Conventional recording of defects when decoding images and documenting the results of radiographic inspection
NON-DESTRUCTIVE TESTING
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
GOST 7512-82
PUBLISHING HOUSE OF STANDARDS
Moscow
STATE STANDARD OF THE USSR UNION
Date of introduction 01.01.84
This standard establishes a method for radiographic testing of welded joints made of metals and their alloys, made by fusion welding, 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 testing is used to detect cracks, lack of penetration, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic testing is also used to identify burns, undercuts, and assess the magnitude of convexity and concavity of the root of the seam, which are unacceptable for external inspection.
any discontinuities and inclusions with a size in the direction of transmission less than twice 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 foreign parts, sharp corners or sharp changes in cracks of the metal being scanned.
1.1 - 1.3.
Table 1
mm
|
You should use size markings established by GOST 15843-79. 2.2. During radiographic testing, radiographic films should be used that meet the requirements of the technical specifications for them. The type of radiographic film must be established in the technical documentation for inspection 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 established depending on the thickness of the material being examined by the technical documentation for inspection or acceptance of welded joints. 2.4. Metal and fluorescent screens should be used as intensifying screens during radiographic testing. The type of reinforcing screen must be established in the technical documentation for inspection or acceptance of welded joints. The thickness of metal intensifying screens and methods of loading film into cassettes using screens are given in. 2.5. Screens must have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed. 2.6. Film loading cassettes must be lightproof and ensure tight pressing of the intensifying screens to the film. 2.7. To protect the film from scattered radiation, it is recommended to screen the film cassette on the side opposite the radiation source with lead screens. The thickness of the protective screens is given in .
1 - liner; 2 - cover. Crap. 1. 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 the basis of the controlled welded joint. 2.10. The shape and dimensions of wire sensitivity standards are shown 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 mm
(Changed edition, Amendment No. 1). Table 4
Symbols for the sensitivity standard material: for iron-based alloys - 1, aluminum and magnesium - 2, titanium - 3, copper - 4, nickel - 5. 2.14. To mark groove standards, it is allowed to use cutouts and holes or only the holes indicated in. In this case, the thickness of the standard at the marking site should be equal to h. When marking standards with holes, the length of 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, the use of other types of sensitivity standards is allowed if this is provided for by the export conditions. 3. PREPARATION FOR CONTROL3.1. Radiographic testing should be carried out after eliminating external defects discovered during an external inspection of the welded joint and cleaning it from irregularities, slag, metal splashes, scale and other contaminants, the images of which in the image may interfere with the decoding of the image. 3.2. After cleaning the welded joint and eliminating external defects, the welded joint must be marked into sections and the sections must be marked (numbered). 3.1, 3.2. (Changed edition, Amendment No. 1). 3.3. The system for marking and marking areas is established by technical documentation for inspection or acceptance of welded joints. 3.4. When monitoring, sensitivity standards and markings must be installed at each site. 3.5. Sensitivity standards should be installed in the controlled area on the side facing the radiation source. 3.6. Wire standards should be installed 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 direction of the standard across the seam so that the images of the standard markings do not overlap the image of the seam in the photograph. 3.9. When inspecting circumferential welds 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 grooves directed along the seam. 3.10. If it is impossible to install standards from the side of the radiation source when monitoring welded joints of cylindrical, spherical and other hollow products through two walls with deciphering only the area of the welded joint adjacent to the film, as well as during panoramic transmission, it is allowed to install sensitivity standards from the side of the cassette with film. 3.11.(Deleted, Amendment No. 1). 3.12. Markings used to limit the length of 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 deposited and base metal when monitoring welded joints without reinforcement or with the weld reinforcement removed. 3.13. Markings used for numbering inspected areas should be installed on the inspected area or directly on the film cassette so that the images of the markings on the photographs do not overlap with the image of the seam and the heat-affected zone. 3.14. If it is impossible to install sensitivity standards and (or) markings on the controlled area of the welded joint in accordance with the requirements of this standard, the procedure for conducting inspection without installing sensitivity standards and (or) markings must be provided for in the technical documentation for inspection or acceptance of welded joints. 4. CONTROL SCHEME4.1. Welded joints should be controlled by and. 4.2. If the width of the welded element is limited, it is permissible to control T-welded joints with the direction of radiation along the generatrix of this element in accordance with. 4.2a. When inspecting circumferential welded joints of cylindrical and spherical hollow products, one should, as a rule, use transmission patterns through one wall of the product (schemes of Fig. 5 A, b, e, and, h). In this case, it is recommended to use transmission schemes with the location of the radiation source inside the controlled product: 5.1, 5.2 (Changed edition, Amendment No. 1). for butt and lap joints: not less than 5 mm - with a thickness of welded edges up to 5 mm; not less than the thickness of the welded edges - with a thickness of the welded edges of St. 5 to 20 mm; not less than 20 mm - with a thickness of welded edges of St. 20 mm; for T-joints and corner connections - is established by the technical documentation for the control or acceptance of these connections. 6. DECODING IMAGES6.1. Viewing and decoding of images should be done after they have completely dried in a darkened room using special illuminators-negatoscopes. You should use negatoscopes with adjustable brightness and size of the illuminated field. The maximum brightness of the illuminated field must be at least 10 D+2 cd/m 2, where D- optical density of the image. The size of the illuminated field should be adjusted using movable curtains or mask screens within such limits that the illuminated field is completely covered by the image. (Changed edition, Amendment No. 1). 6.2. Images accepted for decryption must meet the following requirements: The photographs should not contain spots, stripes, dirt or damage to the emulsion layer that would make them difficult to decipher; Images of restrictive marks, markings and sensitivity standards must be visible on the photographs; the optical density of the images of the inspected section of the seam, the heat-affected zone and the sensitivity standard 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 compared to 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 standard detected in the image, the smallest depth of the groove of the groove standard identified in the image, 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 image) should not exceed the values given in. Table 6 mm
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
NON-DESTRUCTIVE TESTING
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
GOST 7512-82
PUBLISHING HOUSE OF STANDARDS
Moscow
STATE STANDARD OF THE USSR UNION
Date of introduction 01.01.84
This standard establishes a method for radiographic testing of welded joints made of metals and their alloys, made by fusion welding, 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 testing is used to detect cracks, lack of penetration, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic testing is also used to identify burns, undercuts, and assess the magnitude of convexity and concavity of the root of the seam, which are unacceptable for external inspection.
