ISO/TC 108/SC 2 - Measurement and evaluation of mechanical vibration and shock as applied to machines, vehicles and structures

This document provides guidelines for the assessment of torsional natural frequencies and component strength, under normal operating conditions, for the coupled shaft train, including long elastic rotor blades, of steam and gas turbine generator sets. In particular, the guidelines apply to the torsional responses of the coupled shaft train at grid and twice grid frequencies due to electrical excitation of the electrical network to which the turbine generator set is connected. Excitation at other frequencies (e.g. subharmonic frequencies) are not covered in this document. No guidelines are given regarding the torsional vibration response caused by steam excitation or other excitation mechanisms not related to the electrical network. Where the shaft cross sections and couplings do not fulfil the required strength criteria and/or torsional natural frequencies do not conform with defined frequency margins, other actions shall be defined to resolve the problem. The requirements included in this document are applicable to a) steam turbine generator sets connected to the electrical network, and b) gas turbine generator sets connected to the electrical network. Methods currently available for carrying out both analytical assessment and test validation of the shaft train torsional natural frequencies are also described. NOTE Radial (lateral, transverse) and axial vibration of steam and/or gas turbine generator sets is dealt with in ISO 20816-2.

This document sets out guidelines for the specific procedures to be considered when carrying out vibration diagnostics of various types of gas and steam turbines with fluid-film bearings. This document is intended to be used by condition monitoring practitioners, engineers and technicians and provides a practical step-by-step vibration-based approach to fault diagnosis. In addition, it gives examples for a range of machine and component types and their associated fault symptoms. The approach given in this document is based on established good practice, put together by experienced users, although it is acknowledged that other approaches can exist. Recommended actions for a particular diagnosis depend on individual circumstances, the degree of confidence in the fault diagnosis (e.g. has the same diagnosis been made correctly before for this machine), the experience of the practitioner, the fault type and severity as well as on safety and commercial considerations. It is neither possible nor the aim of this document to recommend actions for all circumstances.

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 sets out the specific procedures to be considered when carrying out vibration diagnostics of various types of fans and blowers. This document is intended to be used by condition monitoring practitioners, engineers and technicians and provides a practical, step-by-step, vibration-based approach to fault diagnosis. In addition, it gives a number of examples for a range of machine and component types and their associated fault symptoms. The approach given in this document is based on established good practice, put together by experienced users, although it is acknowledged that other approaches can exist. Recommended actions for a particular diagnosis depend on individual circumstances, the degree of confidence in the fault diagnosis (e.g. has the same diagnosis been made correctly before for this machine), the experience of the practitioner, the fault type and severity as well as on safety and commercial considerations. It is neither possible nor the aim of this document to recommend actions for all circumstances.

This document provides a general background to balancing technology, as used in the ISO 21940 series, and directs the reader to the appropriate parts of the series that include vocabulary, balancing procedures and tolerances, balancing machines and machine design for balancing. Individual procedures are not included here as these can be found in the appropriate parts of ISO 21940.

This document defines terms relating to rotating machinery equipped with active magnetic bearings. NOTE General terms and definitions of mechanical vibration are given in ISO 2041; those relating to balancing are given in ISO 21940-2; those relating to geometric characteristics such as coaxiality, concentricity and runout are explained in ISO 1101.

This document establishes procedures and guidelines for the measurement and classification of mechanical vibration of reciprocating compressor systems. The vibration values are defined primarily to classify the vibration of the compressor system and to avoid fatigue problems with parts in the reciprocating compressor system, i.e. foundation, compressor, dampers, piping and auxiliary equipment mounted on the compressor system. Shaft vibration is not considered. This document applies to reciprocating compressors mounted on rigid foundations with typical rotational speed ratings in the range 120 r/min up to and including 1 800 r/min. The general evaluation criteria which are presented relate to operational measurements. The criteria are also used to ensure that machine vibration does not adversely affect the equipment directly mounted on the machine, e.g. pulsation dampers and the pipe system. NOTE The general guidelines presented in this document can also be applied to reciprocating compressors outside the specified speed range but different evaluation criteria might be appropriate in this case. The machinery driving the reciprocating compressor, however, is evaluated in accordance with the appropriate part of ISO 10816, ISO 20816 or other relevant standards and classification for the intended duty. Drivers are not included in this document. It is recognized that the evaluation criteria might only have limited application when considering the effects of internal machine components, e.g. problems associated with valves, pistons and piston rings might be unlikely to be detected in the measurements. Identification of such problems can require investigative diagnostic techniques which are outside the scope of this document. Examples of reciprocating compressor systems covered by this document are — horizontal, vertical, V-, W- and L-type compressor systems, — constant and variable speed compressors, — compressors driven by electric motors, gas and diesel engines, steam turbines, with or without a gearbox, flexible or rigid coupling, and — dry running and lubricated reciprocating compressors. This document does not apply to hyper compressors. The guidelines are not intended for condition monitoring purposes. Noise is also outside the scope of this document.

