Setting of turbine rotor float

Float check and zero setting are done when the rotor is in stationary condition. If there is face-out in the thrust-collar, (though possible) it is difficult to make out during the 'float check'. This existence of 'face-out' would make a different reading while running from that set condition. Face out could be a local problem of thrust-collar or due to a bend in the shaft (which developed on the run due to reasons like imbalance).

Float check and zero setting are done when the rotor is in stationary condition. If there is face-out in the thrust-collar, (though possible) it is difficult to make out during the 'float check'. This existence of 'face-out' would make a different reading while running from that set condition. Face out could be a local problem of thrust-collar or due to a bend in the shaft (which developed on the run due to reasons like imbalance).

The XT reading fixed during assembly of Thrust bearing always increase during operation. It is very rare when there is no increase in set value. There are three main reasons:

1. Thermal Growth of Rotor

2. Springness effect on operationg loads

3. Residual run out of collar

In my point of view XT reading of + 0.20 mm is quite normal provided it is stable and bearing babbitt temperatures are less than 95 celcious.