GOST 7512-82
UDC 621.791.053: 620.179: 006.354 Group B09
STATE STANDARD OF THE UNION OF SSR
CONTROL NON-DESTRUCTIVE
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
Nonde-structive testing. Welded joints. Radiography method
Date of introduction 1984-01-01
INFORMATION DATA
1. CONTRACTORS
G.I. Nikolaev, B.A. Khripunov, Yu.I. Udralov, E.G. Volkovyskaya
2. APPROVED AND COMMITTED INTO ACTION Decree of the USSR State Committee for Standards dated 20.12.82 No. 4923
3. REPLACE GOST 7512-75
4. REFERENCE REGULATORY AND TECHNICAL DOCUMENTS
5. The limitation of the validity period was lifted by the decision of the Interstate Council for Standardization, Metrology and Certification (IUS 5-6-93)
6. Reissue (December 1994) with Amendment No. 1, approved in March 1988 (IUS 6-88)
This standard establishes a method for radiographic inspection of fusion welded joints of metals and their alloys, with a thickness of welded elements from 1 to 400 mm, using X-ray, gamma and bremsstrahlung radiation and radiographic film.
1. GENERAL PROVISIONS
1.1. Radiographic control is used to detect cracks, lack of penetration, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic control is also used to detect burn-throughs, undercuts, assess the size of the convexity and concavity of the root of the seam, which are unacceptable for external examination.
1.3. Radiographic control does not reveal:
any discontinuities and inclusions with a size in the direction of transmission less than double the control sensitivity;
lack of penetration and cracks, the opening plane of which does not coincide with the direction of transmission and (or) the opening value is less than the values given in table. one;
any discontinuities and inclusions, if their images in the photographs coincide with the images of extraneous parts, sharp corners or sharp drops of cracks in the translucent metal.
Table 1
mm
|
Radiation thickness (according to GOST 24034-80) |
Opening lack of penetration (cracks) |
|
Up to 40 |
0,1 |
|
St. 40 to 100 incl. |
0,2 |
|
" 100 " 150 " |
0,3 |
|
" 150 " 200 " |
0,4 |
|
" 200 |
0,5 |
1.1-1.3.
1.4. Welded joints with a ratio of the radiation thickness of the deposited weld metal to the total radiation thickness of at least 0.2, having two-sided access, providing the ability to install a cassette with a radiographic film and a radiation source in accordance with the requirements of this standard, are subjected to radiographic control.
2. REQUIREMENTS FOR CONTROL ACCESSORIES
2.1. For radiographic inspection, markings should be used that are made of material capable of being clearly imaged on radiographic images.
It is necessary to use markings of the sizes established by GOST 15843-79.
2.2. For radiographic inspection, radiographic films should be used that meet the requirements technical conditions on them.
The type of radiographic film should be established by the technical documentation for the control or acceptance of welded joints.
2.3. For radiographic inspection, radiation sources provided for by GOST 20426-82 should be used.
The type of radioactive source, the voltage on the X-ray tube and the energy of accelerated electrons must be set depending on the thickness of the material being translucent by the technical documentation for the inspection or acceptance of welded joints.
2.4. Metallic and fluorescent screens should be used as reinforcing screens for radiographic inspection.
The type of reinforcing screen must be established by the technical documentation for the inspection or acceptance of welded joints.
The thickness of the metal reinforcing screens and the methods of charging the film into cassettes using screens are given in Appendix 1.
2.5. Screens should have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed.
2.6. The cassettes for loading the film must be opaque and ensure that the reinforcing screens are tightly pressed against the film.
2.7. To protect the film from scattered radiation, it is recommended to shield the cassette with the film from the side opposite to the radiation source with lead shields.
The thickness of the protective screens is given in Appendix 2.
2.8. To determine the sensitivity of control, wire, groove or plate sensitivity standards should be used.
2.9. Sensitivity standards should be made of metal or alloy, the basis of which, according to chemical composition similar to the basis of the inspected welded joint.
2.10. The shape and dimensions of the wire sensitivity standards are shown in Fig. 1 and in table. 2. The length of the wires in the standards is (20 ± 0.5) mm. Limit deviations for wire diameters:
up to 0.2 mm ± 0.01 mm
St. 0.2 to 1.6 mm ± 0.03 mm
"1.6" 4.0 mm ± 0.04 mm
1 - insert; 2 - cover
Crap. one
table 2
mm
|
Reference number |
d 1 |
d 2 |
d 3 |
d 4 |
d 5 |
d 6 |
d 7 |
|
|
0,2 |
0,16 |
0,125 |
0,10 |
0,08 |
0,063 |
0,05 |
1,2 |
|
|
0,4 |
0,32 |
0,25 |
0,20 |
0,16 |
0,125 |
0,10 |
1,4 |
|
|
1,25 |
1,00 |
0,80 |
0,63 |
0,50 |
0,40 |
0,32 |
2,2 |
|
|
4,0 |
3,20 |
2,50 |
2,00 |
1,60 |
1,25 |
1,00 |
5,0 |
Limit deviations of other sizes - ± 0.5 mm.
The inlay and cover for wire standards should be made of flexible transparent plastic.
2.11. The shape and dimensions of the groove sensitivity standards are shown in Fig. 2 and in table. 3.
Crap. 2
Table 3
mm
|
But- |
Groove depth |
Prev |
||||||||||||||||
|
standard measures |
off groove depth |
no more |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
||||||
|
0,60 |
0,5 |
0,40 |
0,3 |
0,20 |
0,10 |
0,05 |
0,1 |
2,5 |
± 0.30; |
0,5 |
0,2; |
0,360 |
0,100 |
0,52 |
||||
|
± 0.150 |
0,1 |
|||||||||||||||||
|
1,75 |
1,5 |
1,25 |
1,0 |
0,75 |
0,50 |
0,10 |
0,2 |
4,0 |
± 0.40 |
1,5 |
0,3 |
0,430 |
0,120 |
0,62 |
||||
|
3,00 |
2,5 |
2,00 |
1,50 |
0,25 |
0,3 |
6,0 |
± 0.40 |
3,0 |
0,3 |
0,430 |
0,120 |
0,74 |
||||||
|
4,00 |
3,5 |
0,30 |
||||||||||||||||
(Modified edition, Amendment No. 1).
2.12. The shape and dimensions of the plate sensitivity standards are shown in Fig. 3 and in table. 4.
Crap. 3
Table 4
mm
|
Number |
||||||||||||||
|
standard |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
|
0,1 |
0,01 |
0,2 |
0,01 |
0,1 |
0,01 |
± 0.15 |
± 0.15 |
0,36 |
0,52 |
|||||
|
0,2 |
0,025 |
0,4 |
0,025 |
0,2 |
0,025 |
|||||||||
|
0,3 |
0,6 |
0,3 |
||||||||||||
|
0,4 |
0,8 |
0,4 |
||||||||||||
|
0,5 |
1,0 |
0,5 |
||||||||||||
|
0,60 |
0,06 |
1,2 |
0,06 |
0,60 |
± 0.06 |
± 0.18 |
0,43 |
0,62 |
||||||
|
0,75 |
1,5 |
0,75 |
||||||||||||
|
1,00 |
2,0 |
1,00 |
||||||||||||
|
1,25 |
2,5 |
1,25 |
||||||||||||
|
1,5 |
0,1 |
3,0 |
0,10 |
1,5 |
0,1 |
± 0.18 |
||||||||
|
2,0 |
4,0 |
0,12 |
2,0 |
|||||||||||
|
2,5 |
5,0 |
0,12 |
2,5 |
|||||||||||
2.13. The marking of the sensitivity standards should be carried out with lead numbers in accordance with GOST 15843-79 in accordance with Appendix 3. The first number of the marking should indicate the material of the standard, the next (one or two numbers) - the number of the standard.
Symbols of the sensitivity standard material: for iron-based alloys - 1, aluminum and magnesium - 2, titanium - 3, copper - 4, nickel - 5.
2.14. For marking of groove standards, it is allowed to use cutouts and holes or only holes specified in Appendix 3. In this case, the thickness of the standard at the mark should be equal to h.
When marking the standards with holes, the length of the standard No. 1 is 27 -0.52 mm, No. 2 - 38.5 -0.62 mm, No. 3 - 53 -0.74 mm.
2.15. For welded products intended for export, it is allowed to use other types of sensitivity standards, if it is provided for by the export conditions.
3. PREPARATION FOR CONTROL
3.1. Radiographic control should be carried out after elimination of external defects detected during external examination of the welded joint and cleaning it from irregularities, slag, metal spatter, scale and other contaminants, the images of which on the photograph may interfere with the interpretation of the photograph.
3.2. After cleaning the welded joint and eliminating external defects, the marking of the welded joint into sections and marking (numbering) of the sections should be made.
3.1, 3.2. (Modified edition, Amendment No. 1).
3.3. The system for marking and marking sections is established by technical documentation for the control or acceptance of welded joints.
3.4. During control, sensitivity standards and markings must be established at each site.
3.5. Sensitivity standards should be installed in the controlled area from the side facing the radiation source.
3.6. Wire standards should be placed directly on the seam with the wires directed across the seam.
3.7. Groove standards should be installed at a distance of at least 5 mm from the seam with the direction of the grooves across the seam.