This document provides guidelines for evaluating the vibration measurements made at the bearings, bearing pedestals or bearing housings and also for evaluating relative shaft vibration measurements made on machine sets in hydraulic power generating and pump-storage plants when the machine is operating within its normal operating range. The normal operating ranges for each type of turbine covered by this document are defined in Annex A. This document is applicable to machine sets in hydraulic power generating plants and in pump-storage plants with typical rotational speeds of 60 r/min to 1 000 r/min fitted with shell or pad (shoe) type oil-lubricated bearings. NOTE The current database includes machine speeds ranging from 60 r/min to 750 r/min (with a very small sample of 1 000 r/min machines). This document defines different limit values of bearing housing and shaft vibration depending on the type of turbine, the orientation of the shaft (i.e. horizontal or vertical) and for each of the bearing locations. This document is based on statistical analysis and provides criteria for the most common types of turbines, pump-turbines and pumps. For specific information on which types of units are covered in this document, see Annex A. Machine sets covered by this document can have the following configurations: a) generators driven by hydraulic turbines; b) motor-generators driven by pump-turbines; c) motor-generators driven by hydraulic turbines and separate pumps; d) pumps driven by electric motors. This document is not applicable to the following unit configurations, parameters and operating conditions: — hydraulic machines with water-lubricated bearings; — hydraulic machines or machine sets having rolling element bearings (for these machines, see IEC 62006 and/or ISO 10816‑3); — pumps in thermal power plants or industrial installations (for these machines, see ISO 10816‑7); — electrical machines operating as motors except for the use of these machines in pump-storage applications; — hydro generators operating as synchronous condensers (with the water in the turbine depressed by compressed air); — assessment of absolute bearing housing vibration displacement; — assessment of axial vibration; — assessment of transient conditions; — non-synchronous operation; — assessment of vibration of the generator stator core or the stator frame level. Measurements made of the bearing housing vibration and shaft vibration occurring in machine sets in hydraulic power generating and pump-storage plants can be used for the following purposes: 1) Purpose A: to prevent damage arising from excessive vibration magnitudes; 2) Purpose B: to monitor changes in vibrational behaviour in order to allow diagnosis and/or prognosis. The criteria are applicable for the vibration produced by the machine set itself. Special investigation is needed for vibration transmitted to the machine set from external sources, e.g. transmitted to the machine via the station foundations.

