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1、BRITISH STANDARD BS ISO 7919-4:1996 Implementation of ISO 7919-4:1996 Mechanical vibration of non-reciprocating machines Measurements on rotating shafts and evaluation criteria Part 4: Gas turbine sets ICS 17.160; 27.040 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:03:18 GMT+00:00 2006,
2、 Uncontrolled Copy, (c) BSI BS ISO 7919-4:1996 This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 November 1996 BSI 12-1998 The following BSI references relate to the wo
3、rk on this standard: Committee reference GME/21 Draft for comment: 89/79539 DC ISBN 0 580 26099 2 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee GME/21, Mechanical vibration and shock, upon which the following bodies wer
4、e represented: Federation of Civil Engineering Contractors Imperial College of Science and Technology Institute of Sound and Vibration Research Institution of Mechanical Engineers Lloyds Register of Shipping Ministry of Defence Open University Power Generation Contractors Association (PGCA (BEAMA Lt
5、d.) Railway Industry Association Society of British Aerospace Companies Limited Society of Environmental Engineers The following body was also represented in the drafting of the standard, through subcommittees and panels: Electricity Association Amendments issued since publication Amd. No.DateCommen
6、ts Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:03:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 7919-4:1996 BSI 12-1998i Contents Page Committees responsibleInside front cover National forewordii Forewordii Text of ISO 7919-41 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov
7、26 04:03:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 7919-4:1996 ii BSI 12-1998 National foreword This British Standard reproduces verbatim ISO 7919-4:1996 and implements it as the UK national standard. This British Standard is published under the direction of the Engineering Sector Board w
8、hose Technical Committee GME/21 has the responsibility to: aid enquirers to understand the text; present to the responsible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and pr
9、omulgate them in the UK. NOTEInternational and European Standards, as well as overseas standards, are available from Customer Services, BSI, 389 Chiswick High Road, London W4 4AL. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards ar
10、e responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the ISO title page, page ii, pages 1 to 4 and a back cover. This s
11、tandard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:03:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Licensed Copy: sheffieldun sheff
12、ieldun, na, Sun Nov 26 04:03:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 7919-4:1996 ii BSI 12-1998 Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is nor
13、mally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in
14、the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard r
15、equires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 7919-4 was prepared by Technical Committee ISO/TC 108, Mechanical vibration and shock, Subcommittee SC 2, Measurement and evaluation of mechanical vibration and shock as applied to machines, vehicles an
16、d structures. ISO 7919 consists of the following parts, under the general title Mechanical vibration of non-reciprocating machines Measurements on rotating shafts and evaluation criteria: Part 1: General guidelines; Part 2: Large land-based steam turbine generator sets; Part 3: Coupled industrial ma
17、chines; Part 4: Gas turbine sets; Part 5: Machine sets in hydraulic power generating and pumping plants. Annex A forms an integral part of this part of ISO 7919. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:03:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 7919-4:1996 BSI 12-19981
18、 Introduction This part of ISO 7919 deals with the special features required for measuring transverse shaft vibration on the coupled rotor systems of gas turbine sets. Evaluation criteria, based on previous experience, are presented which may be used as guidelines for assessing the vibratory conditi
19、ons of such machines. A general description of the principles which are generally applicable for the measurement and evaluation of shaft vibration of non-reciprocating machines is given in ISO 7919-1. 1 Scope This part of ISO 7919 gives guidelines for applying evaluation criteria for shaft vibration
20、 under normal operating conditions, measured at or close to the bearings of gas turbine sets. These guidelines are presented in terms of both steady running vibration and any magnitude changes which may occur in these steady values. The numerical values specified are not intended to serve as the onl
21、y basis for vibration evaluation since, in general, the vibratory condition of a machine is assessed by consideration of both the shaft vibration and the associated structural vibration (see the introduction to ISO 7919-1). This part of ISO 7919 applies to all gas turbine sets (including those with
22、gears) with fluid-film bearings, outputs greater than 3 MW and shaft rotational frequencies from 3 000 r/min to 30 000 r/min. Aircraft derivative engines are excluded, since they differ fundamentally from industrial gas turbine sets, both in the type of bearings (rolling element bearings) and in the
23、 stiffness and mass ratios of the rotor and support structure. Depending on the construction and mode of operation, there are three principle groupings of gas turbine sets: single-shaft constant-speed gas turbine sets; single-shaft variable-speed gas turbine sets; gas turbine sets with separate shaf
24、ts for hot gas generation and power delivery. NOTE 1Initially these three groups will be assessed in a uniform manner. It is possible, however, that individual cases will have to be assessed differently. 2 Normative references The following standards contain provisions which, through reference in th
25、is text, constitute provisions of this part of ISO 7919. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 7919 are encouraged to investigate the possibility of applying the most recent editions o
26、f the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 7919-1:1996, Mechanical vibration of non-reciprocating machines Measurements on rotating shafts and evaluation criteria Part 1: General guidelines. ISO 10816-1:1995, Mechanical
27、vibration Evaluation of machine vibration by measurements on non-rotating parts Part 1: General guidelines. 3 Measurement procedures The measurement procedures to be followed and the instrumentation used shall be as described in ISO 7919-1. In gas turbine sets, shaft vibration relative to the bearin
