INTERNATIONAL STANDARD

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1 NTERNATONAL STANDARD NTERNATONAL ORGANZATON FOR STANDARDZATON.MEXAYHAPOAHAJ OP-AHW3AWX lo CTAHAAPTW3AJWW.ORGANSATON NTERNATONALE DE NORMALSATON Dit document mag slechts op een stand-alone PC worden geinstalleerd. Gebruik op een netwerk is alleen. toestaan als een aanvullende licentieovereenkomst voor netwerkgebruik met NEN is afgesloten. This document may only be used on a stand-alone PC. Use in a network is only permitted when a supplementary license agreement for us in a network with NEN has been concluded. Radiography of welds and viewing conditions for films - Utilization of recommended patterns of image quality indicators (.Q..) First edition UDC : Ref. No. S (E) Descriptors : welded joints, nondestructive tests, radiography, image quality indicators, viewing conditions. Price based on 6 pages

2 FOREWORD S0 (the nternational Organization for Standardization) is a worldwide federation of national standards institutes (S0 Member Bodies). The work of developing nternational Standards is carried out through S0 Technical Committees. Every Member Body interested in a subject for which a Technical Committee has been set up has the right to be represented on that Committee. nternational organizations, governmental and non-governmental, in liaison with SO, also take part in the work. Draft nternational Standards adopted by the Technical Committees are circulated to the Member Bodies for approval before their acceptance as nternational Standards by the S0 Council. nternational Standard S was drawn up by Technical Committee SO/TC 44, Welding. t was approved in February 1972 by the Member Bodies of the following countries : Australia Austria Belgium Canada Czechoslovakia Egypt, Arab Rep. of Finland France Germany ndia reland srael taly Netherlands New Zealand Norway Portugal Romania South Africa, Rep. of Spain Sweden Thailand Turkey United Kingdom U.S.A. U.S.S.R. The Member Body of the following country ex document on technical grounds : Switzerland pressed d isappr oval of the (9 nternational Organization for Standardization, Printed in Switzerland

3 NTERNATONAL STANDARD S (E) Radiography of welds and viewing conditions for films - Utilization of recommended patterns of image quality indicators (.Q..) 1 SCOPE AND FELD OF APPLCATON This nternational Standard relates to the conditions for use of recommended patterns of image quality indicators (.Q..) for radiography of welds and viewing conditions for films. 2 REFERENCES SO/ R 947, Recommended practice for radiographic inspection of circumferential fusion welded butt joints in steel pipes up to 50 mm (2 in) wall thickness. &O/R 1027, Radiographic image quality indicators - Principles and identification. SOf R 1106, Recommended practice for radiographic inspection of fusion welded butt joints for steel plates up to 50 mm (2 in) thick. SO 2405, Recommended practice for radiographic inspection of fusion welded butt joints for steel plates 50 to 200 mm thick. 3 POSTON OF NDCATORS An image quality indicator of one or other of the two types specified in lso/r 1027 shall be placed on the surface of the weld facing the source of radiation, so that the image of the Q.. appears on the radiograph near the end of each film. f the wire type.q.. is used, the wires shall be placed across the weld or, alternatively, a shim shall be placed under the.q.l. so that the metal thickness penetrated by the radiation is equal to the maximum thickness penetrated through the weld. n this latter case the wire 01. may be placed beside the weld. f the step and hole type of.q.. is used, it shall be placed close to the weld with the thinnest steps towards the end of the radiograph and on a shim so that the thickness of metal under the.q.. penetrated by the radiation is equal to the maximum thickness penetrated through the weld. Whichever.Q.. is used, the diameters of the elements (wires or holes) shall be chosen so that one element along the.q.l. represents a just discernible image. NOTES 1 n cases where a continuous length of film is used to cover a circumferential weld (or similar applications) at least three ~ shall be used. They shall be placed equidistantly at distances apart not greater than 1 m. 2 n the case of the double-wall/double-image technique, used for circumferential welds on pipes, the.q.. shall be placed near the ends of the portion of weld under examination, on the surface of the piece nearest the source. 3 f the surface of the weld facing the source is not accessible for the placement of the.q.l., it is not possible to utilize an.q.. directly. The sensitivity of the radiographic technique to be used shall be determined separately, by radiography of a piece which is similar to the work piece under examination, but in which the surfaces are accessible. n this test, an shall be placed on each face. By comparison of the readings of the.q.. sensitivity from both.q.., an indication of the actual sensitivity can be obtained. Great care shall be taken that the same radiographic technique and conditions are used. 4 f all the elements (holes or wires) in the.q.l. are visible on the radiograph, a correct measure of sensitivity will not be obtained. 4 DETERMNATON OF.Q.. SENSTVTY (MAGE QUALTY VALUES) The radiograph shall be examined on a film-viewing screen, constructed for this purpose. The conditions for viewing radiographs, including some tests of the operator, are detailed in separate recommendations (see section 6). Generally the image of the.q.. shall be examined in its entirety without the use of a mask to conceal any part of the image. Masks to prevent glare from other areas of the radiograph may be necessary and can be employed. For the wire type.q.., when this is laid across the weld, the discernibility shall be determined for that part of the image of the.q.l. which is across the weld region. From the examination of the image of the.q.. on the radiograph, the diameter of the smallest wire or hole which can be discerned is determined. n the case of the step and hole type.q.., if there are two holes of the same diameter, both shall be discernible, in order that the step be considered as visible. The image quality obtained shall be indicated on the report of the radiographic examination. This can be done in various ways, but in each case the type of indicator used shall be clearly stated, as shown on the.q.. 1