any discontinuities and inclusions with a size in the direction of transmission less than twice 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 foreign parts, sharp corners or sharp changes in cracks of the metal being scanned.
1.1 - 1.3.
Table 1
1.4. Radiographic testing is carried out on welded joints with a ratio of the radiation thickness of the deposited weld metal to the total radiation thickness of at least 0.2, which have two-way access, allowing the installation of a cassette with radiographic film and a radiation source in accordance with the requirements of this standard.
(Introduced additionally, Amendment No. 1).
2. REQUIREMENTS FOR CONTROL ACCESSORIES
You should use size markings established by GOST 15843-79.
2.2. During radiographic testing, radiographic films should be used that meet the requirements of the technical specifications for them.
The type of radiographic film must be established in the technical documentation for inspection 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 established depending on the thickness of the material being examined by the technical documentation for inspection or acceptance of welded joints.
2.4. Metal and fluorescent screens should be used as intensifying screens during radiographic testing.
The type of reinforcing screen must be established in the technical documentation for inspection or acceptance of welded joints.
The thickness of metal intensifying screens and methods of loading film into cassettes using screens are given in.
2.5. Screens must have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed.
2.6. Film loading cassettes must be lightproof and ensure tight pressing of the intensifying screens to the film.
2.7. To protect the film from scattered radiation, it is recommended to screen the film cassette on the side opposite the radiation source with lead screens.
The thickness of the protective screens is given in .
1 - liner; 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 the basis of the controlled welded joint.
2.10. The shape and dimensions of wire sensitivity standards are shown 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
Maximum deviations for other sizes are ± 0.5 mm. The insert and cover for wire standards should be made of flexible transparent plastic.
(Changed edition, Amendment No. 1).
2.11. The shape and dimensions of the groove sensitivity standards are shown in and in.
2.12. The shape and dimensions of plate sensitivity standards are shown in and in.
Groove depth
Prev. off groove depths
R, no more
Prev. off
Prev. off
Prev. off
Prev. off
Prev. off
(Changed edition, Amendment No. 1).
Table 4
|
L |
||||||||||||||
|
Prev. off |
Prev. off |
Prev. off |
Prev. off |
Prev. off |
Prev. off |
Prev. off |
||||||||
Symbols for the sensitivity standard material: for iron-based alloys - 1, aluminum and magnesium - 2, titanium - 3, copper - 4, nickel - 5.
2.14. To mark groove standards, it is allowed to use cutouts and holes or only the holes indicated in. In this case, the thickness of the standard at the marking site should be equal to h.
When marking standards with holes, the length of 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, the use of other types of sensitivity standards is allowed if this is provided for by the export conditions.
3. PREPARATION FOR CONTROL
3.1. Radiographic testing should be carried out after eliminating external defects discovered during an external inspection of the welded joint and cleaning it from irregularities, slag, metal splashes, scale and other contaminants, the images of which in the image may interfere with the decoding of the image.
3.2. After cleaning the welded joint and eliminating external defects, the welded joint must be marked into sections and the sections must be marked (numbered).
3.1, 3.2. (Changed edition, Amendment No. 1).
3.3. The system for marking and marking areas is established by technical documentation for inspection or acceptance of welded joints.
3.4. When monitoring, sensitivity standards and markings must be installed at each site.
3.5. Sensitivity standards should be installed in the controlled area on the side facing the radiation source.
3.6. Wire standards should be installed 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 direction of the standard across the seam so that the images of the standard markings do not overlap the image of the seam in the photograph.
3.9. When inspecting circumferential welds 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 grooves directed along the seam.
3.10. If it is impossible to install standards from the side of the radiation source when monitoring welded joints of cylindrical, spherical and other hollow products through two walls with deciphering only the area of the welded joint adjacent to the film, as well as during panoramic transmission, it is allowed to install sensitivity standards from the side of the cassette with film.
3.11.(Deleted, Amendment No. 1).
3.12. Markings used to limit the length of 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 deposited and base metal when monitoring welded joints without reinforcement or with the weld reinforcement removed.
