ISO/TC 108/SC 2/WG 1 - Rotordynamics and vibration of machines

This document specifies requirements for determining and classifying mechanical vibration of individually housed, enclosed, speed increasing or speed reducing gear units. It specifies methods for measuring housing and shaft vibrations, and the types of instrumentation, measurement methods and testing procedures for determining vibration magnitudes. Vibration grades for acceptance are included. Torsional vibration measurements are outside the scope of this document. It applies to a gear unit operating within its design speed, load, temperature and lubrication range for acceptance testing at the manufacturer's facility. By agreement between manufacturer and customer and/or operator, it can be used for guidelines for on-site acceptance testing and for routine operational measurements. This document applies to gear units of nominal power rating from 10 kW to 100 MW and nominal rotational speeds between 30 r/min and 12 000 r/min (0,5 Hz to 200 Hz). This document does not apply to special or auxiliary drive trains, such as integrated gear-driven compressors, pumps, turbines, etc., or gear type clutches used on combined-cycle turbo generators and power take-off gears. The evaluation criteria provided in this document can be applied to the vibration of the main input and output bearings of the gearbox and to the vibration of internal shaft bearings. They can have limited application to the evaluation of the condition of those gears. Specialist techniques for evaluating the condition of gears are outside the scope of this document. This document establishes provisions under normal steady-state operating conditions for evaluating the severity of the following in-situ broad-band vibration: a) structural vibration at all main bearing housings or pedestals measured radially (i.e. transverse) to the shaft axis; b) structural vibration at thrust bearing housings measured in the axial direction; c) vibration of rotating shafts radially (i.e. transverse) to the shaft axis at, or close to, the main bearings; d) structural vibration on the gear casing. NOTE Vibration occurring during non-steady-state conditions (when transient changes are taking place), including run up or run down, initial loading and load changes are outside the scope of this document.

This document is applicable to land-based gas turbines with fluid-film bearings and power outputs greater than 3 MW and an operating speed under load between 3 000 r/min and 30 000 r/min. In some cases (see the list of exclusions below), this includes other rotating machinery coupled either directly or through a gearbox. The evaluation criteria provided in this document are applicable to the vibration of the main input and output bearings of the gearbox but are not applicable to the vibration of the internal gearbox bearings nor to the assessment of the condition of those gears. Specialist techniques required for evaluating the condition of gears are outside the scope of this document. This document is not applicable to the following: i) gas turbines with power outputs greater than 40 MW at rated speeds of 1 500 r/min, 1 800 r/min, 3 000 r/min or 3 600 r/min (see ISO 20816-2); ii) aero-derivative gas turbines (including gas turbines with dynamic properties similar to those of aero-derivatives); NOTE ISO 3977-3 defines aero-derivatives as aircraft propulsion gas generators adapted to drive mechanical, electrical or marine propulsion equipment. Large differences exist between heavy-duty and aero-derivative gas turbines, for example, in casing flexibility, bearing design, rotor-to-stator mass ratio and mounting structure. Different criteria, therefore, apply for these two turbine types. iii) gas turbines with outputs less than or equal to 3 MW (see ISO 7919-3 and ISO 10816-3); iv) turbine driven generators (see ISO 20816-2, ISO 7919-3 and ISO 10816-3); v) turbine driven pumps (see ISO 10816-7); vi) turbine driven rotary compressors (see ISO 7919-3 and ISO 10816-3); vii) the evaluation of gearbox vibration (see this clause) but does not preclude monitoring of gearbox vibration; viii) the evaluation of combustion vibration but does not preclude monitoring of combustion vibration; ix) rolling element bearing vibration. This document establishes provisions for evaluating the severity of the following in-situ broad-band vibrations: a) structural vibration at all main bearing housings or pedestals measured radial (i.e. transverse) to the shaft axis; b) structural vibration at thrust bearing housings measured in the axial direction; c) vibration of rotating shafts radial (i.e. transverse) to the shaft axis at, or close to, the main bearings. These are in terms of the following: - 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.

