1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 16016-4:2011Non destructive testing Radiation methods Computed tomographyPart 4: QualificationBS EN 16016-4:2011 BRITISH STANDARDNational forewordThis British Standard is t
2、he UK implementation of EN 16016-4:2011.The UK participation in its preparation was entrusted to TechnicalCommittee WEE/46, Non-destructive testing.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the ne
3、cessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 62741 5ICS 19.100Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Commi
4、ttee on 30 September 2011.Amendments issued since publicationDate Text affectedBS EN 16016-4:2011EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 16016-4 August 2011 ICS 19.100 English Version Non destructive testing - Radiation methods - Computed tomography - Part 4: Qualification Essais non de
5、structifs - Mthodes par rayonnements - Tomographie numrise - Partie 4 : Qualification Zerstrungsfreie Prfung - Durchstrahlungsverfahren - Computertomographie - Teil 4: Qualifizierung This European Standard was approved by CEN on 29 July 2011. CEN members are bound to comply with the CEN/CENELEC Inte
6、rnal 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 CEN-CENELEC Management Centre or to any
7、 CEN member. This European Standard exists 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 CEN-CENELEC Management Centre has the same status as the official ve
8、rsions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia,
9、Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for C
10、EN national Members. Ref. No. EN 16016-4:2011: EBS EN 16016-4:2011EN 16016-4:2011 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Normative references 53 Terms and definitions .54 Qualification of the inspection .54.1 General 54.2 Qualification of defect testing 54.2.1 General 54.2.2 Quality
11、 feature 54.2.3 Feature detectability/test system/system parameterisation .64.2.4 Verification of suitability .74.2.5 Consistency check 74.2.6 Documentation .74.3 Qualification of dimensional testing 84.3.1 General 84.3.2 Test and measurement task .84.3.3 Dimensional testing/test system/system param
12、eterisation 84.3.4 Degree of accuracy 94.3.5 Consistency check 94.3.6 Documentation .95 Qualification of the CT system .95.1 General 95.2 Integral overall system test . 105.3 Checking the system components . 105.3.1 General . 105.3.2 Manipulation system 105.3.3 Image scale 105.3.4 Beam axis perpendi
13、cularity . 105.3.5 Tube focal spot . 105.3.6 Tube stability . 105.3.7 Detector . 115.3.8 Reconstruction 115.3.9 Visualisation 115.4 Documentation 116 Example of CT system resolution evaluation methods 116.1 Pre-amble . 116.2 Acquisition parameters 126.3 Recommendations for creating reference objects
14、 126.4 Density resolution measurement method 126.4.1 General . 126.4.2 High energy reference object 136.4.3 Low energy reference object . 136.4.4 Experimental measurements . 13BS EN 16016-4:2011EN 16016-4:2011 (E) 3 Foreword This document (EN 16016-4:2011) has been prepared by Technical Committee CE
15、N/TC 138 “Non-destructive testing”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by February 2012, and conflicting national standards shall be withdrawn
16、at the latest by February 2012. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. EN 16016 consists of the following parts: Non destruct
17、ive testing Radiation methods Computed tomography Part 1: Terminology; Non destructive testing Radiation methods Computed tomography Part 2: Principle, equipment and samples; Non destructive testing Radiation methods Computed tomography Part 3: Operation and interpretation; Non destructive testing R
18、adiation methods Computed tomography Part 4: Qualification. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
19、 Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 16016-4:2011EN 16016-4:2011 (E) 4 Introduction This document gives g
20、uidelines for the general principles of X-ray computed tomography (CT) applicable to industrial imaging (in the context of this standard, industrial means non-medical applications); it also gives a consistent set of CT performance parameter definitions, including how these performance parameters rel
21、ate to CT system specifications. This document deals with computed axial tomography and excludes other types of tomography such as translational tomography and tomosynthesis. BS EN 16016-4:2011EN 16016-4:2011 (E) 5 1 Scope This European Standard specifies guidelines for the qualification of the perf
22、ormance of a CT system with respect to various inspection tasks. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced docume
23、nt (including any amendments) applies. EN 16016-1:2011, Non destructive testing Radiation method Computed tomography Part 1: Terminology EN 16016-3:2011, Non destructive testing Radiation methods Computed tomography Part 3: Operation and interpretation 3 Terms and definitions For the purposes of thi
24、s document, the terms and definitions given in EN 16016-1:2011 apply. 4 Qualification of the inspection 4.1 General CT is used in industry both for defect testing and dimensional testing and measurement. Since CT does not directly provide measurement of desired quantities such as, for example, pore
25、size or wall thickness, these quantities must be derived from the X-ray linear attenuation data represented by the CT grey values. The detectability of features and the degree of accuracy required depend on the inspection task, the specification of the available test equipment and the analysis and e
26、valuation methods used. When determination of such quantities is required, a special task-specific qualification test of the CT system is required. The qualification measures are described in 4.2 and 4.3. The qualification should be carried out by trained personnel. 4.2 Qualification of defect testi
27、ng 4.2.1 General Under test qualification, the suitability of the CT inspection technique for measuring a quantity to the required precision should be verified. The following steps described are typical of those for the successful verification of the suitability of CT for industrial applications. 4.