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/TS 14837-31:2017 gives guidelines to encourage reporting of field measurements of ground-borne noise and vibration in a metric that allows international comparison and future development of empirical models. It also sets out the basic minimum requirements and good practice when taking measurements for the evaluation of human exposure in residential buildings to ensure they are reliable. While national standards or requirements based upon project-specific purposes would normally take priority, this guidance can be used where there are no particular requirements or to provide supplementary guidance. Thereby, this document provides a means of improving general quality and reporting of field measurements in a preferred format. There are a number of reasons for carrying out field measurements of ground-borne noise and vibration arising from rail operations, from complaint investigations to validation of prediction models, diagnostics and research as detailed in ISO 14837‑1:2005, 7.2. In the present document, two levels of evaluation are considered. - Scope 1 corresponds to basic measurements of floor vibration and noise in rooms in buildings to evaluate the human exposure to ground-borne vibration and ground-borne noise. Requirements are presented under two levels of accuracy: basic measurements with minimum accuracy; measurements with reduced uncertainty, also more reproducible and more appropriate for prediction. Ground-borne noise is noise generated by vibrating building elements (e.g. floors, walls and ceilings) in the room of interest and is therefore best expressed by both an acoustic and a vibrational quantity. Its identification as ground-borne noise (as opposed to airborne noise, potentially also present) requires simultaneous noise and vibration measurements. Nevertheless, there are also cases of very low frequency vibration (below 10 Hz to 16 Hz) where only vibration measurements are relevant. Rattle can also arise from vibration, which can be from building components or furniture. This document does not set out to characterize this phenomenon, but to note its presence when it occurs. NOTE In some cases, Scope 1 can relate to measurements on the ground outside a building (to resolve access issues or to comply with national regulations), although measurements at the building are generally preferred. - Scope 2 corresponds to measurements extended to evaluate the vibration immission to buildings, which includes vibration measurements at or near the building foundations and vibration measurements on ground next to the building so that the building coupling loss and building transmissibility can be estimated. Vibration measurements near the tracks (on ground surface or in tunnels) for a proper characterization of the source are outside the scope of this document. Certain requirements are specified in the interest of achieving a consistent minimum data set for each investigation, allowing data comparison between sites.

ISO 13373-9 specifies procedures to be considered when carrying out vibration diagnostics of various types of electric motors. The four motor types covered by ISO 13373-9 are squirrel-cage induction, wound-rotor induction, salient-pole and DC motors. NOTE The first two types are defined in ISO 20958. ISO 13373-9 is mostly applicable to motors with power above 15 kW. ISO 13373-9 is intended to be used by condition monitoring practitioners, engineers and technicians and provides a practical step-by-step vibration-based approach to fault diagnosis. In addition, it gives a number of examples for a range of machine and component types and their associated fault symptoms. The procedures presented in ISO 13373-9 can, in some cases, be applied to other types of electrical machines, such as generators, but there can be other specific techniques associated with such machines that are not included in ISO 13373-9. The use of non-vibration quantities, such as voltage and current, to identify and analyse vibration-related faults in electric motors is outside the scope of ISO 13373-9.

ISO 13373-7:2017 gives guidelines for specific procedures to be considered when carrying out vibration diagnostics of various types of machine sets in hydraulic power generating and pump-storage plants (hydropower units). It is intended to be used by condition monitoring practitioners, engineers and technicians and provides a practical step-by-step vibration-based approach to fault diagnosis. In addition, it includes a number of examples for a range of machine and component types and their associated fault symptoms.

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 21940-2:2017 defines terms on balancing. It complements ISO 2041, which is a general vocabulary on mechanical vibration and shock.

ISO 20283-5:2016 gives guidelines for the measurement, evaluation and reporting of vibration with regard to habitability for all persons on-board passenger and merchant ships, especially for crew. Overall frequency-weighted r.m.s. vibration values in the frequency range 1 Hz to 80 Hz are given as guideline values for different areas on ships. ISO 20283-5:2016 is applicable to passenger and merchant ships with intended voyages of 24 h or more. ISO 20283-5:2016 specifies requirements for the instrumentation and the procedure of measurement in normally occupied spaces. It also contains analysis specifications and guidelines for the evaluation of ship vibration with respect to habitability. The evaluation of low-frequency ship motion which can result in motion sickness is covered by ISO 2631‑1. For the evaluation of the global structural vibration of a ship, however, see ISO 20283‑2.

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 21940-11:2016 establishes procedures and unbalance tolerances for balancing rotors with rigid behaviour. It specifies a) the magnitude of the permissible residual unbalance, b) the necessary number of correction planes, c) the allocation of the permissible residual unbalance to the tolerance planes, and d) how to account for errors in the balancing process. NOTE In ISO 21940‑14, the assessment of balancing errors is considered in detail. Fundamentals of rotor balancing are contained in ISO 19499 which gives an introduction to balancing. ISO 21940-11:2016 does not cover the balancing of rotors with flexible behaviour. Procedures and tolerances for rotors with flexible behaviour are dealt with in ISO 21940‑12.

