1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 21940-13:2012Mechanical vibration RotorbalancingPart 13: Criteria and safeguards for the in-situ balancing of medium and large rotorsBS ISO 21940-13:2012 BRITISH STANDARDN
2、ational forewordThis British Standard is the UK implementation of ISO21940-13:2012. It supersedes BS ISO 20806:2009 which is withdrawn. The UK participation in its preparation was entrusted to TechnicalCommittee GME/21/5, Mechanical vibration, shock and conditionmonitoring - Vibration of machines.A
3、list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2012. Published by BSI StandardsL
4、imited 2012 ISBN 978 0 580 71412 2 ICS 21.120.40 Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 April 2012. Amendments issued since publicationDate T e x t a f
5、 f e c t e dBS ISO 21940-13:2012Reference numberISO 21940-13:2012(E)ISO 2012INTERNATIONAL STANDARD ISO21940-13First edition2012-03-15Mechanical vibration Rotor balancing Part 13: Criteria and safeguards for the in-situ balancing of medium and large rotors Vibrations mcaniques quilibrage des rotors P
6、artie 13: Critres et sauvegardes relatifs lquilibrage in situ des rotors moyens et grands BS ISO 21940-13:2012ISO 21940-13:2012(E) COPYRIGHT PROTECTED DOCUMENT ISO 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any me
7、ans, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copy
8、rightiso.org Web www.iso.org Published in Switzerland ii ISO 2012 All rights reservedBS ISO 21940-13:2012ISO 21940-13:2012(E) ISO 2012 All rights reserved iiiContents Page Foreword ivIntroduction vi1 Scope 12 Normative references 13 Terms and definitions . 24 In-situ balancing 24.1 General . 24.2 Re
9、asons for in-situ balancing 24.3 Objectives of in-situ balancing 35 Criteria for performing in-situ balancing 36 Safeguards . 46.1 Safety of personnel while operating close to a rotating shaft 46.2 Special operating envelope for in-situ balancing 46.3 Integrity and design of the correction masses an
10、d their attachments 46.4 Machinery-specific safety implications . 47 Measurements . 57.1 Vibration measurement equipment . 57.2 Measurement errors 57.3 Phase reference signals . 68 Operational conditions . 79 Reporting 89.1 General . 89.2 Report introduction . 99.3 Vibration measurement equipment .
11、99.4 Results 99.5 Text information 10Annex A (normative) Precautions and safeguards for specific machine types during in-situ balancing 12Annex B (informative) Example of an in-situ balancing report for a boiler fan 1 MW 13Annex C (informative) Example of an in-situ balancing report for a large 50 M
12、W turbine generator set 17Bibliography 23BS ISO 21940-13:2012ISO 21940-13:2012(E) iv ISO 2012 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards
13、 is normally 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 p
14、art in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. 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
15、 prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility t
16、hat 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 patent rights. ISO 21940-13 was prepared by Technical Committee ISO/TC 108, Mechanical vibration, shock and condition monitoring, Subcommittee SC 2, Measur
17、ement and evaluation of mechanical vibration and shock as applied to machines, vehicles and structures. This first edition of ISO 21940-13 cancels and replaces ISO 20806:2009, of which it constitutes a minor editorial revision. ISO 21940 consists of the following parts, under the general title Mecha
18、nical vibration Rotor balancing: Part 1: Introduction1) Part 2: Vocabulary2) Part 11: Procedures and tolerances for rotors with rigid behaviour3) Part 12: Procedures and tolerances for rotors with flexible behaviour4) Part 13: Criteria and safeguards for the in-situ balancing of medium and large rot
19、ors5) Part 14: Procedures for assessing balance errors6)1) Revision of ISO 19499:2007, Mechanical vibration Balancing Guidance on the use and application of balancing standards 2) Revision of ISO 1925:2001, Mechanical vibration Balancing Vocabulary 3) Revision of ISO 1940-1:2003, Mechanical vibratio
20、n Balance quality requirements for rotors in a constant (rigid) state Part 1: Specification and verification of balance tolerances (+ Cor.1:2005) 4) Revision of ISO 11342:1998, Mechanical vibration Methods and criteria for the mechanical balancing of flexible rotors (+ Cor.1:2000) 5) Revision of ISO
21、 20806:2009, Mechanical vibration Criteria and safeguards for the in-situ balancing of medium and large rotors 6) Revision of ISO 1940-2:1997, Mechanical vibration Balance quality requirements of rigid rotors Part 2: Balance errors BS ISO 21940-13:2012ISO 21940-13:2012(E) ISO 2012 All rights reserve
22、d v Part 21: Description and evaluation of balancing machines7) Part 23: Enclosures and other protective measures for balancing machines8) Part 31: Susceptibility and sensitivity of machines to unbalance9) Part 32: Shaft and fitment key convention10)7) Revision of ISO 2953:1999, Mechanical vibration
23、 Balancing machines Description and evaluation 8) Revision of ISO 7475:2002, Mechanical vibration Balancing machines Enclosures and other protective measures for the measuring station 9) Revision of ISO 10814:1996, Mechanical vibration Susceptibility and sensitivity of machines to unbalance 10) Revi
24、sion of ISO 8821:1989, Mechanical vibration Balancing Shaft and fitment key convention BS ISO 21940-13:2012ISO 21940-13:2012(E) vi ISO 2012 All rights reservedIntroduction Balancing is the process by which the mass distribution of a rotor is checked and, if necessary, adjusted to ensure that the res
25、idual unbalance or the vibrations of the journals or bearing supports and/or the 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
