1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS 9690-1:2011Non-destructive testing Guided wave testingPart 1: General guidance andprinciplesPublishing and copyright informationThe BSI copyright notice displayed in this docu
2、ment indicates when the documentwas last issued. BSI 2011ISBN 978 0 580 73793 0ICS 19.100The following BSI references relate to the work on this standard:Committee reference WEE/46Draft for comment 11/30238601 DCPublication historyFirst published October 2011Amendments issued since publicationDate T
3、ext affectedBS 9690-1:2011 BRITISH STANDARDContentsForeword ii1 Scope 12 Normative references 13 Terms and definitions 14 Qualification and certification of personnel 65 Information required prior to testing 66 Principles of GWT 77 Equipment 118 Settings 129 Summary 12AnnexesAnnex A (informative) Th
4、eoretical basis for GWT of hollow cylindricalobjects 14Bibliography 20List of figuresFigure 1 Schematic diagram of pulse-echo, pitch-catch and throughtransmission configurations 10Figure A.1 Group velocity dispersion curves for 6 inch Schedule 40 pipe 14Figure A.2 Displacement mode shapes of modes w
5、ith different circumferentialorders 15Figure A.3 Typical reflection coefficients for a through-wall notch in a pipeversus the circumferential extent of the notch 17Figure A.4 Typical reflection coefficients for a through-wall notch in a pipeversus the circumferential extent of the notch 18Figure A.5
6、 Typical reflection coefficients for a through-wall notch in a pipeversus the circumferential extent of the notch 19Summary of pagesThis document comprises a front cover, an inside front cover, pages i to ii,pages 1 to 20, an inside back cover and a back cover.BRITISH STANDARD BS 9690-1:2011 BSI 201
7、1 iForewordPublishing informationThis British Standard is published by BSI and came into effecton 31 October 2011. It was prepared by Technical Committee WEE/46,Non-destructive testing. A list of organizations represented on this committeecan be obtained on request to its secretary.Information about
8、 this documentThe purpose of this document is to define a standard for non-destructive testing(NDT) using guided stress waves.Guided stress waves used for NDT are sonic or ultrasonic waves which travelalong an object and are guided by its surfaces or shape, and whose wavelengthis large compared to a
9、 characteristic dimension such as wall thickness. NDT usingguided waves offers the possibility of performing rapid testing of 100% of thevolume of the components in which they can travel and is therefore particularlysuited to elongated objects such as pipes, tubes and rails. The nature of guidedwave
10、s differs substantially from the ultrasonic waves used in conventionalultrasonic testing (UT), and therefore it is necessary to define guided wavetesting (GWT) as a method in its own right and manage this branch ofinspection under its own standard.The standard has been written to incorporate flexibi
11、lity to include differentapplications of guided waves, by separate parts of the standard, as thecapability and needs arise.Currently, BS 9690, Non-destructive testing Guided wave testing, comprises thefollowing parts.Part 1: General guidance and principles.Part 2: Basic requirements for guided wave
12、testing of pipes, pipelines andstructural tubulars.However, it is anticipated that further parts of the standard will be introducedto cover the interpretation of measurements; the testing of advanced cases ofpipes, pipelines and structural tubulars; and the application of GWT to otherstructures and
13、components.Presentational conventionsAs a guide, this part of BS 9690 takes the form of guidance andrecommendations. It should not be quoted as if it were a specification or a codeof practice and claims of compliance cannot be made to it.Contractual and legal considerationsThis publication does not
14、purport to include all the necessary provisions of acontract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legalobligations.BRITISH STANDARDBS 9690-1:2011ii BSI 20111 ScopeThis part of BS 9690 provides the general principles for gui
15、ded wave testing.The specific conditions of application and use of guided wave testing, whichdepend on the type of object tested, are described in documents which couldinclude:a) product standards;b) specifications;c) codes;d) contractual documents;e) written procedures.Unless otherwise specified in