3.8. Plate standards should be installed along the seam at a distance of at least 5 mm from it or directly on the seam with the standard directed across the seam so that the images of the standard markings do not overlap with the image of the seam in the photograph.
3.9. When inspecting circumferential seams of pipelines with a diameter of less than 100 mm, it is allowed to install groove standards at a distance of at least 5 mm from the seam with the direction of the grooves along the seam.
3.10. If it is impossible to install standards from the side of the radiation source when inspecting welded joints of cylindrical, spherical and other hollow products through two walls with decoding only the welded joint area adjacent to the film, as well as with panoramic transmission, it is allowed to set sensitivity standards from the side of the cassette with the film.
3.11. (Deleted, Amendment No. 1).
3.12. The markings used to limit the length of the sections of welded joints inspected during one exposure should be installed at the boundaries of the marked sections, as well as at the boundaries of the weld metal and base metal when inspecting welded joints without reinforcement or with removed weld reinforcement.
3.13. The markings used for the numbering of the controlled areas should be installed in the controlled area or directly on the cassette with the film so that the images of markings in the photographs do not overlap the image of the seam and the near-weld zone according to clause 5.7.
3.14. If it is impossible to install sensitivity standards and (or) markings on the inspected section of the welded joint in accordance with the requirements of this standard, the procedure for conducting control without installing sensitivity standards and (or) markings should be provided for in the technical documentation for the control or acceptance of welded joints.
(Modified edition, Amendment No. 1).
4. CONTROL CIRCUITS
4.1. Welded joints should be monitored as per dash. 4 and 5.
Inspection schemes for butt, lap, corner and tee connections
Crap. 4
Inspection schemes for circular (butt, overlap, corner and tee) welded joints
1 - radiation source; 2 - controlled area; 3 - cassette with film
Crap. 5
4.2. With a limited width of the welded element, it is allowed to control T-welded joints with the radiation direction along the generatrix of this element in accordance with Fig. 6.
1 - radiation source; 2 - controlled area; 3 - cassette with film
Crap. 6
4.2a. When inspecting circular welded joints of cylindrical and spherical hollow products, one should, as a rule, use transillumination schemes through one wall of the product (diagrams of Fig. 5a, b, f, g, h). In this case, it is recommended to use transillumination schemes with the location of the radiation source inside the controlled item:
diagram of dash. 5e (panoramic transillumination) - for control of products with a diameter of up to 2 m, regardless of the volume of control and a diameter of 2 m or more with 100% control;
diagram of dash. 5g - at 100% and selective control, if the use of the scheme of dash. 5e is impossible;
diagram of dash. 5h - for random inspection of products with a diameter of 2 m and more;
schemes of damn. 5a, b - for products with an inner diameter of 10 m or more, if the use of the diagram of drawing. 5e is impossible.
(Introduced additionally, Amendment No. 1).
4.3. When controlled through two walls, the diagram of dash. 5c is recommended for transillumination of products with a diameter of up to 100 mm; schemes of damn. 5d, d - for translucent products with a diameter of more than 50 mm.
4.4. When inspecting butt welded joints according to the diagrams of Fig. 5a, b, f, g, h, the direction of radiation should coincide with the plane of the tested welded joint. When checking fillet welds according to these diagrams, welding of pipes, fittings, etc. the angle between the direction of radiation and the plane of the welded joint should not exceed 45 °.
4.5. When inspecting welded joints according to the diagrams of Fig. 5c, d, e the direction of radiation should be chosen so that the images of the opposite areas weld did not overlap in the picture.
In this case, the angle between the direction of radiation and the plane of the weld should be minimal and in any case should not exceed 45 °.
4.3-4.5 (Modified edition, Amendment No. 1).
4.6. (Deleted, Amendment No. 1).
4.7. In addition to control according to the schemes shown in Fig. 4-6, depending on the design features of the welded joints and the requirements imposed on them, other schemes and directions of radiation can be used.
These schemes and directions of radiation should be provided for by the technical documentation for the control and acceptance of welded joints.
4.8. To reduce the difference in optical densities of different sections of the image when inspecting welded joints with a large difference in thickness, as well as in the case when the inspected welded joint does not protect the radiographic film from direct radiation (for example, when inspecting the end welds of welding pipes into tube sheets, when inspecting surfacing of edges for welding, etc.), control should be carried out using expansion joint attachments.
It is allowed to use compensators made of any material providing the required radiation attenuation.
4.9. When choosing a scheme and direction of radiation, one should take into account:
the distance from the controlled welded joint to the radiographic film should be minimal and in any case should not exceed 150 mm;
the angle between the direction of radiation and the normal to the radiographic film within the area of the welded joint monitored in one exposure should be minimal and in any case should not exceed 45 °.
4.7-4.9. (Modified edition, Amendment No. 1).
5. SELECTION OF RADIOGRAPHIC CONTROL PARAMETERS
5.1. The distance from the radiation source to the surface of the controlled section of the welded joint closest to the source (when scanning welded joints of cylindrical and spherical hollow products through two walls - to the surface of the controlled welded joint adjacent to the source) and the size or number of areas controlled during one exposure for all transillumination schemes ( with the exception of the diagram of Fig.5e) should be chosen such that the following requirements are met during transmission:
the geometric unsharpness of the images of defects in the photographs when the film is located close to the tested welded joint should not exceed half the required sensitivity of the test at a sensitivity of up to 2 mm and 1 mm at a sensitivity of more than 2 mm;
the relative increase in the size of the images of defects located on the side of the radiation source (in relation to the defects located on the side of the film) should not exceed 1.25;
the angle between the direction of radiation and the normal to the film within the area of the welded joint monitored for one exposure should not exceed 45 °;
the decrease in the optical density of the image of the welded joint in any part of this image in relation to the optical density in the place where the wire sensitivity standard is installed or in relation to the optical density of the image of the groove or plate sensitivity standard should not exceed 1.0.
5.2. Formulas for determining the minimum permissible distances from the radiation source to the tested welded joint, as well as the maximum dimensions and minimum quantity areas controlled for one exposure when controlled according to the schemes of features. 4-6 are given in Appendix 4.
5.1, 5.2 (Modified edition, Amendment No. 1).
5.3. When inspecting welded joints according to the drawing. 5h (panoramic transillumination), the ratio of the inner diameter d to the outer diameter D of the tested compound should not be less than 0.8, and the maximum focal spot size Ф of the radiation source should not be more, where К is the control sensitivity.
5.4. In cases where the dimensions of the defects are not determined (for example, defects are not allowed regardless of their size), the ratio given in clause 5.3 between the inner and outer diameters of the tested joint may not be observed.
5.5. In the absence of a radiation source that meets the requirement of clause 5.3, it is allowed when checking according to the drawing. 5h use radiation sources with a maximum focal spot size that satisfies the ratio
In this case, the sensitivity standard should be installed on the welded joint or simulator of the welded joint used in determining the sensitivity, only from the side of the radiation source.
5.6. The length of the images should ensure that the images of adjacent sections of welded joints overlap when the length of the controlled section is up to 100 mm, not less than 0.2 of the length of the section, with the length of the controlled section sv. 100 mm - not less than 20 mm.
5.7. The width of the images should ensure the acquisition of images of the weld, sensitivity standards, markings and heat-affected zones with the width:
for butt and lap joints:
not less than 5 mm - with the thickness of the welded edges up to 5 mm,
not less than the thickness of the welded edges - with the thickness of the welded edges St. 5 to 20 mm,
not less than 20 mm - with the thickness of the welded edges St. 20 mm;
for tee and corner joints - established by the technical documentation for the control or acceptance of these joints.
6. DESCRIPTION OF IMAGES
6.1. Viewing and decoding the images should be carried out after they have completely dried in a darkened room using special illuminators-negatoscopes.
Use negatoscopes with adjustable brightness and illuminated field sizes. The maximum brightness of the illuminated field should be at least 10 D + 2 cd / m2, where D is the optical density of the image. The size of the illuminated field should be adjusted using movable shutters or screens-masks within such limits that the illuminated field is completely covered by the picture.
(Modified edition, Amendment No. 1).
6.2. Pictures allowed for decryption must meet the requirements:
the photographs should not have spots, stripes, dirt and damage to the emulsion layer, making it difficult to decipher them;
images of limit marks, markings and sensitivity standards should be visible on the photographs;
the optical density of the images of the monitored section of the seam, the near-weld zone and the standard of sensitivity must be at least 1.5;
the decrease in the optical density of the image of the welded joint in any part of this image in comparison with the optical density of the image of the sensitivity standard should not exceed 1.0.
6.3. The sensitivity of control (the smallest diameter of the wire of the wire standard detected in the photograph, the smallest depth of the groove of the groove standard detected in the photograph, the smallest thickness of the plate standard, at which a hole with a diameter equal to twice the thickness of the standard is revealed in the photograph) should not exceed the values given in Table. 6.