3.13. Markings used for numbering inspected areas should be installed on the inspected area or directly on the film cassette so that the images of the markings on the photographs do not overlap with the image of the seam and the heat-affected zone.
3.14. If it is impossible to install sensitivity standards and (or) markings on the controlled area of the welded joint in accordance with the requirements of this standard, the procedure for conducting inspection without installing sensitivity standards and (or) markings must be provided for in the technical documentation for inspection or acceptance of welded joints.
4. CONTROL SCHEME
4.1. Welded joints should be controlled by and.
4.2. If the width of the welded element is limited, it is permissible to control T-welded joints with the direction of radiation along the generatrix of this element in accordance with.
4.2a. When inspecting circumferential welded joints of cylindrical and spherical hollow products, one should, as a rule, use transmission patterns through one wall of the product (schemes of Fig. 5 A, b, e, and, h). In this case, it is recommended to use transmission schemes with the location of the radiation source inside the controlled product:
5.1, 5.2 (Changed edition, Amendment No. 1).
for butt and lap joints:
not less than 5 mm - with a thickness of welded edges up to 5 mm;
not less than the thickness of the welded edges - with a thickness of the welded edges of St. 5 to 20 mm;
not less than 20 mm - with a thickness of welded edges of St. 20 mm;
for T-joints and corner connections - is established by the technical documentation for the control or acceptance of these connections.
6. DECODING IMAGES
6.1. Viewing and decoding of images should be done after they have completely dried in a darkened room using special illuminators-negatoscopes.
You should use negatoscopes with adjustable brightness and size of the illuminated field. The maximum brightness of the illuminated field must be at least 10D+2 cd/m2, where D- optical density of the image. The size of the illuminated field should be adjusted using movable curtains or mask screens within such limits that the illuminated field is completely covered by the image.
(Changed edition, Amendment No. 1).
6.2. Images accepted for decryption must meet the following requirements:
The photographs should not contain spots, stripes, dirt or damage to the emulsion layer that would make them difficult to decipher;
Images of restrictive marks, markings and sensitivity standards must be visible on the photographs;
the optical density of the images of the inspected section of the seam, the heat-affected zone and the sensitivity standard 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 compared to 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 standard detected in the image, the smallest depth of the groove of the groove standard identified in the image, 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 image) should not exceed the values given in.
Table 6
|
Sensitivity class |
|||
|
St. 5 to 9 inclusive. |
|||
|
» 100 » 140 » |
|||
|
» 140 » 200 » |
|||
|
» 200 » 300 » |
|||
|
» 300 » 400 » |
|||
Note. When using wire sensitivity standards, the values are 0.30; 0.60; 0.75 and 1.50 mm are replaced by the values 0.32; 0.63; 0.80 and 1.60 mm.
(Changed edition, Amendment No. 1).
Specific sensitivity values must be established by technical documentation (drawing requirements, technical conditions, control and acceptance rules) for controlled products.
For nuclear power plants, sensitivity requirements are established by relevant regulatory documents.
6.4. In accordance with the requirements of technical documentation for controlled products, it is allowed to determine sensitivity ( k) as a percentage according to the formula
Where TO- sensitivity, mm;
S- thickness of the metal being scanned, mm.
6.5. Interpretation and assessment of the quality of welded joints from photographs that do not have images of sensitivity standards is allowed:
for panoramic scanning of circumferential welded joints with simultaneous exposure of more than four films. In these cases, regardless of the total number of images, it is allowed to install one sensitivity standard for each quarter of the circumference of the welded joint;
if it is impossible to use sensitivity standards.
In these cases, sensitivity is determined on welded joint simulators when processing control modes.
6.6. When interpreting the images, the dimensions of the images of cracks, lack of fusion, pores and inclusions are determined, and also, if necessary, the amount of concavity and convexity of the weld root is assessed (in cases where the weld root is inaccessible for external inspection).
The list of dimensions to be determined and the methodology for assessing the amount of concavity and convexity of the weld root must be given in the technical documentation for the inspection and acceptance of welded joints.
6.7. When documenting the results of image decoding, the dimensions determined from the images should be rounded to the nearest values from the series 0.2; 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 number in millimeters if the size determined from the image exceeds 3.0 mm.
6.8. If during inspection the film is located at a distance H from the surface of the controlled welded joint facing the film and the relation is satisfied
It is recommended to multiply the dimensions determined from the image by a factor before rounding them
Where f- distance from the radiation source to the surface of the controlled section of the welded joint facing the source, mm;
s- radiation thickness, mm.
6.6 - 6.8. (Changed edition, Amendment No. 1).
6.9. When measuring the size of defects up to 1.5 mm, use a measuring lens with a division value of 0.1 mm, st. 1.5 mm - any measuring device with a division value of 1 mm.
6.10. The results of decoding the images and the sensitivity of the control must be recorded in the conclusion or 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 indicate defects in the conclusion or log of control results, the symbols given in .
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 control are exposure to ionizing radiation and harmful gases formed in the air under the influence of radiation, and electric shock.
7.2. Radiographic monitoring and recharging of radioactive sources must be carried out only using equipment specially designed for these purposes and in good condition, documentation for the manufacture and operation of which, when produced in quantities of more than three copies, must be agreed upon with the USSR State Committee for the Use of Atomic Energy and the Main Sanitary -epidemiological department of the USSR Ministry of Health; up to three copies - with local sanitary and epidemiological service authorities.