4 S (E) For example :.Q.. lso/r 1027, 11 wires/l.25 mm;.q.. SO/R 1027, 5 holed3.2 mm. ) The designation of the shall be followed by the image quality value obtained, given in one of the following ways : - number of wires or steps visible; - diameter of the smallest discernible wire or thickness of step; A series of radiographs or a series of readings for the same radiograph shall be accepted for examination if the image quality attained is at least 70 % of the readings for a wire diameter or step thickness equal to the values in Tables 1 to 3, provided that no reading found exceeds by more than one step the value shown in the Tables. TABLE 1 - X-ray examination - Class B (lso/r 1106 and &O/R 947) - sensitivity obtained, in %; Values in millimetres Steel t hit knesses Visibility required - index of visibility in the case of the step and hole type of.q.l. (see Annex). under or of the hole of wire with above The image quality value obtained is valid only for the equal to with diameter diameter particular type of.q.. used; it will not be the same for a step and hole.q.. as for a wire.q The image quality value may be compared with acceptable o 0.4 values which are detailed below for the different radiographic techniques and metal thicknesses. 1 5 ACCEPTABLE MAGE QUALTY VALUES ON STEEL TABLE 2 - Examination by gamma rays from ridium 192 Malues in millimetres Steel thicknesses Visibility required above under or of the hole of wire with equal to with diameter diameter 5.1 Required values The image quality values given in Tables 1 to 3 represent values which should be attained or improved upon if the techniques detailed in S0 documents are properly applied. They are to be regarded only as a guide to the correct use of these radiographic techniques. O o o The upper thickness limit of 85 mm for steel represents, with X-rays, the use of 400 kv X-rays.2) For thicknesses above 60 mm the image quality values can be improved by the use of front screen materials of low atomic number and high specific densities (for instance Ni, Cu, Zn and their alloys) instead of lead front screens and with lead back screens. 5.2 Tolerances All the radiographs for which the diameter of the wire or step thickness is under or equal to the values shown in Tables 1 to 3 shall be accepted for examination. TABLE 3 - Examination by gamma rays from Cobalt 60 Values in millimetres Steel thicknesses Visibility required above under or of the hole of wire with equal to with diameter diameter t o ) These are not necessarily equivalent values. 2) The use of higher X-ray energies is detailed in S

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