Table 6
mm
|
Radiation thickness (at the place where the sensitivity standard is installed) |
Sensitivity class |
||
|
Up to 5 |
0,10 |
0,10 |
0,20 |
|
St. 5 to 9 incl. |
0,20 |
0,20 |
0,30 |
|
" 9 " 12 " |
0,20 |
0,30 |
0,40 |
|
" 12 " 20 " |
0,30 |
0,40 |
0,50 |
|
" 20 " 30 " |
0,40 |
0,50 |
0,60 |
|
" 30 " 40 " |
0,50 |
0,60 |
0,75 |
|
" 40 " 50 " |
0,60 |
0,75 |
1,00 |
|
" 50 " 70 " |
0,75 |
1,00 |
1,25 |
|
" 70 " 100 " |
1,00 |
1,25 |
1,50 |
|
" 100 " 140 " |
1,25 |
1,50 |
2,00 |
|
" 140 " 200 " |
1,50 |
2,00 |
2,50 |
|
" 200 " 300 " |
2,00 |
2,50 |
|
|
" 300 " 400 " |
2,50 |
||
Note. When using wire standards, the sensitivity values are 0.30; 0.60; 0.75 and 1.50 mm are replaced by 0.32; 0.63; 0.80 and 1.60 mm.
(Modified edition, Amendment No. 1).
Specific sensitivity values should be established by technical documentation (drawing requirements, specifications, control and acceptance rules) for the controlled products.
For nuclear power plants, the sensitivity requirements are established by the relevant regulatory documents.
6.4. In accordance with the requirements of the technical documentation for the controlled products, it is allowed to determine the sensitivity ( k ) as a percentage according to the formula
where K is the sensitivity, mm;
S is the thickness of the translucent metal, mm.
6.5. Deciphering and assessment of the quality of welded joints based on photographs that do not have images of sensitivity standards is allowed:
with panoramic transmission of circular welded joints with simultaneous exposure of more than four films. In these cases, regardless of the total number of images, it is allowed to set one sensitivity standard for each quarter of the circumference of the welded joint;
when it is impossible to apply sensitivity standards.
In these cases, the sensitivity is determined on simulators of a welded joint during processing of control modes.
6.6. When decoding the images, the dimensions of the images of cracks, lack of penetration, pores and inclusions are determined, and, if necessary, the value of the concavity and convexity of the weld root is estimated (in cases where the root of the weld is not accessible for external examination).
The list of dimensions to be determined and the method for assessing the value of the concavity and convexity of the root of the weld should be given in the technical documentation for the control and acceptance of welded joints.
6.7. When documenting the results of decoding images, the dimensions determined from the images should be rounded to the nearest values from the 0.2 series; 0.3; 0.4; 0.5; 0.6; 0.8; 1.0; 1.2; 1.5; 2.0; 2.5; 3.0 mm or the nearest whole values in millimeters, if the size determined from the photograph is greater than 3.0 mm.
6.8. If, during testing, the film is located at a distance H from the surface of the tested welded joint facing the film and the relation is fulfilled
the dimensions determined from the photograph are recommended to be multiplied by a factor before rounding them
where f - distance from the radiation source to the surface of the inspected section of the welded joint facing the source, mm;
s - radiation thickness, mm.
6.6-6.8. (Modified edition, Amendment 1).
6.9. When measuring the size of defects up to 1.5 mm, use a measuring magnifier with a graduation of 0.1 mm, St. 1.5 mm - any measuring device with a scale of 1 mm.
6.10. The results of decoding the photographs and the sensitivity of the control must be recorded in the conclusion or the log of the control results, the form of which must be established by the technical documentation for the control or acceptance of welded joints.
6.11. To denote defects in the conclusion or register of the results of control, the symbols given in Appendix 5 should be used.
Examples of abbreviated recording of defects when decoding images are given in Appendix 6.
7. SAFETY REQUIREMENTS
7.1. The main types of danger for personnel during radiographic monitoring are exposure to the body of ionizing radiation and harmful gases formed in the air under the influence of radiation, and electric shock.
GOST 7512-82
UDC 621.791.053: 620.179: 006.354 Group B09
STATE STANDARD OF THE UNION OF SSR
CONTROL NON-DESTRUCTIVE
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
Nonde-structive testing. Welded joints. Radiography method
Date of introduction 1984-01-01
INFORMATION DATA
1. CONTRACTORS
G.I. Nikolaev, B.A. Khripunov, Yu.I. Udralov, E.G. Volkovyskaya
2. APPROVED AND COMMITTED INTO ACTION Decree of the USSR State Committee for Standards dated 20.12.82 No. 4923
3. REPLACE GOST 7512-75
4. REFERENCE REGULATORY AND TECHNICAL DOCUMENTS
5. The limitation of the validity period was lifted by the decision of the Interstate Council for Standardization, Metrology and Certification (IUS 5-6-93)
6. Reissue (December 1994) with Amendment No. 1, approved in March 1988 (IUS 6-88)
This standard establishes a method for radiographic inspection of fusion welded joints of metals and their alloys, with a thickness of welded elements from 1 to 400 mm, using X-ray, gamma and bremsstrahlung radiation and radiographic film.
1. GENERAL PROVISIONS
1.1. Radiographic control is used to detect cracks, lack of penetration, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic control is also used to detect burn-throughs, undercuts, assess the size of the convexity and concavity of the root of the seam, which are unacceptable for external examination.
1.3. Radiographic control does not reveal:
any discontinuities and inclusions with a size in the direction of transmission less than double the control sensitivity;
lack of penetration and cracks, the opening plane of which does not coincide with the direction of transmission and (or) the opening value is less than the values given in table. one;
any discontinuities and inclusions, if their images in the photographs coincide with the images of extraneous parts, sharp corners or sharp drops of cracks in the translucent metal.
Table 1
mm
1.1-1.3.
1.4. Welded joints with a ratio of the radiation thickness of the deposited weld metal to the total radiation thickness of at least 0.2, having two-sided access, providing the ability to install a cassette with a radiographic film and a radiation source in accordance with the requirements of this standard, are subjected to radiographic control.
(Introduced additionally, Amendment No. 1).
2. REQUIREMENTS FOR CONTROL ACCESSORIES
2.1. For radiographic inspection, markings should be used that are made of material capable of being clearly imaged on radiographic images.
It is necessary to use markings of the sizes established by GOST 15843-79.
2.2. For radiographic control, radiographic films should be used that meet the requirements of the technical specifications for them.
The type of radiographic film should be established by the technical documentation for the control or acceptance of welded joints.
2.3. For radiographic inspection, radiation sources provided for by GOST 20426-82 should be used.
The type of radioactive source, the voltage on the X-ray tube and the energy of accelerated electrons must be set depending on the thickness of the material being translucent by the technical documentation for the inspection or acceptance of welded joints.
2.4. Metallic and fluorescent screens should be used as reinforcing screens for radiographic inspection.
The type of reinforcing screen must be established by the technical documentation for the inspection or acceptance of welded joints.
The thickness of the metal reinforcing screens and the methods of charging the film into cassettes using screens are given in Appendix 1.
2.5. Screens should have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed.
2.6. The cassettes for loading the film must be opaque and ensure that the reinforcing screens are tightly pressed against the film.
2.7. To protect the film from scattered radiation, it is recommended to shield the cassette with the film from the side opposite to the radiation source with lead shields.
The thickness of the protective screens is given in Appendix 2.
2.8. To determine the sensitivity of control, wire, groove or plate sensitivity standards should be used.
2.9. Sensitivity standards should be made of a metal or alloy, the basis of which is similar in chemical composition to that of the tested welded joint.
2.10. The shape and dimensions of the wire sensitivity standards are shown in Fig. 1 and in table. 2. The length of the wires in the standards is (20 ± 0.5) mm. Limit deviations for wire diameters:
up to 0.2 mm ± 0.01 mm
St. 0.2 to 1.6 mm ± 0.03 mm
"1.6" 4.0 mm ± 0.04 mm
1 - insert; 2 - cover
Crap. one
table 2
mm
|
Reference number |
d 1 |
d 2 |
d 3 |
d 4 |
d 5 |
d 6 |
d 7 |
|
|
0,2 |
0,16 |
0,125 |
0,10 |
0,08 |
0,063 |
0,05 |
1,2 |
|
|
0,4 |
0,32 |
0,25 |
0,20 |
0,16 |
0,125 |
0,10 |
1,4 |
|
|
1,25 |
1,00 |
0,80 |
0,63 |
0,50 |
0,40 |
0,32 |
2,2 |
|
|
4,0 |
3,20 |
2,50 |
2,00 |
1,60 |
1,25 |
1,00 |
5,0 |
Limit deviations of other sizes - ± 0.5 mm.
The inlay and cover for wire standards should be made of flexible transparent plastic.
(Modified edition, Amendment No. 1).
