SIST EN 12681-2:2018
(Main)Founding - Radiographic testing - Part 2: Techniques with digital detectors
Founding - Radiographic testing - Part 2: Techniques with digital detectors
This European Standard gives specific procedures for industrial X-ray and gamma radiography for discontinuity detection purposes, using NDT (Non-destructive testing) digital X-ray image detectors. This part of EN 12681 specifies the requirements for digital radiographic testing by either computed radiography (CR) or radiography with digital detector arrays (DDA) of castings.
Digital detectors provide a digital grey value image which can be viewed and evaluated using a computer.
NOTE This part of EN 12681 complies with EN 14784-2 for CR. Some clauses and annexes are taken from EN ISO 17636-2.
This part of EN 12681 describes the recommended procedure for detector selection and radiographic practice. Selection of computer, software, monitor, printer and viewing conditions are important but are not the main focus of this standard. The procedure specified in this standard provides the minimum requirements for radiographic practice which permit exposure and acquisition of digital radiographs with equivalent sensitivity for detection of imperfections as film radiography, as specified in Part 1 of this standard.
The requirements on image quality in class A and B testing of Annex A consider the good workmanship quality for general casting applications as also required in Part 1 of this standard for film radiography.
The classes AA and BA reflect the quality requirements of current automated and semi-automated radiographic inspection systems with DDAs (computer based flaw recognition or visual inspection) and mini or micro focus tubes (spot size ≤ 1 mm) with reduced requirements to the unsharpness.
The described procedures are applicable to castings produced by any casting process, especially for steel, cast iron, aluminium, cobalt, copper, magnesium, nickel, titanium, zinc and any alloys of them.
This part of this European Standard does not apply to:
- the testing of welded joints (see EN ISO 17636-2);
- film radiography;
- real time testing with radioscopy.
Gießereiwesen - Durchstrahlungsprüfung - Teil 2: Technik mit Digitaldetektoren
Fonderie - Contrôle par radiographie - Partie 2 : Techniques à l'aide de détecteurs numériques
La présente Norme européenne décrit les procédures spécifiques de radiographie industrielle au moyen
de rayons X et gamma, pour la détection de discontinuités, en utilisant des détecteurs numériques
radiographiques pour END (essais non destructifs). La présente partie de l'EN 12681 spécifie les
exigences relatives au contrôle par radiographie numérique des pièces moulées, soit par radiographie
numérique (CR), soit par radiographie avec des panneaux de détecteurs numériques (DDA).
Les détecteurs numériques produisent une image numérique en niveaux de gris qui peut être visualisée
et évaluée à l'aide d'un ordinateur.
NOTE La présente partie de l'EN 12681 est conforme à l'EN 14784-2 en ce qui concerne la radiographie
numérique (CR). Certains articles et annexes sont pris de l'EN ISO 17636-2.
La présente partie de l'EN 12681 spécifie la procédure recommandée pour le choix des détecteurs et la
pratique radiographique. Le choix de l'ordinateur, du logiciel, de l'écran, de l'imprimante et les
conditions d'observation est important, mais ne constitue pas le centre d'intérêt de la présente norme.
Le mode opératoire spécifié dans la présente norme fournit les exigences minimales pour la pratique
radiographique permettant l'exposition et l'acquisition des images numériques avec une sensibilité de
détection des imperfections équivalente à celle de la radiographie à l'aide de films, spécifiée dans la
Partie 1 de la présente norme.
La présente norme ne traite pas des essais d'aptitude à l'emploi en radiographie ou radioscopie
appliqués à des pièces moulées, sur la base d'exigences et de modes opératoires internes définis par le
fabricant.
Les exigences relatives à la qualité d'image lors des contrôles en classe A ou B, définies en Annexe A,
tiennent compte de la bonne qualité d'exécution pour les applications générales des pièces moulées,
telles que requises également dans la Partie 1 de la présente norme pour la radiographie à l'aide de
films.
Les classes AA et BA reflètent les exigences de qualité des systèmes automatisés et semi-automatisés
actuels de contrôle par radiographie avec des panneaux de détecteurs numériques (DDA) et évaluation
d'image par ordinateur ou par opérateur et des tubes à mini ou micro-foyer (dimension du
foyer ≤ 1 mm) avec des exigences réduites concernant l'indice de flou, mais avec des exigences
identiques concernant la sensibilité différentielle comme cela est également requis dans la Partie 1 de la
présente norme traitant de la radiographie à l'aide de films.
Les procédures spécifiées sont applicables aux pièces moulées, fabriquées par tous les procédés de
moulage, particulièrement pour les aciers, les fontes, l'aluminium, le cobalt, le cuivre, le magnésium, le
nickel, le titane, le zinc et leurs alliages.
Cette partie de la présente Norme européenne ne s'applique pas :
- au contrôle des assemblages soudés (voir l'EN ISO 17636-2) ;
- à la radiographie à l'aide de films (voir l’EN 12681-1 :2017) ;
- au contrôle en temps réel par radioscopie (voir l'EN 13068-1 ; radioscopie avec intensificateurs
d'image).
