1、DEUTSCHE NORM December 1999 Characteristics of focal spots in industrial X-ray systems for use in non-destructive testing Part 4: Edge method English version of DIN EN 12543-4 DIN - EN 12543-4 ICs 19.100 Zerstrungsfreie Prfung - Charakterisierung von Brennflecken in Industrie-Rntgenanlagen fr die ze
2、rstrungsfreie Prfung - Teil 4: Kanten-Verfahren European Standard EN 12543-4 : 1999 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard has been prepared by CEN/TC 138. The responsible German body involved in its preparation was the Normenausschu
3、Materialprfung (Mate- rials Testing Standards Committee), Technical Committee Durchstrahlungsprfung und Strahlenschutz. EN comprises 7 pages. No pari of this standard may be reproduced without the prior permission of Y Deutsches Institut fr Normung e. V., Berlin. wth Verlag GmbH, D-10772 Berlin, has
4、 the exclusive right of sale for German Standards (DIN-Normen). Ref. No. DIN EN 12543-4 : 1999-1 English price group O7 Sales No. 1107 05.00 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12543-4 September 1999 ICs 19.1 O0 English version Non-destructive testing Characteristics of focal spots
5、in industrial X-ray systems for use in non-destructive testing Part 4: Edge method Essais non destructifs - Caractris- tiques des foyers missifs des tubes radiognes industriels utiliss dans les essais non destructifs - Partie 4: Mthode par effet de bord Zerstrungsfreie Prfung - Charakterisierung von
6、 Brennflecken in Industrie-Rntgenanlagen fr die zerstrungsfreie Prfung - Teil 4: Kanten-Verfahren This European Standard was approved by CEN on 1999-08-1 6. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the s
7、tatus of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national stand- ards may be obtained on application to the Central Secretariat or to any CEN member. The European Standards exist in three official versions (English, French, German).
8、 A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, the Czech Republic, Denmark, Fi
9、nland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36
10、, B-1050 Brussels O 1999. CEN - All rights of exploitation in any form and by any means reserved worldwide for CEN national members. Ref. No. EN 12543-4 : 1999 E Page 2 EN 12543-4 : 1999 Contents Page Foreword 2 Introduction . 3 1 Scope . 3 2 Normative references 3 3 Terms and definitions 3 4Tectmet
11、hod 3 5 Measurement and determination of the focal spot size 5 Annex A (informative) Data analysis 7 Foreword This European Standard has been prepared by Technical Committee CENTTC 138 “Non-destructive testing“, the secretariat of which is held by AFNOR. This European Standard shall be given the sta
12、tus of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2000, and conflicting national standards shall be withdrawn at the latest by March 2000. According to the CENICENELEC Internal Regulations, the national standards organizations of the fol
13、lowing countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. In the framework of its scope, Technical
14、 Cornmittee CENTTC 138 entrusted CENITC 138iWG 1 “Ionizing Radiation“ with preparing the following standard: EN 12543-4, Non-destructive testing - Characteristics of focal spots in industrial X-ray systems for use in non- destructive testing - Part 4: Edge method EN 12543-4 is a part of series of Eu
15、ropean Standards with the same number; the other Parts are the following: EN 12543-1 Non-destructive testing - Characteristics of focal spots in industrial X-ray systems for use in non- destructive testing - Part 7: Scanning method EN 12543-2, Non-destructive testing - Characteristics of focal spots
16、 in industrial X-ray systems for use in non- destructive testing - Part 2: Pinhole camera radiographic method EN 12543-3, Non-destructive testing - Characteristics of focal spots in industrial X-ray systems for use in non- destructive testing - Part 3: Slit camera radiographic method EN 12543-5, Non
17、-destructive testing - Characteristics of focal spots in industrial X-ray systems for use in non- destructive testing - Part 5: Measurement of the effective focal spot size of mini and micro focus X-ray tubes. Page 3 EN 12543-4 : 1999 Introduction In order to cover the different requirements for foc
18、al spot size measurement, five different methods are described in EN 12543-1 to EN 12543-5. The scanning method (EN 12543-1) is dedicated to those applications where quantitative values for the intensity distribution and spot size are needed, i. e. calibration and image processing purposes. The radi