2.11. The shape and dimensions of the groove sensitivity standards are shown in Fig. 2 and in table. 3.
Crap. 2
Table 3
mm
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But- |
Groove depth |
Prev |
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|
standard measures |
off groove depth |
no more |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
Nominal |
Prev off |
||||||
|
0,60 |
0,5 |
0,40 |
0,3 |
0,20 |
0,10 |
0,05 |
0,1 |
2,5 |
± 0.30; |
0,5 |
0,2; |
0,360 |
0,100 |
0,52 |
||||
|
± 0.150 |
0,1 |
|||||||||||||||||
|
1,75 |
1,5 |
1,25 |
1,0 |
0,75 |
0,50 |
0,10 |
0,2 |
4,0 |
± 0.40 |
1,5 |
0,3 |
0,430 |
0,120 |
0,62 |
||||
|
3,00 |
2,5 |
2,00 |
1,50 |
0,25 |
0,3 |
6,0 |
± 0.40 |
3,0 |
0,3 |
0,430 |
0,120 |
0,74 |
||||||
|
4,00 |
3,5 |
0,30 |
||||||||||||||||
CONTROL NON-DESTRUCTIVE
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
GOST 7512-82
PUBLISHING STANDARDS
Moscow
STATE STANDARD OF THE UNION OF SSR
Date of introduction 01.01.84
This standard establishes a method for radiographic inspection of fusion welded joints of metals and their alloys, with a thickness of welded elements from 1 to 400 mm, using X-ray, gamma and bremsstrahlung radiation and radiographic film.
1. GENERAL PROVISIONS
1.1. Radiographic control is used to detect cracks, lack of penetration, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic control is also used to detect burn-throughs, undercuts, assess the size of the convexity and concavity of the root of the seam, which are unacceptable for external examination.
any discontinuities and inclusions with a size in the direction of transmission less than double the control sensitivity;
lack of penetration and cracks, the opening plane of which does not coincide with the direction of transmission and (or) the opening value is less than the values given in;
any discontinuities and inclusions, if their images in the photographs coincide with the images of extraneous parts, sharp corners or sharp drops of cracks in the translucent metal.
1.1 - 1.3.
Table 1
1.4. Welded joints with a ratio of the radiation thickness of the deposited weld metal to the total radiation thickness of at least 0.2, having two-sided access, providing the ability to install a cassette with a radiographic film and a radiation source in accordance with the requirements of this standard, are subjected to radiographic control.
(Introduced additionally, Amendment No. 1).
2. REQUIREMENTS FOR CONTROL ACCESSORIES
It is necessary to use markings of the sizes established by GOST 15843-79.
2.2. For radiographic control, radiographic films should be used that meet the requirements of the technical specifications for them.
The type of radiographic film should be established by the technical documentation for the control or acceptance of welded joints.
The type of radioactive source, the voltage on the X-ray tube and the energy of accelerated electrons must be set depending on the thickness of the material being translucent by the technical documentation for the inspection or acceptance of welded joints.
2.4. Metallic and fluorescent screens should be used as reinforcing screens for radiographic inspection.
The type of reinforcing screen must be established by the technical documentation for the inspection or acceptance of welded joints.
The thickness of the metal reinforcing screens and the methods of loading film into cassettes using screens are given in.
2.5. Screens should have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed.
2.6. The cassettes for loading the film must be opaque and ensure that the reinforcing screens are tightly pressed against the film.
2.7. To protect the film from scattered radiation, it is recommended to shield the cassette with the film from the side opposite to the radiation source with lead shields.
The thickness of the protective screens is given in.
1 - insert; 2 - cover.
2.8. To determine the sensitivity of control, wire, groove or plate sensitivity standards should be used.
2.9. Sensitivity standards should be made of a metal or alloy, the basis of which is similar in chemical composition to that of the tested welded joint.
2.10. The shape and dimensions of the wire sensitivity standards are given in and in. The length of the wires in the standards is (20 ± 0.5) mm. Limit deviations for wire diameters:
up to 0.2 mm ... + 0.01 mm
St. 0.2 to 1.6 mm ... ± 0.03 mm
"1.6" 4.0 mm ... ± 0.04 mm.
table 2
Limit deviations of other sizes - ± 0.5 mm. The inlay and cover for wire standards should be made of flexible transparent plastic.
(Modified edition, Amendment No. 1).
2.11. The shape and dimensions of the groove sensitivity standards are shown on and in.
2.12. The shape and dimensions of the plate sensitivity standards are shown on and in.
Groove depth
Prev off groove depth
R, no more
Prev off
Prev off
Prev off
Prev off
Prev off
(Modified edition, Amendment No. 1).
Table 4
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L |
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Symbols of the sensitivity standard material: for iron-based alloys - 1, aluminum and magnesium - 2, titanium - 3, copper - 4, nickel - 5.
2.14. For marking groove standards, it is allowed to use cutouts and holes or only holes indicated in. In this case, the thickness of the standard at the mark should be equal to h.
When marking the standards with holes, the length of the standard No. 1 is 27-0.52 mm, No. 2 - 38.5-0.62 mm, No. 3 - 53-0.74 mm.
2.15. For welded products intended for export, it is allowed to use other types of sensitivity standards, if it is provided for by the export conditions.
3. PREPARATION FOR CONTROL
3.1. Radiographic control should be carried out after elimination of external defects detected during external examination of the welded joint and cleaning it from irregularities, slag, metal spatter, scale and other contaminants, the images of which on the photograph may interfere with the interpretation of the photograph.
3.2. After cleaning the welded joint and eliminating external defects, the marking of the welded joint into sections and marking (numbering) of the sections should be made.
3.1, 3.2. (Modified edition, Amendment No. 1).
3.3. The system for marking and marking sections is established by technical documentation for the control or acceptance of welded joints.
3.4. During control, sensitivity standards and markings must be established at each site.
3.5. Sensitivity standards should be installed in the controlled area from the side facing the radiation source.
3.6. Wire standards should be placed directly on the seam with the wires directed across the seam.
3.7. Groove standards should be installed at a distance of at least 5 mm from the seam with the direction of the grooves across the seam.
3.8. Plate standards should be installed along the seam at a distance of at least 5 mm from it or directly on the seam with the standard directed across the seam so that the images of the standard markings do not overlap with the image of the seam in the photograph.
3.9. When inspecting circumferential seams of pipelines with a diameter of less than 100 mm, it is allowed to install groove standards at a distance of at least 5 mm from the seam with the direction of the grooves along the seam.
3.10. If it is impossible to install standards from the side of the radiation source when inspecting welded joints of cylindrical, spherical and other hollow products through two walls with decoding only the welded joint area adjacent to the film, as well as with panoramic transmission, it is allowed to set sensitivity standards from the side of the cassette with the film.
3.11.(Deleted, Amendment No. 1).
3.12. The markings used to limit the length of the sections of welded joints inspected during one exposure should be installed at the boundaries of the marked sections, as well as at the boundaries of the weld metal and base metal when inspecting welded joints without reinforcement or with removed weld reinforcement.
3.13. The markings used for the numbering of the controlled areas should be installed in the controlled area or directly on the cassette with the film so that the images of markings on the images do not overlap with the image of the seam and the near-weld zone along.
3.14. If it is impossible to install sensitivity standards and (or) markings on the inspected section of the welded joint in accordance with the requirements of this standard, the procedure for conducting control without installing sensitivity standards and (or) markings should be provided for in the technical documentation for the control or acceptance of welded joints.
4. CONTROL CIRCUITS
4.1. Welded joints should be controlled by and.
4.2. With a limited width of the welded element, it is allowed to control T-welded joints with the radiation direction along the generatrix of this element in accordance with.
4.2a. When inspecting circular welded joints of cylindrical and spherical hollow products, one should, as a rule, use transmission patterns through one wall of the product (diagrams Fig. 5 a, b, e, f, s). In this case, it is recommended to use transillumination schemes with the location of the radiation source inside the controlled item:
5.1, 5.2 (Modified edition, Amendment No. 1).
for butt and lap joints:
not less than 5 mm - with the thickness of the welded edges up to 5 mm;
not less than the thickness of the welded edges - with the thickness of the welded edges St. 5 to 20 mm;
not less than 20 mm - with the thickness of the welded edges St. 20 mm;
for tee and corner joints - established by the technical documentation for the control or acceptance of these joints.
6. DESCRIPTION OF IMAGES
6.1. Viewing and decoding the images should be carried out after they have completely dried in a darkened room using special illuminators-negatoscopes.
Use negatoscopes with adjustable brightness and illuminated field sizes. The maximum brightness of the illuminated field should be at least 10D + 2 cd / m2, where D is the optical density of the image. The size of the illuminated field should be adjusted using movable shutters or screens-masks within such limits that the illuminated field is completely covered by the picture.
(Modified edition, Amendment No. 1).
6.2. Pictures allowed for decryption must meet the requirements:
the photographs should not have spots, stripes, dirt and damage to the emulsion layer, making it difficult to decipher them;
images of limit marks, markings and sensitivity standards should be visible on the photographs;
the optical density of the images of the monitored section of the seam, the near-weld zone and the standard of sensitivity must be at least 1.5;
the decrease in the optical density of the image of the welded joint in any part of this image in comparison with the optical density of the image of the sensitivity standard should not exceed 1.0.
6.3. The sensitivity of the control (the smallest diameter of the wire of the wire standard detected in the photograph, the smallest depth of the groove of the groove standard detected in the photograph, the smallest thickness of the plate standard, at which a hole with a diameter equal to twice the thickness of the standard is revealed in the photograph) should not exceed the values given in.