Livarstvo - Radiografsko preskušanje - 2. del: Tehnike z digitalnimi detektorji
Ta evropski standard določa posebne postopke za industrijsko radiografijo z rentgenskimi ali gama žarki za namene odkrivanja prekinitev na podlagi digitalnih detektorjev rentgenskih slik NDT (neporušitveno preskušanje). Ta del standarda EN 12681 določa zahteve za digitalno radiografsko preskušanje z računalniško radiografijo (CR) ali radiografijo z digitalnimi detektorskimi nizi (DDA) pri ulitkih. Digitalni detektorji zagotavljajo digitalno sivinsko sliko (GV), ki jo je mogoče prikazati in ovrednotiti prek računalnika. OPOMBA: Ta del standarda EN 12681 je v skladu s standardom EN 14784-2 za CR. Nekatere točke in dodatki so pridobljeni iz standarda EN ISO 17636-2. Ta del standarda EN 12681 določa priporočen postopek za izbiro detektorja in radiografsko prakso. Izbira računalnika, programske opreme, monitorja, tiskalnika in pogojev prikaza je pomembna, vendar ni ključni del tega standarda. Postopek, določen v tem standardu, zagotavlja minimalne zahteve za radiografsko prakso, ki omogočajo izpostavljenost in pridobivanje digitalnih radiografskih slik z občutljivostjo zaznavanja napak, enako kot pri radiografskem filmu, kot je opredeljeno v 1. delu tega standarda. Zahteve glede kakovosti slike pri preskušanju v skladu z razredoma A in B iz dodatka A obravnavajo dobro kakovost izdelave pri splošnih postopkih litja kot zahtevano tudi v 1. delu tega standarda za filmsko radiografijo. Razreda AA in BA odražata zahteve glede kakovosti sedanjih avtomatiziranih in polavtomatiziranih sistemov radiografskih pregledov z nizi DDA (računalniško prepoznavanje napak ali vizualni pregled) in mini ali mikro fokusnih cevk (velikost zaznavanja ≤ 1 mm) z zmanjšanimi zahtevami glede neostrine. Opisani postopki se uporabljajo za ulitke, ki nastanejo pri postopku litja, zlasti za jeklo, lito železo, aluminij, kobalt, baker, magnezij, nikelj, titan, cink in njihove zlitine. Ta del tega evropskega standarda se ne uporablja za: – preskušanje varjenih spojev (glej EN ISO 17636-2); – filmsko radiografijo; – preskušanje v realnem času z radioskopijo.
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Livarstvo - Radiografsko preskušanje - 2. del: Tehnike z digitalnimi detektorjiGießereiwesen - Durchstrahlungsprüfung - Teil 2: Technik mit DigitaldetektorenFonderie - Contrôle par radiographie - Partie 2 : Techniques à l'aide de détecteurs numériquesFounding - Radiographic testing - Part 2: Techniques with digital detectors77.040.20Neporušitveno preskušanje kovinNon-destructive testing of metalsICS:Ta slovenski standard je istoveten z:EN 12681-2:2017SIST EN 12681-2:2018en,fr,de01-februar-2018SIST EN 12681-2:2018SLOVENSKI
STANDARD
SIST EN 12681-2:2018
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12681-2
November
t r s y ICS
y yä r v rä t r English Version
Founding æ Radiographic testing æ Part
tã Techniques with digital detectors Fonderie æ Contrôle par radiographie æ Partie
t ã Techniques à l 5aide de dßtecteurs numßriques
Gießereiwesen æ Durchstrahlungsprüfung æ Teil
tã Technik mit digitalen Detektoren This European Standard was approved by CEN on
s x July
t r s yä
egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä
translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä
CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels
9
t r s y CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN
s t x z sæ tã t r s y ESIST EN 12681-2:2018
EN 12681-2:2017 (E) 2 Contents Page European foreword . 4 Introduction . 5 1 Scope . 6 2 Normative references . 6 3 Terms and definitions . 7 4 Symbols and abbreviations . 13 5 Classification of radiographic techniques and compensation principles . 14 5.1 Classification . 14 5.2 Compensation principles . 14 6 General preparations and requirements . 15 6.1 Protection against ionizing radiation . 15 6.2 Surface preparation and stage of manufacture . 15 6.3 Agreements . 15 6.4 Personnel qualification . 16 7 Test arrangements . 16 7.1 General . 16 7.2 Single wall radiography of plane areas . 16 7.3 Single wall radiography of curved areas . 16 7.4 Double wall radiography of plane and curved areas . 17 7.5 Choice of test arrangements for complex geometries . 17 7.6 Acceptable test area dimensions . 17 8 Choice of tube voltage and radiation source . 21 8.1 X-ray devices up to 1 000 kV . 21 8.2 Other radiation sources . 23 9 Metal screens for IPs and shielding . 23 10 Reduction of scattered radiation . 25 10.1 Metal filters and collimators . 25 10.2 Interception of backscattered radiation. 26 11 Source object and detector position . 26 11.1 General . 26 11.2 Source-to-object distance for magnification < 1,5 . 26 11.3 Conditions for magnification
1,5 . 28 11.4 Identification of image, test area, detector position plan. 30 12 Data processing . 30 12.1 Scan and read out of image . 30 12.2 Calibration of DDAs . 30 12.3 Bad pixel interpolation . 31 12.4 Image processing . 31 13 Monitor viewing conditions and storage of digital images . 32 14 Techniques for increasing the covered thickness range . 32 14.1 General . 32 SIST EN 12681-2:2018
EN 12681-2:2017 (E) 3 14.2 Contrast decreasing by higher radiation energy . 33 14.3 Beam hardening . 33 14.4 Thickness equalization . 33 15 Requirements on images . 34 15.1 Identification of images . 34 15.2 Marking of the test areas . 34 15.3 Overlap of digital images . 34 16 Image quality . 34 16.1 Types and positions of image quality indicators (IQI) . 34 16.2 Minimum image quality values . 35 16.3 Minimum normalized signal-to-noise ratio (SNRN). 35 16.4 Compensation principle CP II . 36 16.5 Regular performance verification of digital radiography systems . 36 17 Influence of crystalline structure . 36 18 Acceptances criteria . 37 18.1 General . 37 18.2 Severity levels . 37 18.3 Wall section zones . 37 19 Test report . 38 Annex A (normative)
Minimum image quality values . 40 Annex B (normative)
Severity levels for steel castings . 44 Annex C (normative)
Severity levels for cast iron castings . 47 Annex D (normative)
