BS M 42-1972 Methods for non-destructive testing of fusion and resistance welds in thin gauge materials《薄型量具材料熔焊和电阻焊无损试验法》.pdf

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1、BSI M*q2 72 W lb24bb7 0079400 7 W I UDC 629.7.02 : 669-415 : 621.791.7 : 620.179 M. 42, May, 1972 BRITISH STANDARDS INSTITUTION p- BRITISH STANDARDS HOUSE, 2 PARK STREET. LONDON, WlY4AA Telegrams: STANDARDS LONDON WI BRITISH STANDARD : AEROSPACE SERIES METHODS FOR NON-DESTRUCTIVE TESTING OF FUSION A

2、ND RESISTANCE WELDS IN THIN GAUGE MATERIALS CONTENTS PAGE PAGE Foreword . . 2 6. Proceduresforresistancewelds . .5 6.1 Visual inspection . .5 6.2 Penetrant inspection. . .5 METHODS 6.3 Magnetic particle inspection . .5 6.4 Radiographic inspection . .5 TABLE 1. Application of NDT methods other than v

3、isual O 1. scope . .2 2. Definitions . 3. Classification of welds . .2 inspection . .6 FIGURES 4. Application of methods . .2 1. Weld accessible: internal diameter 40 mm or 4.1 Visual inspection . 4.2 Othermethods . .3 2. Weld inaccessible: internal diameter 40 mm or 5. Procedures for fusion welds .

4、 5.1 Visual inspection . .3 5.2 Penetrant inspection. . .4 5.3 Magnetic particle inspection . . 4 3. Internal diameter greater than 6 mm and less than 5.4 Radiommhic inswtion . .4 4omm . ,9 greater . .8 greater . .8 5.5 Ultra& inspeition . . 4 4. Internal diameter less than 6 mm . .9 Gr 6 BSI M*42 7

5、2 S Lb24bbcl 0099403 9 E M. 42, May, 1972 FOREWORD This British Standard, prepared under the authority of the Aerospace Industry Standards Committee, is one of a series on the non-destructive testing and inspection of aerospace materials, components and structures. Other sfandards in this Series, to

6、 which reference as appropriate is made, cover radiographic, ultrasonic, magnetic particle, etch and penetrant inspection methods. The standard is intended to provide general guidance on the procedures for carrying out inspection by non-destructive testing methods of fusion and resistance welds in t

7、hin gauge materials used in aerospace components and structures. The standard is not intended to be used as a level of acceptance or rejection, as both of these aspects should be covered in an appropriate application standard or be agreed between the interested parties. It is emphasized that non-des

8、tructive testing methods, being complementary to one another, should always be con- sidered in relationship to testing as a whole. When non-destructive testing methods are specified, the most suitable method and amount of inspection compatible with the ultimate application for the product should be

9、employed. The effectiveness of non-destructive testing rests on the technical competence of the personnel employed on the work and on their ability to interpret indications given by the appropriate techniques. In interpreting results, it is necessary to distinguish between relevant indications from

10、flaws and spurious indications arising from other causes. BS 499. Welding terms and symbols. BS 2600. Methods for the radiographic examination of fusion welded butt joints in steel. Part 1.5 mm up to and including 50 mm thick. (In course of preparation.) BS 3683. Glossary of terms used in non-destru

11、ctive testing. BS 4331, Methods for assessing the performance characteristics of ultrasonic flaw detection equipment. BS M 34. Method of preparation and use of radiographic techniques. B!3 M 35. Magnetic particle flaw detection of materials and components. aS M 39. Method for penetrant inspection of

12、 aerospace materials and components. This standard makes reference to the following British Standards: METHODS 1. SCOPE 1.1 This British Standard covers the non-destructive testing of fusion and resistance welds in aerospace mat- erials having a thickness of 2.5 mm and less. It applies to the inspec

13、tion of materials and components both during the manufacturing stage and in service. 1.2 The standard accordingly covers visual, penetrant, magnetic particle, radiographic and ultrasonic inspection appropriate to the type of defect being sought, together with any limitations in the use of particular

14、 techniques. 2. DEFINITIONS For the purposes of this British Standard the definitions given in BS 3683 apply. Attention is particularly drawn to BS 499 in regard to welding terms and symbols. 3. CLASSFiCAMON OF WELDS 3.1 Welds are generaily classified as to their engineering requirements on the engi

15、neering drawings. For the purposes of this standard, welds are classified as follows: Class I. A stressed weld whose failure or leakage, in flight, landing, takeoff, or at any other significant time might directly affect the safety or efciency of the aircraft or missile, or be the direct cause of in

