This standard specifies the general requirements for radiography of carbon steel and low alloy steel welds for ships, the radiographic process and the grading of weld quality. This standard applies to X-ray and gamma-ray photography of fusion welded butt joints of steel with a base material thickness of 3 to 200 mm, and also applies to radiography of other components and finished products provided for shipbuilding. CB/T 3558-1994 Radiographic process and quality grading of ship steel welds CB/T3558-1994 Standard download decompression password: www.bzxz.net

Shipbuilding Industry Standard of the People's Republic of China
CB/T 3558—94
Radiographic Process and Quality Grading of Ship Steel Welds Issued on February 1, 1994
China State Shipbuilding Corporation
Implementation on August 1, 1994
Shipbuilding Industry Standard of the People's Republic of China
Radiographic Process and Quality Grading of Ship Steel Welds 1 Main content and scope of application
CB/T 3558—94
Classification number U06
Code name CB: 3127—82
CB- 3176---83
This standard specifies the general requirements for radiography of carbon steel and low alloy steel welds, the radiographic process and the grading of weld quality for ships. This standard applies to X-ray and radiographic photography of steel fusion welded butt joints (hereinafter referred to as welds) with a base metal thickness of 3 to 200 mm, and also applies to radiographic photography of other components and finished products provided for shipbuilding. 2 Reference standards
GB4792 Basic standard for radiation health protection
GB5618 Linear image quality meter
GB11226 Industrial radiographic film viewing lamp GJB593.2 X-ray photography inspection
CB/T 3177 Rules for radiographic and ultrasonic inspection of ship steel welds ZBY201 General technical conditions for industrial X-ray flaw detectors 3 General requirements
3.1 Personnel
3.1.1 Personnel engaged in radiographic inspection must hold a technical grade qualification certificate recognized by the ship inspection department and a radiation safety operation qualification certificate issued by the national health protection department. 3.1.2 Personnel who evaluate, review and issue the result report of the film shall have a Class I or Class II radiographic flaw detection qualification certificate, and the calibration force shall not be less than 1.0.
3.2 Inspection site
3.2.1 The radiographic inspection site shall meet the relevant protection requirements of GB4792 standard, and set signs and obvious safety cordons. 3.2.2 Any possible scattering sources in and around the inspection site shall be removed as much as possible. 3.3 Darkroom
The darkroom should be divided into two parts: "dry area" and "wet area". The dry area is used for film storage, unpacking and disassembly, and the wet area is used for film processing. The temperature and humidity of the dry area and the temperature of the wet area should be controlled within the range recommended by the film manufacturer, and good ventilation facilities should be set up. 3.4 Film Drying Room
When manually processing films, a special film drying room, dryer or drying box should be set up, and the room should be kept clean. 3.5 Film Review Room
The light in the film review room should be soft, and the light intensity where the film reviewer is located should be 25 1x. 3-6 Equipment and Instruments
3.6.1, Radiation Source
X-ray machine should meet the requirements of ZBY201; r-ray equipment should meet the factory requirements. 3.6.2 Density Meter (Optical Densitometer)
The accuracy of the density meter should be higher than ±0. 05, the maximum measurable blackness is 4. 00, and it is regularly sent to the relevant metrology departments for verification. Approved by China State Shipbuilding Corporation on February 1, 1994 and implemented on August 1, 1994
CB/T3558-94
3.6.3 Viewing lights
The performance of the film viewing lights shall comply with the requirements of GB11226 standard, and the brightness through the inspected film shall not be less than 30cd/m. For films with different blackness (D), the minimum brightness of the viewing lights shall meet the requirements of Table 1. Table 1 Brightness requirements of viewing lights
Maximum blackness D of film
Minimum brightness of viewing lights, cd/m
10 000
30 000
100 00-0
300 000
3.6.4 Safety red light
The safety red light used in the darkroom should use the safety voltage and the safety filter recommended by the film factory. The safety of the red light can be checked according to GJB593.2.
3.6.5 Auxiliary radiation dose monitoring instruments
Radiation dose meters, plug-in radiation dose alarms and personal dose meters worn by inspectors should be sent for inspection on time according to the cycle specified in the national metrology regulations.
