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1、 Reference number ISO 20806:2004(E) ISO 2004 INTERNATIONAL STANDARD ISO 20806 First edition 2004-10-15 Mechanical vibration Criteria and safeguards for the in-situ balancing of medium and large rotors Vibrations mcaniques Critres et sauvegardes relatifs lquilibrage in situ des rotors moyens et grand
2、s Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:02:50 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20806:2004(E) PDF disclaimer This PDF file may contain emb
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7、Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2004 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/998075510
8、0 Not for Resale, 04/16/2007 10:02:50 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20806:2004(E) ISO 2004 All rights reserved iii Contents Page Forewordiv Introduction v 1 Scope1 2 Normative references .1 3 Terms and definitions.1 4 In-situ balancing2 4.1 General.2 4
9、.2 Reasons for in-situ balancing2 4.3 Objectives for in-situ balancing 3 5 Criteria for performing in-situ balancing3 6 Safeguards.4 6.1 General.4 6.2 Safety of personnel while operating close to a rotating shaft .4 6.3 Special operating envelope for in-situ balancing4 6.4 Integrity and design of th
10、e correction masses and their attachments .4 6.5 Machinery-specific safety implications 4 7 Measurements.4 7.1 Vibration measurement equipment.4 7.2 Measurement errors5 7.3 Phase reference signals.6 8 Operational conditions.7 9 Reporting .8 9.1 General.8 9.2 Report introduction.8 9.3 Vibration measu
11、rement equipment.10 9.4 Results .10 9.5 Text information11 Annex A (normative) Precautions and safeguards for specific machine types during in-situ balancing12 Annex B (informative) Example of in-situ balancing report for a boiler fan 50 MW turbine generator17 Bibliography .23 Copyright Internationa
12、l Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:02:50 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20806:2004(E) iv ISO 2004 All rights reserved Foreword ISO (the International Orga
13、nization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been establis
14、hed has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization
15、. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. P
16、ublication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such pate
17、nt rights. ISO 20806 was prepared by Technical Committee ISO/TC 108, Mechanical vibration and shock. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:02:50 MDTNo reproduction or networking perm
18、itted without license from IHS -,-,- ISO 20806:2004(E) ISO 2004 All rights reserved v Introduction Balancing is the process by which the mass distribution of a rotor is checked and, if necessary, adjusted to ensure that the residual unbalance or the vibrations of the journals/bearing supports and/or
19、 forces at the bearings are within specified limits. Many rotors are balanced in specially designed balancing facilities prior to installation into their bearings on site. However, if remedial work is carried out locally or a balancing machine is not available, it is becoming increasingly common to
20、balance the rotor in situ. In-situ balancing is the process of balancing a rotor in its own bearings and support structure, rather than in a balancing machine. NOTE This is the same definition as field balancing in ISO 1925:2001, but in-situ balancing is easier to understand and will be used in the
21、future. At the next revision of ISO 1925, this term will be updated. Unlike balancing in a specially designed balancing machine, in-situ balancing has the advantage that the rotor is installed in its working environment. Therefore there is no compromise with regard to the dynamic properties of its b
22、earings and support structure, nor from the influence of other elements in the complete rotor train. However, it has the large disadvantage of restricted access and the need to operate the whole machine. Restricted access can limit the planes at which correction masses can be added, and using the wh
23、ole machine has commercial penalties of both downtime and running costs. Where gross unbalance exists, it may not be possible to balance a rotor in situ due to limited access to balance planes and the size of correction masses available. A general guide to the International Standards associated with
24、 mechanical balancing of rotors will be given in ISO 19499 (under preparation). Rotors in a constant (rigid) state are covered by ISO 1940-1 and rotors in a shaft elastic (flexible) state are covered by ISO 11342. Copyright International Organization for Standardization Provided by IHS under license
25、 with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:02:50 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/20
26、07 10:02:50 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 20806:2004(E) ISO 2004 All rights reserved 1 Mechanical vibration Criteria and safeguards for the in-situ balancing of medium and large rotors 1 Scope This International Standard specifie
27、s 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 maintainin
28、g records. This International Standard 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. NOTE The procedures covered in this International Standard are suitable for m
29、edium and large machines. However, many of the principles will be equally applicable to machines of a smaller size, where it is necessary to maintain good records of the vibration behaviour and the correction mass configurations. 2 Normative references The following referenced documents are indispen