Severity levels for aluminium and magnesium alloy castings . 49 Annex E (normative)
Severity levels for titanium and titanium alloy castings . 52 Annex F (normative)
Determination of basic spatial resolution . 54 Annex G (normative)
Determination of minimum grey values for CR practice . 58 Annex H (informative)
Grey values, general remarks (from EN ISO 17636-2:2013, Annex E) . 63 SIST EN 12681-2:2018
EN 12681-2:2017 (E) 4 European foreword This document (EN 12681-2:2017) has been prepared by Technical Committee CEN/TC 190 “Foundry Technology”, the secretariat of which is held by DIN. 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 May 2018, and conflicting national standards shall be withdrawn at the latest by May 2018. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights. Within its programme of work, Technical Committee CEN/TC 190 requested CEN/TC 190/WG 10 “Testing for inner discontinuities”: — to revise EN 12681:2003 into EN 12681-1, Founding — Radiographic testing — Part 1: Film techniques; — and the preparation of a further standard EN 12681-2, Founding — Radiographic testing — Part 2: Techniques with digital detectors. According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 12681-2:2018
EN 12681-2:2017 (E) 5 Introduction Radiography can be used to detect internal discontinuities in a casting. The discontinuities can be gas holes, non-metallic inclusions, shrinkage, cracks, inserts or chills or inclusions that have lower or higher densities than the parent metal. This European Standard gives acceptance criteria through severity levels. SIST EN 12681-2:2018
EN 12681-2:2017 (E) 6 1 Scope This European Standard gives specific procedures for industrial X-ray and gamma radiography for discontinuity detection purposes, using NDT (non-destructive testing) digital X-ray image detectors. This part of EN 12681 specifies the requirements for digital radiographic testing by either computed radiography (CR) or radiography with digital detector arrays (DDA) of castings. Digital detectors provide a digital grey value image which can be viewed and evaluated using a computer. NOTE This part of EN 12681 complies with EN 14784–2 for CR. Some clauses and annexes are taken from EN ISO 17636-2. This part of EN 12681 specifies the recommended procedure for detector selection and radiographic practice. Selection of computer, software, monitor, printer and viewing conditions are important but are not the main focus of this standard. The procedure specified in this standard provides the minimum requirements for radiographic practice which permit exposure and acquisition of digital images with equivalent sensitivity for detection of imperfections as film radiography, as specified in Part 1 of this standard. This standard does not consider radiographic or radioscopic fitness for purpose testing as applied for specific castings based on manufacturer’s internal requirements and procedures. The requirements on image quality in class A and B testing of Annex A consider the good workmanship quality for general casting applications as also required in Part 1 of this standard for film radiography. The classes AA and BA reflect the quality requirements of current automated and semi-automated radiographic testing systems with DDAs and computer or operator based image evaluation, and mini or micro focus tubes (spot size
¶ 1 mm) with reduced requirements to the unsharpness, but unchanged requirements to contrast sensitivity as also required in Part 1 of this standard for film radiography. The specified procedures are applicable to castings produced by any casting process, especially for steels, cast irons, aluminium, cobalt, copper, magnesium, nickel, titanium, zinc and any alloys of them. This part of this European Standard does not apply to: — the testing of welded joints (see EN ISO 17636-2); — film radiography (see EN 12681-1:2017); — real time testing with radioscopy (see EN 13068-1; radioscopy with image intensifiers). 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 12543 (all parts), Non-destructive testing — Characteristics of focal spots in industrial X-ray systems for use in non-destructive testing EN 12679, Non-destructive testing - Determination of the size of industrial radiographic sources - Radiographic method EN 14784-1, Non-destructive testing - Industrial computed radiography with storage phosphor imaging plates - Part 1: Classification of systems EN ISO 9712, Non-destructive testing - Qualification and certification of NDT personnel (ISO 9712:2012) SIST EN 12681-2:2018
EN 12681-2:2017 (E) 7 EN ISO 17636-2:2013, Non-destructive testing of welds - Radiographic testing - Part 2: X- and gamma-ray techniques with digital detectors (ISO 17636-2:2013) EN ISO 19232-1, Non-destructive testing - Image quality of radiographs - Part 1: Determination of the image quality value using wire-type image quality indicators (ISO 19232-1:2013) EN ISO 19232-2, Non-destructive testing - Image quality of radiographs - Part 2: Determination of the image quality value using step/hole-type image quality indicators (ISO 19232-2:2013) EN ISO 19232-4, Non-destructive testing - Image quality of radiographs - Part 4: Experimental evaluation of image quality values and image quality tables (ISO 19232-4:2013) EN ISO 19232-5, Non-destructive testing - Image quality of radiographs - Part 5: Determination of the image unsharpness value using duplex wire-type image quality indicators (ISO 19232-5:2013) ISO 5576, Non-destructive testing — Industrial X-ray and gamma-ray radiology — Vocabulary ISO 16371-1:2011, Non-destructive testing — Industrial computed radiography with storage phosphor imaging plates — Part 1: Classification of systems 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 5576 and EN ISO 17636-2 and the following apply. 3.1 wall thickness t thickness as measured on the casting 3.2 nominal wall thickness tn thickness as specified on the drawing 3.3 penetrated thickness w thickness of material in the direction of the radiation beam calculated on the basis of the real thicknesses of all penetrated walls 3.4 source size d size of the radiation source or focal spot size [SOURCE: EN ISO 17636-2:2013, definition 3.20] SIST EN 12681-2:2018
