EN_1714_中文

一、欧洲标准EN1714-1998焊缝超声波检验一、国际标准ISO17640：2005焊缝无损检测-焊接接头超声波检测1 范围本欧洲标准规定厚度为8mm及以上低超声衰减(特别是散射衰减)的金属材料(超声衰减特别是散射衰减较小)的熔化焊缝的手工超声检验方法。

主要用于焊缝和母材均为铁素体的全焊透焊接接头。

本标准规定的四种检验等级（A、B、C和D）（见条款11），每种等级对应于不同缺陷检出概率。

有关选择检验等级A、B、C的导则见附录A。

经签约单位同意后，可通过下列方法使用本国际标准对缺陷讯号进行评价：(1)主要根据讯号的回波幅度和指示长度；(2)用探头移动法对缺陷定性、定量。

如有规定，且合适，经签约单位同意，该国际标准中有关技术也可用于：(1)除上述材料以外的其他材料；(2)部分焊透焊缝；(3)自动检测设备。

每种情况下使用的技术必须被证实有足够的灵敏度。

注：本标准规定的材料有关的超声波参数，是根据纵波声速为（5920±50）m／s，横波声速为（3255±30）m／s的钢材得出的。

检测不同声速的材料时,就必须考虑到这一点。

本标准规定的材料有关的超声波参数，是根据纵波声速为（5920±50）m／s，横波声速为（3255±30）m／s的钢材得出的。

检测不同声速的材料时,就必须考虑到这一点。

本标准规定的四种检验等级，每种等级对应于不同缺陷检出概率。

有关选择检验等级A、B、C的导则见附录A。

适于具体应用的检验等级要求需遵循本标准的一般要求，并征得签约单位同意。

经签约单位同意后，本标准评价允许采用下列方法对缺陷讯号进行评价和验收：(1)要根据讯号的回波幅度和指示长度；(2)用探头移动法对缺陷定性、定量。

2 引用标准下列参考文献对于本标准的应用是非常必要的。

本欧洲标准引用了其他现行标准或旧标准拟成新条文。

这些引用标准引述于文中相应处，篇名如下。

对旧标准只引用含修改条文的修订版，而对现标准则引用最新版（包含所有修正）。

European Standard EN 1714:1997 + A1:2002 has the status of a DIN Standard.National forewordThis standard has been prepared by CEN/TC 121.The responsible German body involved in its preparation was the Normenausschuss Materialprüfung (Ma-terials Testing Standards Committee), Technical Committee Ultraschallprüfung.AmendmentsThis standard differs from the October 1997 edition in that it has been editorially revised.Previous editionsDIN 54125: 1989-01; DIN EN 1714: 1997-10.ICS 25.160.40Zerstörungsfreie Prüfung von Schweißverbindungen –Ultraschallprüfung von Schweißverbindungen (enthält Änderung A1:2002)Ref.No.DIN EN 1714:2002-09English price group 13Sales No.111303.03DEUTSCHE NORMSeptember 2002EN 1714{EN comprises 25 pages.©No part of this standard may be reproduced without the prior permission ofDIN Deutsches Institut für Normung e.V., Berlin. Beuth Verlag GmbH , 10772Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).Non-destructive testing of weldsUltrasonic testing of welded joints(includes Amendment A1)English version of DIN EN 1714:1997 + A1:2002SupersedesOctober 1997 edition.N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01English versionICS 25.160.40Management Centre: rue de Stassart 36, B-1050 BrusselsEuropean Committee for Standardization Comit é Europ éen de Normalisation Europ äisches Komitee f ür NormungNon-destructive testing of weldsUltrasonic testing of welded joints(includes Amendment A1)©2002.CEN –All rights of exploitation in any form and by any means reserved worldwide for CEN national members.Ref. No. EN 1714:1997+A1:2002EContr ôle non destructif des assem-blages soud és – Contr ôle par ultra-sons des assemblages soud és (Amendement A1 inclus)Zerst örungsfreie Pr üfung vonSchwei ßverbindungen – Ultraschall-pr üfung von Schwei ßverbindungen (enth ält Änderung A1:2002)This European Standard was approved by CEN on 1997-08-02. Amendment A1was approved by CEN on 2002-05-01.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Management Centre or to any CEN member.The European Standards exist in three official versions (English, French, German).A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official versions.CEN members are the national standards bodies of Austria, Belgium, the Czech Republic, Denmark, Finland, France, G ermany, G reece, Iceland, Ireland, Italy,Luxembourg, Malta, the Netherlands, Norway, Portugal, Spain, Sweden, Switzer-land, and the United Kingdom.ÈÉËEN 1714 October 1997+A1M ay 2002N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01Page 2EN 1714:1997+A1:2002PageForeword to EN 1714:1997 . . . . . . . . . . . . . . . 2Foreword to EN 1714:1997/A1:2002 . . . . . . 21Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Normative references . . . . . . . . . . . . . . . . . 33Definitions and symbols . . . . . . . . . . . . . . . 34General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Information required prior to testing . . . . 45.1Items to be specified . . . . . . . . . . . . . . . . . 45.2Specific information required prior totesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.3Written test procedure . . . . . . . . . . . . . . . . 56Requirements for personnel andequipment . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.1Personnel qualifications . . . . . . . . . . . . . . . 56.2Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 56.3Probe parameters . . . . . . . . . . . . . . . . . . . . 56.3.1Frequency . . . . . . . . . . . . . . . . . . . . . . . . 56.3.2Angles of incidence . . . . . . . . . . . . . . . . . 56.3.3Adaption of probes to curvedscanning surfaces . . . . . . . . . . . . . . . . . .57Testing volume . . . . . . . . . . . . . . . . . . . . . . . 68Preparation of scanning surfaces . . . . . . . 69Parent metal testing . . . . . . . . . . . . . . . . . . 610Range and sensitivity setting . . . . . . . . . 710.1General . . . . . . . . . . . . . . . . . . . . . . . . . . . 710.2Reference level . . . . . . . . . . . . . . . . . . . . . 7Page10.3Evaluation levels . . . . . . . . . . . . . . . . . . . . 810.4Transfer correction . . . . . . . . . . . . . . . . . . 810.5Signal-to-noise ratio . . . . . . . . . . . . . . . . 811Testing levels . . . . . . . . . . . . . . . . . . . . . . . 812Testing technique . . . . . . . . . . . . . . . . . . . 912.1General . . . . . . . . . . . . . . . . . . . . . . . . . . . 912.2Manual scan path . . . . . . . . . . . . . . . . . . . 912.3Testing for imperfections perpendicularto the test surface . . . . . . . . . . . . . . . . . .912.4Location of indications . . . . . . . . . . . . . . 912.5Evaluation of indications . . . . . . . . . . . . . 912.5.1General . . . . . . . . . . . . . . . . . . . . . . . . . . 