16、jury to personnel, on account of: (1) structural collapse, (2) loss of control, (3) failure of motive power, or (4) unintentional operation of, or inability to operate, any essential service or equipment. Class II. A stressed or otherwise important weid not covered by the terms of Class I. Class III

17、. An unstressed or only lightly stressed weld of minor structural importance not covered by the terms of Classes I and II. 3.2 Notwithstanding the classification given in 3.1, when specifically required by the terms of a contract, the classifi- cations shall be interpreted by the method described in

18、, or as having the meaning defined by, the current relevant sections of appropriate documents, e.g. D Eng 2300, Aviation Publications and British Civil Airworthiness Requirements. 4. APPLICATION OF METHODS 4.1 Visnaiinspection 4.1.1 Visual inspection shall be carried out on all classes of welds in a

19、ccordance with the requirements of 5.1 and 6.1. In addition, the requirements of 4.2 shall be met. 4.1.2 In the case of a component fabricated from a number of detail parts by means of intersecting welds, ali the welds shall be visually inspected after completion of 2 I M. 42, May, 1972 the fnal wel

20、d, regardless of whether each weld has been inspected immediately after it was made. 4.13 The whole of both the top and penetration beads shall be examined unless the geometric configuration of the component precludes this. In such circumstances as much as possible of both beads shall be inspected a

21、nd, except in the case of Class III welds, reliance placed on other NDT methods for the inspection of those areas which are inaccessible to visual examination. The method selected for this purpose shali be agreed between the interested parties. 4.2 Other methods 42.1 Znrrodrrction. Table 1 lists the

22、 most suitable NDT methods according to material of manufacture, form of joint, method of welding and the type of defect which it may be necessary to detect. The symbols used in compiling Table 1 are as follows: (I) Form of joirrt. The symbols used comply with those given in BS 499, Part 2, to which

23、 reference should be made. (2) Method of welding Gas. . . OA Electric arc , . MA Inert gas shielded arc . . TIG Spark starting TIG (HF ignition) . HF Electronbeam . . EB Resistance . .R (3) Type of defect. The symbols used comply with those given in BS 499, Part 3, to which reference should be made,

24、 with the folIowing additions, each of which implies the detectability of those defects of the same type listed in that standard: Crack, general . KG Misalignment . . MS Porosity, general . . PA (4) Method of NDT Penetrant . .P Magnetic particle . .M Radiography . .x Ultrasonic . .u Ultrasonic, delt

25、a-scan . . UA 4.2.2 Class Z welds. Unless otherwise agreed by the design authority, all Class I welds shall be examined by means of a radiographic technique and, in addition, by not less than one other of the methods given in Table 1, Column 5, as applicable. 4.2.5 Fabricated components. In the case

26、 of a component fabricated from a number of detail parts by means of intersecting Class I or II weld lines, the NDT inspections required for compliance with the requirements of 4.2.2, 4.2.3 and, when necessary, 4.2.4 shall be carried out after completion of the final line, regardless of whether each

27、 line has been inspected individually after it was made. When two or more welds of differing structural sig- nificance intersect, e.g. a Class II intersecting a Class I, the standard of inspection required for the welded com- posite shall be that specified for the weld having the greatest structural

28、 significance, i.e. the Class I weld in the above example. 5. PROCEDURES FOR FUSION WEiDS The following procedures shall be used for inspection purposes in accordance with the requirements of 4 and Table 1. However, in order to prevent contamination of electron beam welds should weld rectification s

29、ubse- quently be necessary, visual and radiographic methods shall be applied before carrying out any other method of inspection. 5.1 Visual inspection 5.1.1 General. A great deal of information about the quality of all types of fusion weld can be obtained by visual inspection. In general, a good wel

30、d will look neat, having even, well-formed top and penetration beads along its whole length, without pronounced changes in the specified width and height. Visual inspection may be carried out with or without magnification, the latter being of particular use in the inspection of the thinner gauges of

31、 inateriais. Where one side of the weld is enclosed, inspection shall be made, where practicable, by means of a suitable mirror, intrascope or similar instrument, due allowance being made in interpretation for any inherent magnification which the instrument may possess. 5.1.2 Preparation of material

32、. Evidence of correct pre- treatment shall be available. The material in the welding area shall be free from corrosion products, grease, etc. 5.1.3 Inspection for defects Prior to dressing or polishing, the weld shall be inspected along the whole welded length on both surfaces for evidence of the fo

33、llowing defects: (1) Misalignment. (2) Lack of penetration. (3) Undercutting. (4) Porosity. (5) Cracking. (In general, only gross cracks will be detectable by visual inspection.) (6) Oxide folds. (These are usually indicated by the appearance of a thin, usually black, line running dom the centre of

34、the penetration bead.) (7) Colour of weld. (This applies to welds in titanium ony, where the colour of the bead is of particular sip nificance and should be within the acceptance level specified by the design authority.) 4.2.3 Class ZZ welds. All Class II welds shall be examined by at least one of t

35、he methods given in Table 1, Column 5, as applicable. 42.4 Clars HZ nels. Unless particularly specified by the design authority, Class III welds need not be examined by any NDT method other than visual inspection (sec 4.1). 3 M. 42, May, 1972 BSI M*42 72 D lb24bb9 0099403 2 I ! (8) Top bead profile.