EN 12681-2:2017 (E) 8 3.5 object-to-detector distance b largest (maximum) distance between the radiation side of the radiographed part of the test object and the sensitive layer of the detector along the central axis of the radiation beam [SOURCE: EN ISO 17636-2:2013, definition 3.19] 3.6 source-to-object distance f distance between the source of radiation and the source side of the test object, most distant from the detector, measured along the central axis of the radiation beam [SOURCE: EN ISO 17636-2:2013, definition 3.22] 3.7 source-to-detector distance SDD distance between the source of radiation and the detector, measured in the direction of the beam Note 1 to entry: SDD = f + b where f source-to-object distance b object-to-detector distance [SOURCE: EN ISO 17636-2:2013, definition 3.21] 3.8 geometric magnification v ratio of source-to-detector distance SDD to source-to-object distance f [SOURCE: EN ISO 17636-2:2013, definition 3.24] 3.9 computed radiography CR storage phosphor imaging plate system complete system comprising a storage phosphor imaging plate (IP) and a corresponding read out unit (scanner or reader), which converts the information from the IP into a digital image [SOURCE: EN ISO 17636-2:2013, definition 3.1] SIST EN 12681-2:2018
EN 12681-2:2017 (E) 9 3.10 storage phosphor imaging plate IP photostimulable luminescent material capable of storing a latent radiographic image of a material being examined and, upon stimulation by a source of red light of appropriate wavelength, generates luminescence proportional to radiation absorbed Note 1 to entry: When performing computed radiography, an IP is used in lieu of a film. When establishing techniques related to source size or focal geometries, the IP is referred to as a detector, i.e. source-to-detector distance (SDD). [SOURCE: EN ISO 17636-2:2013, definition 3.2] 3.11 digital detector array system DDA system electronic device converting ionizing or penetrating radiation into a discrete array of analogue signals which are subsequently digitized and transferred to a computer for display as a digital image corresponding to the radiologic energy pattern imparted upon the input region of the device [SOURCE: EN ISO 17636-2:2013, definition 3.3] 3.12 structure noise of imaging plate (IP) structure noise of IP structure due to inhomogeneities in the sensitive layer (graininess) and surface of an imaging plate Note 1 to entry: After scanning of the exposed imaging plate the inhomogeneities appear as overlaid fixed pattern noise in the digital image. Note 2 to entry: This noise limits the maximum achievable image quality of digital CR images and can be compared with the graininess in film images. [SOURCE: EN ISO 17636-2:2013, definition 3.4] 3.13 structure noise of digital detector array (DDA) structure noise of DDA structure due to different properties of detector elements (pixels) Note 1 to entry: After read out of the exposed uncalibrated DDA, the inhomogeneities of the DDA appear as overlaid fixed pattern noise in the digital image. Therefore, all DDAs require after read-out a software based calibration (software and guidelines are provided by the manufacturer). A suitable calibration procedure reduces the structure noise. [SOURCE: EN ISO 17636-2:2013, definition 3.5] SIST EN 12681-2:2018
EN 12681-2:2017 (E) 10 3.14 grey value GV numeric value of a pixel in a digital image Note 1 to entry: This is typically interchangeable with the terms pixel value, detector response, analogue-to-digital unit, and detector signal. [SOURCE: EN ISO 17636-2:2013, definition 3.6] 3.15 linearized grey value GVlin numeric value of a pixel which is directly proportional to the detector exposure dose, having a value of zero if the detector was not exposed Note 1 to entry: This is typically interchangeable with the terms linearized pixel value, and linearized detector signal. [SOURCE: EN ISO 17636-2:2013, definition 3.7] 3.16 basic spatial resolution of a digital detector SRbdetector corresponds to half of the measured detector unsharpness in a digital image and corresponds to the effective pixel size and indicates the smallest geometrical detail, which can be resolved with a digital detector at magnification equal to one Note 1 to entry: For this measurement, the duplex wire IQI according EN ISO 19232-5 is placed directly on the digital detector array or imaging plate. The measurement of unsharpness is described in EN ISO 19232-5, see also ASTM E 2736 and ASTM E 1000. [SOURCE: EN ISO 17636-2:2013, definition 3.8] 3.17 basic spatial resolution of a digital image SRbimage corresponds to half of the measured image unsharpness in a digital image and corresponds to the effective pixel size and indicates the smallest geometrical detail, which can be resolved in a digital image Note 1 to entry:
For this measurement, the duplex wire IQI is placed directly on the object (source side). Note 2 to entry: The measurement of unsharpness is described in EN ISO 19232-5, see also ASTM E 2736, and ASTM E 1000. [SOURCE: EN ISO 17636-2:2013, definition 3.9] SIST EN 12681-2:2018
