SIST EN 12681-1:2018

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Livarstvo - Radiografsko preskušanje - 1. del: Filmske tehnikeGießereiwesen - Durchstrahlungsprüfung - Teil 1: FilmtechnikenFonderie - Contrôle par radiographie - Partie 1 : Techniques à l'aide de filmsFounding - Radiographic testing - Part 1: Film techniques77.040.20Neporušitveno preskušanje kovinNon-destructive testing of metalsICS:Ta slovenski standard je istoveten z:EN 12681-1:2017SIST EN 12681-1:2018en,fr,de01-februar-2018SIST EN 12681-1:2018SLOVENSKI
STANDARDSIST EN 12681:20031DGRPHãþD

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12681-1
November
t r s y ICS
y yä r v rä t r Supersedes EN
s t x z sã t r r uEnglish Version
Founding æ Radiographic testing æ Part
sã Film techniquesFonderie æ Contrôle par radiographie æ Partie
s ã Techniques à l 5aide de films
Gießereiwesen æ Durchstrahlungsprüfung æ Teil
sã Filmtechniken 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
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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 sã t r s y ESIST EN 12681-1:2018

Minimum image quality values . 30 Annex B (normative)
Severity levels for steel castings . 33 Annex C (normative)
Severity levels for cast iron castings . 36 Annex D (normative)
Severity levels for aluminium alloy and magnesium alloy castings . 39 Annex E (normative)
Severity levels for copper alloy castings . 43 Annex F (normative)
Severity levels for titanium and titanium alloy castings . 45 Annex G (informative)
Significant technical changes between this European Standard and the previous edition . 47 Bibliography . 48
Figure 1 — Test arrangement for single wall radiography of plane areas SIST EN 12681-1:2018

a) with flexible cassette b) with rigid cassette Figure 2 — Test arrangement for single wall radiography of curved areas with the source on the convex side and the film on the concave side of the test area
a) with flexible cassette b) with rigid cassette Figure 3 — Test arrangement for single wall radiography of curved areas with eccentric positioning of the source on the concave side and the film 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 film on the convex side of the test area SIST EN 12681-1:2018

Figure 5 — Test arrangement for double wall radiography of plane or curved test areas; source and film outside the test area, only the film side wall imaged for interpretation
Figure 6 — Test arrangement for double wall radiography of plane or curved test areas; several exposures; source and film 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 film outside of the test area; both walls imaged for interpretation SIST EN 12681-1:2018

a) b) should only be used, if a) is not possible. Figure 8 — Examples for edges and flanges
a)
b) should only be used, if a) is not possible. Figure 9 — Examples for ribs SIST EN 12681-1:2018

Figure 10 — Example for cross like geometries
Figure 11 — Example for wedge geometries SIST EN 12681-1:2018

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. The maximum values of X-ray tube voltage versus thickness are given in Figure 13. SIST EN 12681-1:2018

Key 1 copper/nickel and alloys 2 steel and cast irons 3 titanium and alloys 4 aluminium and alloys w penetrated thickness in mm U X-ray voltage in kV Figure 13 — Maximum 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. 8.2 Other radiation sources The penetrated thickness ranges for gamma ray sources and X-ray equipment above 1 MeV are given in Table 2 for steels, cast irons, cobalt, copper and nickel based alloys. For aluminium, magnesium, titanium and zinc testing using Se 75, the penetrated material thickness is 35 mm
¶ w
¶ 120 mm for class A. Gamma rays from Se 75, Ir 192 and Co 60 sources will not produce radiographs having as good detection sensitivity as X-rays used with appropriate technique parameters. 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. SIST EN 12681-1:2018

¶ w
¶ 40 14
¶ w
¶ 40 Ir 192 10
¶ 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
¶ 300 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 wall thickness may be reduced by 10 mm in class A and by 20 mm in class B, if film system class C1 according to EN ISO 11699-1 is used, provided the IQI requirements are met. 9 Film systems and metal screens For radiographic testing film system classes shall be used in accordance with EN ISO 11699-1. For different radiation sources the minimum film system classes are given in Tables 3 and 4. When using metal screens good contact between films and screens are required. This may be achieved either by using vacuum-packed films or by applying pressure. Other screen thicknesses may be also agreed between the contracting parties provided the required image quality is achieved. SIST EN 12681-1:2018