19、ographic methods (EN 12543-2 and EN 12543-3) describe the traditional techniques and are dedicated for certification purposes and for field applications up to 200 kV. Where no pinhole or slit cameras are available in the field, the edge method (EN 12543-4) may be applied. It repre- sents a very simp
20、le method for field application. In order to cover also the micro focus systems, a specific method is presented in EN 12543-5. 1 Scope This European standard specifies the checking of focal spot dimensions above 0,5 mm of X-ray systems up to and including 500 kV tube voltage, by means of radiographs
21、 of sharp edges. The image quality and the resolution of X-ray images depend highly on the characteristics of the focal spot. The imaging qualities of a focal spot are based on the two dimensional intensity distribution in the object plane. The edge method is especially useful for the checking of fo
22、cal spots under field conditions in order to find changes of the focal spot. It cannot be used for an absolute measurement of the focal spot. For absolute measurements the method according to Annex A is applied. 2 Normative references This European Standard incorporates by dated or undated reference
23、, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated
24、in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 12543-1, Non-destructive testing - Characteristics of focal spots in industrial X-ray systems for use in non- destructive testing - Pad 1: Scanning method EN 584-1, Non-destructive te
25、sting - Industrial radiographic film - Pati 1: Classification of fim systems for industrial radiography EN 25580, Non-destructive testing - Industrial radiographic illuminators - Minimum requirements (IS0 5580: 1985). 3 Terms and definitions For the purposes of this standard, the following definitio
26、n applies: Focal spot: the X-ray emitting area on the anode of the X-ray tube as seen from the measuring device EN 12543-11. 4 Test method 4.1 Principle and equipment This method is based on indirect measurement of the focal spot size by measuring the geometric unsharpness. For this purpose a sharp
27、edge is imaged on a film using a relatively high geometric magnification. The following equipment is required for the measurement: - - - - - - - films with a minimum length of 24 cm without screens, film cassettes made of thin plastic material or aluminium, lead letters L and W, a collimating diaphr
28、agm in front of the tube window compatible with the size of the film, a steel cylinder or a thick walled pipe of 50 mm to 100 mm diameter and about 100 mm length, a support (tripod) to carry the steel cylinder, a sheet of lead approximately 200 mm x 100 mm, 1 mm thick or thicker, Page 4 EN 12543-4 :
29、 1999 - a film processsing unit, - - an illuminator with a uniform and constant brightness according to EN 25580, an optical densitometer capable of reading densities of D t 3,O. The densitometer shall permit contrast measurements of A D = 0,Ol. Its input diaphragm 4 shall be 2 mm or smaller. A cyli
30、ndrical surface is placed as an edge in the beam direction (figure 1). An ordinary steel cylinder or a thick walled pipe with a diameter of 50 mm to 100 mm and with a length of about 100 mm is used for this purpose. A sheet of lead with a thickness of 1 mm or larger is to be wrapped around the cylin
31、der. Scattering shall be avoided as far as possible. A collimating diaphragm with an opening compatible to the size of the film shall be placed in front of the tube window. Any use of additional X-ray prefiltering shall be avoided. For the characterization of the focal spot its size shall be measure
32、d in two perpendicular directions. The two measurements shall be made so that: 1) the tube axis and cylinder edge shall be perpendicular for one measurement, lead letter L on film, and 2) the tube axis and cylinder edge shall be parallel to each other for the other measurement, lead letter W on film
33、. The image of the lead letters shall be in the dark part of the film. The film shall be positioned always with its longer dimension perpendicular to the cylinder axis. As a result the unsharp image of the edge shall be crosswise on the film in either case. 4.2 Referring to figure 1, the distances f
34、and s represent respectively the source to edge and the edge to film distances and d, is the diameter of the steel cylinder including the lead covering. An estimate for the relation between fand s may be derived from a given nominal value of the focal spot size. The relation s/fshall be larger than
35、or equal to ten times the diameter of the density meter input diaphragm 0: divided by the focal spot size d, provided by the manufacturer (see equation1 ). Selection of distances and exposure time S,jf 10 q/ d, (1) NOTE decreased to 1 rnm or below The ratio Ld shall be larger than 5 As an example a