36、 (The size and shape of the weld fillet (top bead) should be as specified by the design authority.) NOTE. In comer welds it is important to ensure by visual inspection that an adequate penetration bead is present. 5.2 Penetrant inspection. Where specified, penetrant inspection shall be carried out i

37、n accordance with the requirements of BS M 39. 53 Magnetic particle inspection. Where specified, magnetic particle inspection shall generally be carried out in accord- ance with the requirements of BS M 35. This method is not, however, recommended for the inspection of electron beam welds and when u

38、sed on other types of fusion weld may produce spurious indications which are extremely difficult to assess. 5.4 Radiographic inspecion. Where specified, radiographic inspection shall be carried out in accordance with the requirements of BS M 34, but in the case of electron beam welds and other types

39、 of weld in pipes and end fittings for pressure purposes the following requirements shall also apply. 5.4.1 Electron beam welds. The X-ray technique devised shall stipulate the use of the following. 5.4.1.1 X-ray tube. A fine-focus X-ray tube (not greater than 2.5 mm) shall be used and, if possible,

40、 the tube shall be of the beryllium window type. 5.4.1.2 Focus-to-film distance. The focus-to-film distance should be not less than 900 mm. 5.4.1.3 Film. An ultra-ne grain X-ray film shall be used. 5.4.1.4 &um angle. The main X-ray beam shall be as near as practicable in line with the joint faces an

41、d shall not deviate by more than 5“. (This will result in the coverage of the X-ray film in electron beam weld radio- graphy being somewhat less than that in other weld radiography.) 5.4.2 Welded pipes and end fitthgs for pressure purposes. For other than electron beam welds (see 5.4.1), the X-ray t

42、echnique devised shall stipulate the use of the following. 5.4.2.1 Focus-to-film distance. Taking due account of focal spot size, the focus-to-film distance shall not normally be less than 60 mm. 5.4.23 Film. The X-ray film shall be of a suitable high- contrast ultra-ne grain type. 5.423 Beam angle

43、and number of exposures. Wherever possible, welds shall be radiographed using a single-wail technique. However, as pipes vary considerably in diameter and weld position, the following shall also apply. (1) pipes over 40 mm 0.d. Where the weld is acmsibie, i.e. near the end of the pipe, the single-wa

44、ll technique shall be used (see Fig. 1). Where the weld is inaccesible, Le. remote from the ends of the pipe, the double-wail singte- image technique shall be used. The beam offset shall be sufficient to separate the image of the part of the weld under inspection from the remainder of the weld. The

45、separation shall in any case be not less than 2.5 mm (see Fig. 2). The number of exposures to be taken shall be determined in accordance with the formula given in BS 2600, Part 1, Figs. 3 and 4. (2) Pipes over 6 mm but not exceeding 40 mm 0.d. Pipes within this size range shall be radiographed by th

46、e double- wall double-image technique, employing two exposures at 90“. The beam offset shall be sufficient to produce an elliptical image of the weld on the radiograph. The sep aration shall in any case be not less than 2.5mm (see Fig. 3). (3) Pipes of 6mm 0.d. and less. Pipes within this size range

47、 shall be radiographed using the double-wall, double- image technique, employing two exposures at Wo, but the beam angle shall be in the plane of the weld, thereby resulting in an in-line image on the radiogaphs (see Fig. 4). 5.5 Ultrasonic inspection 5.5.1 General. A number of important defects, in

48、cluding lack of fusion and lack of penetration, e.g. electron beam welds, may not be detectable by the methods mentioned in 5.1, 5.2, 5.3 and 5.4. It may, however, be possible to detect such defects by ultrasonic means, but the principal limitation in the use of any ultrasonic technique is the geome

49、try of the part. Hence, due allowance shall be made for this when selecting an appropriate technique. 5.5.2 Preparation of part. The surfaces of the weld and also the areas of contact for the probe or probes, or the area of the beam entry in the case of immersion testing, shall be clean. Ideally, the weld should have both the top and penetration beads machined off or otherwise spurious indications will be obtained. 5.5.3 Inspection. Several techniques are available, depend- ing on the position of the weld and the geometry of the part. In general, these techniques invoIve