30、sable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including amendments) applies. ISO 1925:2001, Mechanical vibration Balancing Vocabulary ISO 2041, Vibration and shock Vocabulary IS
31、O 2954, Mechanical vibration of rotating and reciprocating machinery Requirements for instruments for measuring vibration severity ISO 7919 (all parts), Mechanical vibration Evaluation of machine vibration by measurements on rotating shafts ISO 10816 (all parts), Mechanical vibration Evaluation of m
32、achine vibration by measurements on non- rotating parts IS0 10817-1, Rotating shaft vibration measuring systems Part 1: Relative and absolute sensing of radial vibration 3 Terms and definitions For the purpose of this document, the terms and definitions given in ISO 1925 and ISO 2041 apply. Copyrigh
33、t International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:02:50 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20806:2004(E) 2 ISO 2004 All rights reserved 4 In-situ balancing 4.1
34、 General For in-situ balancing, correction masses are added to the rotor at a limited number of conveniently engineered and accessible locations along the rotor. By doing this the magnitude of shaft and/or pedestal vibrations and/or unbalance is reduced to within acceptable values, so that the machi
35、ne can operate safely throughout its whole operating envelope. NOTE In certain cases, machines that are very sensitive to unbalance may not be successfully balanced over the complete operating envelope. This usually occurs when a machine is operating at a speed close to a lightly damped system mode
36、(see ISO 10814), and has load-dependent unbalance. Most sites have limited instrumentation and data-processing capabilities, when compared to a balancing facility, and additional instrumentation will be required to undertake in-situ balancing in these situations. In addition, the potential safety im
37、plications of running a rotor with correction masses shall be taken into account. 4.2 Reasons for in-situ balancing 4.2.1 Although individual rotors may be correctly balanced, as appropriate, in a high- or low-speed balancing machine, in-situ balancing might be required when the rotors are coupled i
38、nto the complete rotor train. This could be due to a range of differences between the real machine and the isolated environment in the balancing machine, including a difference in dynamic characteristics of the rotor supports between the balancing facility and the installed machine, assembly errors
39、that occur during the installation of the machine in situ, rotor systems that cannot be balanced prior to assembly, and a changing unbalance state of the rotor under full functional operating conditions. 4.2.2 Balancing might also be required to compensate for in-service changes to the rotor, includ
40、ing wear, loss of components, such as rotor blade erosion shields, repair work, where components could be changed or replaced, and movement of components on the rotor train causing unbalance, such as couplings, gas turbine discs and generator end rings. NOTE Rotor blades will be normally added as ba
41、lanced sets but this may not be possible if a small number of blades are replaced. 4.2.3 Additionally in-situ balancing might be necessary due to a range of economic and technical reasons, including the investment in a balancing machine cannot be justified, when a suitable balancing machine is not a
42、vailable in the correct location or at the required time, and when it is not economic to dismantle the machine and transport the rotor(s) to a suitable balancing facility. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 No
43、t for Resale, 04/16/2007 10:02:50 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20806:2004(E) ISO 2004 All rights reserved 3 4.3 Objectives for in-situ balancing The reason for balancing is to reduce the vibration magnitude(s) to acceptable values for long-term operat
44、ion. For most machines, the overall vibration magnitude(s) limits shall either be based on normal practice or the appropriate part of ISO 10816 and ISO 7919 for pedestals and shafts, respectively. Where the magnitude of unbalance is important, it is necessary to reduce the magnitude of unbalance to
45、within permissible limits (see ISO 1940-1 for details). 5 Criteria for performing in-situ balancing Machines under normal operation and/or during speed variations (following remedial work, or after commissioning) might have unacceptable magnitudes of vibration when compared with normal practice, con
46、tractual requirements, or International Standards such as the ISO 10816 and ISO 7919 series. In many cases, it may be possible to bring the machine to within acceptable vibration magnitude by in-situ balancing. Prior to in-situ balancing, a feasibility study shall be carried out to assess if the ava
47、ilable correction planes are suitable to influence the vibration behaviour being observed, since limited access to correction planes and measurement points on the fully built-up machine can make in-situ balancing impractical. Where possible, experience from previous in-situ balancing should be used.
48、 Sometimes modal analysis may be required. In-situ balancing shall only be attempted in the following circumstances: the reasons for the high vibrations are understood and cannot be corrected at source; after analysis of the vibration behaviour, it is judged that balancing is a safe and practical approach; under the required normal operating conditions, the vibration vector is steady and repeatable prior to in- situ balancing; the addition of corre