3.7 Inspection materials
3. 7. 1 Film
3.7.1.1 Film for radiography should be selected according to the requirements of radiation energy and image quality. Newly purchased film should be inspected according to GJB593.2.
3.7.1.2 The gray fog of the film shall not be higher than 0.30. 3.7-2 Intensifying screen
3.7.2.1 Generally, metal intensifying screen is used. In special cases, ordinary metal Dongguang intensifying screen can also be used with the consent of both parties to the contract. 3.7.2 .2 The intensifying screen should be selected according to different radiation sources and similar radiation energies. The selection of metal intensifying screens is shown in Table 2. 3.7.2.3 The intensifying screen and the film should always be close to each other during the transmission process. 3.7.2.4 It is strictly forbidden to use damaged, warped, scratched, or wrinkled metal intensifying screens, and avoid the accumulation of dust, dirt, oxides, or any foreign matter.
Radiation source
120~250kV
250~400 kv
I~aMev
3~8 Mev
8-35 Mev
Table 2 Selection of metal intensifying screen
Wall cancer screen material
Steel, lead
Molybdenum, tungsten, lead
Copper, copper, lead
Note, ① The detection sensitivity obtained by the screen or tungsten screen is higher than that of the lead screen. 2
Front screen thickness
0. 025 ~0. 125
0. 05 0.16
1.00~1.60
0.05~0.16
0. 50 ~~2. 00
Rear screen thickness
1.00~1.60
0.25~1.00
CE/T 3558 94
Using copper or steel screen can obtain the best sensitivity, but the required light resistance time is longer than that of using lead screen. 3. 7. 3 Dark box
A dark box made of low-absorption material that does not emit light under the action of radiation should be used, and it must be light-proofed before use. 3.7.4 Linear Image Quality Meter
3.7.4.1 The diameter of the steel wire of the linear image quality meter shall be R10 series, and its model and specification shall comply with the provisions of GB5618. 37.4.2 For steel pipes with an outer diameter less than 10.89mm, the special image quality meter specified in Appendix A (Supplement) shall be used for weld penetration. 3.7.5 Special Comparison Block
For pipes that allow pits and one-sided incomplete penetration, the special comparison block or groove comparison block specified in Appendix A (Supplement) shall be used to determine the relative depth of incomplete penetration. The length of the special comparison block is about half the outer length of the pipe. 3.7.6 Lead Mark
The thickness of the lead mark is generally 2mm. When using higher radiation energy for penetration (such as X-ray greater than 1 MeV), a lead mark with a thickness of 3 mm or more is required.
4 Inspection procedures and requirements
4.1 Inspection time
4.1.1 Radiographic inspection of welds shall be carried out at an appropriate time after welding. The time after welding shall be in accordance with the relevant technical documents or agreed upon by the supplier and the buyer.
4.1.2 Unless otherwise specified in the regulations or contracts, weld radiography should generally be carried out after heat treatment and correction of the weldment. 4.2 Surface condition
The surface quality of the weld and the heat-affected zone (including the height of the excess height) shall be inspected and qualified before radiography can be carried out. The image of the irregular state of the weld surface on the negative film shall not cover up the defects in the weld or be confused with it, otherwise appropriate repairs shall be made. 4.3 Selection of radiation source and energy
4.3.1 When radiography of welds with a tube voltage of less than 400 kV is used, the maximum tube voltage allowed shall be based on the radiography thickness T^L (see Appendix H (Supplement) for the determination of the radiography thickness of fusion welded butt joints), see Figure 1. 3
Dirt thickness 7., mm
2304000
Figure 1 Transmission degree and maximum permissible voltage 4.3.2 X-rays and X-rays above 1MeV transmissible base material thickness and range are shown in Table 3.3
X-ray source
X-rays are 1~2MeV
X-rays are above 2MeV
CB/T3558—94
Table 3 Y-rays and 1 MeV and above X-ray penetration thickness range Mother material thickness
Ordinary grade
40-175
50~175
Note: If the internal penetration method (center method or heart method) is used, the mother material thickness can be 1/2 of the limit value in Table 3. Special grade
50~150
60~150
4.4 Penetration method
4.4.1 According to the relative position relationship between the radiation source, the workpiece and the film, the radiation method includes longitudinal seam radiation method, annular seam external radiation method, annular seam internal radiation method, double-wall single shadow method (frequency oblique radiation method, vertical radiation method) and double-wall double shadow method. See Figure 2. Timeline device