Table 6
|
Sensitivity class |
|||
|
St. 5 to 9 incl. |
|||
|
"100" 140 " |
|||
|
"140" 200 " |
|||
|
"200" 300 " |
|||
|
"300" 400 " |
|||
Note. When using wire standards, the sensitivity values are 0.30; 0.60; 0.75 and 1.50 mm are replaced by 0.32; 0.63; 0.80 and 1.60 mm.
(Modified edition, Amendment No. 1).
Specific sensitivity values should be established by technical documentation (drawing requirements, specifications, control and acceptance rules) for the controlled products.
For nuclear power plants, the sensitivity requirements are established by the relevant regulatory documents.
6.4. In accordance with the requirements of the technical documentation for the controlled products, it is allowed to determine the sensitivity ( k) as a percentage according to the formula
where TO- sensitivity, mm;
S- thickness of the translucent metal, mm.
6.5. Deciphering and assessment of the quality of welded joints based on photographs that do not have images of sensitivity standards is allowed:
with panoramic transmission of circular welded joints with simultaneous exposure of more than four films. In these cases, regardless of the total number of images, it is allowed to set one sensitivity standard for each quarter of the circumference of the welded joint;
when it is impossible to apply sensitivity standards.
In these cases, the sensitivity is determined on simulators of a welded joint during processing of control modes.
6.6. When decoding the images, the dimensions of the images of cracks, lack of penetration, pores and inclusions are determined, and, if necessary, the value of the concavity and convexity of the weld root is estimated (in cases where the root of the weld is not accessible for external examination).
The list of dimensions to be determined and the method for assessing the value of the concavity and convexity of the root of the weld should be given in the technical documentation for the control and acceptance of welded joints.
6.7. When documenting the results of decoding images, the dimensions determined from the images should be rounded to the nearest values from the 0.2 series; 0.3; 0.4; 0.5; 0.6; 0.8; 1.0; 1.2; 1.5; 2.0; 2.5; 3.0 mm or the nearest whole values in millimeters, if the size determined from the photograph is greater than 3.0 mm.
6.8. If during inspection the film is located at a distance H from the surface of the tested welded joint facing the film and the relation
the dimensions determined from the photograph are recommended to be multiplied by a factor before rounding them
where f- distance from the radiation source to the surface of the inspected section of the welded joint facing the source, mm;
s- radiation thickness, mm.
6.6 - 6.8... (Modified edition, Amendment No. 1).
6.9. When measuring the size of defects up to 1.5 mm, use a measuring magnifier with a graduation of 0.1 mm, St. 1.5 mm - any measuring device with a scale of 1 mm.
6.10. The results of decoding the photographs and the sensitivity of the control must be recorded in the conclusion or the log of the control results, the form of which must be established by the technical documentation for the control or acceptance of welded joints.
6.11. To denote defects in the conclusion or the log of registration of the results of control, the symbols given in clause should be used.
Examples of abbreviated recording of defects when decoding images are given in.
7. SAFETY REQUIREMENTS
7.1. The main types of danger for personnel during radiographic monitoring are exposure to the body of ionizing radiation and harmful gases formed in the air under the influence of radiation, and electric shock.
7.2. Radiographic control and recharging of radioactive sources should be carried out only with the use of equipment specially designed for these purposes and in good working order, the documentation for the manufacture and operation of which, when released in an amount of more than three copies, must be agreed with the USSR State Committee for the Use of Atomic Energy and the Chief Sanitary - the epidemiological department of the USSR Ministry of Health; up to three copies - from local authorities sanitary and epidemiological service.
APPENDIX 4
1. Distance f from the radiation source to the surface of the tested welded joint facing the source (when transmitting circular welded joints through two walls - to the surface of the circular joint adjacent to the source) should not be less than the values determined by the formulas given in table. one.
Table 1
|
Transillumination scheme D- outer diameter of the tested welded joint, mm; T- the ratio of the inner and outer diameters of the tested welded joint; F- the maximum size of the focal spot of the radiation source, mm; TO- the required sensitivity of control, mm. |
page 1
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p. 19
CONTROL NON-DESTRUCTIVE
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
IPK PUBLISHING STANDARDS
Moscow
INTERSTATE STANDARD
Date of introduction 01/01/84
This standard establishes a method for radiographic inspection of fusion welded joints of metals and their alloys, with a thickness of welded elements from 1 to 400 mm, using X-ray, gamma and bremsstrahlung radiation and radiographic film.
1. GENERAL PROVISIONS
1.1. Radiographic control is used to detect cracks, lack of penetration, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic control is also used to detect burn-throughs, undercuts, assess the size of the convexity and concavity of the root of the seam, which are unacceptable for external examination.
1.3. Radiographic control does not reveal:
Any discontinuities and inclusions with a size in the direction of transmission less than double the sensitivity of the control;
Lack of penetration and cracks, the opening plane of which does not coincide with the direction of transmission and (or) the opening value is less than the values given in table. one;
Any discontinuities and inclusions, if their images in the photographs coincide with the images of extraneous parts, sharp corners or sharp changes in cracks in the translucent metal.
1.1 - 1.3.
Table 1
1.4. Welded joints with a ratio of the radiation thickness of the deposited weld metal to the total radiation thickness of at least 0.2, having two-sided access, providing the ability to install a cassette with a radiographic film and a radiation source in accordance with the requirements of this standard, are subjected to radiographic control.
2. REQUIREMENTS FOR CONTROL ACCESSORIES
2.1. For radiographic inspection, markings should be used that are made of material capable of being clearly imaged on radiographic images.
The markings of the dimensions established by GOST 15843 should be used.
2.2. For radiographic control, radiographic films should be used that meet the requirements of the technical specifications for them.
The type of radiographic film should be established by the technical documentation for the control or acceptance of welded joints.
2.3. For radiographic monitoring, radiation sources provided for in GOST 20426 should be used.
The type of radioactive source, the voltage on the X-ray tube and the energy of accelerated electrons must be set depending on the thickness of the material being translucent by the technical documentation for the inspection or acceptance of welded joints.
2.4. Metallic and fluorescent screens should be used as reinforcing screens for radiographic inspection.
The type of reinforcing screen must be established by the technical documentation for the inspection or acceptance of welded joints.
The thickness of the metal reinforcing screens and the methods of charging the film into cassettes using screens are given in Appendix 1.
2.5. Screens should have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed.
2.6. The cassettes for loading the film must be opaque and ensure that the reinforcing screens are tightly pressed against the film.
2.7. To protect the film from scattered radiation, it is recommended to shield the cassette with the film from the side opposite to the radiation source with lead shields.
The thickness of the protective screens is given in Appendix 2.
2.8. To determine the sensitivity of control, wire, groove or plate sensitivity standards should be used.
2.9. Sensitivity standards should be made of a metal or alloy, the basis of which is similar in chemical composition to that of the tested welded joint.
1 - insert; 2 - case
2.10. The shape and dimensions of the wire sensitivity standards are shown in Fig. 1 and in table. 2. The length of the wires in the standards is (20 ± 0.5) mm. Limit deviations for wire diameters:
up to 0.2 mm ... ± 0.01 mm
St. 0.2 "1.6 mm ... ± 0.03 mm
"1.6" 4.0 mm ... ± 0.04 mm.
table 2
|
Reference number |
||||||||
Limit deviations of other sizes - ± 0.5 mm.
The inlay and cover for wire standards should be made of flexible transparent plastic.
2.11. The shape and dimensions of the groove sensitivity standards are shown in Fig. 2 and in table. 3.
Table 3
|
Reference number |
Groove depth |
Prev off groove depth |
R, no more |
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|
Prev off |
Prev off |
Pre Off |
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||||||||||||||
2.12. The shape and dimensions of the plate sensitivity standards are shown in Fig. 3 and in table. 4.
Table 4
|
Reference number |
||||||||||||||
|
Prev off |
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Prev off |
Prev off |
Prev off |
Prev off |
Prev off |
||||||||
2.13. The marking of the sensitivity standards should be carried out with lead numbers in accordance with GOST 15843 in accordance with Appendix 3. The first number of the marking should indicate the material of the standard, the next (one or two numbers) - the number of the standard.
Symbols of the sensitivity standard material: for iron-based alloys - 1, aluminum and magnesium - 2, titanium - 3, copper - 4, nickel - 5.
2.14. For marking groove standards, it is allowed to use notches and holes or only holes specified in Appendix 3. In this case, the thickness of the standard at the marking site should be equal to h.
When marking the standards with holes, the length of the standard No. 1 is 27 -0.52 mm, No. 2 - 38.5 -0.62 mm, No. 3 - 53 0.74 mm.
2.15. For welded products intended for export, it is allowed to use other types of sensitivity standards, if it is provided for by the export conditions.
3. PREPARATION FOR CONTROL
3.1. Radiographic control should be carried out after elimination of external defects detected during external examination of the welded joint and cleaning it from irregularities, slag, metal spatter, scale and other contaminants, the images of which on the photograph may interfere with the interpretation of the photograph.