APPENDIX 4
1. Distance f from the radiation source to the surface of the controlled welded joint facing the source (when radiating ring welded joints through two walls - to the surface of the ring joint closest to the source) should not be less than the values determined by the formulas given in table. 1.
Table 1
|
Transillumination scheme D- outer diameter of the controlled welded joint, mm; T- the ratio of the internal and external diameters of the controlled welded joint; F- maximum size of the focal spot of the radiation source, mm; TO- required control sensitivity, mm. |
GOST 7512-82
UDC 621.791.053:620.179:006.354 Group B09
STATE STANDARD OF THE USSR UNION
NON-DESTRUCTIVE TESTING
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
Nondestructive testing. Welded joints. Radiography method
Date of introduction 1984-01-01
INFORMATION DATA
1. PERFORMERS
G.I. Nikolaev, B.A. Khripunov, Yu.I. Udralov, E.G. Volkovyskaya
2. APPROVED AND PUT INTO EFFECT Resolution of the USSR State Committee on Standards dated December 20, 1982 No. 4923
3. IN REPLACE GOST 7512-75
4. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS
5. The validity period was lifted by decision of the Interstate Council for Standardization, Metrology and Certification (IUS 5-6-93)
6. Reissue (December 1994) with Change No. 1, approved in March 1988 (IUS 6-88)
This standard establishes a method for radiographic testing of welded joints made of metals and their alloys, made by fusion welding, 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 testing is used to detect cracks, lack of penetration, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic testing is also used to identify burns, undercuts, and assess the magnitude of convexity and concavity of the root of the seam, which are unacceptable for external inspection.
1.3. Radiographic monitoring does not reveal:
any discontinuities and inclusions with a size in the direction of transmission less than twice 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 the table. 1;
any discontinuities and inclusions, if their images in the photographs coincide with the images of foreign parts, sharp corners or sharp changes in cracks of the metal being scanned.
Table 1
mm
|
Radiation thickness (according to GOST 24034-80) |
Opening of lack of penetration (cracks) |
|
Up to 40 |
0,1 |
|
Over 40 to 100 incl. |
0,2 |
|
" 100 " 150 " |
0,3 |
|
" 150 " 200 " |
0,4 |
|
" 200 |
0,5 |
1.1-1.3.
1.4. Radiographic testing is carried out on welded joints with a ratio of the radiation thickness of the deposited weld metal to the total radiation thickness of at least 0.2, which have two-way access, allowing the installation of a cassette with radiographic film and a radiation source in accordance with the requirements of this standard.
2. REQUIREMENTS FOR CONTROL ACCESSORIES
2.1. During radiographic inspection, markings should be used that are made of a material that allows them to be clearly visible on radiographic photographs.
You should use size markings established by GOST 15843-79.
2.2. During radiographic testing, radiographic films should be used that meet the requirements of the technical specifications for them.
The type of radiographic film must be established in the technical documentation for inspection or acceptance of welded joints.
2.3. During radiographic testing, 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 established depending on the thickness of the material being examined by the technical documentation for inspection or acceptance of welded joints.
2.4. Metal and fluorescent screens should be used as intensifying screens during radiographic testing.
The type of reinforcing screen must be established in the technical documentation for inspection or acceptance of welded joints.
The thickness of metal intensifying screens and methods of loading film into cassettes using screens are given in Appendix 1.
2.5. Screens must have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed.
2.6. Film loading cassettes must be lightproof and ensure tight pressing of the intensifying screens to the film.
2.7. To protect the film from scattered radiation, it is recommended to screen the film cassette on the side opposite the radiation source with lead screens.
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 the basis of the controlled welded joint.
2.10. The shape and dimensions of 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 - liner; 2 - cover
Crap. 1
table 2
mm
|
Standard 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 |
Maximum deviations of other sizes are ±0.5 mm.
The insert 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 depths |
no more |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
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 |
||||||||||||||||
(Changed edition, Amendment No. 1).
2.12. The shape and dimensions of plate sensitivity standards are shown in Fig. 3 and in table. 4.
Crap. 3
Table 4
mm
|
Number |
||||||||||||||
|
standard |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
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. Sensitivity standards should be marked with lead digits in accordance with GOST 15843-79 in accordance with Appendix 3. The first digit of the marking should indicate the standard material, the next (one or two digits) - the standard number.
Symbols for the sensitivity standard material: for iron-based alloys - 1, aluminum and magnesium - 2, titanium - 3, copper - 4, nickel - 5.
2.14. To mark groove standards, it is allowed to use cutouts and holes or only the holes specified in Appendix 3. In this case, the thickness of the standard at the marking site must be equal to h.
When marking standards with holes, the length of 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, the use of other types of sensitivity standards is allowed if this is provided for by the export conditions.
3. PREPARATION FOR CONTROL
3.1. Radiographic testing should be carried out after eliminating external defects discovered during an external inspection of the welded joint and cleaning it from irregularities, slag, metal splashes, scale and other contaminants, the images of which in the image may interfere with the decoding of the image.