26、 or a balancing machine is not available, it is common to balance the rotor in situ. 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 pr
27、operties of its bearings 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,
28、 and using the whole 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 correction planes and the size of correction masses available. BS ISO 21940-13:2012INTERNATIONAL STANDARD
29、 ISO 21940-13:2012(E) ISO 2012 All rights reserved 1Mechanical vibration Rotor balancing Part 13: Criteria and safeguards for the in-situ balancing of medium and large rotors 1 Scope This part of ISO 21940 specifies procedures to be adopted when balancing medium and large rotors installed in their o
30、wn 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. This part of ISO 21940 can be used as a basis for a contract to undertake i
31、n-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 part of ISO 21940 are suitable for medium and large machines. However, many of the principles are equally applicable to machines of
32、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 indispensable for the application of this document. For dated references, only the edition cited applies. Fo
33、r undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1925, Mechanical vibration Balancing Vocabulary11)ISO 1940-1, Mechanical vibration Balance quality requirements for rotors in a constant (rigid) state Part 1: Specification and verification of
34、 balance tolerances12)ISO 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 v
35、ibration Evaluation of machine vibration by measurements on non-rotating parts 11) To become ISO 21940-2 when revised. 12) To become ISO 21940-11 when revised. BS ISO 21940-13:2012ISO 21940-13:2012(E) 2 ISO 2012 All rights reservedISO 10817-1, Rotating shaft vibration measuring systems Part 1: Relat
36、ive and absolute sensing of radial vibration ISO 11342, Mechanical vibration Methods and criteria for the mechanical balancing of flexible rotors13)3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 1925 apply. 4 In-situ balancing 4.1 General For in-sit
37、u 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 machine can operate saf
38、ely throughout its whole operating envelope. As part of a successful balance, transient-speed vibration might be comprom-ised to some degree to obtain acceptable normal running speed vibration on a fixed-speed machinery train. NOTE In certain cases, machines that are very sensitive to unbalance cann
39、ot 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 (see ISO 10814 to become ISO 21940-31 when revised) and has load-dependent unbalance. Most sites have limited instrumentation and data-pr
40、ocessing capabilities, when compared to a balancing machine, and additional instrumentation is required to undertake in-situ balancing in these situations. In addition, the potential safety implications of running a rotor with correction masses shall be taken into account. 4.2 Reasons for in-situ ba
41、lancing 4.2.1 Although individual rotors might be correctly balanced, as appropriate, in a high- or low-speed balancing machine, in-situ balancing may be required when the rotors are coupled into the complete rotor train. This can be due to a range of differences between the real machine and the iso
42、lated environment in the balancing machine, including: a) a difference in dynamic characteristics of the rotor supports between the balancing facility and the installed machine; b) assembly errors that occur during installation, which cannot be reasonably found and corrected; c) rotor systems that c
43、annot be balanced prior to assembly; d) a changing unbalance behaviour of the rotor under full functional operating conditions. 4.2.2 Balancing may also be required to compensate for in-service changes to the rotor, including: a) wear; b) loss of components, such as rotor blade erosion shields; c) r
44、epair work, where components can be changed or replaced; d) movement of components on the rotor train causing unbalance, such as couplings, gas turbine discs and generator end rings. NOTE Rotor blades are normally added as balanced sets, but this can be impossible if a small number of blades are rep
45、laced. 13) To become ISO 21940-12 when revised. BS ISO 21940-13:2012ISO 21940-13:2012(E) ISO 2012 All rights reserved 34.2.3 In-situ balancing may be necessary due to a range of economic and technical reasons, including: a) the investment in a balancing machine cannot be justified; b) when a suitabl
46、e balancing machine is not available in the correct location or at the required time; c) when it is not economic to dismantle the machine and transport the rotor(s) to a suitable balancing facility. 4.2.4 Machines under normal operation or during speed variations (following remedial work, or after c
47、ommissioning) can have unacceptable magnitudes of vibration when compared with common practice, contractual requirements, or International Standards such as ISO 7919 and ISO 10816. In many cases, it is possible to bring the machine within acceptable vibration magnitude by in-situ balancing. 4.3 Obje
48、ctives of in-situ balancing The reason for balancing is to reduce the vibration magnitudes to acceptable values for long-term operation. For most machines, the overall vibration magnitude limits shall either be based on common practice or the appropriate part of ISO 7919 (for shaft vibration) and IS
49、O 10816 (for bearing housing and pedestal vibration). Where the magnitude of unbalance is of concern, reduce the magnitude of unbalance to within permissible limits (see ISO 1940-1 and ISO 11342 for details). 5 Criteria for performing in-situ balancing Prior to in-situ balancing, a feasibility study shall be carried out to assess if the available correction planes are suitable to influence the vibration behaviour being observed, since limited access to correction pl