3.2. After cleaning the welded joint and eliminating external defects, the marking of the welded joint into sections and marking (numbering) of the sections should be made.
3.3. The system for marking and marking sections is established by technical documentation for the control or acceptance of welded joints.
3.4. During control, sensitivity standards and markings must be established at each site.
3.5. Sensitivity standards should be installed in the controlled area from the side facing the radiation source.
3.6. Wire standards should be placed directly on the seam with the wires directed across the seam.
3.7. Groove standards should be installed at a distance of at least 5 mm from the seam with the direction of the grooves across the seam.
3.8. Plate standards should be installed along the seam at a distance of at least 5 mm from it or directly on the seam with the standard directed across the seam so that the images of the standard markings do not overlap with the image of the seam in the photograph.
3.9. When inspecting circumferential seams of pipelines with a diameter of less than 100 mm, it is allowed to install groove standards at a distance of at least 5 mm from the seam with the direction of the grooves along the seam.
3.10. If it is impossible to install standards from the side of the radiation source when inspecting welded joints of cylindrical, spherical and other hollow products through two walls with decoding only the welded joint area adjacent to the film, as well as with panoramic transmission, it is allowed to set sensitivity standards from the side of the cassette with the film.
3.11. (Deleted, Amendment No. 1).
3.12. The markings used to limit the length of the sections of welded joints inspected during one exposure should be installed at the boundaries of the marked sections, as well as at the boundaries of the weld metal and base metal when inspecting welded joints without reinforcement or with removed weld reinforcement.
3.13. The markings used for the numbering of the controlled areas should be installed in the controlled area or directly on the cassette with the film so that the images of markings in the photographs do not overlap the image of the seam and the near-weld zone according to clause 5.7.
3.14. If it is impossible to install sensitivity standards and (or) markings on the inspected section of the welded joint in accordance with the requirements of this standard, the procedure for conducting control without installing sensitivity standards and (or) markings should be provided for in the technical documentation for the control or acceptance of welded joints.
4. CONTROL SCHEME
4.1. Welded joints should be monitored as per dash. 4 and 5.
4.2. With a limited width of the welded element, it is allowed to control T-welded joints with the radiation direction along the generatrix of this element in accordance with Fig. 6.
4.2a. When inspecting circular welded joints of cylindrical and spherical hollow products, one should, as a rule, use transmission patterns through one wall of the product (diagrams Fig. 5 a, b, f, g, h). In this case, it is recommended to use transillumination schemes with the location of the radiation source inside the controlled item:
The diagram of the devil. 5 e(panoramic transillumination) - for control of products with a diameter of up to 2 m, regardless of the volume of control and a diameter of 2 m or more with 100% control;
The diagram of the devil. 5 f- with 100% and sampling control, if the use of the scheme features. 5 e impossible;
The diagram of the devil. 5 s- for selective inspection of products with a diameter of 2 m and more;
Dash schemes. 5 a, b- for products with an inner diameter of 10 m or more, if the use of the diagram of the drawing. 5 e impossible.
4.3. When controlled through two walls, the diagram of dash. 5 v recommended for translucent products with a diameter of up to 100 mm; schemes of damn. 5 d, d- for transillumination of products with a diameter of more than 50 mm.
Inspection schemes for butt, lap, corner and tee connections
1 - radiation source; 2 - controlled area; 3 - cassette with film
Inspection schemes for circular (butt, lap, corner and tee) welded joints
1 - radiation source; 2 - controlled area; 3 - film cassette
1 - radiation source; 2 - controlled area; 3 - film cassette
4.4. When inspecting butt welded joints according to the diagrams of Fig. 5 a, b, f, g, h the direction of radiation should coincide with the plane of the tested welded joint. When checking fillet welds according to these diagrams, welding of pipes, fittings, etc. the angle between the direction of radiation and the plane of the welded joint should not exceed 45 °.
4.5. When inspecting welded joints according to the diagrams of Fig. 5 c, d, d the direction of radiation should be chosen so that the images of the opposite areas of the weld in the photograph do not overlap.
In this case, the angle between the direction of radiation and the plane of the weld should be minimal and in any case should not exceed 45 °.
4.3 - 4.5. (Modified edition, Amendment No. 1).
4.6. (Deleted, Rev.№ 1).
4.7. In addition to control according to the schemes shown in Fig. 4 - 6, depending on the design features of the welded joints and the requirements imposed on them, other schemes and directions of radiation can be used.
These schemes and directions of radiation should be provided for by the technical documentation for the control and acceptance of welded joints.
4.8. To reduce the difference in optical densities of different sections of the image when inspecting welded joints with a large difference in thickness, as well as in the case when the inspected welded joint does not protect the radiographic film from direct radiation (for example, when inspecting the end welds of welding pipes into tube sheets, when inspecting surfacing edges for welding, etc.), control should be carried out using expansion joint attachments.
It is allowed to use compensators made of any material providing the required radiation attenuation.
4.9. When choosing a scheme and direction of radiation, one should take into account:
The distance from the controlled welded joint to the radiographic film should be minimal and in any case should not exceed 150 mm;
The angle between the direction of radiation and the normal to the radiographic film within the area of the welded joint monitored for one exposure should be minimal and in any case should not exceed 45 °.
4.7 - 4.9. (Modified edition, Amendment No. 1).
5. SELECTION OF RADIOGRAPHIC CONTROL PARAMETERS
5.1. The distance from the radiation source to the surface of the inspected welded joint closest to the source (when scanning welded joints of cylindrical and spherical hollow products through two walls - to the surface of the inspected welded joint adjacent to the source) and the size or number of areas monitored in one exposure for all transillumination schemes ( except for the scheme Fig. 5 e) should be chosen such that the following requirements are met during transmission:
The geometric unsharpness of the images of defects in the photographs when the film is located close to the tested welded joint should not exceed half of the required sensitivity of the test at a sensitivity of up to 2 mm and 1 mm at a sensitivity of more than 2 mm;
The relative increase in the size of the images of defects located on the side of the radiation source (in relation to the defects located on the side of the film) should not exceed 1.25;
The angle between the direction of radiation and the normal to the film within the area of the welded joint monitored for one exposure should not exceed 45 °;
The decrease in the optical density of the image of the welded joint in any part of this image in relation to the optical density in the place where the wire sensitivity standard is installed or in relation to the optical density of the image of the groove or plate sensitivity standard should not exceed 1.0.
5.2. Formulas for determining the minimum permissible distances from the radiation source to the controlled welded joint, as well as the maximum dimensions and the minimum number of areas controlled for one exposure when controlled according to the drawing diagrams. 4 - 6 are given in Appendix 4.
5.1, 5.2. (Modified edition, Amendment No. 1).
5.3. When inspecting welded joints according to the drawing. 5h (panoramic transmission) the ratio of the inner diameter d to outer diameter D controlled connection should not be less than 0.8, and the maximum size of the focal spot F the radiation source should not be more than where K- control sensitivity.
5.4. In cases where the dimensions of the defects are not determined (for example, defects are not allowed regardless of their size), the ratio given in clause 5.3 between the inner and outer diameters of the tested joint may not be observed.
5.5. In the absence of a radiation source that meets the requirement of clause 5.3, it is allowed when checking according to the drawing. 5 s use radiation sources with a maximum focal spot size that satisfies the ratio
In this case, the sensitivity standard should be installed on the welded joint or simulator of the welded joint used in determining the sensitivity, only from the side of the radiation source.
5.6. The length of the images should ensure that the images of adjacent sections of welded joints overlap when the length of the controlled section is up to 100 mm, not less than 0.2 of the length of the section, with the length of the controlled section sv. 100 mm - not less than 20 mm.
5.7 The width of the images should ensure the receipt of images of the weld, sensitivity standards, markings and near-weld zones with the width:
For butt and lap joints:
not less than 5 mm - with the thickness of the welded edges up to 5 mm;
not less than the thickness of the welded edges - with the thickness of the welded edges St. 5 to 20 mm;
not less than 20 mm - with the thickness of the welded edges St. 20 mm;
For tee and corner joints - it is established by the technical documentation for the control or acceptance of these joints.
6. DESCRIPTION OF IMAGES
6.1. Viewing and decoding images should be carried out after they have completely dried in a darkened room using special illuminators - negatoscopes.
Use negatoscopes with adjustable brightness and illuminated field sizes. The maximum brightness of the illuminated field should be at least 10 D + 2 cd / m2, where D is the optical density of the image. The size of the illuminated field should be adjusted using movable shutters or screens-masks within such limits that the illuminated field is completely covered by the picture.
6.2. Pictures allowed for decryption must meet the requirements:
The photographs should not have spots, stripes, dirt and damage to the emulsion layer, which makes it difficult to decipher them;
The photographs should show images of limit marks, markings and sensitivity standards;
The optical density of the images of the monitored section of the seam, the near-weld zone and the standard of sensitivity must be at least 1.5;
The decrease in the optical density of the image of the welded joint in any part of this image in comparison with the optical density of the image of the sensitivity standard should not exceed 1.0.