3.2. After cleaning the welded joint and eliminating external defects, the welded joint must be marked into sections and the sections must be marked (numbered).
3.1, 3.2. (Changed edition, Amendment No. 1).
3.3. The system for marking and marking areas is established by technical documentation for inspection or acceptance of welded joints.
3.4. When monitoring, sensitivity standards and markings must be installed at each site.
3.5. Sensitivity standards should be installed in the controlled area on the side facing the radiation source.
3.6. Wire standards should be installed 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 direction of the standard across the seam so that the images of the standard markings do not overlap the image of the seam in the photograph.
3.9. When inspecting circumferential welds 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 grooves directed along the seam.
3.10. If it is impossible to install standards from the side of the radiation source when monitoring welded joints of cylindrical, spherical and other hollow products through two walls with deciphering only the area of the welded joint adjacent to the film, as well as during panoramic transmission, it is allowed to install sensitivity standards from the side of the cassette with film.
3.11. (Deleted, Amendment No. 1).
3.12. Markings used to limit the length of 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 deposited and base metal when monitoring welded joints without reinforcement or with the weld reinforcement removed.
3.13. Markings used for numbering inspected areas should be installed on the inspected area or directly on the film cassette so that the images of the markings on the photographs do not overlap the image of the seam and the heat-affected zone according to clause 5.7.
3.14. If it is impossible to install sensitivity standards and (or) markings on the controlled area of the welded joint in accordance with the requirements of this standard, the procedure for conducting inspection without installing sensitivity standards and (or) markings must be provided for in the technical documentation for inspection or acceptance of welded joints.
(Changed edition, Amendment No. 1).
4. CONTROL SCHEME
4.1. Welded joints should be controlled according to drawings. 4 and 5.
Inspection schemes for butt, lap, corner and T-joints
Crap. 4
Inspection schemes for circumferential (butt, lap, corner and T) welded joints
1 - radiation source; 2 - controlled area; 3 - film cassette
Crap. 5
4.2. If the width of the welded element is limited, it is permissible to control T-welded joints with the direction of radiation along the generatrix of this element in accordance with Fig. 6.
1 - radiation source; 2 - controlled area; 3 - film cassette
Crap. 6
4.2a. When inspecting circumferential welded joints of cylindrical and spherical hollow products, one should, as a rule, use transmission schemes through one wall of the product (diagrams 5a, b, f, g, h). In this case, it is recommended to use transmission schemes with the location of the radiation source inside the controlled product:
diagram of features 5e (panoramic scanning) - for control of products with a diameter of up to 2 m, regardless of the scope of control, and with a diameter of 2 m or more with 100% control;
diagram of features 5g - with 100% and selective control, if using a trait scheme. 5e is impossible;
diagram of features 5z - for selective inspection of products with a diameter of 2 m or more;
diagrams of traits. 5a, b - for products with an internal diameter of 10 m or more, if the diagram is used. 5e is impossible.
(Introduced additionally, Amendment No. 1).
4.3. When monitoring through two walls, the diagram of features. 5v is recommended for illuminating products with a diameter of up to 100 mm; diagrams of traits. 5g, d - for illuminating products with a diameter of more than 50 mm.
4.4. When inspecting butt welded joints according to drawing diagrams. 5a, b, f, g, h, the direction of radiation must coincide with the plane of the controlled welded joint. When inspecting fillet welds for welding pipes, fittings, etc. using these patterns. 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 drawing diagrams. 5c, d, e, the direction of radiation should be chosen such that the images of opposite sections of the weld in the image do not overlap each other.
In this case, the angle between the direction of radiation and the plane of the weld should be minimal and in any case not exceed 45°.
4.3-4.5 (Changed edition, Amendment No. 1).
4.6. (Deleted, Amendment No. 1).
4.7. In addition to control according to the diagrams shown in Fig. 4-6, depending on the design features of the welded joints and the requirements placed on them, other radiation schemes and directions can be used.
These radiation patterns and directions must be provided for in the technical documentation for inspection 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 the effects of direct radiation (for example, when inspecting end seams for welding pipes into tube sheets, when inspecting surfacing of edges for welding, etc.), control should be carried out using compensator attachments.
It is allowed to use compensators made of any material that provides the required attenuation of radiation.
4.9. When choosing a scheme and direction of radiation, the following should be taken into account:
the distance from the controlled welded joint to the radiographic film should be minimal and in any case not exceed 150 mm;
the angle between the direction of radiation and the normal to the radiographic film within the welded joint area controlled in one exposure should be minimal and in any case not exceed 45°.
4.7-4.9. (Changed edition, Amendment No. 1).
5. SELECTION OF RADIOGRAPHIC CONTROL PARAMETERS
5.1. The distance from the radiation source to the surface of the controlled area 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 closest to the source) and the dimensions or number of areas controlled per one exposure for all transmission schemes ( with the exception of diagram 5e) should be chosen such that the following requirements are met when transilluminating:
the geometric blur of the images of defects in the photographs when the film is positioned close to the controlled welded joint should not exceed half of the required monitoring sensitivity for sensitivity up to 2 mm and 1 mm for sensitivity more than 2 mm;
the relative increase in the size of images of defects located on the side of the radiation source (relative to defects located on the film side) should not exceed 1.25;
the angle between the direction of radiation and the normal to the film within the welded joint area controlled during one exposure should not exceed 45°;
the decrease in the optical density of the image of a welded joint in any part of this image in relation to the optical density at the location of the wire sensitivity standard or in relation to the optical density of the image of a 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 minimum number of areas controlled during one exposure when testing using feature diagrams. 4-6 are given in Appendix 4.