28、g is normally measured. Therefore, unless stated otherwise, the vibration displacements referred to in this part of ISO 7919 conform to this convention. In view of the relatively high rotational frequencies involved with gas turbine sets, measuring methods using non-contacting transducers are most c
29、ommon and are generally preferred on rotor elements with operating frequencies of 3 000 r/min and above. For monitoring purposes, the measuring system shall be capable of covering overall vibration up to a frequency equivalent to 2,5 times the maximum service speed. However, it should be noted that
30、for diagnostic purposes it may be desirable to cover a wider frequency range. 4 Evaluation criteria Criteria for vibration magnitude, changes in vibration magnitude and operational limits are presented in annex A. The vibration magnitude is the higher value of the peak-to-peak displacement measured
31、in two selected orthogonal measurement directions. The values presented are the result of experience with machinery of this type and, if due regard is paid to them, acceptable operation may be expected. If only one measuring direction is used, care should be taken to ensure that it provides adequate
32、 information (see ISO 7919-1). The criteria are presented for the specified steady-state operating conditions at the rated speed and load ranges. They apply for normal slow changes in load but do not apply when different conditions exist or during transient changes, for example during start-up and s
33、hut-down and when passing through resonance ranges. In these cases alternative criteria are necessary. It should be noted that an overall judgement of the vibratory state of a machine is often made on the basis of both relative shaft vibration as defined above and of measurements made on non-rotatin
34、g parts (see ISO 10816-1). Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:03:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 7919-4:1996 2 BSI 12-1998 Annex A (normative) Evaluation criteria for relative shaft vibration of gas turbine sets under specified operating conditions A.1 Gen
35、eral Two evaluation criteria are used to assess the relative shaft vibration of gas turbine sets, measured at or close to the bearings. One criterion considers the magnitude of the observed broad-band relative shaft vibration; the second considers changes in magnitude, irrespective of whether they a
36、re increases or decreases. A.2 Criterion I: Vibration magnitude at rated speed under steady operating conditions This criterion is concerned with defining limits for shaft vibration magnitude consistent with acceptable dynamic loads on the bearing, adequate margins on the radial clearance envelope o
37、f the machine, and acceptable vibration transmission into the support structure and foundation. The maximum shaft vibration magnitude observed at each bearing is assessed against four evaluation zones established from international experience. A.2.1 Evaluation zones The following typical evaluation
38、zones are defined to permit a qualitative assessment of the shaft vibration on a given machine and provide guidelines on possible actions. Zone A The vibration of newly commissioned machines would normally fall within this zone. Zone B: Machines with vibration within this zone are normally considere
39、d acceptable for unrestricted long-term operation. Zone C: Machines with vibration within this zone are normally considered unsatisfactory for long-term continuous operation. Generally, the machine may be operated for a limited period in this condition until a suitable opportunity arises for remedia
40、l action. Zone D: Vibration values within this zone are normally considered to be of sufficient severity to cause damage to the machine. A.2.2 Evaluation zone limits In accordance with present accumulated experience of shaft vibration measurements in this field, the recommended values for the zone b
41、oundaries are inversely proportional to the square root of the shaft rotational frequency n (in revolutions per minute). The recommended values presented in Figure A.1 are derived from the expressions below: Zone boundary A/B Zone boundary B/C Zone boundary C/D NOTE 2For a definition of S(p-p), see
42、ISO 7919-1. These values are not intended to serve as acceptance specifications, which shall be subject to agreement between the machine manufacturer and customer. However, they provide guidelines for ensuring that gross deficiencies or unrealistic requirements are avoided. In certain cases, there m
43、ay be specific features associated with a particular machine which would require different zone boundary values (higher or lower) to be used. For example, with a tilting pad bearing it may be necessary to specify alternative vibration values, whilst in the case of an elliptical bearing, different vi
44、bration criteria may apply for the directions of maximum and minimum bearing clearances. In particular, it should be recognised that the allowable vibration may be related to the journal diameter since, generally, running clearances will be greater for larger diameter bearings. Consequently differen
45、t values may apply for measurements taken at different bearings on the same rotor line. In such cases, it is normally necessary to explain the reasons for this and, in particular, to confirm that the machine will not be endangered by operating with higher vibration values. Higher values of vibration
46、 can be permitted at other measuring positions and under transient conditions, such as start-up and run-down (including passage through critical speed ranges). A.3 Criterion II: Change in vibration magnitude This criterion provides an assessment of a change in vibration magnitude from a previously e
47、stablished reference or baseline value. A significant increase or decrease in shaft vibration magnitude may occur which requires some action even though zone C of Criterion I has not been reached. Such changes can be instantaneous or progressive with time and may indicate that damage has occurred or
48、 be a warning of an impending failure or some other irregularity. Criterion II is specified on the basis of the change in shaft vibration magnitude occurring under steady-state operating conditions. S p p() 4 800/n m= S p p() 9 000/n m= S p p() 13 200/n m= Licensed Copy: sheffieldun sheffieldun, na,
49、 Sun Nov 26 04:03:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 7919-4:1996 BSI 12-19983 The reference value for this criterion is the typical, reproducible normal vibration, known from previous measurements for the specific operating conditions. If this reference value changes by a significant amount, and certainly if it exceeds 25 % of the upper limiting value for zone B, regardless of whether this increases or decreases the magnitude of vibration, steps should be taken to ascertain the reasons for the change. A decision on wh