912.5.2Maximum echo amplitude . . . . . . . . . . 912.5.3Indication length . . . . . . . . . . . . . . . . . . 1012.5.4Indication height . . . . . . . . . . . . . . . . . . 1012.5.5Characterization of imperfections . . . . 1013Test report . . . . . . . . . . . . . . . . . . . . . . . . . 1013.1General . . . . . . . . . . . . . . . . . . . . . . . . . . . 1013.2General data . . . . . . . . . . . . . . . . . . . . . . . 1013.3Information relating to equipment . . . . . . 1013.4Information relating to testingtechnique . . . . . . . . . . . . . . . . . . . . . . . . .1013.5Results of testing . . . . . . . . . . . . . . . . . . .11Annex A (normative)Testing levels forvarious types of welded joints . . . . . . . . 11Annex ZA (informative)Clauses of thisEuropean Standard addressing essential requirements or otherprovisions of EU directives . . . . . . . . . . . 25ContentsForeword to EN 1714:1997This European Standard has been prepared by CEN/TC 121 ‘Welding ’, the Secretariat of which is held by DS.This European Standard has been prepared under a mandate given to CEN by the Commission of European Communities and the European Free Trade Association and supports essential requirements of the relevant EC Directive. For relationship with this directive, see Annex ZA.This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, and conflicting national standards withdrawn, by February 1998 at the latest.In accordance with the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard:Austria, Belgium, the Czech Republic, Denmark, Finland, France, G ermany, G reece, Iceland, Ireland, Italy,Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom.Foreword to EN 1714:1997/A1:2002This Amendment to EN 1714:1997 has been prepared by Technical Committee CEN/TC 121 ‘Welding ’, the Secretariat of which is held by DS.This Amendment has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of the relevant EC Directive. For rela-tionship with this directive, see Annex ZA.This Amendment shall be given the status of a national standard, either by publication of an identical text or by endorsement, and conflicting national standards withdrawn, by November 2002 at the latest.In accordance with the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard:N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01Page 3EN 1714:1997+A1:2002Austria, Belgium, the Czech Republic, Denmark, Finland, France, G ermany, G reece, Iceland, Ireland, Italy,Luxembourg, Malta, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom.1ScopeThis European Standard specifies methods for the manual ultrasonic testing of fusion welded joints in metallic materials equal to and above 8 mm thick which exhibit low ultrasonic attenuation (especially that due to scatter).It is primarily intended for use on full-penetration welded joints where both the welded and parent material are ferritic.The techniques may also be used:–on materials other than those stated,–on partial-penetration welds,–with automated equipment,if required by specification.Where material-dependent ultrasonic values are specified in this standard, they are based on steel having an ultrasonic sound velocity of (5920 t 50) m/s for longitudinal waves, and (3255 t 30)m/s for transverse waves.This is to be taken into account when examining materials with a different velocity.The standard specifies four testing levels, each corresponding to a different probability of detection of imper-fections. Guidance on the selection of testing levels A, B and C is given in Annex A. The requirements of the fourth testing level, which is intended for use in special applications, shall be in accordance with the general requirements of this standard and may only be used when defined by specification.This standard may be used for the assessment of indications, for acceptance purposes, by either of the following methods:1)evaluation based primarily on length and echo amplitude of the signal indication;2)evaluation based on characterization and sizing of the indication by probe movement methods.The methods used shall be specified.2Normative referencesThis European Standard incorporates by dated or undated references provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed as follows.For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies:EN 473Qualification and certication of NDT personnel – General principlesEN 583-1Non-destructive testing – Ultrasonic examination – Part 1: General principlesEN 583-2Non-destructive testing – Ultrasonic examination – Part 2: Sensitivity and range setting EN 1330-4Non-destructive testing – Terminology – Part 4: Terms used in ultrasonic testingEN 1712Non-destructive testing of welds – Ultrasonic testing of welded joints – Acceptance levelsEN 1713Non-destructive testing of welds – Ultrasonic testing – Characterization of imperfections in welds EN 12062Non-destructive examination of welds – General rules for metallic materialsEN 25817Arc-welded joints in steel – Guidance on quality levels for imperfections (ISO 5817:1992)3Definitions and symbolsFor the purposes of this standard, the definitions given in EN 1330-4 and EN 12062 apply.For quantities and symbols, see table 1.Indications shall be considered to be either longitudinal or transverse, depending on the direction of their major dimension with respect to the weld axis, x , in accordance with figure 2.N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01Page 4EN 1714:1997+A1:2002Table 1:Quantities and symbolsSymbolQuantityUnit t Thickness