《R）Longitudinal seam radiation method
rh）Chain external radiation method
Figure 2 Schematic diagram of the radiation method
Radiation source is not in the center of the component
Frequency oblique radiation
CB/T 3558-94
Radiation source is in the center of the component
(c) Ring key internal radiation method
Sealed line source
No direct radiation
(d) Double-wall single shadow method
(e) Double-wall double shadow method
Continued Figure 2
CB/T 3558-94
4.4.2 When the double-wall double-projection method is used for the butt weld of the pipe with an outer diameter less than or equal to 89mm, the direction of the ray beam should be such that the color images of the upper and lower welds are displayed in an elliptical shape on the film, and the spacing is preferably 3~~10mm, and the maximum spacing shall not exceed 15mm. Only when it is difficult to display the upper and lower welds in an elliptical shape can vertical transillumination be performed (see Figure 2(d)). 4.5 Geometric conditions
4.5.1 Distance from the radiation source to the film
4.5.1.1 The minimum distance from the radiation source to the film shall be calculated according to formula (1): Fmin
Where: mi - minimum distance from the radiation source to the film, mm; l - distance from the workpiece surface to the film on the radiation source side, mm;
- maximum permissible geometric unsharpness. mm
4.5.1.2 For different values, the maximum permissible geometric unsharpness V within the range of values ​​is shown in Table 4. Table 4 Different values ​​within the range of values ​​
(value range
Ordinary level
>50~-100
100~150
+++++++++++++++-.+++( 1 4.5.1.3 The effective focal length Fd of the radiation source shall be calculated according to Appendix C (Supplement); for the effective focal length of the radiation source less than 3mm, the F- calculated according to formula (1> shall be multiplied by the correction factor R2.6 from Figure 3. Length, mm 4.5.1.4 When the double-entry double-projection method is used to illuminate the butt weld of pipes with an outer diameter less than or equal to 89mm, the distance from the radiation source to the film shall not be less than 600 mm. Secondary inspection range 4.5.2.1 The primary inspection range refers to the length of the weld inspected by each illumination when segmented illumination is used. The film quality shall comply with the provisions of Article 4.11. 4.5.2.2 The illumination thickness ratio K value of the weld shall be calculated according to formula (2). The ordinary grade K value of the circumferential weld (excluding small-diameter steel pipe welds) is generally CB/ 355894
Not big 1.1. Special grade K value is generally not big" 1.06: The ordinary grade K value of the longitudinal seam is generally not more than 1.03, and the special grade K value is generally not more than 1.01.
Where: K-thickness ratio;
T-parent material thickness (see Figure 4), mm;
T-maximum thickness of the oblique beam penetration (see Figure 4), mm. Time source
Figure 4 shows the thickness ratio of the weld penetration Note: 4.5.2.3 If the whole pipe circumferential seam is required to be radiographed, for steel pipes with an outer diameter less than 76mm and less than 89mm, the welds shall be radiographed by double-wall double-shadow method at least twice, each time at an interval of 90°; for steel pipes with an outer diameter less than 76mm and less than 89mm, the welds shall be radiographed by double-wall double-shadow method, and the inspection range shall not be less than 90% of the circumference at one time, and the measurement method shall comply with the provisions of Appendix D (Supplement). The quality of the negative film shall meet the requirements of 4.11. 4.5.3 Direction of projection of the ray beam The ray beam should be directed to the center of the part to be irradiated and perpendicular to the tangent plane of the surface or curved surface of the irradiated area at that point. It can also be irradiated from other directions that are favorable for finding defects. 4.6 Shielding of useless rays and scattered rays 4.6.1 In order to reduce the shadow of scattered rays, shielding materials such as lead plates should be used to block the non-irradiated area or lead light barriers and cone covers should be used to block the radiation. The line is limited to the range of the transillumination area.
4.6.2 To prevent the harmful effects of backscatter, the back of the dark box should be supplemented with a lead plate of appropriate thickness. To check backscatter, a lead letter \B\ with a height of 13mm and a thickness of 1.6mm is attached to the back of the dark box. If a relatively clear \B\ image appears on the darker background of the film, the thickness of the lead plate on the back of the dark box should be increased.
