1、AECMA STANDARD NORME AECMA AECMA NORM Edition approved for publication 1996-02-29 prEN 2002-20 Edition P 1 February 1996 Comments should be sent within six months after the date of publication to Gulledelle 94 C5 Chairman AECMA Mr Odorico B-1200 BRUXELLES PUBLISHED BY THE EUROPEAN ASSOCIATION OF AER
2、OSPACE INDUSTRIES (AECMA) Gulledelle 94 - 8-1200 BRUXELLES - Tel. (32) 2 775 81 10 - Fax. (32) 2 775 81 11 ICC : 49-040-10 Descriptors ENGLISH VERSION Aerospace series Test methods for metallic materials Part 20 : Eddy current testing of circular cross-section tubes Srie arospatiale Mthodes dessais
3、applicables aux matriaux mtalliques Partie 20 : Contrle par courants de Foucault des tubes section circulaire Luft- und Raumfahrt Prfverfahren fr metallische Werkstoffe Teil 20 : Wirbelstrompriifung an Rohren mit rundem Querschnitt This “Aerospace Series“ Prestandard has been drawn up under the resp
4、onsibility of AECMA (The European Association of Aerospace Industries). It is published on green paper for the needs of AECMA-Members. it has been technically approved by the experts of the concerned Technical Committee following comment by the Member countries. Subsequent to the publication of this
5、 Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre (NPSI and formal agreement of the Official Services
6、of the Member countries it will be submitted as a draft European Standard to CEN (European Committee for Standardization) for formal vote. I l aecrna 1996 - Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction
7、 or networking permitted without license from IHS-,-,- AECMA PREN*2002-20 96 3032333 0030673 793 Page 2 prEN 2002-20 : 1996 Contents list Page 1 2 3 4 5 6 7 8 9 10 11 12 13 Scope . Normative reference Definition Principle of test method . Equipment . Test parameters . Reference tubes . Test techniqu
8、e . Condition of tubes for testing . Acceptance criteria . Personnel qualification . Testing procedures . Test report 3 3 3 4 4 5 5 6 6 6 6 7 7 Annex A (informative) Standard depth of penetration (6) for varying frequencies and conductivities . 12 Copyright Association Europeene des Constructeurs de
9、 Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,- AECMA PREN*2002-20 9b LO123LL OOLOb7Y 688 H Page 3 prEN 2002-20 : 1996 1 Scope This standard specifies a method for the eddy current testing of either sea
10、mless or longitudinally welded circular cross section metal tubes in aluminium or aluminium alloys, copper or copper alloys, titanium or titanium alloys, heat resisting alloys or steels. 2 Normative reference This European Standard incorporates by dated or undated reference provisions from other pub
11、lications. These normative references are cited at the appropriate places in the text and the publications are Ijsted hereafter. 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 revis
12、ion. For undated references the latest edition of the publication referred to applies. EN 4179 Aerospace series - Qualification and approval of personnel for non-destructive testing 1) 3 Definition For the purposes of this standard, the following definition applies : Eddy current standard depth of p
13、enetration (6) : Depth within a material at which the eddy current density has decayed to approximately 37% of its density at the surface. 1) Published as AECMA Prestandard at the date of publication of this standard Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided
14、by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,- - - AECMA PREN*2002-20 9b = L0123LL 00LOb75 514 Page 4 prEN 2002-20 : 1996 4 Principle of test method This test method is applicable to all metal tubes whose wall thickness does not exc
15、eed the eddy current standard depth of penetration (61, for the particular combination of alloy, conductivity and permeability being tested and the test frequency being used. The method involves inducing eddy currents at one or more frequencies into a tube, using an alternative current (a.c.) coil (
16、or coils) which may consist of one or more windings and may also contain a separate saturation coil for inspection of ferromagnetic tubes. The tube is passed lengthwise relative to the test coil and metallurgical or mechanical discontinuities in the tube modify the induced eddy currents, producing v
17、ariations in the coil impedance. The magnitude of impedance variation depends upon the distances between the coil and the tube, the electrical conductivity and magnetic permeability of the tube, the selected test parameters and the dimensions and location of any discontinuities. Variations in coil i
