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 - 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 referen
7、ce Definition Principle of test method . Equipment . Test parameters . Reference tubes . Test technique . 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
8、) for varying frequencies and conductivities . 12 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 seamless or longitudinally welded circular cross section metal tubes in aluminium or aluminium allo
9、ys, 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 publications. These normative references are cited at the appropriate places in the text and the pu
10、blications 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 revision. For undated references the latest edition of the publication referred to applies. EN 4179 A
11、erospace 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 penetration (6) : Depth within a material at which the eddy current density has decayed to approx
12、imately 37% of its density at the surface. 1) Published as AECMA Prestandard at the date of publication of this standard - - 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 n
13、ot exceed 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.)
14、coil (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, produ
15、cing variations 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
16、coil impedance 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 magni
17、tude of 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
18、properties. 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 i
19、ndicator 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,
20、e.g. the 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
21、equipment 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
22、shall 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 com
23、pany approved by them. AECMA PREN*Za02-20 96 1032333 0030676 450 Page 5 prEN 2002-20 : 1996 6 Test parameters 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. Ferromagneti
24、c tubes shall be magnetically saturated when tested to allow the tubes to be treated in the same manner as non-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
25、 the tube wall thickness does not exceed the eddy current standard depth of penetration (6). The maximum allowed 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 conduct
26、ivity, in megasiemens per metre ; is the relative magnetic permeability. NOTE 1 : 1 MS/m = 1,724 IACS (International 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 refe
27、rence tube with through drilled hole type discontinuities (see figure 1) or with slot type discontinuities in 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 b
28、e determined by trial, since the eddy current standard depth of penetration (6) may be confirmed by detection 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, mag
29、netic permeability and surface finish as the tube to be tested and shall be free of eddy current signals exceeding 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 throug
30、h drilled hole type discontinuities (see figure 1) shall have at least three through drilled holes. These shall 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.
31、 NOTE 1 : The hole should be at least 100 mm from the ends of the tube. NOTE 2 : Hole diameters are given in 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 %
32、 and 80 % of the wall thickness. These slots shall be spaced at 120 O intervals around the circumference of the 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 t
33、he tube. NOTE 2 : Slot dimensions are given in table 3. Reference tubes with slot type discontinuities but of open section for use with saddle type coils (see figure 3) shall as far as possible conform with the above requirements. AECMA PREN*2002-20 96 1012311 0010677 397 = Page 6 prEN 2002-20 : 199
34、6 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 point where a 3:l signal to noise ratio was achieved from a through drilled hole. The tr
35、igger 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 tube feed relative to the test coil shall be the same as that used when calibrating the t
36、est 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 interrupted. Test equipment settings may be carried out in the static condition, however final ca
37、libration 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 are found to be incorrect between calibration checks, then all tubes tested prior to the
38、 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 be performed on tubes in the delivery condition ; aluminium tubes to be supplied in the an
39、nealed 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 produces a signal response equal to, or greater than the trigger level, the manufacturer
40、 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 purchasers requirements, remove the reject the defective tube length. a) current requirements are
41、 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 certified according to EN 4179. AECBA PREN*2002-2Kl 96 m LOL23LL 0010678 223 m Page 7 prE
42、N 2002-20 : 1996 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 de
43、scribed shall 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
44、 procedures shall 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; -
45、identification 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 verifica
46、tion; - periodic checks to be performed; - preparation of the tube prior to testing; - type of equipment used to perform the testing; - coil arrangement for magnetic saturation in case of ferromagnetic tubes; - test coil arrangement relative to the tube; - testing parameters (frequency or frequencie
47、s, filter and filter positions, exciting wave form, current driver, attenuation, preamplifier, sensitivity Y, sensitivity XY, threshold levels, mode Xt or XY, etc.); - testing procedure; - rules for evaluating discontinuity indications; - acceptance criteria; - types of records and marking procedure
48、; - post testing requirements. 13 Test report The results of all eddy current testing shall be recorded. The test reports shall contain the following information : - material standard; - cast number(s) and batch numberb) or unique identification, where applicable; - condition of the tube and its dim
49、ensions; - quantity of tube tested; - details of the test facility and procedures used; - reference to this standard. The test reports shall be made available upon request. AECPIA PREN*2002-20 7b m 1012311 001Ob79 LbT m 0,6 25 Slot length 0,l 2 a 2 0,6 0,40 0,50 0,60 0,65 0,75 O, 80 0,95 0,35 0,40 0,45 0,55 0,65 0,70 0,85 NOTE 1 : “a“ is the tube wall thickness NOTE 2 : Tolerance on hole diameter : f 0,05 mm 0,30 0,35 0,40 0,50 0,60 0,75 Table 2 : Reference tube hole diameters (Steels, titanium alloys, heat resisting alloys) Dimensions in millimetres D I