36、film to focus distance (f+ s) of about 2 meters is appropriate for a 300 kVi5 mA X-ray tube. If the distance s gets impractically long, the diameter of the densitometer input diaphragm 4 should be Page 5 EN 12543-4 : 1999 1 2 3 f S - Dimension in milimetre O 3 N Al - Key 1 sourceifocal spot 2 edge 3
37、 lmm lead sheet 4 film Figure 1 - Setup for measuring the focal spot size If the nominal focal spot size is not known, the relation between s and f has to be found experimentally by a preliminary determination of the focal spot size using the present edge method. The part of the film completely expo
38、sed shall have a density of D= 2,5 * 0,3. The exposure time shall exceed 30 s. 5 5.1 Measurement Subsequently, the density profile on the processed film (figure 2) is evaluated in order to measure ug. If one considers the film to be divided into three zones of differing density, namely the light zon
39、e, the transition zone and the dark zone, then the density profiles in the light and the dark zones shall be as uniform as possible, i. e. no sharp fluctuations. If the density variation over the length of either zone (i. e. along the length of the film) is more than 2 of the total contrast, then it
40、 is necessary to check the protection against scattered radiation and to repeat the exposure. The geometric unsharpness us will be determined in terms of the contrast which is the difference in density (o) measured at the darkest and the brightest region on the film. If a hand held density meter is
41、used, the density shall be measured at a fixed point on the illuminator. where the zero adjustment of the densitometer was made. In this case, it is necessary to slide the film instead of moving the densitometer. The zero adjustment of the densitometer shall be checked before and after the measureme
42、nt. In case of deviations the measurement has to be repeated. First the total contrast between dark and bright zone is measured. Then the two points of 5 % and 95 Yo of the contrast are marked on the film. The distance between these points is the geometric unsharpness us. In order to illustrate the
43、procedure for the measurement of the geometric unsharpness, a density profile is shown in figure 2, and the points with 5 Yo and 95 % of the total contrast are projected on the abscissa. The length of this projection is us, or usw dependent on the orientation of the tube axis. Measurement and determ
44、ination of the focal spot size Page 6 EN 12543-4 : 1999 The focal spot size shall be determined according to the following equations : I = ug, f/s w = u gw f/s (2) (3) where I focal spot length w focal spot width f s edge to film distance. distance between focal spot and edge (figure I), “O 10 20 30
45、 40 50 rnm 60 Length X - Figure 2 - Example for a density profile on the film and its evaluation 5.2 Determination Each focal spot size is defined by its size / (length) in the direction of the tube axis and its size w (width) in the perpendicular direction. The larger of these sizes shall be used a
46、s the “focal spot size d“. If the larger of the values / or w exceeds the value d, given within the specification of the tube, a more precise method for the measurement of the focal spot size shall be applied before further use of the tube (see for example Annex A). If the focal spot size will be ce
47、rtified. the measurement result has to meet the values of EN 12543-1 within an uncertainty of I 10 OO. Page 7 EN 12543-4 : 1999 Annex A (informative) Data analysis The radiographs can be used for a more precise focal spot size determination. If this should be necessary the following procedure is app
48、lied. - - Scan the density profile from the film document using a microdensitometer: Calculate the first derivative according to equation (A.l) DI= I (Dk) - D,x-d,)/d, 1 (A.1) where d, is the step width of the microdensitometer; - Determine the geometric unsharpness us from the crosspoints of the Ci
49、 curve with the 10 % line (A, B)- according to figure A.l with us = ET (A.2) - NOTE 1 This method is only applicable if exact values of s and fare known. NOTE 2 This method requires a high signalhoke ratio. Therefore, a film system class C 4 or better is used according to EN 584-1 and several scans are averaged across the edge projection. NOTE 3 For the determination of the focal spot size above 200 kV tube voltage the cylinder diameter should have a diameter of 2 100 mm with ffd, 5. The film system class should be at least C 4. Calculate the focal spot leng