5.1, 5.2 (Changed edition, Amendment No. 1).
5.3. When inspecting welded joints according to Fig. 5h (panoramic transmission), the ratio of the internal diameter d to the external diameter D of the controlled connection should not be less than 0.8, and the maximum focal spot size F of the radiation source should not be more than, where K is the sensitivity of the control.
5.4. In cases where the size of defects is not determined (for example, defects are not allowed regardless of their size), the ratio between the internal and external diameters of the controlled connection given in clause 5.3 may not be observed.
5.5. In the absence of a radiation source that satisfies the requirement of clause 5.3, it is allowed during control according to the line. 5h use radiation sources with a maximum focal spot size that satisfies the relation
In this case, the sensitivity standard must be installed on the welded joint or welded joint simulator used in determining the sensitivity, only on 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 with a length of the controlled section of up to 100 mm, at least 0.2 of the length of the section, with a length of the controlled section of more than 100 mm. 100 mm - at least 20 mm.
5.7. The width of the images should ensure that images of the weld, sensitivity standards, markings and heat-affected zones are obtained with the following width:
for butt and lap joints:
not less than 5 mm - with a thickness of welded edges up to 5 mm,
not less than the thickness of the welded edges - with a thickness of the welded edges of St. 5 to 20 mm,
not less than 20 mm - with a thickness of welded edges of St. 20 mm;
for T-joints and corner connections - is established by the technical documentation for the control or acceptance of these connections.
6. DECODING IMAGES
6.1. Viewing and decoding of images should be done after they have completely dried in a darkened room using special illuminators-negatoscopes.
You should use negatoscopes with adjustable brightness and size of the illuminated field. The maximum brightness of the illuminated field must be at least 10 D+2 cd/m 2, where D is the optical density of the image. The size of the illuminated field should be adjusted using movable curtains or mask screens within such limits that the illuminated field is completely covered by the image.
(Changed edition, Amendment No. 1).
6.2. Images accepted for decryption must meet the following requirements:
The photographs should not contain spots, stripes, dirt or damage to the emulsion layer that would make them difficult to decipher;
Images of restrictive marks, markings and sensitivity standards must be visible on the photographs;
the optical density of the images of the inspected section of the seam, the heat-affected zone and the sensitivity standard 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 compared to 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 a wire standard revealed in the image, the smallest depth of the groove of a groove standard revealed in the image, 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 image) should not exceed the values given in Table. 6.
Table 6
mm
|
Radiation thickness (at the location of the sensitivity standard) |
Sensitivity class |
||
|
Up to 5 |
0,10 |
0,10 |
0,20 |
|
St. 5 to 9 inclusive. |
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 sensitivity standards, the values are 0.30; 0.60; 0.75 and 1.50 mm are replaced by the values 0.32; 0.63; 0.80 and 1.60 mm.
(Changed edition, Amendment No. 1).
Specific sensitivity values must be established by technical documentation (drawing requirements, technical conditions, control and acceptance rules) for controlled products.
For nuclear power plants, sensitivity requirements are established by relevant regulatory documents.
6.4. In accordance with the requirements of technical documentation for controlled products, it is allowed to determine sensitivity ( k ) as a percentage according to the formula
where K is sensitivity, mm;
S - thickness of the metal being scanned, mm.
6.5. Interpretation and assessment of the quality of welded joints from photographs that do not have images of sensitivity standards is allowed:
for panoramic scanning of circumferential welded joints with simultaneous exposure of more than four films. In these cases, regardless of the total number of images, it is allowed to install one sensitivity standard for each quarter of the circumference of the welded joint;
if it is impossible to use sensitivity standards.
In these cases, sensitivity is determined on welded joint simulators when processing control modes.
6.6. When interpreting the images, the dimensions of the images of cracks, lack of fusion, pores and inclusions are determined, and also, if necessary, the amount of concavity and convexity of the weld root is assessed (in cases where the weld root is inaccessible for external inspection).
The list of dimensions to be determined and the methodology for assessing the amount of concavity and convexity of the weld root must be given in the technical documentation for the inspection and acceptance of welded joints.
6.7. When documenting the results of image decoding, the dimensions determined from the images should be rounded to the nearest values from the series 0.2; 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 number in millimeters if the size determined from the image exceeds 3.0 mm.
6.8. If, during inspection, the film is located at a distance H from the surface of the inspected welded joint facing the film and the relation is satisfied
It is recommended to multiply the dimensions determined from the image by a factor before rounding them
Where f - distance from the radiation source to the surface of the controlled section of the welded joint facing the source, mm;
s - radiation thickness, mm.
6.6-6.8. (Changed edition, Rev. 1).
6.9. When measuring the size of defects up to 1.5 mm, use a measuring lens with a division value of 0.1 mm, st. 1.5 mm - any measuring device with a division value of 1 mm.