6.3. The sensitivity of control (the smallest diameter of the wire of the wire standard detected in the photograph, the smallest depth of the groove of the groove standard detected in the photograph, the smallest thickness of the plate standard, at which a hole with a diameter equal to twice the thickness of the standard is revealed in the photograph) should not exceed the values given in Table. 6.
Table 6
|
Radiation thickness (at the place where the sensitivity standard is installed) |
Sensitivity class |
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St. 5 to 9 incl. |
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"100" 140 " |
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"140" 200 " |
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"200" 300 " |
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"300" 400 " |
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Note. When using wire standards, the sensitivity values are 0.30; 0.60; 0.75 and 1.50 mm are replaced by 0.32; 0.63; 0.80 and 1.60 mm.
Specific sensitivity values should be established by technical documentation (drawing requirements, specifications, control and acceptance rules) for the controlled products.
For nuclear power plants, the sensitivity requirements are established by the relevant regulatory documents.
6.4 In accordance with the requirements of the technical documentation for the controlled items, it is allowed to determine the sensitivity (k) as a percentage according to the formula
where K- sensitivity, mm;
S- thickness of the translucent metal, mm.
6.5. Deciphering and assessment of the quality of welded joints based on photographs that do not have images of sensitivity standards is allowed:
With panoramic transmission of circular welded joints with simultaneous exposure of more than four films. In these cases, regardless of the total number of images, it is allowed to set one sensitivity standard for each quarter of the circumference of the welded joint;
If it is impossible to apply sensitivity standards.
In these cases, the sensitivity is determined on simulators of a welded joint during processing of control modes.
6.6. When decoding the images, the dimensions of the images of cracks, lack of penetration, pores and inclusions are determined, and, if necessary, the value of the concavity and convexity of the weld root is estimated (in cases where the root of the weld is not accessible for external examination).
The list of dimensions to be determined and the method for assessing the value of the concavity and convexity of the root of the weld should be given in the technical documentation for the control and acceptance of welded joints.
6.7. When documenting the results of decoding images, the dimensions determined from the images should be rounded to the nearest values from the 0.2 series; 0.3; 0.4; 0.5; 0.6; 0.8; 1.0; 1.2; 1.5; 2.0; 2.5; 3.0 mm or the nearest whole values in millimeters, if the size determined from the photograph is greater than 3.0 mm.
6.8. If during inspection the film is located at a distance N from the surface of the tested welded joint facing the film and the relation
the dimensions determined from the photograph are recommended to be multiplied by a factor before rounding them
where f- distance from the radiation source to the surface of the inspected section of the welded joint facing the source, mm;
s - radiation thickness, mm.
6.6. - 6.8. (Modified edition, Amendment No. 1).
6.9. When measuring the size of defects up to 1.5 mm, use a measuring magnifier with a graduation of 0.1 mm, St. 1.5 mm - any measuring device with a scale of 1 mm.
6.10. The results of decoding the photographs and the sensitivity of the control must be recorded in the conclusion or the log of the control results, the form of which must be established by the technical documentation for the control or acceptance of welded joints.
6.11. To denote defects in the conclusion or register of the results of control, the symbols given in Appendix 5 should be used.
Examples of abbreviated recording of defects when decoding images are given in Appendix 6.
7. SAFETY REQUIREMENTS
7.1. The main types of danger for personnel during radiographic monitoring are exposure to the body of ionizing radiation and harmful gases formed in the air under the influence of radiation, and electric shock.
7.2. Radiographic control and recharging of radioactive sources should be carried out only with the use of equipment specially designed for these purposes and in good working order, the documentation for the manufacture and operation of which, when released in an amount of more than three copies, must be agreed with the USSR State Committee for the Use of Atomic Energy and the Chief Sanitary - the epidemiological department of the USSR Ministry of Health; up to three copies - with the local authorities of the sanitary and epidemiological service.
7.3. Electrical equipment of existing stationary and portable installations for radiographic control must comply with the requirements of GOST 12.2.007.0 and the "Rules for the Installation of Electrical Installations" approved by the Main Technical Directorate for the Operation of Energy Systems and the State Energy Supervision of the USSR Ministry of Energy.
7.4. When carrying out radiographic control, storage and recharging of radioactive radiation sources, the safety of work must be ensured in accordance with the requirements of the "Basic Sanitary Rules for Working with Radioactive Substances and Other Sources of Ionizing Radiation" OSP-72/80 No. 2120-80, approved by the Chief State Sanitary Doctor of the USSR January 18, 1980, "Standards of radiation safety" NRB-76 No. 141-76, approved by the Chief State Sanitary Doctor of the USSR on June 7, 1976, " Sanitary regulations on radioisotope flaw detection "No. 1171-74, approved by the Deputy Chief State Sanitary Doctor of the USSR on August 7, 1974 and GOST 23764.
7.5. When operating stationary and portable installations for radiographic control connected to the industrial power grid, the safety of work must be ensured in accordance with the requirements of the "Rules for the technical operation of consumer electrical installations" and "Safety rules for the operation of electrical installations of consumers" approved by the State Energy Supervision Service on April 12, 1969.
7.6. When transporting radioactive radiation sources, the requirements of the "Safety Rules for the Transport of Radioactive Substances" PBTRV-73 No. 1139-73, approved by the Chief State Sanitary Doctor of the USSR on December 27, 1973, must be observed.
7.7. Enterprises performing radiographic control of welded joints develop, in accordance with the safety requirements of this section, documentation that defines the rules and methods for the safe organization of work, the scope and means of radiographic control, taking into account local production conditions and bring them to workers in the prescribed manner.
8. METROLOGICAL SUPPORT
8.1. The groove and plate sensitivity standards used for testing should be subject to metrological verification during their release and subsequent verification at least once every 5 years. When these standards are issued, the trademark of the company that made the standard and the year of issue must be electrochemically applied to the reverse side of each standard; at the next verification - the trademark or conventional mark of the company that carried out the verification, and the year of verification.
8.2. Wire standards of sensitivity are not subject to verification, however, they should be withdrawn from circulation in case of any damage to the plastic cover or detection during visual inspection of traces of corrosion of the wires of the standard.
8.3. Densitometers and sets of optical densities used to determine the optical density of images are subject to verification at least once a year with the obligatory execution of a document (certificate) on the results of verification.
8.4. Negatoscopes are subject to verification only when they are released with the obligatory indication in the passport (certificate) of the negatoscope of the maximum brightness of the illuminated field and the optical density of the image.
8.5. Measuring instruments used to determine the dimensions of images of cracks, lack of penetration, pores and inclusions in photographs (measuring rulers and magnifiers) are verified in accordance with the current provisions applicable to these instruments.
8.6. Non-standardized measuring instruments used to determine the dimensions of images of cracks, lack of penetration, pores and inclusions in photographs (measuring templates, stencils, etc.) must be verified at least once a year with the obligatory execution of a document on the results of verification.
Sec. eight. (Introduced additionally, Amendment No. 1).
ANNEX 1
Thickness of metal reinforcing screens
Table 1
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Radiation source |
Screen thickness, mm |
|
X-ray apparatus with an X-ray tube voltage up to 100 kV |
|
|
X-ray apparatus with an X-ray tube voltage over 100 to 300 kV |
|
|
X-ray apparatus with an X-ray tube voltage over 300 kV |
|
|
Accelerator of electrons with radiation energy from 1 to 15 MeV |
Methods for charging cassettes
table 2
Radiographic film;
Reinforcing metal shield;
Intensifying fluorescent screen.
APPENDIX 2
Reference
Thickness of protective lead screens
|
Radiation source |
Screen thickness, mm |
|
X-ray apparatus with an X-ray tube voltage up to 200 kV |
|
|
X-ray apparatus with an X-ray tube voltage over 200 kV |
1.0 to 2.0 |
|
192 Ir; 137 Cs; Co |
1.0 to 2.0 |
|
Accelerator of electrons with radiation energy from 1 to 15 MeV |
APPENDIX 3
Mandatory
Table 1
Sensitivity reference markings
table 2
Marking of groove standards
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Reference number |
Alloys based on |
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aluminum and magnesium |
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1. Distance f from the radiation source to the surface of the tested welded joint facing the source (when transmitting circular welded joints through two walls - to the surface of the circular joint adjacent to the source) should not be less than the values determined by the formulas given in table. one. Table 1
where at and C = 4 at s - radiation thickness, mm; D - outer diameter of the tested welded joint, mm; T - the ratio of the inner and outer diameters of the tested welded joint; F- the maximum size of the focal spot of the radiation source, mm; K - required sensitivity of control, mm. Note. If for the diagram the devil. 5 d, d the conditions 1.5 C (1 - m)> 1 and C (1.4 - m)> 1 are not met, the distance f can be taken equal to zero (i.e., the radiation source can be placed directly on the wall of the article opposite to the controlled section). 2. The length of the areas monitored for one exposure when checking according to the schemes of lines. 4 and 6 should not be more than 0.8 f. 3. The number of areas (expositions) when controlled according to the schemes of lines. 5 a, c, d, e should not be less than the values determined by the formulas given in table. 2. table 2 d - inner diameter of the tested welded joint, mm. 4. For the diagram of the devil. 5 b choose the length of the shot l and distance f, which must satisfy the relations and determine the auxiliary coefficient If the ratio is not satisfied, decrease l or increase f until this ratio is fulfilled, after which the quantity N areas monitored for one exposure, which must satisfy the ratio 5. For the diagram of the features. 5 f determine the maximum possible (based on the inner diameter of the controlled item and the dimensions of the radiation or collimating head of the gamma flaw detector or the dimensions of the emitter of the X-ray machine) distance / (along the diameter of the item), which must satisfy the ratio f ≥ 0.5C (1 - m) D. If this ratio is not met, it is necessary to use a source with a smaller focal spot size for which this ratio is met. When this ratio is fulfilled, an auxiliary coefficient is determined choose quantity N areas monitored for one exposure, which must satisfy the ratio 6. The angle between the directions of radiation for individual exposures when controlled according to the diagram of Fig. 5 v should be and when controlled according to the schemes of features. 5 a, b, d, e, g - 7. The distance from the radiation source to the inspected welded joint and the length of the sections inspected during one exposure when inspecting circular welded joints of cylindrical and spherical hollow products with a diameter of more than 2 m are determined in the same way as for welded joints inspected according to the diagrams of the drawing. 4 and 6. APPENDIX4 . (Modified edition, Amendment No. 1). APPENDIX 5Mandatory CONDITIONAL RECORDING OF DEFECTS WHEN INTERPRETING IMAGES AND DOCUMENTAL REGISTRATION OF THE RESULTS OF RADIOGRAPHIC CONTROL1. For an abbreviated record of defects when decoding images and documenting the results of control, the symbols given in the table should be used.