of parent material (thinnest part)mm D DSR Diameter of disc-shaped reflector mm D SDHDiameter of side-drilled hole mm l Length of indicationmm h Extension of indication in depth direction mm x Position of indication in longitudinal direction mm y Position of indication in transverse direction mm z Position of indication in depth direction mm l z Projected length of indication in depth direction mm l x Projected length of indication in x -direction mm l y Projected length of indication in y -direction mm pFull skip distancemm4GeneralThe purpose of this standard is to describe general methods of ultrasonic testing, using standard criteria, for the most commonly used welded joints. The requirements specified this standard cover the equipment, prepa-ration, performance of the test and reporting. The parameters specified, in particular those for the probes, are compatible with the requirements of EN 1712 and EN 1713, and are also suitable for use with other acceptance criteria standards. The techniques recommended in this standard are suitable for the detection of weld imper-fections as specified in typical weld acceptance standards. Methods to be used for ultrasonic assessment of indications and acceptance criteria shall be defined by specification.If the agreed acceptance criteria require a more precise determination of the height and nature of the defect (e.g.when fitness-for-purpose criteria are applied), this may necessitate the use of techniques or methods outside the scope of this standard.5Information required prior to testing5.1Items to be specified–Method for setting the reference level–Method to be used for evaluation of indications –Acceptance levels –Testing level–Manufacturing and operation stage(s) at which the testing is to be carried out –Qualification of personnel–Scope of testing for transverse indications –Requirements for tandem testing–Parent metal testing prior to and/or after welding –Whether or not a written test procedure is required –Requirements for written test procedures 5.2Specific information required prior to testingBefore any testing of a welded joint can begin, the operator shall have access to the following essential information:–written test procedure, if required (see 5.3);–type(s) of parent material and product form (i.e. cast, forged, rolled);–manufacturing or operation stage at which testing is to be carried out including any heat treatment;–time and extent of any post-weld heat treatment;N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01Page 5EN 1714:1997+A1:2002–joint preparation and dimension;–requirement for surface condition;–welding procedure or relevant information on welding process;–reporting requirements;–acceptance levels;–scope of testing, including requirements for transverse indications, if relevant;–testing level;–personnel qualification level;–procedures for corrective action when unacceptable indications are revealed.5.3Written test procedureThe definitions and requirements given in this standard will normally satisfy the need for a written procedure.Where this is not the case, or where the techniques described in this standard are not applicable to the welded joint to be examined, additional written procedures shall be used, if required by specification.6Requirements for personnel and equipment6.1Personnel qualificationsPersonnel carrying out testing in accordance with this standard shall be qualified to an appropriate level in accordance with EN 473 or equivalent in the relevant industrial sector.In addition to a general knowledge of ultrasonic weld inspection, they shall also be familiar with testing problems specifically associated with the type of welded joints to be examined.6.2EquipmentAny equipment used in conjunction with this standard shall comply with the requirements of relevant European Standards. Prior to the publication of EN Standards related to the subject, the corresponding national stand-ards may be used.6.3Probe parameters6.3.1FrequencyThe frequency shall be within the 2MHz to 5MHz range and shall be selected to comply with the specified acceptance levels.For initial testing, the frequency shall be as low as possible, within the above range, when the evaluation is carried out according to acceptance levels based on length and amplitude (e.g. EN 1712). Higher frequencies may be used to improve range resolution if this is necessary when using standards for acceptance levels based on the characterization of imperfections (e.g. EN 1713).Frequencies of approximately 1MHz may be used for testing at long sound paths where the material shows above average attenuation.6.3.2Angles of incidenceWhen testing is carried out with transverse waves and techniques that require the ultrasonic beam to be reflected from an opposite surface, care shall be taken to ensure that the incident angle of the beam, with the opposite reflecting surface, is not less than 35° and preferably not greater than 70°. Where more than one probe angle is used, at least one of the angle probes used shall conform with this requirement. One of the probe angles used shall ensure that the weld fusion faces are examined at, or as near as possible to, normal incidence. When the use of two or more probe angles is specified, the difference between the nominal beam angles shall be 10°or greater.Angles of incidence at the probe and opposite reflecting surface, when curved, may be determined by drawing a sectional view of the weld or in accordance with the methods given in EN 583-2. Where angles of