EN 12681-2:2017

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 digitalen Detektoren

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

• Status: Published
• Publication Date: 31-Oct-2017
• ICS: 77.040.20 - Non-destructive testing of metals
• Technical Committee: CEN/TC 190 - Foundry technology
• Drafting Committee: CEN/TC 190/WG 10 - Inner defects
• Current Stage: 9093 - Decision to confirm - Review Enquiry
• Start Date: 10-Nov-2022
• Completion Date: 23-Apr-2025
• Ref Project: SIST EN 12681-2:2018 - Founding - Radiographic testing - Part 2: Techniques with digital detectors

Relations

• Revised: prEN 12681-2 - Founding - Radiographic testing - Part 2: Techniques with digital detectors
• Effective Date: 02-Feb-2023

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
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
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

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

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

¶ 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

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

< w), see Formula (1): NimagebSNRCNRconstSReffwµ⋅=⋅∆=(1)=where=eff effective attenuation coefficient, which is equivalent to the specific material contrast; CNRN normalized CNR, as measured in the digital image. 6 General preparations and requirements 6.1 Protection against ionizing radiation Local, national or international safety precautions shall be strictly applied, when using ionizing radiation. WARNING — Exposure of any part of the human body to X-rays or gamma-rays can be highly injurious to health. Wherever X-ray equipment or radioactive sources are in use, appropriate legal requirements shall be applied. 6.2 Surface preparation and stage of manufacture In general, surface preparation is not necessary, but where surface imperfections can cause difficulties in detecting discontinuities, the surface shall be ground smooth. NOTE 1 Surface roughness and internal granularity of test objects appear in digital images similar to image noise. This may hide small discontinuities and reduce the IQI sensitivity. Unless otherwise specified digital radiography shall be carried out after the final stage of manufacture, e.g. after grinding or heat treatment. NOTE 2 For some aluminium and magnesium alloy castings, radiography may be carried out before heat treatment. 6.3 Agreements Castings with a complex geometry can include areas which cannot be tested by radiography or can only be partly tested. Such areas shall be identified before starting the radiographic testing. Areas which cannot be tested by radiography shall be noted by all contracting parties and be marked on the exposure plan. The following items shall be agreed between the contracting parties by the time of acceptance of the order: a) manufacturing stage; b) extent of radiographic testing; c) test areas; d) surface condition; e) testing class; SIST EN 12681-2:2018

Figure 1 — Test arrangement for single wall radiography of plane areas SIST EN 12681-2:2018

a) with flexible detectors b) with rigid detectors Figure 2 — Test arrangement for single wall radiography of curved areas with the source on the convex side and the detector on the concave side of the test area
a) with flexible detectors b) with rigid detectors Figure 3 — Test arrangement for single wall radiography of curved areas with eccentric positioning of the source on the concave side and the detector on the convex side of the test area
Figure 4 — Test arrangement for single wall radiography of curved areas with central positioning of the source on the concave side and the detector on the convex side of the test area, not for rigid detectors SIST EN 12681-2:2018

Figure 5 — Test arrangement for double wall radiography of plane or curved test areas; source and detector outside the test area, only the detector side wall imaged for interpretation
Figure 6 — Test arrangement for double wall radiography of plane or curved test areas; several exposures; source and detector outside of the test area; both walls imaged for interpretation
Figure 7 — Test arrangement for double wall radiography of plane or curved test areas; overview exposure; source and detector outside of the test area; both walls imaged for interpretation SIST EN 12681-2:2018

a)
b) b) should only be used, if a) is not possible. Figure 8 — Examples for edges and flanges
a)
b) b) should only be used, if a) is not possible. Figure 9 — Examples for ribs
Figure 10 — Example for crosslike geometries SIST EN 12681-2:2018

Figure 11 — Example for wedge geometries
a)
b) Figure 12 — Example for ribs and supports 8 Choice of tube voltage and radiation source 8.1 X-ray devices up to 1 000 kV To maintain good detection sensitivity, the X-ray tube voltage should be as low as possible and the SNRN in the digital image should be as high as possible. Recommended maximum values of X-ray tube voltage versus penetrated thickness are given in Figure 13. These maximum values are best practice values for film radiography. After accurate calibration, DDAs can provide sufficient image quality at significantly higher voltages than those shown in Figure 13. Imaging plates with high structure noise in the sensitive IP layer (coarse grained) should be applied with about 20 % less X-ray voltage than indicated in Figure 13 for class B testing. High definition imaging plates, which are exposed similarly to X-ray films and having low structure noise (fine grained) can be exposed with the X-ray voltages of Figure 13 or significantly higher if the SNRN is sufficiently increased. SIST EN 12681-2:2018

SNRN. The contrast sensitivity improves if the increase in SNRN is higher than the contrast reduction due to the higher energy.
Key 1 copper/nickel and alloys 2 steels and cast irons 3 titanium and alloys 4 aluminium and alloys w penetrated thickness in mm U X-ray voltage in kV Figure 13 — Recommended X-ray voltage U for X-ray devices up to 1 000 kV as a function of penetrated thickness w and material For some casting applications where the thickness changes across the area of test object being radiographed, a modification of technique with a higher voltage may be used, but it should be noted that an excessively high tube voltage will lead to a loss of detection sensitivity. If there are different thicknesses imaged with one exposure, an averaged value of these thicknesses can be used. SIST EN 12681-2:2018

¶ w
¶ 120 mm for class A. Gamma rays from Se 75, Ir 192 and Co 60 sources will not produce digital images having as good detection sensitivity as X-rays used with appropriate technique parameters. Because their dose rate of radiation is lower, the contrast-to-noise ratio is worse with gamma ray sources. However because of the advantages of gamma ray sources in handling and accessibility, Table 2 gives a range of thicknesses for which each of these gamma ray sources may be used when the use of X-ray tubes is difficult. By agreement between the contracting parties, the penetrated material thickness for Ir 192 may be further reduced to 10 mm and reduced to 5 mm for Se 75. For certain applications wider material thickness ranges may be permitted, if sufficient image quality can be achieved. In cases where digital images are produced by CR using gamma rays, the total travel time to and from the source exposure position shall not exceed 10 % of the total exposure time. Using DDAs the capture time shall start after the source is in position and shall end before the source is moved back. Table 2 — Penetrated thickness range for gamma ray sources and X-ray equipment with energy above 1 MeV for steels, cast irons, cobalt, copper and nickel base alloy Radiation source Penetrated thicknessa w mm Class A Class B Se 75 10
¶ w
¶ 40 14
w
40 Ir 192 20
¶ w
¶ 100 20
w
90 Co 60 40
¶ w
¶ 200 60
w
150 X-ray equipment with energy from 1 MeV to 4 MeV 30
¶ w
¶ 200 50
w
180 X-ray equipment with energy from 4 MeV to 12 MeV w
· 50b w
70b X-ray equipment with energy above 12 MeV w
· 80b w
100b a If there are different thicknesses imaged with one exposure, an averaged value of these thicknesses can be used. b The minimum penetrated thickness may be reduced by 10 mm in class A and by 20 mm in class B, if image quality requirement are met. 9 Metal screens for IPs and shielding When using metal front screens good contact between the sensitive detector layer and screens is required. This may be achieved either by using vacuum-packed IPs or by applying pressure. Lead screens not in intimate contact with the IPs may contribute to image unsharpness. The intensification obtained by use of lead screens in contact with imaging plates is significantly smaller than in film radiography. SIST EN 12681-2:2018
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