4.7 Positioning marks and identification marks
4.7. 1 Positioning marks
The positioning lead characters indicating the transillumination position of the weld should include the center mark () and the overlap mark (+). The center mark may not be placed on the T-joint and T-joint.
4.7.2 Identification marks
When the weld is transilluminated, a lead identification mark should be placed, which should include the workpiece number, weld number and position number, etc. When penetrating a weld that has been repaired, identification marks such as R1 and R2 shall also be placed to indicate the number of times the weld has been repaired. 4.7.3 Placement of positioning and identification marks 4.7.3.1 When penetrating a weld, positioning and identification marks shall be placed on both sides of the weld and at least 5 mm from the edge of the weld. For the effective position of the overlap mark, see Appendix E (Supplement).
CB/T 3558—94
4.7.3.3 Permanent marks shall be made on the surface of the workpiece to serve as a basis for repositioning each film. If the workpiece is not suitable for printing marks, a detailed penetrating area map or other effective methods shall be used for marking. 4.8 Placement and quantity of linear image quality indicators (image quality indicators) 4. B.1 Placement of image quality indicators
4.8.1.1 The image quality indicator shall be placed on the surface of the workpiece on the side of the radiation source at one end of the weld area to be inspected (1/4 of the effective section). The steel wire should be placed across the weld and perpendicular to the length of the weld, with the thin wire placed on the outside. When the radiation source cannot be placed on one side, it can also be placed on the workpiece surface on the film side, but the actual image quality index value should meet the specified requirements through comparative tests. When the image quality is placed on the workpiece surface on the film side, the image quality meter should be marked with \F\ lead type to distinguish it. 4.8.1.2 When the weld of a steel pipe with an outer diameter of less than or equal to 89mm is transilluminated, a Type I special image quality meter is generally placed between the film and the pipe surface in the effective section.
4.8.1.3 When the steel pipe with an outer diameter of less than or equal to 76mm is transilluminated once by the double-wall double-image method, a Type II special image quality meter is generally placed at the center of the residual height on the annular seam and surrounds the entire circumference. 4.B.2 Number of image quality meters
4.8.2.1 Each image quality meter can only represent one effective inspection range, so there is at least one image quality meter for each film. When the film blackness change of the inspected area exceeds 30% and 15% of the film blackness value near the image quality meter, two image quality meters should be used, of which only one is placed on the opposite side. 4.8.2.2 When the radiation source is placed at the center of the annular weld for circumferential exposure, an image quality meter can be placed every 90°. 4.8.2.3 If the radiation source is placed at the center of a spherical container and a panoramic exposure is performed on welds with the same geometric conditions, the number of image quality meters can be appropriately reduced according to the principle of Article 4.8.2.2. 4.9 Placement of contrast blocks
When using the incomplete penetration depth contrast blocks specified in Appendix A (Supplement), they should be placed parallel to each other and 5mm away from the edge of the weld. 4.10 Film processing
Film processing should be carried out in accordance with the method recommended by the film manufacturer. 4.11 Film image quality
According to the required film image quality, the radiographic method is divided into ordinary and special grades. When the special grade is selected, the weld chain excess height should be ground flat. 4.11.1 Image Quality Index
The image quality index is a numerical value that measures the quality of radiographic transillumination technology and film processing.It is equal to the wire diameter number of the thinnest steel wire that can be identified on the film. Table 5 lists the image quality index and the corresponding wire diameter of different exposure thickness ranges. Table 5 Exposure thickness range and image quality requirements
Required
Rubber index
Ordinary grade
>12~16
>16~-20
>20~25
25--32
>32~50
>50~80
>80~120||tt| |>120~150
150~200
Transillumination thickness TA
>-10--16
>16--25
>25~-32
>32~40
>50~80
>80~150
>150-200
CB/T 3558—94
Note: On the weld image, if the image of the image quality meter wire with a length of not less than 1Umm can be clearly seen, it is considered to be recognizable. When a special image quality meter is used, at least one wire image should be observed on the weld image. 4. 11.2 Film blackness
The blackness range of the weld imaging area within the film effective detection range should be controlled according to the provisions of Table 6. Table 6 Film blackness range
Ray type
X-ray
Note: The D value in the table includes the D. value.