28、2.2 Quality feature Typical quantities to be measured are the sizes of pores, cavities, cracks, inclusions, contaminants as well as studies of the material distribution and the assembly and installation position of components. Because the test sample and the type, position and size of the features t
29、o be detected determine the properties of a CT system to be used, information such as the following should be known: a) test object : 1) dimensions; BS EN 16016-4:2011EN 16016-4:2011 (E) 6 2) weight; 3) materials; 4) path length to be X-rayed in the material; b) test feature: 1) type; 2) position; 3
30、) size; 4) distribution, frequency; c) feature detectability: 1) limiting defect; 2) limiting feature. Since the feature detectability strongly influences the specification and therefore the cost of a CT system, special attention must be taken when defining the sensitivity of the tests required. If,
31、 due to missing information, no limiting values for features are defined, it is recommended that the best possible sensitivity is used for the specific method and CT system and the attained feature detectability is verified using, for example, destructive tests. 4.2.3 Feature detectability/test syst
32、em/system parameterisation The usability of the CT system and the selection of system parameters are determined by the requirements for feature detectability. Typical variables are: a) spatial resolution: 1) overall spatial resolution of the CT image; 2) scan geometry; 3) detector spatial resolution
33、; 4) focal spot size of radiation source; b) contrast resolution: 1) overall contrast resolution of the CT image; 2) detector settings; 3) tube voltage; 4) tube current; c) reconstruction/visualisation: 1) number of projections; 2) CT grey value dynamic range of the reconstruction or visualisation;
34、BS EN 16016-4:2011EN 16016-4:2011 (E) 7 3) CT image size in X, Y and Z axes. CT system set-up and image quality parameters are described in EN 16016-3:2011, 4.1 and 5.1. 4.2.4 Verification of suitability 4.2.4.1 General A reliable statement on the defect detection sensitivity and the defect detectab
35、ility of the CT system used in a test shall be made by stating the degree of accuracy of the test required (tolerance, degree of fluctuation). Several alternative procedures are described in the following. 4.2.4.2 Reference samples with natural defects If a reference sample with a known defect is av
36、ailable, inspection of this sample is carried out and the detectability is stated after the test has been done. If a reference sample with unquantified defects is available, inspection of this part is carried out and the defect detectability is stated using a counter-check, using, for example, a des
37、tructive test after the CT scan has been done. 4.2.4.3 Reference sample with synthetic defect If the test feature can be simulated using a synthetic defect, for example, a hole, the defect detectability verification can take place similar to the previous section. 4.2.4.4 Reference sample without spe
38、cifications If no specifications are available for the reference sample status and a counter-check is not possible, the test is carried out using the system sensitivity. Sample structures like, for example, wall thicknesses and external dimensional measurements can be used for estimating the defect
39、detectability. Alternatively, reference samples like, for example, wires or spheres of known dimensions can be used. 4.2.5 Consistency check The CT scan requires several very complex process steps for which the error sources cannot always be excluded. After the scan, the following can be used to tra
40、ce the possible error sources: reconstruction: size, CT slice positions, possible artefacts ; CT image scale; sinogram (CT grey value and curve progress) or CT projection sequence (comparison between projections, image quality of the projections, intensity changes); system status (error messages). W
41、here errors occur, either they shall be corrected or their causes shall be eliminated and the test repeated. 4.2.6 Documentation In the qualification report, the relevant parameters and results of the qualification steps are to be described and presented. The CT images are to be archived for a perio
42、d which is to be agreed with the end-user. The test parameters are to be archived so that an identical test procedure is possible in the case of recurrent test parts and features. BS EN 16016-4:2011EN 16016-4:2011 (E) 8 4.3 Qualification of dimensional testing 4.3.1 General CT inspection provides in
43、formation about the 3D structure of a sample from which surface and geometry data can be derived. Because these data are based on X-ray-physical absorption differences at the contour transitions, small differences in measured values may arise compared to classical tactile or optical measuring proced
44、ures. In the following sections, those CT scan parameters which influence the results will be described, together with those process steps which affect the accuracy of the results. 4.3.2 Test and measurement task Dimensional measurement tasks include the measurement of single dimensions in the test
45、object, wall thickness measurements, surface extraction, volume extraction or nominal-actual comparisons. The required measurement precision is to be defined for every task and if necessary for different parts of the sample. 4.3.3 Dimensional testing/test system/system parameterisation The degree of
46、 accuracy attainable depends on the test object, the limitations of X-ray physics and the subsequent data handling. An initial estimation of the degree of accuracy of a CT-based dimensional measurement can take place with the following parameters: a) spatial resolution in the test object: 1) dimensi
47、ons; 2) geometric magnification, voxel size; 3) detector resolution; 4) focal spot; b) X-ray penetration of test object : 1) material; 2) maximal wall thickness to be X-rayed; 3) contrast resolution; c) 3D component data : 1) original CT image voxel size; 2) extraction steps and quality; 3) further
48、processing steps and quality; 4) registration method. For this estimation, it must be noted that -physical X-ray effects (like scattered radiation and beam hardening) as well as artefacts due to the detector and reconstruction method can lead to strongly varying degrees of accuracy in different part
49、s of the sample. For a known measuring point, the local- parameters should be used. The inspection task is to be rejected if the set of requirements lie outside the capacity of X-ray technology or the CT system. BS EN 16016-4:2011EN 16016-4:2011 (E) 9 4.3.4 Degree of accuracy 4.3.4.1 General In the following, the procedures are described which, depending