ISO 8608:2016 specifies a uniform method of reporting measured vertical road profile data for either one-track or multiple-track measurements. It applies to the reporting of measured vertical profile data taken on roads, streets and highways, and on off-road terrain. It does not apply to rail-track data. Measurement and processing equipment and methods are not included.

ISO 10815:2016 establishes the basic principles for measuring, processing and evaluating vibration generated internally in railway tunnels by the passage of trains. By establishing a standard procedure, comparative data may be obtained on response of the tunnel elements from time to time, provided that the excitation source is the same. Data obtained in different tunnels may also be compared. The measurements considered in ISO 10815:2016 concern the response of the structure and secondary elements mounted in the tunnel. They do not concern the response of persons in the tunnel or in its vicinity, or of passengers on trains running through the tunnel.

ISO 21940-12:2016 presents typical configurations of rotors with flexible behaviour in accordance with their characteristics and balancing requirements, describes balancing procedures, specifies methods of assessment of the final state of balance, and establishes guidelines for balance quality criteria. ISO 21940-12:2016 can also serve as a basis for more involved investigations, e.g. when a more exact determination of the required balance quality is necessary. If due regard is paid to the specified methods of manufacture and balance tolerances, satisfactory running conditions can be expected. ISO 21940-12:2016 is not intended to serve as an acceptance specification for any rotor, but rather to give indications of how to avoid gross deficiencies and unnecessarily restrictive requirements. Structural resonances and modifications thereof lie outside the scope of this part of ISO 21940. The methods and criteria given are the result of experience with general industrial machinery. It is possible that they are not directly applicable to specialized equipment or to special circumstances. Therefore, in some cases, deviations from this part of ISO 21940 are possible.

ISO 13373-2:2016 recommends procedures for processing and presenting vibration data and analyzing 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 13373-2:2016 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. ISO 13373-2:2016 includes only the most commonly used techniques for the vibration condition monitoring, analysis and diagnostics of machines. There are many other techniques used to determine the behaviour of machines that apply to more in‑depth vibration analysis and diagnostic investigations beyond the normal follow‑on to machinery condition monitoring. A detailed description of these techniques is beyond the scope of ISO 13373-2:2016, but some of these more advanced special purpose techniques are listed in Clause 5 for additional information. For specific machine types and sizes, the ISO 7919 and ISO 10816 series provide guidance for the application of broadband vibration magnitudes for condition monitoring, and other documents such as VDI 3839 provide additional information about machinery‑specific problems that can be detected when conducting vibration diagnostics.

ISO/TS 14837-32:2015 provides guidance and defines methods for the measurement of dynamic properties of the ground through which ground-borne noise and vibration is transmitted, from the operation of rail systems and into foundations of neighbouring buildings. The purpose is to determine the parameters of the ground system which are necessary to reliably predict the noise and vibration transmission, to design railroads and foundations to meet noise and vibration requirements, to design countermeasures and to validate design methods.

ISO 13373-3:2015 sets out guidelines for the general procedures to be considered when carrying out vibration diagnostics of rotating machines. It is intended to be used by vibration practitioners, engineers and technicians and provides a practical structured approach to fault diagnosis. In addition it gives examples of faults common to a wide range of machines. NOTE Guidance for specific machines is provided in other parts of ISO 13373.

ISO 10816-21:2015 specifies the measurement and evaluation of mechanical vibration of wind turbines and their components by taking measurements on non-rotating parts. It applies to horizontal axis wind turbines with mechanical gearbox and rated generator output exceeding 200 kW and the following design and operational characteristics: a) installation on supporting systems (tower and foundation) made of steel and/or concrete; b) horizontal axis rotor with several rotor blades; c) rotor bearing separate from or integrated into the gearbox; d) generators driven via gearbox; e) generators of the synchronous or asynchronous type (mostly equipped with 4-pole generator); f) generators with only a fixed pole number or which are pole-changeable for speed adjustment; g) output control by rotor blades (pitch or stall wind turbines); h) generator coupled to the power grid via converter or directly.