¶ 100 kV all w C 5 C 3 none or up to 0,03 mm front and back screens of lead X-ray potentials > 100 kV to 150 kV up to 0,15 mm front and back screens of lead X-ray potentials > 150 kV to 250 kV C 4 0,02 mm to 0,15 mm front and back screens of lead X-ray potentials > 250 kV to 500 kV w
¶ 50 mm C 5 C 4 0,02 mm to 0,2 mm front and back screens of lead w > 50 mm C 5 0,1 mm to 0,2 mm front screens of leadb 0,02 mm to 0,2 mm back screens of lead X-ray potentials > 500 kV to 1000 kV w
¶ 75 mm C 5 C 4 0,25 mm to 0,7 mm front and back screens of steel or copperc w > 75 mm C 5 C 5 Se 75 all w C 5 C 4 0,02 mm to 0,2 mm front and back screens of lead Ir 192 all w C 5 C 4 0,02 mm to 0,2 mm front screens of lead 0,1 mm to 0,2 mm front screens of leadb 0,02 mm to 0,2 mm back screens of lead Co 60 w
¶ 100 mm C 5 C 4 0,25 mm to 0,7 mm front and back screens of steel or copperc w > 100 mm C 5 X-ray equipment with energy from 1 MeV to 4 MeV w
¶ 100 mm C 5 C 3 0,25 mm to 0,7 mm front and back screens of steel or copperc w > 100 mm C 5 X-ray equipment with energy from 4 MeV to 12 MeV w
¶ 100 mm C 4 C 4 up to 1 mm front screen of copper, steel or tantalumd back screen of copper or steel up to 1 mm or tantalum up to 0,5 mmd 100 mm < w
¶ 300 mm C 5 C 4 w > 300 mm C 5 X-ray equipment with energy above 12 MeV w
¶ 100 mm C 4 C 1 up to 1 mm front screen of tantalume No back screen 100 mm < w
¶ 300 mm C 5 C 4 w > 300 mm C 5 up to 1 mm front screen of tantalume up to 0,5 mm back screen of tantalum a Better film system classes may also be used, see EN ISO 11699-1. b Ready packed films with a front screen up to 0,03 mm may be used if an additional lead screen of 0,1 mm is placed between the test object and the film. c In class A also 0,5 mm to 2,0 mm screens of lead may be used. d In class A lead screens 0,5 mm to 1 mm may be used by agreement between the contracting parties. e Tungsten screens may be used by agreement. SIST EN 12681-1:2018

Class A Class B
X-ray potentials
¶ 150 kV C 5 C 3 none or up to 0,03 mm front and up to 0,15 mm back screens of lead X-ray potentials > 150 kV to 250 kV 0,02 mm to 0,15 mm front and back screens of lead X-ray potentials > 250 kV to 500 kV 0,1 mm to 0,2 mm front and back screens of lead Se 75 not applicable 0,2 mm frontb and 0,1 mm to 0,2 mm back screens of lead a Better film system classes may also be used, see EN ISO 11699-1. b Instead of one 0,2 mm lead screen, two 0,1 mm lead screens may be used. 10 Reduction of scattered radiation 10.1 Metal filters and collimators In order to reduce the effect of scattered radiation, direct radiation shall be collimated as much as possible to the section under examination. With Se 75, Ir 192 and Co 60 radiation sources or in case of edge scatter a sheet of lead can be used as a filter of low energy scattered radiation between the test object and the film. The thickness of this sheet is 0,5 mm to 2 mm in accordance with the penetrated thickness. 10.2 Interception of backscattered radiation It shall be ensured that the effect of backscattered radiation is minimized. If necessary, the film shall be shielded from backscattered radiation by an adequate thickness of lead at least 1 mm, or of tin at least 1,5 mm, placed behind the film-screen combination (or the cassette). The presence of backscattered radiation should be checked for each new test arrangement by a lead letter B (with a minimum height of 10 mm and a minimum thickness of 1,5 mm) placed immediately behind the cassette. If the image of this symbol records as a lighter image on the radiograph, it shall be rejected. If the symbol is darker or invisible the radiograph is acceptable and demonstrates good protection against scattered radiation. 11 Source-to-object distance The minimum source-to-object distance fmin depends on the source size or focal spot size d and on the object-to-film distance b. The source size or focal spot size d shall be in accordance with EN 12543 or EN 12679. When the source size or focal spot size is specified by two dimensions, the larger shall be used. SIST EN 12681-1:2018