4.11.3 Unacceptable false images
Ordinary grade
Film blackness D
1.8--4. 00
1. 20~~4. 00
1.50--4. 00
Gray fog
.0. 30
In the effective evaluation area of ​​the film, there should be no false defects caused by improper film processing or other false defects that hinder the evaluation. 5 Grading of weld quality
According to the nature, size, quantity and distribution of defects in the weld (including the heat-affected zone), it is divided into grades 1~. Grade 1 cannot be used as an acceptable level.
5. 1 Weld acceptance level
Weld acceptance level and applicable objects shall be in accordance with (CB/T3177. 5.2 Assessment of weld defects
5.2.1 Welds of all levels are not allowed to have cracks, lack of fusion, and lack of penetration. 5.2.2 For the assessment of circular defects in welds of all levels, see Article 5.3. 5.2.3 For the assessment of long defects in welds of all levels, see Article 5.4. 5.2.4 For the assessment of single-sided welded pipe welds without pads of all levels, see Articles 5-8. 5.3 Assessment and classification of circular defects
5.3.1 Small aspect ratio, low quality Defects that are not included in the sample are defined as shape defects, including pores, spot inclusions and slag inclusions. 5.3.2 Circular defect size: 5:1
[-length, mm: W-width, mm
Figure 7-100] 5.3.3 Conversion of defects
CB/T3558-94
Convert the defect's long diameter into points. Table 7
Defect long diameter, mm
Conversion of defects
5.3.4 Points are not counted The defect sizes are classified by material thickness as shown in Table 8. Table 8 Defect sizes not counted
Material thickness T
Long diameter size
>25~50
Note: If the thickness of the parent materials on both sides of the weld is different, the friction of the thinner parent material shall prevail (the same as the following table). 5.3.5 Determination of assessment area
5.3-5.1 Determination of assessment area as shown in Table 9. Table 9 Determination of assessment area
Parent material thickness
Assessment area size minimum
10×10||tt ||>25~100
10×20
5.3.5.2 The assessment area must be selected from the most serious part of the defect on the negative film and the long side must be parallel to the direction of the weld. 5.3.5.3 When the defect is in contact with the boundary of the assessment area (excluding tangency), it should be included in the assessment area for counting. 5.3.6 Grading method
5.3.6.1 Add the number of points to be counted in the specified area according to 5.3.3~5.3.5. The sum of the points of each grade of weld in the assessment area is limited to Table 10.5. 3.6.2
3 For the limit values ​​of the number of defects not counted in the assessment area, see Table 11.5.3.6.3
Table 10 Limit values ​​of circular defects
Assessment area, mmXmm
10×10
Acceptance level
Acceptance level
>10~-15
10×20
Parent material thickness T, mm
>15--25
>25~~5)
Number of circular defects
For defects with more than [level
Table 11 Limit values ​​of defects not counted
10×30
>50~100
CB/T 3558—94
5.3.6.4 The long diameter of circular defects is graded at T. 5.3.6.5 When the number of points in the assessment area slightly exceeds the value, after negotiation between the supply and demand parties, it shall be handled in accordance with Appendix F (Supplement). 5.4 Assessment and classification of long defects.
5.4.1 The inclusions or long pores with a length-to-width ratio greater than 3 are defined as long defects. The measurement method is shown in Figure 5. 5.4.2 The size limits of single long defects of various levels of welds are shown in Table 12. Table 12 Limit values ​​of long defects
Original thickness of parent material T
Acceptance level
>12~48
Size of single long defect
Defects greater than level
5.4.3 The distance between adjacent long defects (the shortest straight-line distance) is less than or equal to the longer dimension. The lengths of all defects should be added together to make a single long defect assessment
5.4.4 The total length limit of long defects in welds of all levels within any 12T weld length is shown in Table 13. Table 13 Acceptance level of the limit of long defects within any 12T weld length
Total length of long defects TL
Not more than
Not more than
More than 2T
Not more than 3T
More than N level
5. 4.5 When the length of the weld to be inspected is less than 12T, the total length of long defects shall be converted in proportion. If the converted allowable total length is less than the limit of a single long defect, the limit of a single long defect shall be used as the allowable total length. 5.5 Comprehensive assessment
In the circular defect assessment area, if there are both circular and long defects, the self-assessment level shall be determined first, and then the sum of the two defect levels minus 1 shall be used as the final level.