ISO 21940-31:2013 specifies methods for determining machine vibration sensitivity to unbalance and provides evaluation guidelines as a function of the proximity of relevant resonance rotational speeds to the operating speed. ISO 21940-31:2013 is only concerned with once-per-revolution vibration caused by unbalance. It also makes recommendations on how to apply the numerical sensitivity values in some particular cases. It includes a classification system that can be applied to machines which is related to their susceptibility to a change in unbalance. Machines are classified into three types of susceptibility and five ranges of sensitivity. The sensitivity values are intended for use on simple machine systems, preferably with rotors having only one resonance speed over their entire operating speed range. The sensitivity values can also be used for machines that have more resonance speeds in their operating speed range if the resonance speeds are widely separated (e.g. by more than 20 %). The sensitivity values given are not intended to serve as acceptance specifications for any machine group, but rather to give indications regarding how to avoid gross deficiencies as well as specifying exaggerated or unattainable requirements. They can also serve as a basis for more involved investigations (e.g. when in special cases a more exact determination of the required sensitivity is necessary). If due regard is paid to the values given, satisfactory running conditions can be expected in most cases. The consideration of the sensitivity values alone does not guarantee that a given magnitude of vibration in operating is not exceeded. Many other sources of vibration can occur which lie outside the scope of ISO 21940-31:2013.

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 21940-21:2012 specifies requirements for evaluating the performance of machines for balancing rotating components by the following tests: a) test for minimum achievable residual unbalance, Umar test; b) test for unbalance reduction ratio, URR test; c) test for couple unbalance interference on single-plane machines; d) compensator test. These tests are performed during acceptance of a balancing machine and also later on a periodic basis to ensure that the balancing machine is capable of handling the actual balancing tasks. For periodic tests, simplified procedures are specified. Tests for other machine capacities and performance parameters, however, are not contained in ISO 21940-21:2012. For these tests, three types of especially prepared proving rotors are specified, covering a wide range of applications on horizontal and vertical balancing machines. An annex describes recommended modifications of proving rotors prepared in acccordance with ISO 2953:1985. Moreover, ISO 21940-21:2012 stresses the importance attached to the form in which the balancing machine characteristics are specified by the manufacturer. Adoption of the format specified enables users to compare products from different manufacturers. Additionally, in an annex, guidelines are given on the information by which users provide their data and requirements to a balancing machine manufacturer. ISO 21940-21:2012 is applicable to balancing machines that support and rotate rotors with rigid behaviour at balancing speed and that indicate the amounts and angular locations of a required unbalance correction in one or more planes. Therefore it is applicable to rotors with rigid behaviour as well as to rotors with shaft-elastic behaviour balanced in accordance with low-speed balancing procedures. It covers both soft-bearing balancing machines and hard-bearing balancing machines. Technical requirements for such balancing machines are included; however, special features, such as those associated with automatic correction, are excluded. ISO 21940-21:2012 does not specify balancing criteria; such criteria are specified in ISO 1940-1 and ISO 11342 (only low-speed balancing procedures apply).

This part of ISO 21940 specifies the requirements for the following: a) identifying errors in the unbalance measuring process of a rotor; b) assessing the identified errors; c) taking the errors into account. This part of ISO 21940 specifies balance acceptance criteria, in terms of residual unbalance, for both directly after balancing and for a subsequent check of the balance quality by the user. For the main typical errors, this part of ISO 21940 lists methods for their reduction in an informative annex.

This part of ISO 21940 specifies requirements for enclosures and other protective measures used to minimize mechanical hazards produced by the rotor in the unbalance measuring station of centrifugal (rotational) balancing machines. The hazards are associated with the operation of balancing machines under a variety of rotor and balancing conditions. This part of ISO 21940 defines different classes of protection that enclosures and other protective measures provide and describes the limits of applicability for each class of protection. Devices for adjusting the mass distribution of a rotor and devices to transfer the rotor are not covered by this part of ISO 21940, even if they are combined with the measuring station. Special enclosure features, such as noise reduction, windage reduction or vacuum (which may be required to spin bladed rotors at balancing speed), are not covered by this part of ISO 21940.

ISO 21940-13:2012 specifies procedures to be adopted when balancing medium and large rotors installed in their own bearings on site. It addresses the conditions under which it is appropriate to undertake in-situ balancing, the instrumentation required, the safety implications and the requirements for reporting and maintaining records. ISO 21940-13:2012 can be used as a basis for a contract to undertake in-situ balancing. It does not provide guidance on the methods used to calculate the correction masses from measured vibration data.

