This part of ISO 7919 establishes provisions for evaluating the severity of in-situ, broad-band shaft vibration measured radial (i.e. transverse) to the shaft axis at, or close to, the main bearings. These are in terms of: - vibration under normal steady-state operating conditions;- vibration during other (non-steady-state) conditions when transient changes are taking place, including run up or run down, initial loading and load changes;- changes in vibration which can occur during normal steady-state operation. This part of ISO 7919 is applicable to heavy-duty gas turbine sets used in electrical and mechanical drive applications, with fluid-film bearings, outputs greater than 3 MW and an operating speed range under load between 3 000 r/min and 30 000 r/min. This includes gas turbines coupled to other rotating machinery either directly or through a gearbox. In some cases, this part of ISO 7919 is not applicable to the evaluation of the vibration of the coupled equipment (see the list of exclusions in this clause). EXAMPLE For single-shaft combined-cycle power units in which a gas turbine is coupled to a steam turbine and/or generator, the evaluation of the gas turbine vibration is according to this part of ISO 7919, but that of the steam turbine and generator is according to ISO 7919-2 or ISO 7919-3.