EN 444-1994 pdf download.General principles for radiographic examination of metallic materials using X-rays and gamma-rays.
3.2 Penetrated thickness, w
The thickness of material in the direction of the radiation beam calculated on basis of the nominal thickness.
For multiple wall techniques the penetrated thickness shall be calculated from the nominal thickness.
3.3 Object-to-film distance, b
The distance between the radiation side of the test object and the film surface measured along the central axis of the radiation beam.
3.4 Source size, d
The size of the source of radiation.
3.5 Source—to—film distance (SFD)
The distance between the source of radiation and the film measured In the direction of the beam.
3.6 Source-to-object distance, f
The distance between the source of radiation and the source side of te test object measured along the central axis of the radiation beam.
4 ClassIfication of radiographic techniques
The radiographic techniques are divided Into two classes:
Class A: basic techn1ques
Class B: improved techniques
Class B techniques will be used when class A may be insufficiently sensitive. Better techniques compared with class B are possible and may be agreed between the contracting parties by specification of all appropriate test parameters.
The choice of radiographic technique shall be agreed between the parties concerned.
If, for technical reasons, it is not possible to meet one of the conditions specified for the class B, such as the type of radiation source or the source-to- object distance f it may be agreed between the contracting parties that the condition selected may be that specified for class A. The loss of sensitivity shall be compensated by an Increase of minimum density to 3,0 or by choice of a higher contrast film system. Because of the better sensitivity conared to class A, the test sections may be regarded as examined within class B.
5 General
5.1 Protection against ionizing radiations
WARNING: Exposure of any part of the human body to X-rays or gamTa-rays can be highly Injurious to health. Wherever X—ray equipment or radioactive sources are In use, appropriate legal requirements must be applied.
NOTE: Local or national or international safety precautions wnen using Ionizing radiation shall be strictly applied.
5.2 Surface preparation and stage of manufacture
In general, surface preparation is not necessary, but where surface Imperfections or coatings might cause difficulty in detecting defects, the surface shall be ground smooth or the coatings shall be removed.
Unless otherwise specified radiography shall be carried out after the final stage of manufacture, e.g. after grinding or heat treatment.
5.3 Identification of radlographs
Symbols shall be affixed to each section of the object being radlographed. The images of these symbols shall appear in the radiograph outside the region of interest where possible arid shall ensure unequivocal identification of the sect-
5.4 Marking
Permanent markings on the object to be examined shall be made in order to accurately locate the position of each radiograph.
Where the nature of the material and/or its service conditions do not permit permanent marking, the location may be recorded by means of accurate sketches.
5.5 Overlap of films
When radlographing an area with two or more separate films, the films shall overlap sufficiently to ensure that the conlete region of Interest is radio- graphed. This shall be verified by a high density marker on the surface of the object which will appear on each film.
5.6 Image quality Indicator (101)
The quality of image shall be verified by use of TO! In accordance with specific application standards and EN 462-1, EN 462-2, EN 462-3, EN 462-4.
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EN 444:1994
6 Recomended techniques for making radiographs
6.1 Test arrangements
Test arrangements shall e deter11ined by the specific application stanOars.
6.2 Choice of X-ray tube voltage and radiation source
6.2.1 X-ray-equIpment
To maintain a good flaw sensitivity, the X-ray tube voltage should e as low as possible. The maximum values of tube voltage versus thickness are given in figure 1.EN 444-1994 pdf download.
EN 444-1994 pdf download
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