Class A
Key b object-to-film distance in mm d source size in mm fmin minimum source-to-object distance in mm NOTE This Nomogram does not apply for exposure geometries as shown in Figures 2 b) and 3 b). Figure 14 — Nomogram for fmin in relation to b and d If the radiation source could be placed inside the test object to be radiographed (techniques shown in Figures 3 and 4) to achieve a more suitable direction of exposition and when a double wall technique (see Figures 5 to 7) is avoided this method should be preferred. The reduction in minimum source-to-object distance should not be greater than 40 %. When the source is located centrally inside the test object and film outside (technique shown in Figure 4) and provided that the IQI requirements are met, this percentage may be increased. However, the reduction in minimum source-to-object distance shall not be greater than 50 %. SIST EN 12681-1:2018

· 2,0 B
· 2,3 a A measuring tolerance of ± 0,1 is permitted. b For test areas with different wall thicknesses an optical density > 1,5 for class A and > 2,0 for class B is sufficient, if the image quality requirements given in Tables A.1 to A.3 are met. High optical densities can be used with advantage where the viewing light is sufficiently bright in accordance with 13.2. The maximum readable optical density of the film depends on the film viewer used and its maximum luminance (see EN 25580). The maximum readable optical density shall be posted on the viewer. In order to avoid unduly high fog densities arising from film ageing, development or temperature, the fog density shall be checked periodically on a non-exposed sample taken from the films being used, and handled and processed under the same conditions as the actual radiograph. The fog density shall not exceed 0,3. Fog density here is specified as the total optical density (emulsion and base) of a processed, unexposed film. If double film viewing is requested the optical density of one single film shall not be lower than 1,3. 13 Film processing and viewing 13.1 Processing Films are processed in accordance with the conditions recommended by the film and chemical manufacturer to obtain the selected film system class. Particular attention shall be paid to temperature, developing time and washing time. The film processing shall be controlled regularly in accordance with EN ISO 11699-2. The radiographs should be free from defects due to processing or other causes which would interfere with interpretation. 13.2 Film viewing conditions The radiographs should be examined in a darkened room on an area of the viewing screen with an adjustable luminance in accordance with EN 25580. The viewing screen should be masked to the area of interest. 14 Techniques for increasing the covered thickness range 14.1 General In many applications it is useful to image a larger thickness range within one film exposure. Figure 15 provides information on the expected thickness range (difference between maximum penetrated thickness and minimum penetrated thickness) for steels and cast irons depending on the optical density ratio in the radiograph. This can be done by one of the following techniques: — multiple film technique; SIST EN 12681-1:2018

Key X Thickness range in millimetres (mm) Y Quotient of optical density Dmax/Dmin for films Figure 15 — Estimation of possible covered thickness range for different radiation energy levels for steels and cast irons 14.2 Multiple film technique For multiple film technique two or more films with different sensitivities are exposed at the same time (see Figure 16) and viewed singly or together. SIST EN 12681-1:2018

Key D optical density of film a film system with a higher film system class (higher ISO speed, see EN ISO 11699-1) b film system with a lower film system class (lower ISO speed, see EN ISO 11699-1) c lateral dimension Figure 16 — Arrangement for multiple film technique There shall be at least one screen between each of the films. When paper backed lead screens are used for film radiography two screens shall be inserted with the metal layer to the film side. Films and front and back screens shall be chosen in accordance with Tables 3 and 4. Areas on the radiograph with high light intensities shall be masked to avoid dazzle while viewing. Viewing identification marks (at least 2) shall be imaged to ensure the exact positioning of multiple films on top of each other. The geometrical features of the casting and of their images on the radiographs shall correspond. If double film viewing is used the optical density of a single film (see Clause 12) shall not be less than 1,3. 14.3 Contrast decreasing by higher radiation energy For X-ray sources up to 800 kV, the maximum permissible tube voltage according to Figure 13 may be exceeded by max. 30 %. For increasing the covered thickness range, X-ray sources may be replaced by gamma ray sources or linear accelerators. The image quality requirement(s) given in Tables A.1 to A.3 shall be met. 14.4 Contrast decreasing by beam hardening Beam hardening for contrast decreasing is permissible, if the image quality requirement(s) given in Tables A.1 to A.3 are met. SIST EN 12681-1:2018
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