The voestalpine Foundry Group casts components for the Siemens SGT5-8000H gas turbine, the largest gas turbine in the world today. The casting of the steel for the turbine components is a highly complex process offered by only a few companies around the world.
The Siemens SGT5-8000H gas turbine is 13 meters long, five meters high and weighs 444 tons. Not only is it the largest gas turbine to date, it is also one of the most efficient. It has a total capacity of 578 MW and achieves an efficiency of 60.75 percent in combined gas/steam turbine operation. During operation, the components of such a high performance turbine are subject to enormous forces—the centrifugal force for example is comparable to 10,000 times the force of gravity. In addition to mechanical stresses, the steel in a turbine must withstand the extreme pressure and tremendous heat in the turbine’s combustion chamber. The temperature can reach 1,500 degrees Celsius (just over 2,700 degrees Fahrenheit). The material used must be able to withstand extreme loads and requires a lot of production know-how and experience.
Complex and sophisticated casting
The voestalpine foundries in Linz and Traisen were chosen as the producers and suppliers of the main casting parts. The Linz foundry produces the part known as the cone (both the top and bottom half) and the vane carriers, each of which weighs more than 40 tons. The Traisen foundry is the sole supplier of the inner and outer diffusers for the Siemens turbine. The compressor vane carriers are also cast in Traisen. Heat resistant steel with around 1.25% chromium is used because it retains its good mechanical properties at high temperatures.
The first components have already been delivered, and more components have been ordered.