African Fusion March 2015

Wind tower fabrication

Wind Tower fabrication: the DCD way

DCD Wind Towers was set up in March 2013 and be- gan producing tower sections later that year. African Fusion visits the company’s fabrication facilities in the Coega industrial development zone (IDZ) and talks to productionmanager, Leonard Jauka, about its processes and capabilities.

Wind Towers’ production manager, Leonard Jauka.

T rainedat theNelsonMandelaMet- ropolitan University (NMMU) in Port Elizabeth, Jauka joined DCD Wind Towers in November 2013 at the starting point of commercial production. “I did a degree in industrial engineering and, after working at a local Goodyear facility for a few years, I joined DCD to improve the production efficiency of the wind tower fabrication process. To re- main competitive, we need to find ways to cut away non value adding operations and to promote those activities that are directly incorporated into theprice of our product,” he tells African Fusion. “The core value adding activity of this facility is welding, and we employ mainlyGMAW, FCAWandsemi-automatic submerged arc welding,” Jauka contin- ues. “But my experience is production, so I am learning about welding all the time,” he adds. Describing the particular require- ments for wind tower manufacturing, he says that the key productivity goal is to balance each part of the production line so that the fabrication of each wind tower segment proceeds steadily and efficiently through the plant, without causing delays or inactivity further into the process. The plate for the first commercial can was cut on Saturday February 15, 2014, for a Vestas V112, 3,075 kW wind turbine destined for InnoWind’s Grass Ridge project 25 km South of PE. DCD Wind Towers has now completed and delivered five three-section towers for this project, which was commissioned during January this year. In total, this plant has 20 turbines capable of produc- ing 61.5 MW which, at a capacity factor of 25%, is equivalent to 134.7 GWh of

join that can to the previously completed one. So we join and grow, join and grow until the tower is the required length. Thenwe add the end flange. But balanc- ing the work on the growing lines is also important. Fabricating bottomsections, for example, takes up 45% of the total welding time, because of the thicker section plate being welded particularly on the threebottomsectionswith38mm plate thicknesses,” he tells AfricanFusion. “At any one time in the plant, we aim tohave one canbeing joined to the tower section in one of the lines, a can-to can- fit-up being completed on the second line, can rolling on the third line and plate cutting for the fourth,” he notes. At the fabrication starting point a plate is put through a wheel abrator to take off the rough scale. “The abrator blasts grit onto both sides of plate as it enters the facility. From there, a three headed CNC-controlled ESAB oxyfuel cutting system cuts the plate to size, while simultaneously bevelling the edges for welding. Due to the different conical shapes of each can in a segment, each sequential can has a different size, so automatic control of this process is essential and each can has its own unique identifier that is generated be- fore the plate enters the facility,” Jauka explains. The cut plate is then taken toa cham- fering table to polish and clean the bevel and take off the dross. “At this stage we have our first quality hold point. The quality controller checks that the plate is dimensionally accurate for the specific can and tower section being fabricated, to within around 1.0 mm of tolerance. If okay, he places a green sticker on it, but the plate will remain at the holding

power per year – enough to supply the basic annual needs of up to 40 000 South African households. “Our current work also involves Vestas turbines for a secondwindproject dubbed ‘Chaba’.” The requirement is for seven towers split into 21 separate sections, which will support turbines supplying 21 MW of power to the Great Kei municipality at Komga, up near the Kei River north of East London. The first turbine is due to be operational in July 2015, with the facility reaching full capacity in September. For this project, DCD Wind Towers will locally build all of the wind towers. DCD’s fabrication process, accord- ing to Jauka involves fabricating three structural section for each tower, a top section, a middle section and a base section. Each of these is flanged so that the 84 mtowers can be erected onsite by bolting them together. Each individual section is made by welding together a series of cans, which vary in diameter and plate thickness – 5.0 m in diameter and 38mm for a typical base section and 3,5 to 4,0mand 16mm thickness for top sections. “Each section consists of 9, 10 to 11 cans, most of which are tapered, so fabrication has to be done in a strict sequence,” he explains. Four growing lines The concept being employed to achieve production and cost efficiency is ‘grow’ each tower section, can by can, on a growing line. “We have four parallel growing lines at this facility, which all need to be busy and balanced for maxi- mum output capacity and efficiency,” says Jauka. “For each line, the idea is that we cut, roll and seal a can, then we

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March 2015

AFRICAN FUSION