18、mpedance generate electrical signals which are used to actuate acoustic, or visual warnings or a mechanical device which indicates the position of the discontinuity along the length of the tube. Induced eddy currents reduce in strength as they penetrate deeper into the material until the magnitude o
19、f impedance changes preventing detection of discontinuities. The main factors which affect penetration are frequency, magnetic permeability and electrical conductivity. 5 Equipment The test coils shall be capable of inducing eddy currents in the tube and sensing variations in their electrical proper
20、ties. The equipment shall be capable of generating a suitable alternative current to excite the coils and of detecting variations in their impedance. It shall include a signal generator to provide an excitation signal to the test coil, signal processor to amplify and filter the signal and an indicat
21、or or display for the information. NOTE : Other equipment such as gating circuits and phase discriminators may also be included. The test coil arrangement shall be selected according to the particular orientation of discontinuity being sought. The tube to coil clearance shall not exceed 1 mm, e.g. t
22、he test coil internal diameter shall not exceed the outside tube diameter by more than 2 mm. The tube feed and handling equipment shall be capable of maintaining a constant coil-tube distance and a uniform feed speed within k 10 %. Mechanical vibrations generated by the tube feed and handling equipm
23、ent shall be kept to a minimum. A general visual examination of the equipment for wear and damage shall be carried out at least once a day. Any sign of wear or damage shall be investigated and immediate corrective action taken, if required, to repair the fault. The inspection equipment system shall
24、be checked at regular intervals of not more than 12 months and after any repair, to verify that the electronic and mechanical performance of the equipment remains within the manufacturers original specification. The equipment check shall be carried out by the equipment manufacturer or by a company a
25、pproved by them. Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-AECMA PREN*Za02-20 96 1032333 0030676 450 Page 5 prEN 2002-20 : 1996 6 Test parameters
26、 The frequency, phase, filters and gain shall be selected such that artificial discontinuities in a reference tube can be detected with a signal to noise ratio of 3:t or greater. Ferromagnetic tubes shall be magnetically saturated when tested to allow the tubes to be treated in the same manner as no
27、n-ferromagnetic tubes. NOTE : Non-ferromagnetic tubes and magnetically saturated tubes are assumed to have a relative magnetic permeability of 1. The frequency (f) shall be selected such that the tube wall thickness does not exceed the eddy current standard depth of penetration (6). The maximum allo
28、wed frequency is defined by the equation 252,3 x 103 F2.y apr f= Where : f 6 y pr is the frequency, in hertz ; is the standard depth of penetration, in millimetres ; is the electrical conductivity, in megasiemens per metre ; is the relative magnetic permeability. NOTE 1 : 1 MS/m = 1,724 IACS (Intern
29、ational Annealed Copper Standard) 1 IACS = 0,58 MS/m NOTE 2 : The 6 for varying frequencies is given in Annex A. 7 Reference tubes Equipment calibration shall be performed using either a reference tube with through drilled hole type discontinuities (see figure 1) or with slot type discontinuities in
30、 the internal wall (see figures 2 and 3). NOTE : If the reference tube used for calibration contains slot type discontinuities in the internal wall, then the eddy current test frequency may be determined by trial, since the eddy current standard depth of penetration (6) may be confirmed by detection
31、 of the slot which is 20 % through the thickness of the wall. Reference tubes shall be produced from material which has the same dimensions, chemical composition, electrical conductivity, magnetic permeability and surface finish as the tube to be tested and shall be free of eddy current signals exce
32、eding the noise level. Reference tubes shall have a hole drilled through the tube wall at one end for the purpose of determining the extent of the tube end effect. Reference tubes with through drilled hole type discontinuities (see figure 1) shall have at least three through drilled holes. These sha
33、ll be spaced at 120 O intervals around the circumference of the tube and spaced to allow the eddy current responses from each hole to be determined without interference from an adjacent hole. NOTE 1 : The hole should be at least 100 mm from the ends of the tube. NOTE 2 : Hole diameters are given in