5.6 Enlarged inspection
For welds inspected by proportional inspection, if one or both ends of the film show that the hazardous defects (cracks, lack of fusion, lack of penetration) are extended, an enlarged inspection should be carried out at the extended end. The penetration length shall be in accordance with Article 9 of CB/T3177. 5.7 Treatment of welds below the acceptance level
When the quality of the weld is lower than the requirements of the corresponding acceptance level, it shall be treated in accordance with Article 9 of CB/T 3177. 5.8 Acceptance level of single-sided welding of circumferential butt welds for marine pressure channels without pads 5.8.1 This acceptance level instrument is applicable to the assessment of the root concave and lack of welds of pipe butt welds with a weld coefficient of less than or equal to 0.75 and an outer diameter of less than or equal to 89 mm.
5.8.2 The limit values ​​of the root lack of penetration of welds of various levels are shown in Table 14.30
There should be no false defects caused by improper film processing or other false defects that hinder the evaluation in the effective evaluation area of ​​the film. 5 Grading of weld quality
According to the nature, size, quantity and distribution of defects in the weld (including the heat affected zone), it is divided into grades 1~. Grade 1 cannot be used as an acceptable quality level.
5. 1 Weld acceptance level
Weld acceptance level and applicable objects shall be in accordance with (CB/T3177. 5.2 Assessment of weld defects
5.2.1 Welds of all levels are not allowed to have cracks, lack of fusion, and lack of penetration. 5.2.2 For the assessment of circular defects in welds of all levels, see Article 5.3. 5.2.3 For the assessment of long defects in welds of all levels, see Article 5.4. 5.2.4 For the assessment of single-sided welded pipe welds without pads of all levels, see Articles 5-8. 5.3 Assessment and classification of circular defects
5.3.1 Small aspect ratio, low quality Defects that are not included in the sample are defined as shape defects, including pores, spot inclusions and slag inclusions. 5.3.2 Circular defect size: 5:1
[-length, mm: W-width, mm
Figure 7-100] 5.3.3 Conversion of defects
CB/T3558-94
Convert the defect's long diameter into points. Table 7
Defect long diameter, mm
Conversion of defects
5.3.4 Points are not counted The defect sizes are classified by material thickness as shown in Table 8. Table 8 Defect sizes not counted
Material thickness T
Long diameter size
>25~50
Note: If the thickness of the parent materials on both sides of the weld is different, the friction of the thinner parent material shall prevail (the same as the following table). 5.3.5 Determination of assessment area
5.3-5.1 Determination of assessment area as shown in Table 9. Table 9 Determination of assessment area
Parent material thickness
Assessment area size minimum
10×10||tt ||>25~100
10×20
5.3.5.2 The assessment area must be selected from the most serious part of the defect on the negative film and the long side must be parallel to the direction of the weld. 5.3.5.3 When the defect is in contact with the boundary of the assessment area (excluding tangency), it should be included in the assessment area for counting. 5.3.6 Grading method
5.3.6.1 Add the number of points to be counted in the specified area according to 5.3.3~5.3.5. The sum of the points of each grade of weld in the assessment area is limited to Table 10.5. 3.6.2
3 For the limit values ​​of the number of defects not counted in the assessment area, see Table 11.5.3.6.3
Table 10 Limit values ​​of circular defects
Assessment area, mmXmm
10×10
Acceptance level
Acceptance level
>10~-15
10×20
Parent material thickness T, mm
>15--25
>25~~5)
Number of circular defects
For defects with more than [level
Table 11 Limit values ​​of defects not counted
10×30
>50~100
CB/T 3558—94
5.3.6.4 The long diameter of circular defects is graded at T. 5.3.6.5 When the number of points in the assessment area slightly exceeds the value, after negotiation between the supply and demand parties, it shall be handled in accordance with Appendix F (Supplement). 5.4 Assessment and classification of long defects.