EN 12681-2:2017 (E) 11 3.18 signal-to-noise ratio SNR ratio of mean value of the linearized grey values to the standard deviation of the linearized grey values (noise) in a given region of interest in a digital image Note 1 to entry: The region of interest shall contain at least 1 100 pixels. 3.19 normalised signal-to-noise ratio SNRN SNR, normalised by the basic spatial resolution SRbimage as measured directly in the digital image and/or calculated from measured SNRmeasured Note 1 to entry: SNRN = SNRmeasured × (88,6 bimage) Note 2 to entry: SRbimage is used for images with magnification. 3.20 contrast-to-noise ratio CNR ratio of the difference of the mean signal levels between two image areas to the averaged standard deviation of the signal levels Note 1 to entry: The contrast-to-noise ratio describes a component of image quality and depends approximately on the product of radiographic attenuation coefficient and SNR. In addition to adequate CNR, it is also necessary for a digital radiograph to possess adequate unsharpness or basic spatial resolution to resolve desired features of interest. [SOURCE: EN ISO 17636-2:2013, definition 3.12] 3.21 normalised contrast-to-noise ratio CNRN CNR, normalised by the basic spatial resolution SRbimage as measured directly in the digital image and/or calculated from measured CNR Note 1 to entry: CNRN = CNR × (88,6 bimage) 3.22 aliasing artefacts that appear in an image when the spatial frequency of the input is higher than the output is capable of reproducing Note 1 to entry: Aliasing often appears as jagged or stepped sections in a line or as moiré patterns. [SOURCE: EN ISO 17636-2:2013, definition 3.14] SIST EN 12681-2:2018
EN 12681-2:2017 (E) 12 3.23 cluster kernel pixels CKP bad pixels which do not have five or more good neighbourhood pixels Note 1 to entry: See ASTM E 2597 for details on bad pixels and CKP. [SOURCE: EN ISO 17636-2:2013, definition 3.15 3.24 inherent unsharpness ui unsharpness of the detector system, excluding any geometric unsharpness, measured from the digital image with a duplex wire IQI adjacent to the detector Note 1 to entry: ui = 2 × SRbdetector 3.25 image unsharpness uim unsharpness measured in the digital image at the object plane with a duplex wire IQI at this plane too 3.26 total image unsharpness uT including geometric and inherent unsharpness, measured in the digital image at the detector plane with a duplex wire IQI at the object plane Note 1 to entry: uT is calculated by 22TGiuuu=+=3.27 geometric unsharpness uG unsharpness measured in the digital image at the detector plane with a duplex wire IQI at the object plane with a high resolution detector excluding the inherent detector unsharpness Note 1 to entry: uG is calculated by Gbudf=⋅=SIST EN 12681-2:2018
EN 12681-2:2017 (E) 13 4 Symbols and abbreviations For the purposes of this document, the symbols and abbreviations given in Table 1 apply. Table 1 — Symbols and abbreviations Symbol or abbreviation Term Clause, Figure w penetrated thickness Clause 3.3 t wall thickness Clause 3.1 tn nominal wall thickness Clause 3.2 b object-to-detector distance Clause 3.5 d source size Clause 3.4 f source-to-object distance Clause 3.6 fmin minimum source-to-object distance Clause 11.1 S source of radiation Figures 1 to 12 D radiographic detector Figures 1 to 12 SDD source-to-detector distance Clause 3.7 v geometric magnification Clause 3.8 CR computed radiography Clause 3.9 IP storage phosphor imaging plate Clause 3.10 DDA digital detector array system Clause 3.11 GV grey value Clause 3.14 GVlin linearized grey value Clause 3.15 IQI image quality indicator Clause 16 SRbdetector basic spatial resolution of a digital detector Clause 3.16 SRbimage basic spatial resolution of a digital image Clause 3.17 SNR signal-to-noise ratio Clause 3.18 SNRN normalized signal-to-noise ratio Clause 3.19 CNR contrast-to-noise ratio Clause 3.20 CNRN normalized contrast-to-noise ratio Clause 3.21 uG geometric unsharpness Clause 3.27 CKP cluster kernel pixel Clause 3.23 ui inherent unsharpness. Clause 3.24 uim image unsharpness Clause 3.25 uT total image unsharpness Clause 3.26 SIST EN 12681-2:2018
EN 12681-2:2017 (E) 14 5 Classification of radiographic techniques and compensation principles 5.1 Classification The radiographic techniques for film replacement are divided into two classes: — Class A: basic techniques; — Class B: improved techniques. The techniques for automated DDA based testing are divided into two classes: — Class AA: basic automated techniques; — Class BA: improved automated technique. NOTE Automated DDA based techniques are used in industry for fast testing of castings mainly in serial production. These automated techniques are not considered as film replacement technique. It is recommended to perform the testing according to class A or AA, if not otherwise specified in the order, class B or BA techniques will be used when class A or AA might be insufficiently sensitive. This standard does not cover fitness for purpose testing with IQI requirements different from Tables A.1 to A.3. Automated testing in the classes AA and BA, shall fulfil the contrast sensitivity requirements (Tables A.1 and A.2) of class A or B, but reduced unsharpness requirements as specified in Table A.4. If, for technical or industrial reasons, it is not possible to meet one of the conditions specified for class B, such as the energy of radiation source or the source to object distance f, it may be agreed by contracting parties that the condition selected ma
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SLOVENSKI STANDARD
oSIST prEN 12681-2:2016
01-maj-2016
Livarstvo - Radiografsko preskušanje - 2. del: Tehnike z digitalnimi detektorji
Founding - Radiographic testing - Part 2: Techniques with digital detectors
Gießereiwesen - Durchstrahlungsprüfung - Teil 2: Technik mit Digitaldetektoren
Fonderie - Contrôle par radiographie - Partie 2 : Techniques à l'aide de détecteurs
numériques
Ta slovenski standard je istoveten z: prEN 12681-2
ICS:
77.040.20 Neporušitveno preskušanje Non-destructive testing of
kovin metals
oSIST prEN 12681-2:2016 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 12681-2:2016
DRAFT
EUROPEAN STANDARD
prEN 12681-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2016
ICS 77.040.20
English Version
Founding - Radiographic testing - Part 2: Techniques with
digital detectors
Fonderie - Contrôle par radiographie - Partie 2 : Gießereiwesen - Durchstrahlungsprüfung - Teil 2:
Techniques à l'aide de détecteurs numériques Technik mit Digitaldetektoren
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 190.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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 versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12681-2:2016 E
worldwide for CEN national Members.
