SCHAAF and SCHAAF Service finished the large retrofit program successfully to replace the reamer bolts by ETC ExpaTen bolts. Itís for steam turbine generator connection at 670 MW thermal power plant (ETC - Efficient Turbine Connection, ExpaTen bolt - Expansion Tension bolt).
In the early 2016 SCHAAF got the order to deliver all necessary bolts and nuts including the pre-tensioning devices and support accessories from one of the biggest steam turbine manufacturer in China.
One main part of the contract scope of supply was line boring for the two rotor flanges connection with the turning gear wheel. The requirement of bore surface quality and diameter preciseness was very high since the whole power of the turbine has to be transmitted at maximum speed of 3000 rpm. That is a speed of 150 m/sec which is equivalent to more than 500 km/h in regard of the PCD of 873 mm.
Within only one week the in-situ line boring was done within the tolerance of 0.01 mm, the tapered sleeves of the ExpaTen ETC bolts were machined according to the FEA calculation. Furthermore, the weight balancing of the ExpaTen bolt ETC was carried out within this time period. The unbalance mass reaches highest performance with the tolerance of +/- 2 grams in total.
We thank our customer for the good support and looking forward to the next projects.