2. For an abbreviated record of the maximum total length of defects (in a section of a photograph with a length of 100 mm or in the entire photograph if its length is less than 100 mm), the symbol Σ should be used. 3. After the symbol of defects, their sizes are indicated in millimeters: For spherical pores, slag and tungsten inclusions - diameter; For elongated pores, slag and tungsten inclusions - width and length (through the multiplication sign); For chains, accumulations, oxide inclusions, lack of penetration and cracks - length. 4. For chains and accumulations of pores, slag and tungsten inclusions, after the symbolic designation of defects included in the chain or accumulation, the maximum diameter or width and length of these defects are indicated (through the multiplication sign). 5. If there are images of the same defects (defects of the same type with the same dimensions) in the image, it is allowed not to write down each of the defects separately, but to indicate their number before the symbol of the defects. 6. After the symbolic designation of the maximum total length of defects (in the area of the photograph with a length of 100 mm), this length is indicated in millimeters. 7. In the absence of images of defects in the photograph, as well as in cases when the length, width and total length of defects do not exceed the specified maximum permissible values, in the column of the documentation "Complies with the requirements" is written "yes", in the opposite case - "no". 8. If any defects not listed in clause 1 are found on the images, the full name of the defects should be indicated in the conclusion or the log of the control results. APPENDIX5 . (Modified edition, Amendment No. 1). APPENDIX 6Reference EXAMPLES OF ABBREVIATED RECORDING OF DEFECTS WHEN INTERPRETING IMAGES AND DOCUMENTAL REGISTRATION OF THE RESULTS OF RADIOGRAPHIC CONTROL1. The image shows images of five pores with a diameter of 3 mm each, a chain of pores with a length of 30 mm and a maximum length and width of pores in a chain of 5 and 3 mm, and a slag inclusion with a length of 15 mm and a width of 2 mm. The maximum total length of defects in an area of a photograph with a length of 100 mm is 20 mm. Record in the documentation: 5P3; Ts30P5 × 3; W15 × 2; Σ20. 2. The image shows images of two pore clusters (length of each cluster 10 mm, maximum pore diameter 0.5 mm) and an accumulation of slag inclusions (cluster length 8 mm, maximum length and width of inclusions 2 and 1 mm). The maximum total length of defects in an area of a photograph with a length of 100 mm is 18 mm. Record in the documentation: 2S10P0.5; S8SH2 × 1; Σ18. 3. The image shows images of two lack of penetration, 15 mm long each, and cracks 40 mm long. Record of documentation: 2H15; T40. 4. The image shows images of five pores with a diameter of 4 mm each and lack of penetration 20 mm long. The maximum total pore length in a 100 mm long image area is 12 mm. Record in the documentation: 5P4; Σ12; H20. INFORMATION DATA 1 ... APPROVED AND INTRODUCED INTO EFFECT by the Resolution of the USSR State Committee for Standards dated 20.12.82 No. 4923 3 ... REFERENCE REGULATORY AND TECHNICAL DOCUMENTS 4 ... The limitation of the validity period was lifted according to the protocol No. 3-93 of the Interstate Council for Standardization, Metrology and Certification 5 ... EDITION (May 2004) with Amendment No. 1 approved in March 1988
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GOST 7512-82
Group B09
STATE STANDARD OF THE UNION OF SSR
CONTROL NON-DESTRUCTIVE
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
Nonde-structive testing. Welded joints. Radiography method
Date of introduction 1984-01-01
INFORMATION DATA
1. DEVELOPERS
G.I. Nikolaev, B.A. Khripunov, Yu.I. Udralov, E.G. Volkovyskaya
2. APPROVED AND INTRODUCED INTO EFFECT by the Decree of the USSR State Committee for Standards dated 20.12.82 N 4923
3. REPLACE GOST 7512-75
4. REFERENCE REGULATORY AND TECHNICAL DOCUMENTS
5. The limitation of the validity period was lifted by the decision of the Interstate Council for Standardization, Metrology and Certification (IUS 5-6-93)
6. REPUBLICATION (December 1994) with Amendment No. 1, approved in March 1988 (IUS 6-88)
This standard establishes a method for radiographic inspection of fusion welded joints of metals and their alloys, with a thickness of welded elements from 1 to 400 mm, using X-ray, gamma and bremsstrahlung radiation and radiographic film.
1. GENERAL PROVISIONS
1.1. Radiographic control is used to detect cracks, lack of penetration, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic control is also used to detect burn-throughs, undercuts, assess the size of the convexity and concavity of the root of the seam, which are unacceptable for external examination.
1.3. Radiographic control does not reveal:
any discontinuities and inclusions with a size in the direction of transmission less than double the control sensitivity;
lack of penetration and cracks, the opening plane of which does not coincide with the direction of transmission and (or) the opening value is less than the values given in Table 1;
any discontinuities and inclusions, if their images in the photographs coincide with the images of extraneous parts, sharp corners or sharp drops of cracks in the translucent metal.
Table 1
1.1-1.3. (Modified edition, Amendment N 1).
1.4. Welded joints with a ratio of the radiation thickness of the deposited weld metal to the total radiation thickness of at least 0.2, having two-sided access, providing the ability to install a cassette with a radiographic film and a radiation source in accordance with the requirements of this standard, are subjected to radiographic control.
(Introduced additionally, Rev. N 1).
2. REQUIREMENTS FOR CONTROL ACCESSORIES
2.1. For radiographic inspection, markings should be used that are made of material capable of being clearly imaged on radiographic images.
It is necessary to use markings of the sizes established by GOST 15843-79.
2.2. For radiographic control, radiographic films should be used that meet the requirements of the technical specifications for them.
The type of radiographic film should be established by the technical documentation for the control or acceptance of welded joints.
2.3. For radiographic inspection, radiation sources provided for by GOST 20426-82 should be used.
The type of radioactive source, the voltage on the X-ray tube and the energy of accelerated electrons must be set depending on the thickness of the material being translucent by the technical documentation for the inspection or acceptance of welded joints.
2.4. Metallic and fluorescent screens should be used as reinforcing screens for radiographic inspection.
The type of reinforcing screen must be established by the technical documentation for the inspection or acceptance of welded joints.
The thickness of the metal reinforcing screens and the methods of charging the film into cassettes using screens are given in Appendix 1.
2.5. Screens should have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed.
2.6. The cassettes for loading the film must be opaque and ensure that the reinforcing screens are tightly pressed against the film.
2.7. To protect the film from scattered radiation, it is recommended to shield the cassette with the film from the side opposite to the radiation source with lead shields.
The thickness of the protective screens is given in Appendix 2.
2.8. To determine the sensitivity of control, wire, groove or plate sensitivity standards should be used.
2.9. Sensitivity standards should be made of a metal or alloy, the basis of which is similar in chemical composition to that of the tested welded joint.
2.10. The shape and dimensions of the wire sensitivity standards are shown in Fig. 1 and in Table 2. The length of the wires in the standards is (20 ± 0.5) mm. Limit deviations for wire diameters:
up to 0.2 mm ± 0.01 mm
St. 0.2 to 1.6 mm ± 0.03 mm
"1.6" 4.0 mm ± 0.04 mm
1 - insert; 2 - cover
table 2
|
Reference number |
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Limit deviations of other sizes - ± 0.5 mm.
The inlay and cover for wire standards should be made of flexible transparent plastic.
(Modified edition, Amendment N 1).
2.11. The shape and dimensions of the groove sensitivity standards are shown in Fig. 2 and in Table 3.
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