DIN ISO 7919-4:2010-06

The document provides specific guidance for assessing the severity of radial vibration measured on the shafts of gas turbines with fluid-film bearings in situ. The criteria provided in this document apply to heavy-duty gas turbine sets used in electrical and mechanical drive applications, with outputs greater than 3 MW and a speed range under load between 3000 r/min and 30000 r/min. This includes gas turbines coupled to other rotating machinery either directly or through a gearbox. 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 should be in accordance with this part of ISO 7919 but that of the steam turbine and generator should be assessed using ISO 7919-2 or ISO 7919-3. Two criteria are provided for assessing the machine vibration when operating under steady state conditions. One criterion considers the magnitude of the observed vibration; the second considers changes in the magnitude. In addition, different criteria are provided for transient operating conditions, such as run-up and coast-down. The evaluation procedures presented in this part of ISO 7919 are based on broad-band measurements.