ISO 20816-2:2017 is applicable to land-based gas turbines, steam turbines and generators (whether coupled with gas and/or steam turbines) with power outputs greater than 40 MW, fluid-film bearings and rated speeds of 1 500 r/min, 1 800 r/min, 3 000 r/min or 3 600 r/min. The criteria provided in ISO 20816-2:2017 can be applied to the vibration of the gas turbine, steam turbine and generator (including synchronizing clutches). ISO 20816-2:2017 establishes provisions for evaluating the severity of the following in-situ, broad-band vibration: a) structural vibration at all main bearing housings or pedestals measured radial (i.e. transverse) to the shaft axis; b) structural vibration at thrust bearing housings measured in the axial direction; c) vibration of rotating shafts radial (i.e. transverse) to the shaft axis at, or close to, the main bearings. These are in terms of the following: - 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. ISO 20816-2:2017 is not applicable to the following: i) electromagnetic excited vibration with twice line frequency at the generator stator windings, core and housing; ii) aero-derivative gas turbines (including gas turbines with dynamic properties similar to those of aero-derivatives); NOTE ISO 3977‑3 defines aero-derivatives as aircraft propulsion gas generators adapted to drive mechanical, electrical or marine propulsion equipment. Large differences exist between heavy-duty and aero-derivative gas turbines, for example, in casing flexibility, bearing design, rotor-to-stator mass ratio and mounting structure. Different criteria, therefore, apply for these two turbine types. iii) steam turbines and/or generators with outputs less than or equal to 40 MW or with rated speeds other than 1 500 r/min, 1 800 r/min, 3 000 r/min or 3 600 r/min (although generators seldom fall into this latter category) (see ISO 7919‑3 and ISO 10816‑3); iv) gas turbines with outputs less than or equal to 40 MW or with rated speeds other than 1 500 r/min, 1 800 r/min, 3 000 r/min or 3 600 r/min (see ISO 7919‑3 or ISO 7919‑4 and ISO 10816‑3 or ISO 10816‑4); v) the evaluation of combustion vibration but does not preclude monitoring of combustion vibration.

ISO 20816-1:2016 establishes general conditions and procedures for the measurement and evaluation of vibration using measurements made on rotating, non-rotating and non-reciprocating parts of complete machines. It is applicable to measurements of both absolute and relative radial shaft vibration with regard to the monitoring of radial clearances, but excludes axial shaft vibration. The general evaluation criteria, which are presented in terms of both vibration magnitude and change of vibration, relate to both operational monitoring and acceptance testing. They have been provided primarily with regard to securing reliable, safe, long-term operation of the machine while minimizing adverse effects on associated equipment. Guidelines are also presented for setting operational limits. NOTE 1 The evaluation criteria for different classes of machinery will be included in other parts of ISO 20816 when they become available. In the meantime, guidelines are given in Clause 6. NOTE 2 The term "shaft vibration" is used throughout ISO 20816 because, in most cases, measurements are made on machine shafts. However, the ISO 20816 series is also applicable to measurements made on other rotating elements if such elements are found to be more suitable, provided that the guidelines are respected. For the purposes of ISO 20816, operational monitoring is considered to be those vibration measurements made during the normal operation of a machine. The ISO 20816 series permits the use of different measurement quantities and methods, provided that they are well-defined and their limitations are set out, so that the interpretation of the measurements is well-understood. The evaluation criteria relate only to the vibration produced by the machine itself and not the vibration transmitted to it from outside. ISO 20816-1:2016 does not include consideration of torsional vibration. NOTE 3 For torsional vibration, see, for example, ISO 3046‑5, ISO 22266‑1 or VDI 2039.

ISO/TR 19201:2013 provides guidance for selecting appropriate vibration standards for specific machine types, and thus selecting the appropriate vibration measurement and evaluation method. Synopses are given of ISO 10816 (evaluation of machine vibration on non-rotating parts) and ISO 7919 (evaluation of machine vibration on rotating parts), together with further International Standards related to machinery. ISO/TR 19201:2013 provides an overview of the relevant International Standards, giving a summary of their scopes. It also provides a theoretical, analytical basis for establishing whether vibration measurements should be carried out on non-rotating parts, rotating shafts or both for those machines where no previous experience exists. It is not intended to supersede established manufacturers' or users' practical experience with specific machine types since there can be specific features associated with a particular machine which lead to a different selection of the most relevant measurement procedure. The aim of ISO/TR 19201:2013 is not to equip the reader with all the technical details provided in the International Standards necessary to carry out a measurement or evaluation task on a particular machine; rather it guides the reader to the appropriate International Standards. It is these International Standards that provide the necessary details; and then, with suitable training, the reader is in a position to carry out the measurement or evaluation task.