34、tables 1 and 2. Reference tubes with slot type discontinuities in the internal wall (see figure 2) shall have at least three longitudinal and/or three transverse slots at depths of 20 %, 50 % and 80 % of the wall thickness. These slots shall be spaced at 120 O intervals around the circumference of t
35、he tube and spaced to allow the eddy current responses from each slot to be analyzed without interference from an adjacent slot. NOTE 1 : The slots should be at least 100 mm from the end of the tube. NOTE 2 : Slot dimensions are given in table 3. Reference tubes with slot type discontinuities but of
36、 open section for use with saddle type coils (see figure 3) shall as far as possible conform with the above requirements. Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without li
37、cense from IHS-,-,- AECMA PREN*2002-20 96 1012311 0010677 397 = Page 6 prEN 2002-20 : 1996 8 Test technique The test parameters shall conform to 6. The extent of tube end effect shall be determined by the use of suitable reference tubes. The tube and effect length is the length of tube from the last
38、 point where a 3:l signal to noise ratio was achieved from a through drilled hole. The trigger level shall be set so that acoustic or visual warnings or a mechanical marking device operate from the smallest eddy current signal response from the reference tube artificial discontinuities. The rate of
39、tube feed relative to the test coil shall be the same as that used when calibrating the test equipment. Calibration checks using the appropriate reference tube shall be carried out : a) b) at intervals not exceeding 1 h and at the commencement and completion of testing; each time testing is interrup
40、ted. Test equipment settings may be carried out in the static condition, however final calibration shall be confirmed in the dynamic condition. They shall not be changed between the moment at which the calibration is recognised as satisfactory for tube testing and the next calibration check. If they
41、 are found to be incorrect between calibration checks, then all tubes tested prior to the last check shall be re-tested. Untested ends of tubes shall be marked. 9 Condition of tubes for testing The tube surface condition shall conform to the requirements of the material standard. The testing shall b
42、e performed on tubes in the delivery condition ; aluminium tubes to be supplied in the annealed condition may be inspected after final annealing. 1 O Acceptance criteria Any tube which produces a signal response below the trigger level shall be considered to be acceptable. If any tube or part a tube
43、 produces a signal response equal to, or greater than the trigger level, the manufacturer shall treat the tube by one of the following procedures : re-work the tube as defined in the material standard and repeat the test to ensure the eddy providing the remaining tube lengthk) will meet the purchase
44、rs requirements, remove the reject the defective tube length. a) current requirements are satisfied; b) doubtful zone, then repeat the test to ensure the eddy current requirements are satisfied; c) 11 Personnel qualification Eddy current inspection shall only be performed by personnel qualified and
45、certified according to EN 4179. Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-AECBA PREN*2002-2Kl 96 m LOL23LL 0010678 223 m Page 7 prEN 2002-20 : 19
46、96 12 Testing procedures Eddy current testing of circular cross section tubes shall be performed in accordance with a written procedure applicable to the tubes or groups of tubes to be tested. The procedure shall be in accordance with the requirements of this standard. The technique described shall
47、be capable of detecting the smallest rejectable discontinuity specified in the acceptance criteria. NOTE : The written procedure may be a general one if it clearly applies to all the specified tubes or group of tubes to be tested and meets the requirements of this standard. All written procedures sh
48、all be approved by an individual qualified to level 3 of EN 4179 for eddy current testing and shall be submitted upon request. A written procedure shall contain the following information : - part and identification number of the tube or group of tubes to which the procedure applies; - identification
49、 of relevant design drawings; - identification of testing areab), critical zones and description of possible discontinuities; - sequence of eddy current testing as related to manufacturing process operations; - identification of the testing standard used for system performance verification; - periodic checks to be performed; - preparation of the tube prior to testing; - type of equipment used to perform the testing; - coil arrangement for magn