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Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Symbols and abbreviations . 13
5 Classification of radiographic techniques and compensation principles . 14
5.1 Classification . 14
5.2 Compensation principles . 14
6 General preparations and requirements . 15
6.1 Protection against ionizing radiation . 15
6.2 Surface preparation and stage of manufacture . 15
6.3 Agreements . 15
6.4 Personnel qualification . 16
7 Test arrangements . 16
7.1 General . 16
7.2 Single wall radiography of plane areas . 16
7.3 Single wall radiography of curved areas . 16
7.4 Double wall radiography of plane and curved areas . 17
7.5 Choice of test arrangements for complex geometries . 17
7.6 Acceptable test area dimensions . 17
8 Choice of tube voltage and radiation source . 21
8.1 X-ray devices up to 1 000 kV . 21
8.2 Other radiation sources . 23
9 Metal screens for IPs and shielding . 24
10 Reduction of scattered radiation . 26
10.1 Metal filters and collimators . 26
10.2 Interception of backscattered radiation. 26
11 Source object and detector position . 27
11.1 Source-to-object distance . 27
11.2 Geometric magnification technique . 29
11.3 Identification of radiograph, test area, detector position plan . 30
12 Processing . 30
12.1 Scan and read out of image . 30
12.2 Calibration of DDAs . 30
12.3 Bad pixel interpolation . 30
12.4 Image processing . 31
13 Monitor viewing conditions and storage of digital radiographs. 31
14 Techniques for increasing the covered thickness range . 32
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14.1 General . 32
14.2 Contrast decreasing by higher radiation energy . 32
14.3 Beam hardening . 33
14.4 Thickness equalization . 33
15 Radiographs . 33
15.1 Identification of radiographs . 33
15.2 Marking of the test areas . 33
15.3 Overlap of digital images . 33
16 Image quality . 33
16.1 Types and positions of image quality indicators (IQI) . 33
16.2 Minimum image quality values . 34
16.3 Minimum normalized signal-to-noise ratio (SNR ). 34
N
16.4 Compensation principle CP II . 35
16.5 Regular performance verification of digital radiography systems . 35
17 Influence of crystalline structure . 35
18 Acceptances criteria . 36
18.1 General . 36
18.2 Severity levels . 36
18.3 Wall section zones . 36
19 Test report . 37
Annex A (normative) Minimum image quality values . 39
Annex B (normative) Severity levels for steel castings . 44
Annex C (normative) Severity levels for iron castings . 47
Annex D (normative) Severity levels for aluminium and magnesium alloy castings . 48
Annex E (normative) Severity levels for titanium and titanium alloy castings . 50
Annex F (normative) Determination of basic spatial resolution (from EN ISO 17636-2:2013,
Annex C) . 52
Annex G (normative) Determination of minimum grey values for CR practice (from
EN ISO 17636-2:2013, Annex D) . 56
G.1 Determination of SNR from SNR . 56
N measured
G.2 Determination of minimum grey values . 57
Annex H (informative) Grey values, general remarks (from EN ISO 17636-2:2013, Annex E) . 61
H.1 Introduction. 61
H.2 Noise control . 61
Bibliography . 63
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European foreword
This document (prEN 12681-2:2016) has been prepared by Technical Committee CEN/TC 190
“Foundry Technology”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
Within its programme of work, Technical Committee CEN/TC 190 requested CEN/TC 190/WG 10
“Inner defects” to revise and to split the following standard:
EN 12681:2003, Founding — Radiographic testing
into:
— prEN 12681-1, Founding — Radiographic testing — Part 1: Film techniques (replacement for
EN 12681:2003)
— prEN 12681-2, Founding — Radiographic testing — Part 2: Techniques with digital detectors (new
issue and part of EN 12681:2003)
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Introduction
Radiography can be used to detect internal discontinuities in a casting. The discontinuities can be gas
holes, non-metallic inclusions, shrinkage, cracks, inserts or chills or inclusions that have lower or higher
densities than the parent metal. This European Standard gives acceptance criteria through severity
levels.
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1 Scope
This European Standard gives specific procedures for industrial X-ray and gamma radiography for
discontinuity detection purposes, using NDT (Non-destructive testing) digital X-ray image detectors.
This part of EN 12681 specifies the requirements for digital radiographic testing by either computed
radiography (CR) or radiography with digital detector arrays (DDA) of castings.
Digital detectors provide a digital grey value image which can be viewed and evaluated using a
computer.
NOTE This part of EN 12681 complies with EN 14784–2 for CR. Some clauses and annexes are taken from
EN ISO 17636-2.