16、 the referencing documents the minimumrecommendations of this standard are applicable.This standard does not define:1) extent of testing;2) optimum test parameters for specific applications; or3) acceptance criteria.2 Normative referencesThe following referenced documents are indispensable for the a
17、pplication ofthis document. For dated references, only the edition cited applies. For undatedreferences, the latest edition of the referenced document (including anyamendments) applies.BS EN 473, Qualification and certification of NDT personnel General principlesBS EN 1330-2, Non-destructive testing
18、 Terminology Part 2: Terms common tothe non-destructive testing methodsBS EN 1330-4, Non-destructive testing Terminology Part 4: Terms used inultrasonic testing3 Terms and definitionsFor the purposes of this British Standard, the terms and definitions inBS EN 1330-2 and BS EN 1330-4 apply, together
19、with the following.3.1 axial directionprincipal direction of propagation of the guided waves, particularly in a pipewhere this is parallel to the pipe axis3.2 axial lengthlength of a discontinuity in the axial direction normally parallel to the directionof propagation of the guided waves3.3 call lev
20、el distance amplitude correction (DAC) or time-corrected gain(TCG)DAC curve or TCG threshold above which indications are required to be reportedBRITISH STANDARD BS 9690-1:2011 BSI 2011 13.4 circumferential directiondirection of propagation or displacement perpendicular to the axis and parallelto a t
21、angent to the surface at any pointNOTE Applicable to objects of circular cross section, such as pipes.3.5 circumferential ordernumber of vibration nodes of a guided wave mode around the circumferenceNOTE Applicable to objects of circular cross section, such as pipes.3.6 corrosiondeterioration of a m
22、aterial, usually a metal, that results from a chemical orelectrochemical reaction with its environment3.7 cross sectiontotal area of the wave guide perpendicular to the direction of propagationNOTE The amplitude of a reflection is assumed, typically as a first approximation,to be proportional to the
23、 CSC.3.8 cross section change (CSC)equivalent cross section change calculated, assuming that an indication is purelycaused by a change in the cross section of the objectNOTE Also referred to as “estimated cross section loss” (ECL). It is given as apercentage of the nominal cross section. The amplitu
24、de of a reflection can also beaffected by stiffness changes and the axial dimensions of a feature.3.9 cut-off frequency of guided wave modefrequency at which the energy velocity changes from non-zero to zeroNOTE The definition differs from the term “cut-off frequency” in BS EN 1330-4,which relates t
25、o limits of the bandwidth of an ultrasonic signal.3.10 data capture rangedistance over which data are gathered in a particular directionNOTE This is not necessarily the same as the diagnostic range.3.11 datumreference point for reporting a test position and for correlating test results withactual po
26、sition on the test object, normally a localized physical feature on, or ina fixed relationship to, the test objectNOTE In the case of a pipe this can be a weld, flange or any other suitablepermanent feature. The distance from the datum to the test position is alsoreported.3.12 dead zonedistance alon
27、g the test length of object on either side of the test position, andequal to or slightly greater than the length of the transmitted pulse, wherereflectors of interest cannot be detectedNOTE This definition differs from that in BS EN 1330-4, in which the term relates todistance from the scanning surf
28、ace.3.13 diagnostic rangeaxial length of the test object (excluding the dead zone), measured from thetest position, for which the amplitude of the call level lies above the maximumusable sensitivity lineNOTE Also known as the “end of test”.BRITISH STANDARDBS 9690-1:20112 BSI 20113.14 dispersionfrequ
29、ency dependence of the acoustic properties of a guided wave, such asvelocity and attenuation3.15 dispersion curvegraph of the variation of an acoustic property of a guided wave, for examplethe group velocity, as a function of frequencyNOTE Dispersion curves can be shown for any number of guided wave
30、 modes inthe same graph.3.16 energy velocityvelocity with which the energy of a guided wave signal propagatesNOTE See also “group velocity”.3.17 envelope (signal)outline A-Scan trace bounding the oscillations in each pulse of ultrasound,obtained by a smoothing processNOTE See also “result trace” (3.