5.4.1 The inclusions or long pores with a length-to-width ratio greater than 3 are defined as long defects. The measurement method is shown in Figure 5. 5.4.2 The size limits of single long defects of various levels of welds are shown in Table 12. Table 12 Limit values ​​of long defects
Original thickness of parent material T
Acceptance level
>12~48
Size of single long defect
Defects greater than level
5.4.3 The distance between adjacent long defects (the shortest straight-line distance) is less than or equal to the longer dimension. The lengths of all defects should be added together to make a single long defect assessment
5.4.4 The total length limit of long defects in welds of all levels within any 12T weld length is shown in Table 13. Table 13 Acceptance level of the limit of long defects within any 12T weld length
Total length of long defects TL
Not more than
Not more than
More than 2T
Not more than 3T
More than N level
5. 4.5 When the length of the weld to be inspected is less than 12T, the total length of long defects shall be converted in proportion. If the converted allowable total length is less than the limit of a single long defect, the limit of a single long defect shall be used as the allowable total length. 5.5 Comprehensive assessment
In the circular defect assessment area, if there are both circular and long defects, the self-assessment level shall be determined first, and then the sum of the two defect levels minus 1 shall be used as the final level.
5.6 Enlarged inspection
For welds inspected by proportional inspection, if one or both ends of the film show that the hazardous defects (cracks, lack of fusion, lack of penetration) are extended, an enlarged inspection should be carried out at the extended end. The penetration length shall be in accordance with Article 9 of CB/T3177. 5.7 Treatment of welds below the acceptance level
When the quality of the weld is lower than the requirements of the corresponding acceptance level, it shall be treated in accordance with Article 9 of CB/T 3177. 5.8 Acceptance level of single-sided welding of circumferential butt welds for marine pressure channels without pads 5.8.1 This acceptance level instrument is applicable to the assessment of the root concave and lack of welds of pipe butt welds with a weld coefficient of less than or equal to 0.75 and an outer diameter of less than or equal to 89 mm.
5.8.2 The limit values ​​of the root lack of penetration of welds of various levels are shown in Table 14.30
There should be no false defects caused by improper film processing or other false defects that hinder the evaluation in the effective evaluation area of ​​the film. 5 Grading of weld quality
According to the nature, size, quantity and distribution of defects in the weld (including the heat affected zone), it is divided into grades 1~. Grade 1 cannot be used as an acceptable quality level.
5. 1 Weld acceptance level
Weld acceptance level and applicable objects shall be in accordance with (CB/T3177. 5.2 Assessment of weld defects
5.2.1 Welds of all levels are not allowed to have cracks, lack of fusion, and lack of penetration. 5.2.2 For the assessment of circular defects in welds of all levels, see Article 5.3. 5.2.3 For the assessment of long defects in welds of all levels, see Article 5.4. 5.2.4 For the assessment of single-sided welded pipe welds without pads of all levels, see Articles 5-8. 5.3 Assessment and classification of circular defects
5.3.1 Small aspect ratio, low quality Defects that are not included in the sample are defined as shape defects, including pores, spot inclusions and slag inclusions. 5.3.2 Circular defect size: 5:1
[-length, mm: W-width, mm
Figure 7-100] 5.3.3 Conversion of defects
CB/T3558-94
Convert the defect's long diameter into points. Table 7
Defect long diameter, mm
Conversion of defects
5.3.4 Points are not counted The defect sizes are classified by material thickness as shown in Table 8. Table 8 Defect sizes not counted
Material thickness T
Long diameter size
>25~50
Note: If the thickness of the parent materials on both sides of the weld is different, the friction of the thinner parent material shall prevail (the same as the following table). 5.3.5 Determination of assessment area
5.3-5.1 Determination of assessment area as shown in Table 9. Table 9 Determination of assessment area
Parent material thickness
Assessment area size minimum
10×10||tt ||>25~100
10×20
5.3.5.2 The assessment area must be selected from the most serious part of the defect on the negative film and the long side must be parallel to the direction of the weld. 5.3.5.3 When the defect is in contact with the boundary of the assessment area (excluding tangency), it should be included in the assessment area for counting. 5.3.6 Grading method
5.3.6.1 Add the number of points to be counted in the specified area according to 5.3.3~5.3.5. The sum of the points of each grade of weld in the assessment area is limited to Table 10.5. 3.6.2
3 For the limit values ​​of the number of defects not counted in the assessment area, see Table 11.5.3.6.3
Table 10 Limit values ​​of circular defects
Assessment area, mmXmm
10×10
Acceptance level
Acceptance level
>10~-15
10×20
Parent material thickness T, mm
>15--25
>25~~5)
Number of circular defects
For defects with more than [level
Table 11 Limit values ​​of defects not counted
10×30
>50~100
CB/T 3558—94
5.3.6.4 The long diameter of circular defects is graded at T. 5.3.6.5 When the number of points in the assessment area slightly exceeds the value, after negotiation between the supply and demand parties, it shall be handled in accordance with Appendix F (Supplement). 5.4 Assessment and classification of long defects.