ISO 21940-32:2012 specifies one convention for balancing the individual components (shaft and fitments) of a keyed rotor assembly. This provides compatibility of all balanced components so that when they have been assembled the overall balance tolerance and/or vibration limit for the rotor assembly is met. ISO 21940-32:2012 specifies that half-keys be used when balancing the individual components of a keyed rotor assembly. It also specifies a marking of the components balanced in accordance with the key convention used. ISO 21940-32:2012 applies to rotors balanced in a balancing machine, in their own bearings or in situ. The key convention can also be applied when measuring the residual unbalance and/or vibration of rotors with keyways, but to which fitments have not yet been assembled. In addition to applying to keys of constant rectangular or square cross-section mounted parallel to the shaft centreline, ISO 21940-32:2012 also applies to keys mounted on tapered shaft surfaces, to woodruff, gibhead, dowel and other special keys. The principle of the half-key convention is applied as is appropriate to the particular shape and location of the special key.

ISO 14839-4:2012: a) indicates a typical architecture of an active magnetic bearing (AMB) system so that users can understand which components are likely to comprise such systems and which functions these components provide; b) identifies the primary similarities and differences between AMB systems and conventional mechanical bearings; c) identifies the environmental factors that have significant impact on AMB system performance; d) identifies the operating limitations that are unique to AMB systems and defines standardized methods of assessing these limitations; e) identifies typical mechanisms for managing these limitations, especially rotor unbalance; f) provides considerations for the design and performance of touchdown bearing systems; g) defines a typical signal set for provision in an AMB system for proper system/process interface as well as condition and diagnostic monitoring; h) details current best practices for monitoring, operation and maintenance to achieve highest operational system reliability; i) identifies typical fault-handling practices; j) recommends inspection and preventive maintenance processes for AMB systems.

ISO 10302-2:2011 covers vibration levels from small air moving devices (AMDs) with mounting footprints of less than 0,48 m × 0,90 m for the full-size test plenum defined in ISO 10302‑1 and less than 0,18 m × 0,3 m for the half-size plenum. It covers all types of AMDs which can be mounted on, and are self-supported at, the discharge or inlet plane of a test plenum box as specified in ISO 10302‑1. The procedures defined in ISO 10302-2:2011 specify methods for determining the vibration levels that a small AMD would induce in an average structure used in information technology and telecommunications equipment. The methods specified in ISO 10302-2:2011 allow the determination of induced vibration levels for the individual AMD that is tested. These data can be used to determine the statistical values of vibration levels for a production series if levels are measured for several units of that series.

ISO 4866:2010 establishes principles for carrying out vibration measurement and processing data with regard to evaluating vibration effects on structures. It does not cover the source of excitation except when the source dictates dynamic range, frequency or other relevant parameters. The evaluation of the effects of structural vibration is primarily obtained from the response of the structure, using appropriate analytical methods by which the frequency, duration and amplitude can be defined. ISO 4866:2010 only deals with the measurement of structural vibration and excludes the measurement of airborne sound pressure and other pressure fluctuations, although response to such excitations is taken into consideration. ISO 4866:2010 applies to all structures built above or below ground. Such structures are used or maintained and include buildings, structures of archaeological and historical value (cultural heritage), bridges and tunnels, gas and liquid installations including pipelines, earth structures (e.g. dykes and embankments), and fixed marine installations (e.g. quays and wharfs). ISO 4866:2010 does not apply to some special structures, including nuclear plants and dams. The response of structures depends upon the excitation. ISO 4866:2010 examines the methods of measurement as affected by the source of excitation, i.e. frequency, duration, and amplitude as induced by any source (e.g. earthquake, hurricane, explosion, wind loading, airborne noise, sonic boom, internal machinery, traffic, and construction activities).

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 10816-7:2009 gives instructions for the evaluation of vibration on rotodynamic pumps for industrial applications with nominal power above 1 kW. It defines the special requirements for evaluation of vibration when the vibration measurements are made on non-rotating parts (bearing housing vibration).

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.

