This part of ISO 7919 gives guidelines for applying evaluation criteria for shaft vibration measured in the radial direction at or close to the bearings of steam turbines and generators. These guidelines are presented in terms of:

• vibration under normal steady-state operating conditions;
• vibration during transient operation, including passage through resonant speeds during run up or run down;
• changes in vibration which can occur during normal steady-state operation.

The numerical values specified are not intended to serve as the only basis for vibration evaluation since, in general as described in the introduction to ISO 7919-1, the vibratory condition of a machine is assessed by consideration of both the shaft vibration and the associated structural vibration (see ISO 10816-2).

This part of ISO 7919 is applicable to land-based steam turbines and generators with a normal operating speed of 1 500 r/min, 1 800 r/min, 3 000 r/min or 3 600 r/min, and power outputs greater than 50 MW. It also includes steam turbines and/or generators which are directly coupled to a gas turbine (such as for combined cycle applications). In such cases the criteria of this part of ISO 7919 apply only to the steam turbine and the generator. Evaluation of the gas turbine vibration should be carried out in accordance with ISO 7919-4 and ISO 10816-4.