incidence cannot be determined as specified by this standard, the test report shall include a comprehensive description of the scans used and the extent of any incomplete coverage caused together with an explanation of the difficulties encountered.6.3.3Adaption of probes to curved scanning surfacesThe gap between test surface and bottom of the probe shoe shall not be greater than 0,5 mm. For cylindrical or spherical surfaces, this requirement will normally be met when the following equation is fulfilled:D ö 15 awhereD is the diameter of the component, in mm;a is the dimension of the probe shoe in the direction of testing, in mm.N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01Page 6EN 1714:1997+A1:2002If this requirement cannot be met the probe shoe shall be adapted to the surface and the sensitivity and range shall be set accordingly.7Testing volumeThe testing volume (see figure 1) is defined as the zone which includes weld and parent material for at least 10mm on each side of the weld, or the width of the heat-affected zone, whichever is greater.In all cases, scanning shall cover the whole testing volume. If individual sections of this volume cannot be covered in at least one scanning direction, or if the angles of incidence with the opposite surface do not meet the requirements specified in 6.3.2, alternative or supplementary ultrasonic techniques or other non-destructive methods shall be agreed upon. This may, in some cases, require removal of any excess weld metal.Supplementary methods may require testing using twin crystal angle beam probes, creeping wave probes,further ultrasonic techniques or any other suitable method (e.g. liquid penetrant, magnetic particle, radio-graphic testing). In selecting alternative or supplementary methods, due consideration should be given to the type of weld and probable orientation of any imperfections to be detected.8Preparation of scanning surfacesScanning surfaces shall be wide enough to permit the testing volume (see figure 1) to be fully covered. Alter-natively the width of the scanning surfaces may be smaller if equivalent coverage of the testing volume can be achieved by scanning from both the upper and the lower surface of the joint.Scanning surfaces shall be even and free from foreign matter likely to interfere with probe coupling (e.g. rust,loose scale, weld spatter, notches, grooves). Waviness of the test surface shall not result in a gap between the probe and test surfaces greater than 0,5mm. These requirements shall be ensured by dressing if necessary.Local variations in surface contour (e.g. along the edge of the weld), which result in a gap beneath the probe of up to 1mm, is only permitted if at least one additional probe angle is employed from the affected side at the weld. This additional scanning is necessary to compensate for the reduced weld coverage that will occur with a gap of this dimension.In all cases, the maximum permitted gap on areas of the test surface from which the evaluation of indications is to be carried out shall be 0,5mm. Scanning surfaces and surfaces from which the sound beam is reflected may be assumed to be satisfactory if the surface roughness, R a , is not greater than 6,3µm for machined surfaces, or not greater than 12,5µm for shotblasted surfaces.9Parent metal testingThe parent metal, in the scanning zone area, shall be examined with straight beam probes prior to or after welding, unless it can be demonstrated (e.g. by testing during the fabrication process) that the angle probe testing of the weld will not be influenced by the presence of the imperfections or high attenuation.Where imperfections are found their influence on the proposed angle beam testing shall be assessed and, if necessary, the techniques adjusted correspondingly. When satisfactory coverage by ultrasonic testing is se-riously affected, by agreement, other inspection methods (e.g. radiography) may need to be considered.N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01Page 7EN 1714:1997+A1:20021Width of testing volume 2Scanning surfaceFigure 1:Example of testing volume to be covered when scanning for longitudinal indications10Range and sensitivity setting10.1GeneralSetting of range and sensitivity shall be carried out prior to each test in accordance with this standard and EN 583-2. Checks to confirm these settings shall be performed at least every four hours and on completion of the test. Checks shall also be carried out whenever a system parameter is changed or changes in the equivalent settings are suspected.If deviations are found during these checks, the corrections given in table 2 shall be carried out.Table 2:Sensitivity and range correctionsSensitivity1Deviations ß 4dBThe setting shall be corrected before testing is continued.2Reduction of the sensitivity > 4 dB Setting shall be corrected and all tests carried out with the equipment over the previous period shall be repeated.3Increase in sensitivity > 4 dBSetting shall be corrected and all recorded indications shall be reassessed.Range1Deviations ß 2% of the range The setting shall be corrected before testing is continued.2Deviations > 2% of the rangeSetting shall be corrected and testing carried out with the equipment over the previous period shall be repeated.10.2Reference levelOne of the following methods for setting reference levels shall be used:–method 1: The reference level is a distance-amplitude-curve (DAC-curve) for a 3 mm side-drilled hole;–method 2: The reference levels for transverse and longitudinal waves using the distance gain size (DGS)system based on a disc-shaped reflector (DSR) are given in tables 3 and 4 respectively;–method 3: The reference level is equal to a DAC curve for a 1 mm deep rectangular notch.