ISO 22266-1:2009 provides guidelines for applying shaft torsional vibration criteria, under normal operating conditions, for the coupled shaft system and long blades of a turbine generator set. In particular, these apply to the torsional natural frequencies of the coupled shaft system at line and twice‑line frequencies of the electrical network to which the turbine generator set is connected. In the event that torsional natural frequencies do not conform with defined frequency margins, other possible actions available to vendors are defined. ISO 22266-1:2009 is applicable to land-based steam turbine generator sets for power stations with power outputs greater than 50 MW and normal operating speeds of 1 500 r/min, 1 800 r/min, 3 000 r/min and 3 600 r/min, and to land-based gas turbine generator sets for power stations with power outputs greater than 50 MW and normal operating speeds of 3 000 r/min and 3 600 r/min. Methods currently available for carrying out both analytical assessments and test validation of the shaft system torsional natural frequencies are also described.

ISO 7919-3:2008 gives guidelines for applying evaluation criteria of shaft vibration under normal operating conditions, measured at or close to the bearings of coupled industrial machines.

ISO 10816-3:2009 gives criteria for assessing vibration measurements when made in situ. The criteria specified apply to machine sets having a power above 15 kW and operating speeds between 120 r/min and 15 000 r/min.

This part of ISO 13373 provides general guidelines for the measurement and data collection functions of machinery vibration for condition monitoring. It is intended to promote consistency of measurement procedures and practices, which usually concentrate on rotating machines. Because of the diversity of approaches to condition monitoring, recommendations specific to a particular kind of monitoring programme will be addressed in additional parts of ISO 13373. This part of ISO 13373 is a basic document which presents recommendations of a general nature, encompassing  measurement methods,  measurement parameters,  transducer selection,  transducer location,  transducer attachment,  data collection,  machine operating conditions,  vibration monitoring systems,  signal conditioning systems,  interfaces with data-processing systems,  continuous monitoring, and  periodic monitoring. The vibratory conditions of a machine can be monitored by vibration measurements on the bearing or housing structure and/or by vibration measurements of the rotating elements of the machine. In addition, measurements can be continuous or non-continuous. This part of ISO 13373 provides guidance on the types of measurements recommended in both the continuous and the non-continuous modes. It is emphasized that this part of ISO 13373 addresses only the procedures for vibration condition monitoring of machines. In many cases, the complete condition monitoring and diagnostics of a machine can also include other parameters, such as thermography, oil analysis, ferrography, process variations, temperatures and pressures. These non-vibratory parameters will be included in other International Standards. This part of ISO 13373 covers rotating machines. However, many of the procedures included can be applied to other types of machines, for example reciprocating machines.

ISO 10816-2:2009 establishes provisions for evaluating the severity of in-situ, broad-band vibration measured radial (i.e. transverse) to the shaft axis on all main bearing housings or pedestals and in the axial direction on thrust 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. ISO 10816-2:2009 is applicable to land-based steam turbines and generators with power outputs greater than 50 MW and a normal operating speed of 1 500 r/min, 1 800 r/min, 3 000 r/min or 3 600 r/min.

ISO 7919-4:2009 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. ISO 7919-4:2009 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, ISO 7919-4:2009 is not applicable to the evaluation of the vibration of the coupled equipment.

ISO 7919-2:2009 establishes provisions for applying evaluation criteria for 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. ISO 7919-2:2009 is applicable to land-based steam turbines and generators with power outputs greater than 50 MW and a normal operating speed of 1 500 r/min, 1800 r/min, 3 000 r/min or 3 600 r/min.

ISO 10816-4:2009 establishes specific provisions for evaluating the severity of in-situ, broad-band vibration measured radial (i.e. transverse) to the shaft axis on all main bearing housings or pedestals and in the axial direction on thrust 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. ISO 10816-4:2009 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.

ISO 13373-2:2005 recommends procedures for processing and presenting vibration data and analysing vibration signatures for the purpose of monitoring the vibration condition of rotating machinery, and performing diagnostics as appropriate. Different techniques are described for different applications. Signal enhancement techniques and analysis methods used for the investigation of particular machine dynamic phenomena are included. Many of these techniques can be applied to other machine types, including reciprocating machines. Example formats for the parameters that are commonly plotted for evaluation and diagnostic purposes are also given. ISO 13373-2:2005 is divided essentially into two basic approaches when analysing vibration signals: the time domain and the frequency domain. Some approaches to the refinement of diagnostic results, by changing the operational conditions, are also covered.

Gives a specific guidance for assessing the vibration of stationary generator sets by measurements on the bearings of steam turbine generator sets. Applicable to generator sets exceeding 50 MW which are directly coupled to a gas turbine.

Establishes the general conditions and procedures for the measurement and evaluation of vibration, using measurements made on the non-rotating parts of machines. The general evalution criteria relate to both operational monotoring and acceptance testing and have been established primarily with regard to securing reliable long-term operation of the machine. Replaces ISO 2372 and ISO 3945, which have been technically revised.