6.10. The results of decoding the images and the sensitivity of the control must be recorded in the conclusion or 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 indicate defects in the conclusion or log of control results, 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 control are exposure to 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 USSR UNION
NON-DESTRUCTIVE TESTING
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
Nondestructive testing. Welded joints. Radiography method
Date of introduction 1984-01-01
INFORMATION DATA
1. PERFORMERS
G.I. Nikolaev, B.A. Khripunov, Yu.I. Udralov, E.G. Volkovyskaya
2. APPROVED AND PUT INTO EFFECT Resolution of the USSR State Committee on Standards dated December 20, 1982 No. 4923
3. IN REPLACE GOST 7512-75
4. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS
5. The validity period was lifted by decision of the Interstate Council for Standardization, Metrology and Certification (IUS 5-6-93)
6. Reissue (December 1994) with Change No. 1, approved in March 1988 (IUS 6-88)
This standard establishes a method for radiographic testing of welded joints made of metals and their alloys, made by fusion welding, 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 testing is used to detect cracks, lack of penetration, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic testing is also used to identify burns, undercuts, and assess the magnitude of convexity and concavity of the root of the seam, which are unacceptable for external inspection.
1.3. Radiographic monitoring does not reveal:
any discontinuities and inclusions with a size in the direction of transmission less than twice 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 the table. 1;
any discontinuities and inclusions, if their images in the photographs coincide with the images of foreign parts, sharp corners or sharp changes in cracks of the metal being scanned.
Table 1
mm
|
Radiation thickness (according to GOST 24034-80) |
Opening of lack of penetration (cracks) |
|
Up to 40 |
0,1 |
|
Over 40 to 100 incl. |
0,2 |
|
" 100 " 150 " |
0,3 |
|
" 150 " 200 " |
0,4 |
|
" 200 |
0,5 |
1.1-1.3. (Changed edition, Amendment No. 1).
1.4. Radiographic testing is carried out on welded joints with a ratio of the radiation thickness of the deposited weld metal to the total radiation thickness of at least 0.2, which have two-way access, allowing the installation of a cassette with radiographic film and a radiation source in accordance with the requirements of this standard.
(Introduced additionally, Amendment No. 1).
2. REQUIREMENTS FOR CONTROL ACCESSORIES
2.1. During radiographic inspection, markings should be used that are made of a material that allows them to be clearly visible on radiographic photographs.
You should use size markings established by GOST 15843-79.
2.2. During radiographic testing, radiographic films should be used that meet the requirements of the technical specifications for them.
The type of radiographic film must be established in the technical documentation for inspection or acceptance of welded joints.
2.3. During radiographic testing, 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 established depending on the thickness of the material being examined by the technical documentation for inspection or acceptance of welded joints.
2.4. Metal and fluorescent screens should be used as intensifying screens during radiographic testing.
The type of reinforcing screen must be established in the technical documentation for inspection or acceptance of welded joints.
The thickness of metal intensifying screens and methods of loading film into cassettes using screens are given in Appendix 1.
2.5. Screens must have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed.
2.6. Film loading cassettes must be lightproof and ensure tight pressing of the intensifying screens to the film.
2.7. To protect the film from scattered radiation, it is recommended to screen the film cassette on the side opposite the radiation source with lead screens.
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 the basis of the controlled welded joint.
2.10. The shape and dimensions of 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 - liner; 2 - cover
Crap. 1
table 2
mm
|
Standard 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 |
Maximum deviations of other sizes are ±0.5 mm.
The insert 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 depths |
no more |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
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 |
||||||||||||||||
(Changed edition, Amendment No. 1).
2.12. The shape and dimensions of plate sensitivity standards are shown in Fig. 3 and in table. 4.
Crap. 3
Table 4
mm
|
Number |
||||||||||||||
|
standard |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
Prev. off |
Nom. |
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. Sensitivity standards should be marked with lead digits in accordance with GOST 15843-79 in accordance with Appendix 3. The first digit of the marking should indicate the standard material, the next (one or two digits) - the standard number.
Symbols for the sensitivity standard material: for iron-based alloys - 1, aluminum and magnesium - 2, titanium - 3, copper - 4, nickel - 5.
2.14. To mark groove standards, it is allowed to use cutouts and holes or only the holes specified in Appendix 3. In this case, the thickness of the standard at the marking site must be equal to h.
When marking standards with holes, the length of 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, the use of other types of sensitivity standards is allowed if this is provided for by the export conditions.
The standard establishes a method for radiographic testing of welded joints made of metals and their alloys, made by fusion welding, with a thickness of welded elements from 1 to 400 mm, using X-ray, gamma and bremsstrahlung radiation and radiographic film.
NON-DESTRUCTIVE
WELDED CONNECTIONS
RADIOGRAPHIC METHOD
GOST 7512-82
PUBLISHING HOUSE OF STANDARDS
Moscow
STATE STANDARD OF THE USSR UNION
Date of introduction 01.01.84
This standard establishes a method for radiographic testing of welded joints made of metals and their alloys, made by fusion welding, 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 testing is used to detect cracks, lack of fusion, pores, slag, tungsten, oxide and other inclusions in welded joints.