–tandem testing: D DSR= 6 mm (for all thicknesses).N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01Page 8EN 1714:1997+A1:2002Table 3:Reference levels for angle beam scanning with transverse waves for method 2 (DGS)Nominal probe Thickness of parent material (mm)frequency (MHz)8 ß t < 1515 ß t < 4040 ß t ß 1001,5 to 2,5–D DSR = 2 mm D DSR = 3 mm3 to 5D DSR = 1 mmD DSR = 1,5 mm–Table 4:Reference levels for longitudinal waves for method 2 (DGS)Nominal probe Thickness of parent material (mm)frequency (MHz)8 ß t < 1515 ß t < 4040 ß t ß 1001,2 to 2,5–D DSR = 2 mm D DSR = 3 mm 3 to 5D DSR = 2 mmD DSR = 2 mmD DSR = 3 mm10.3Evaluation levelsAll indications equal to or exceeding the following shall be evaluated:–methods 1 and 3: Reference level –10 dB (33% DAC);–method 2: Reference level –4 dB, in accordance with tables 3 and 4, respectively;–tandem testing: DDSR= 6 mm (for all thicknesses).10.4Transfer correctionWhere separate blocks are used for establishing reference levels, measurements shall be made of the transferdifferences, between test object and block, at a representative number of locations. Suitable techniques are described in EN 583-2.If the differences are less than 2dB, correction is not required.If the differences are greater than 2dB but smaller than 12dB, they shall be compensated for.If transfer losses exceed 12dB, the reason shall be considered and further preparation of the scanning surfaces shall be carried out, if applicable.Where there are no apparent reasons for high correction values, the attenuation, at various locations on the test object, shall be measured and, where it is found to vary significantly, corrective actions need be considered.10.5Signal-to-noise ratioDuring testing of the weld the noise level excluding spurious surface indications shall remain at least 12dB below the evaluation level. This requirement may be made less stringent subject to specification.11Testing levelsQuality requirements for welded joints are mainly associated with the material, welding process and service conditions. To accommodate all of these requirements this standard specifies four testing levels (A, B, C and D).From testing level A to testing level C an increasing probability of detection will be achieved by an increasing test coverage (e.g. number of scans, surface dressing). Testing level D may be agreed for special application using a written procedure which shall take into account the general requirements of this standard.In general, the testing levels are related to quality levels (e.g. EN 25817). The appropriate testing level may be specified in standards for testing welds (e.g. EN 12062), product standards or other documents.When EN 12062 is specified, the recommended testing levels are as given in table 5.Table 5:Recommended testing levels Testing levelQuality level in EN 25817A CB BC By agreement DSpecial applicationN o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01Specific requirements for testing levels A to C are given for various types of joints in Annex A. It should be noted that the joint types shown are ideal examples only and where actual welding conditions or accessability do not conform exactly with those shown, the testing technique shall be modified to satisfy the general requirements of this standard and the specific testing level required. For these cases, a written test procedure shall be prepared.12Testing technique 12.1GeneralUltrasonic testing shall be performed in accordance with EN 583-1, taking the following subclauses into ac-count.12.2Manual scan pathDuring angle probe scanning (as illustrated in figure 1) a slight swivelling movement up to and angle of 10° in either side of the nominal beam direction may be applied to the probe.12.3Testing for imperfections perpendicular to the test surfaceSubsurface planar imperfections perpendicular to the test surface are difficult to detect with single angle probe techniques. For such imperfections specific testing techniques should be considered, particularly for welds in thicker materials. Use of these techniques shall be defined by specification.12.4Location of indicationsThe location of all indications shall be defined by reference to a coordinate system (e.g. as shown in figure 2).A point on the test surface shall be selected as the origin for these measurements.Where testing carried out from more than one surface, reference points shall be established on each surface.In this case, care shall be taken to establish a positional relationship between all reference points used, so that the absolute location of all indications can be established from any nominated reference point.In the case of circumferential welds, this may require the establishment of the inner and outer reference points prior to assembly for welding.1Origin Figure 2:Coordinate system for defining the location of indications 12.5Evaluation of indications 12.5.1General All relevant indications above the evaluation level shall be assessed in accordance with clauses 12.5.2 to 12.5.4.12.5.2Maximum echo amplitude The echo amplitude shall be maximized by probe movement and recorded in relation to the agreed reference level.N o r m e n -D o w n l o a d -B e u t h -A l s t o m P o w e r G e n e r a t i o n A G -K d N r .5281078-L f N r .2366787001-2004-04-19 14:01。