This part of EN 12681 specifies the recommended procedure for detector selection and radiographic
practice. Selection of computer, software, monitor, printer and viewing conditions are important but are
not the main focus of this standard. The procedure specified in this standard provides the minimum
requirements for radiographic practice which permit exposure and acquisition of digital radiographs
with equivalent sensitivity for detection of imperfections as film radiography, as specified in Part 1 of
this standard.
This standard does not consider radiographic or radioscopic fitness for purpose testing as applied for
specific castings based on manufacturer’s internal requirements and procedures.
The requirements on image quality in class A and B testing of Annex A consider the good workmanship
quality for general casting applications as also required in Part 1 of this standard for film radiography.
The classes A and B reflect the quality requirements of current automated and semi-automated
A A
radiographic inspection systems with DDAs (computer based flaw recognition or visual inspection) and
mini or micro focus tubes (spot size ≤ 1 mm) with reduced requirements to the unsharpness, but
unchanged requirements to contrast sensitivity as also required in Part 1 of this standard for film
radiography.
The specified procedures are applicable to castings produced by any casting process, especially for
steel, cast irons, aluminium, cobalt, copper, magnesium, nickel, titanium, zinc and any alloys of them.
This part of this European Standard does not apply to:
— the testing of welded joints (see EN ISO 17636-2);
— film radiography (see prEN 12681-1);
— real time testing with radioscopy.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 12543, Non-destructive testing — Characteristics of focal spots in industrial X-ray systems for use in
non-destructive testing (all parts)
EN 12679, Non-destructive testing - Determination of the size of industrial radiographic sources -
Radiographic method
EN 14784-1, Non-destructive testing - Industrial computed radiography with storage phosphor imaging
plates - Part 1: Classification of systems
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EN ISO 9712, Non-destructive testing - Qualification and certification of NDT personnel (ISO 9712:2012)
EN ISO 17636-2:2013, Non-destructive testing of welds - Radiographic testing - Part 2: X- and gamma-ray
techniques with digital detectors (ISO 17636-2:2013)
EN ISO 19232-1, Non-destructive testing - Image quality of radiographs - Part 1: Determination of the
image quality value using wire-type image quality indicators (ISO 19232-1)
EN ISO 19232-2, Non-destructive testing - Image quality of radiographs - Part 2: Determination of the
image quality value using step/hole-type image quality indicators (ISO 19232-2)
EN ISO 19232-4, Non-destructive testing - Image quality of radiographs - Part 4: Experimental evaluation
of image quality values and image quality tables (ISO 19232-4)
EN ISO 19232-5, Non-destructive testing - Image quality of radiographs - Part 5: Determination of the
image unsharpness value using duplex wire-type image quality indicators (ISO 19232-5)
ISO 5576, Non-destructive testing — Industrial X-ray and gamma-ray radiology — Vocabulary
ISO 16371-1:2011, Non-destructive testing — Industrial computed radiography with storage phosphor
imaging plates — Part 1: Classification of systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5576 and EN ISO 17636-2 and
the following apply.
3.1
wall thickness
t
thickness as measured on the casting
3.2
nominal wall thickness
t
n
thickness as specified on the drawing
3.3
penetrated thickness
w
thickness of material in the direction of the radiation beam calculated on the basis of the real
thicknesses of all penetrated walls
3.4
source size
d
size of the radiation source or focal spot size
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.20]
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3.5
object-to-detector distance
b
largest (maximum) distance between the radiation side of the radiographed part of the test object and
the sensitive layer of the detector along the central axis of the radiation beam
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.19]
3.6
source-to-object distance
f
distance between the source of radiation and the source side of the test object, most distant from the
detector, measured along the central axis of the radiation beam
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.22]
3.7
source-to-detector distance
SDD
distance between the source of radiation and the detector, measured in the direction of the beam
Note 1 to entry: SDD = f + b
where
f source-to-object distance
b object-to-detector distance
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.21]
3.8
geometric magnification
v
ratio of source-to-detector distance SDD to source-to-object distance f
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.24]
3.9
computed radiography
CR
storage phosphor imaging plate system
complete system comprising a storage phosphor imaging plate (IP) and a corresponding read out unit
(scanner or reader), which converts the information from the IP into a digital image
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.1]
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3.10
storage phosphor imaging plate
IP
photostimulable luminescent material capable of storing a latent radiographic image of a material being
examined and, upon stimulation by a source of red light of appropriate wavelength, generates
luminescence proportional to radiation absorbed
Note 1 to entry: When performing computed radiography, an IP is used in lieu of a film. When establishing
techniques related to source size or focal geometries, the IP is referred to as a detector, i.e. source-to-detector
distance (SDD).
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.2]
3.11
digital detector array system
DDA system
electronic device converting ionizing or penetrating radiation into a discrete array of analogue signals
which are subsequently digitized and transferred to a computer for display as a digital image
corresponding to the radiologic energy pattern imparted upon the input region of the device
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.3]
3.12
structure noise of imaging plate (IP)
structure noise of IP
structure due to inhomogeneities in the sensitive layer (graininess) and surface of an imaging plate
Note 1 to entry: After scanning of the exposed imaging plate the inhomogeneities appear as overlaid fixed
pattern noise in the digital image.
Note 2 to entry: This noise limits the maximum achievable image quality of digital CR images and can be
compared with the graininess in film images.