1.2. Radiographic testing is also used to identify burns, undercuts, and assess the magnitude of convexity and concavity of the root of the seam, which are unacceptable for external inspection.
any discontinuities and inclusions with a size in the direction of transmission of less than twice 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 foreign parts, sharp corners or sharp changes in cracks of the metal being scanned.
1.1 - 1.3.
Table 1
mm
|
You should use size markings established by GOST 15843-79. 2.2. During radiographic testing, radiographic films should be used that meet the requirements of the technical specifications for them. The type of radiographic film must be established in the technical documentation for inspection or acceptance of welded joints. 2.5. Screens must have a clean, smooth surface. The presence of folds, scratches, cracks, tears and other defects on the screens is not allowed. 2.6. Cassettes for loading film must be lightproof and ensure tight pressing of the intensifying screens to the film. 2.7. To protect the scattered radiation film, it is recommended to screen the film cassette on the side opposite the radiation source with lead screens. The thickness of the protective screens is given in .
1 - liner; 2 - cover. Crap. 1. 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 base of which is similar in chemical composition to the base of the welded joint being controlled. 2.10. The shape and dimensions of the wire sensitivity standards are shown 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 mm
(Changed edition, Amendment No. 1). Table 4
Symbols of the sensitivity standard material: for alloys based on iron - 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 the holes specified in. In this case, the thickness of the standard at the marking site should be equal to h. When marking with standard holes, the length of 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, the use of other types of sensitivity standards is allowed if this is provided for by the export conditions. 3. PREPARATION FOR CONTROL3.1. Radiographic testing should be carried out after eliminating external defects discovered during an external inspection of the welded joint and cleaning it from irregularities, slag, spattered metal, scale and other contaminants, the images of which on the image may interfere with the decoding of the image. 3.2. After cleaning the welded joint and eliminating external defects, the welded joint must be marked into sections and the sections must be marked (numbered). 3.1, 3.2. (Changed edition, Amendment No. 1). 3.3. The system for marking and marking areas is established by technical documentation for inspection or acceptance of welded joints. 3.4. When monitoring, sensitivity standards and markings must be installed on each section. 3.5. Sensitivity standards should be installed in the controlled area on the side facing the radiation source. 3.6. Wire standards should be installed 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 direction of the standard across the seam so that the images of the standard markings do not overlap the image of the seam in the photograph. 3.9. When inspecting circumferential welds 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 grooves directed along the seam. 3.10. If it is impossible to install standards from the side of the radiation source when monitoring welded joints of cylindrical, spherical and other hollow products through two walls with deciphering only the area of the welded joint adjacent to the film, as well as during panoramic scanning, it is allowed to install sensitivity standards from the side of the cassette with film. 3.11.(Deleted, Amendment No. 1). 3.12. Markings used to limit the length of sections of welded joints controlled during one exposure should be installed at the boundaries of the marked sections, as well as at the boundaries of the deposited and base metal when monitoring welded joints without reinforcement or with the weld reinforcement removed. 3.13. Markings used for numbering inspected areas should be installed on the inspected area or directly on the film cassette so that the images of the markings on the photographs do not overlap with the image of the seam in the heat-affected zone. 3.14. If it is impossible to install sensitivity standards and (or) markings in the controlled area of the welded joint in accordance with the requirements of this standard, the procedure for conducting inspection without installing sensitivity standards and (or) markings must be provided for in the technical documentation for inspection or acceptance of welded joints. 4. CONTROL SCHEME4.1. Welded joints should be controlled by and. 4.2. If the width of the welded element is limited, it is allowed to control T-welded joints with the direction of radiation along the generatrix of this element in accordance with. 4.2a. When inspecting circumferential welded joints of cylindrical and spherical hollow products, one should, as a rule, use transmission schemes through one wall of the product (diagrams, Fig. 5 A, b, e, and, h). In this case, it is recommended to use transillumination schemes with the location of the radiation source inside the controlled product: 5.1, 5.2 (Changed edition, Amendment No. 1). for butt and overlap joints: not less than 5 mm - with thickness of welded edges up to 5 mm; not less than the thickness of the welded edges - with a thickness of the welded edges of St. 5 to 20 mm; not less than 20 mm - with a thickness of welded edges of St. 20 mm; for T-joints and corner connections - is established by the technical documentation for the control or acceptance of these connections. 6. DECODING IMAGES6.1. Viewing and decoding of photographs should be done after they have completely dried in a darkened room using special illuminators-negatoscopes. You should use X-ray cameras with adjustable brightness and size of the illuminated field. The maximum brightness of the illuminated field must be at least 10 D + 2 cd/m 2, where D- optical density of the image. The size of the illuminated field must be adjusted using movable curtains or mask screens within such limits that the illuminated field is completely covered by the image. (Changed edition, Amendment No. 1). 6.2. Photos accepted for colorization must meet the following requirements: The photographs should not contain spots, stripes, dirt or damage to the emulsion layer that would make them difficult to decipher; The photographs must show images of limit marks, markings and sensitivity standards; the optical density of the images of the controlled weld area, the heat-affected zone and the sensitivity standard must be at least 1.5; the decrease in the optical density of the image of the welded joint in any area of this image compared to 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 a wire standard identified in the image, the smallest depth of the groove of a groove standard identified in the image, 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 image) should not exceed the values given in. Table 6 mm
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