately and to assemble them on site.
Heystek added that there are some challenges on site: "We carefully monitor the wind speeds and wind gusts. Different components are more aerodynamic than others, so they have differing maximum wind speeds in which they can be safely lifted and positioned. On occasion we must simply wait for calmer conditions before we can continue."
For this project Vanguard teamed up with Azari Group, which is the mechanical and electrical installation service provider of the wind turbine generators.