31、35).3.18 featuregeometric change or addition to the uniform base material of the test objectwhich does not constitute a discontinuity3.19 focusing3.19.1 focusdeliberate concentration of guided wave modes at a single circumferential andaxial position3.19.2 synthetic focuspost-processing of a recorded
32、 data set to concentrate guided wave modes at asingle circumferential and axial position3.20 guided wave (GW)sonic or ultrasonic waves which travel along an object and are guided by itssurfaces or shape, and whose wavelength is large compared to a characteristicdimension such as wall thickness3.21 g
33、uided wave testing (GWT)testing of a large volume of material from a test location utilizing the longdistance propagation characteristics of guided waves3.22 interpretationprocess of identifying discontinuities from indications in the result trace andother displays3.23 leakageattenuation of the guid
34、ed wave caused by the transmission of energy into asurrounding material3.24 magnetostrictive transducertransducer which generates and receives signals via the coupling of a changingelectromagnetic field to an elastic strain field, using the magnetostrictive effectNOTE This is best achieved using a s
35、pecific magnetostrictive material in order tomaximize the coupling behaviour.BRITISH STANDARD BS 9690-1:2011 BSI 2011 33.25 maximum usable sensitivity lineline overlaid on the test data, which is a factor of 2 (6 dB) greater in valuecompared with the noise line at all pointsNOTE This represents the
36、lowest level at which responses may be reported withoutsignificant risk that they may arise from noise signals.3.26 modespecific kind of waveNOTE Many kinds of guided waves are possible, and they are distinguished byreference to the nature of their displacements. Longitudinal modes havedisplacements
37、 predominantly in the axial direction; torsional modes havedisplacements in the circumferential direction. Axisymmetric (often simply calledsymmetric) modes have displacements which are uniform around the circumference;flexural modes have displacements which are not uniform around the circumference.
38、3.27 guided wave modedistinct type of guided wave with a specific vibrational patternNOTE A variety of modes might exist in any given geometry of object. In the caseof a pipe there are three families of modes: torsional, longitudinal and flexural. Eachof these mode families has a particular vibratio
39、nal behaviour, with the modes withina family being similar to each other.3.28 nominal wall thicknessnominal reference wall thickness of the test object as per specification, notnecessarily the actual wall thickness3.29 noise lineline overlaid on the test data which describes the variation in noise a
40、mplitudealong the test range, after removing the influence of high amplitude responsesfrom pipe features or discontinuitiesNOTE The basis for determination of the noise level (peak, root mean square,moving average, etc.) is stated in the report.3.30 phase velocitypropagation velocity of a point of c
41、onstant phase of a waveNOTE This can be observed for example as the velocity of the crest of a wave. Thephase velocity is equal to the group velocity in cases when there is no dispersion.3.31 pitch-catch configurationtype of test in which pulses are emitted by one transducer device and reflectionsar
42、e received by another3.32 primary modesingle mode which is generated selectively in the test object as the incidentwave for the test3.33 propagating modeguided wave mode whose energy velocity is non-zero3.34 pulse lengthaxial length of a transmitted pulse in the material under test3.35 result tracep
43、lot of the guided wave signal envelopes as a function of distanceNOTE This includes A-Scans, C-Scans, etc. In the case of a pipe, the result trace mayinclude both symmetric and non-symmetric components.BRITISH STANDARDBS 9690-1:20114 BSI 20113.36 reverberationfalse echo caused by multiple reflection
44、s between discontinuities3.37 screeningprocess of testing for the presence of and classifying discontinuities withoutclaim of direct and accurate sizing3.38 secondary modemode which is generated by mode conversion, in reflection or transmission,when the primary mode is incident at a feature or disco
45、ntinuity3.39 signal amplitudemaximum value of a signal, measured as the peak height on the result traceNOTE This may be in arbitrary units and therefore needs to be referenced.3.40 standard operating procedure (SOP)equipment-specific operating procedure normally supplied by the GWTequipment manufact
46、urer3.41 stress wavemost general term for mechanical wave involving stress oscillations in a materialNOTE This includes infrasonic, sonic and ultrasonic waves, in solids, liquids andgases.3.42 test objectfabrication or component along which the wave is guidedNOTE In the case of pipe testing, the obj
47、ect is the pipe.3.43 test frequencycentre frequency of the tone burst pulse or signal transmitted by the transducersystem for a particular test3.44 test position (TP)defined location relative to a known datum where the transducer device isplacedNOTE The test position is generally reported in terms o
48、f distance from a datum.3.45 time-corrected gainmethod of compensating for reduction in signal amplitude with increasingrange from reflectors of equal areaNOTE This is achieved by increasing the system gain with distance so that thesignals appear of equal amplitude.3.46 time-tracerecord of the unpro
49、cessed signals received by a transducer over a certain timeinterval3.47 tone burstpulse of extended duration designed to apply a controlled excitation to thetransducerBRITISH STANDARD BS 9690-1:2011 BSI 2011 53.48 transducerdevice used to excite sonic or ultrasonic waves by converting electrical energyinto mechanical energy, and vice-versa, which may consist of a number ofindividual active elementsNOTE This definition differs from the term “transducer” in BS EN 1330-4, whichrefers to the ultrasonic “probe”.3.49 waveguideobject along which a gu