ISO 20283-2:2008 gives guidelines, and specifies requirements and procedures for the measurement, diagnostic evaluation and reporting of structural vibration of ships, excited by the propulsion plant. Structural vibration can be of global or of local nature. Here, primarily global vibration is dealt with. Local vibration of deck structures from a habitability point of view is dealt with in ISO 6954. Occurrence of local vibration leading to fatigue damage is rare and strongly related to the individual configuration. Therefore, no general guideline for the measurement of such type of vibration is provided within the scope of ISO 20283 (all parts). For reference, some basic information regarding the design of structures with respect to local structural vibration is provided. ISO 20283-2:2008 does not consider transient ship vibration phenomena, e.g., as excited by slamming. Even though torsional shaft or crankshaft vibration may in some cases cause relevant structural vibration, they are not considered here. In this connection, reference can be made to the relevant classification rules and ISO 20283-4.

ISO 14839-3:2006 establishes the stability requirements of rotating machinery equipped with active magnetic bearings (AMB). It specifies a particular index to evaluate the stability margin and delineates the measurement of this index. It is applicable to industrial rotating machines operating at nominal power greater than 15 kW, and not limited by size or operational rated speed. It covers both rigid AMB rotors and flexible AMB rotors. Small-scale rotors, such as turbo molecular pumps, spindles, etc., are not addressed. ISO 14839-3:2006 concerns the system stability measured during normal steady-state operation in-house and/or on-site. ISO 14839-3:2006 does not address resonance vibration appearing when passing critical speeds. The regulation of resonance vibration at critical speeds is established in ISO 10814.

ISO 20283-3:2006 gives guidelines, requirements and procedures for the measurement of vibration generated by types of shipboard equipment, and which can be transmitted into a ship structure as structure-borne sound, as part of the factory acceptance test (FAT) of the equipment unit. It specifies the measurements to be conducted for well-defined operating and mounting conditions of the unit, e.g. in the supplier's test rig. It provides a framework for providing representative test results. It is applicable to shipboard equipment intended for passenger ships, merchant ships, yachts and high-speed craft.

ISO 14837-1:2005 provides general guidance on ground-borne vibration generated by the operation of rail systems, and the resultant ground-borne noise in buildings. It lists the factors and parameters that need to be taken into consideration and offers guidance on prediction methods appropriate for a range of circumstances (e.g. to support the assessment of effects on human occupants and sensitive equipment or operations inside the buildings in addition to the predictions required to assess the risk of damage to building structures). Attention is paid in ISO 14837-1:2005 to characteristics of the source: emission (e.g. train, wheel, rail, track, supporting infrastructure); propagation path: transmission (e.g. ground condition, distance); and receiving structures: immission: (e.g. foundations, form of building construction). The guidance covers all forms of wheel and rail systems, from light-rail to high-speed trains and freight. ISO 14837-1:2005 provides guidance for rail systems at-grade, on elevated structures and in tunnels. It does not deal with vibration arising from the construction and maintenance of the rail system. It does not deal with airborne noise. Structure-radiated noise from elevated structures, which can have a significant environmental impact, is also excluded.

ISO 14839-2:2004 sets out general guidelines for measuring and evaluating rotating machinery equipped with active magnetic bearings (AMBs) with respect to the following two indices: shaft vibratory displacement measured at or close to the AMBs; and working current and voltage measured in magnetic coils or power supply amplifiers. Both indices are measured under nominal operating conditions in house and/or on site. These guidelines are presented in terms of both steady-state running values of these indices and any magnitude changes which may occur in these steady-state operations. ISO 14839-2:2004 is applicable to industrial rotating machines generating or consuming nominal power greater than 15 kW, and is not limited by size or operational rated speed (i.e. comprising turbo-compressors, turbo-pumps, steam turbines, turbo-generators, turbo-fans, electric drives and other rotors supported by AMBs). It establishes the vibration, current and voltage evaluation of the rotating machinery equipped with AMBs, specified by a comparatively large power capacity as described above, excluding small-scale rotors such as turbo-molecular pumps, spindles and flywheels. ISO 14839-2:2004 covers both AMB-equipped rigid rotors and AMB-equipped flexible rotors.