（3）规定了用于判定声学性能相近似的参数及其指标，但不同标准如NB／T 20003.2—2010、SA－508／SA－508M、SA－578／SA－578M、SA－788／SA－788M、EN 1714、JIS 3060、JB／T 4730.3等，规定的参数及指标各不相同。
（4）对如何判定声学性能相同或相近似未作明确规定，如RCC－M 规范、NF A 04－308等。
在规范性附录F 中规定，焊缝超声检测时，对碳钢和低合金钢板材的材质衰减，在频率低于3MHz、声程不超过300mm 时，或者衰减系数小于0.01dB／mm 时可以不计；声程较大或材质衰减系数超过0.01dB／mm，在确定缺陷反射波幅时，应考虑材质衰减修正，规定了横波超声材质衰减的测量和传输损失差的测定。
横波声速也可以根据图1测定的纵波声速按式（3）计算：
3.2 材质衰减系数的测定
对比试块和被检工件材质衰减系数α，一般可采用二次（或多次）底波与一次底波高度分贝差值ΔN 进行计算：
式中：ΔNg 为材质衰减引起的分贝差值；ΔNe 为声束扩散引起的分贝差值；ΔNd 为检测面曲率半径和粗糙度的分贝差值，即传输损失。
第四种规定不明确，没有具体的参数和指标，不同的人有不同的理解，而且差异很大，实际执行中偏差幅度大，甚至难以执行。
2.2 表征材料声学性能的声学参数
材料声学性能是个物理概念，必须用可量化的声学参数描述，才可以判断两种材料的声学性能是否相同或相近似。超声检测对比试块所有用途可以归结为对反射体的定位和定量，影响定位准确性的是材料的声速，影响定量准确性的是材料的超声衰减；因此，笔者认为在超声检测中，用声速和超声衰减表征材料的声学性能是比较合适的。对文中所列举的国内外超声检测标准关于判定对比试块和被检件声学性能相近似的规定，笔者认为NB／T 20003.2—2010标准中第3 条采用声速、声阻抗和衰减系数的相差值作为判据是比较合理的。但是，NB／T 20003.2—2010标准中没有规定声速、声阻抗和衰减系数三参数具体测试方法和评价方法。