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.4]
3.13
structure noise of digital detector array (DDA)
structure noise of DDA
structure due to different properties of detector elements (pixels)
Note 1 to entry: After read out of the exposed uncalibrated DDA, the inhomogeneities of the DDA appear as
overlaid fixed pattern noise in the digital image. Therefore, all DDAs require after read-out a software based
calibration (software and guidelines are provided by the manufacturer). A suitable calibration procedure reduces
the structure noise.
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.5]
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3.14
grey value
GV
numeric value of a pixel in a digital image
Note 1 to entry: This is typically interchangeable with the terms pixel value, detector response, analogue-to-
digital unit, and detector signal.
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.6]
3.15
linearized grey value
GV
lin
numeric value of a pixel which is directly proportional to the detector exposure dose, having a value of
zero if the detector was not exposed
Note 1 to entry: This is typically interchangeable with the terms linearized pixel value, and linearized detector
signal.
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.7]
3.16
basic spatial resolution of a digital detector
detector
SR
b
corresponds to half of the measured detector unsharpness in a digital image and corresponds to the
effective pixel size and indicates the smallest geometrical detail, which can be resolved with a digital
detector at magnification equal to one
Note 1 to entry: For this measurement, the duplex wire IQI according EN ISO 19232-5 is placed directly on the
digital detector array or imaging plate. The measurement of unsharpness is described in EN ISO 19232-5, see also
ASTM E 2736 and ASTM E 1000.
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.8]
3.17
basic spatial resolution of a digital image
image
SR
b
corresponds to half of the measured image unsharpness in a digital image and corresponds to the
effective pixel size and indicates the smallest geometrical detail, which can be resolved in a digital
image
Note 1 to entry: For this measurement, the duplex wire IQI is placed directly on the object (source side).
Note 2 to entry: The measurement of unsharpness is described in EN ISO 19232-5, see also ASTM E 2736, and
ASTM E 1000.
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.9]
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3.18
signal-to-noise ratio
SNR
ratio of mean value of the linearized grey values to the standard deviation of the linearized grey values
(noise) in a given region of interest in a digital image
Note 1 to entry: The region of interest shall contain at least 1100 pixels.
3.19
normalised signal-to-noise ratio
SNR
N
image
SNR, normalised by the basic spatial resolution SR as measured directly in the digital image
b
and/or calculated from measured SNR
measured
image
Note 1 to entry: SNR = SNR × (88,6 μm/ SR )
N measured b
3.20
contrast-to-noise ratio
CNR
ratio of the difference of the mean signal levels between two image areas to the averaged standard
deviation of the signal levels
Note 1 to entry: The contrast-to-noise ratio describes a component of image quality and depends approximately
on the product of radiographic attenuation coefficient and SNR. In addition to adequate CNR, it is also necessary
for a digital radiograph to possess adequate unsharpness or basic spatial resolution to resolve desired features of
interest.
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.12]
3.21
normalised contrast-to-noise ratio
CNR
N
image
CNR, normalised by the basic spatial resolution SR as measured directly in the digital image
b
and/or calculated from measured CNR
image
Note 1 to entry: CNR = CNR × (88,6 μm / SR )
N b
3.22
aliasing
artefacts that appear in an image when the spatial frequency of the input is higher than the output is
capable of reproducing
Note 1 to entry: Aliasing often appears as jagged or stepped sections in a line or as moiré patterns.
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.14]
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3.23
cluster kernel pixels
CKP
bad pixels which do not have five or more good neighbourhood pixels
Note 1 to entry: See ASTM E 2597 for details on bad pixels and CKP.
[SOURCE: EN ISO 17636-2:2013, 01, definition 3.15
3.24
inherent unsharpness
u
i
unsharpness of the detector system, excluding any geometric unsharpness, measured from the digital
image with a duplex wire IQI adjacent to the detector
detector
Note 1 to entry: u = 2 × SR
i b
3.25
image unsharpness
u
im
unsharpness measured in the digital image at the object plane with a duplex wire IQI at this plane too
3.26
total image unsharpness
u
T
including geometric and inherent unsharpness, measured in the digital image at the detector plane with
a duplex wire IQI at the object plane
2 2
�
Note 1 to entry: u is calculated by 𝑢 = 𝑢 +𝑢
𝑇 𝐺 𝑖
T
3.27
geometric unsharpness
u
G
unsharpness measured in the digital image at the detector plane with a duplex wire IQI at the object
plane with a high resolution detector excluding the inherent detector unsharpness
𝑏
Note 1 to entry: u is calculated by 𝑢 = ⋅𝑑
𝐺
G
𝑓
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4 Symbols and abbreviations
For the purposes of this document, the symbols and abbreviations given in Table 1 apply.
Table 1 — Symbols and abbreviations
Symbol or
Term Clause, Figure
abbreviation
w penetrated thickness Clause 3.3
t wall thickness Clause 3.1
t
nominal wall thickness Clause 3.2
n
b object-to-detector distance Clause 3.5
d source size Clause 3.4
f source-to-object distance Clause 3.6
f
minimum source-to-object distance Clause 11.1
min
S source of radiation Figures 1 to 12
Clause 12.4,
D radiographic detector
Figures 1 to 12
SDD source-to-detector distance Clause 3.7
v geometric magnification Clause 3.8
CR computed radiography Clause 3.9
IP storage phosphor imaging plate Clause 3.10
DDA digital detector array system Clause 3.11
GV grey value Clause 3.14
GV
linearized grey value Clause 3.15
lin
IQI image quality indicator Clause 16
dete
...
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