一、欧洲标准EN1714-1998焊缝超声波检验一、国际标准ISO17640：2005焊缝无损检测-焊接接头超声波检测1 范围本欧洲标准规定厚度为8mm及以上低超声衰减(特别是散射衰减)的金属材料(超声衰减特别是散射衰减较小)的熔化焊缝的手工超声检验方法。

主要用于焊缝和母材均为铁素体的全焊透焊接接头。

本标准规定的四种检验等级（A、B、C和D）（见条款11），每种等级对应于不同缺陷检出概率。

有关选择检验等级A、B、C的导则见附录A。

经签约单位同意后，可通过下列方法使用本国际标准对缺陷讯号进行评价：(1)主要根据讯号的回波幅度和指示长度；(2)用探头移动法对缺陷定性、定量。

如有规定，且合适，经签约单位同意，该国际标准中有关技术也可用于：(1)除上述材料以外的其他材料；(2)部分焊透焊缝；(3)自动检测设备。

每种情况下使用的技术必须被证实有足够的灵敏度。

注：本标准规定的材料有关的超声波参数，是根据纵波声速为（5920±50）m／s，横波声速为（3255±30）m／s的钢材得出的。

检测不同声速的材料时,就必须考虑到这一点。

本标准规定的材料有关的超声波参数，是根据纵波声速为（5920±50）m／s，横波声速为（3255±30）m／s的钢材得出的。

检测不同声速的材料时,就必须考虑到这一点。

本标准规定的四种检验等级，每种等级对应于不同缺陷检出概率。

有关选择检验等级A、B、C的导则见附录A。

适于具体应用的检验等级要求需遵循本标准的一般要求，并征得签约单位同意。

经签约单位同意后，本标准评价允许采用下列方法对缺陷讯号进行评价和验收：(1)要根据讯号的回波幅度和指示长度；(2)用探头移动法对缺陷定性、定量。

2 引用标准下列参考文献对于本标准的应用是非常必要的。

本欧洲标准引用了其他现行标准或旧标准拟成新条文。

这些引用标准引述于文中相应处，篇名如下。

对旧标准只引用含修改条文的修订版，而对现标准则引用最新版（包含所有修正）。