5.4.1 The inclusions or long pores with a length-to-width ratio greater than 3 are defined as long defects. The measurement method is shown in Figure 5. 5.4.2 The size limits of single long defects of various levels of welds are shown in Table 12. Table 12 Limit values ​​of long defects
Original thickness of parent material Tbzxz.net
Acceptance level
>12~48
Size of single long defect
Defects greater than level
5.4.3 The distance between adjacent long defects (the shortest straight-line distance) is less than or equal to the longer dimension. The lengths of all defects should be added together to make a single long defect assessment
5.4.4 The total length limit of long defects in welds of all levels within any 12T weld length is shown in Table 13. Table 13 Acceptance level of the limit of long defects within any 12T weld length
Total length of long defects TL
Not more than
Not more than
More than 2T
Not more than 3T
More than N level
5. 4.5 When the length of the weld to be inspected is less than 12T, the total length of long defects shall be converted in proportion. If the converted allowable total length is less than the limit of a single long defect, the limit of a single long defect shall be used as the allowable total length. 5.5 Comprehensive assessment
In the circular defect assessment area, if there are both circular and long defects, the self-assessment level shall be determined first, and then the sum of the two defect levels minus 1 shall be used as the final level.
5.6 Enlarged inspection
For welds inspected by proportional inspection, if one or both ends of the film show that the hazardous defects (cracks, lack of fusion, lack of penetration) are extended, an enlarged inspection should be carried out at the extended end. The penetration length shall be in accordance with Article 9 of CB/T3177. 5.7 Treatment of welds below the acceptance level
When the quality of the weld is lower than the requirements of the corresponding acceptance level, it shall be treated in accordance with Article 9 of CB/T 3177. 5.8 Acceptance level of single-sided welding of circumferential butt welds for marine pressure channels without pads 5.8.1 This acceptance level instrument is applicable to the assessment of the root concave and lack of welds of pipe butt welds with a weld coefficient of less than or equal to 0.75 and an outer diameter of less than or equal to 89 mm.
5.8.2 The limit values ​​of the root lack of penetration of welds of various levels are shown in Table 14.Handle according to Appendix F (Supplement). 5.4 Assessment and classification of long defects.
5.4.1 Inclusions or long pores with a length-to-width ratio greater than 3 are defined as long defects. The measurement method is shown in Figure 5. 5.4.2 The size limits of single long defects in welds of all levels are shown in Table 12. Table 12 Limits of long defects
Original thickness of parent material T
Acceptance level
>12~48
Single long defect size
Defects greater than level
5.4.3 The distance between adjacent long defects (the shortest straight-line distance) is less than or equal to the longer dimension. The lengths of each defect should be added together for single long defect assessment
5.4.4 The total length limit of long defects in welds of all levels within any 12T weld length is shown in Table 13. Table 13 Acceptance level of the limit of long defects within any 12T weld length
Total length of long defects TL
Not more than
Not more than
More than 2T
Not more than 3T
More than N level
5. 4.5 When the length of the weld to be inspected is less than 12T, the total length of long defects shall be converted in proportion. If the converted allowable total length is less than the limit of a single long defect, the limit of a single long defect shall be used as the allowable total length. 5.5 Comprehensive assessment
In the circular defect assessment area, if there are both circular and long defects, the self-assessment level shall be determined first, and then the sum of the two defect levels minus 1 shall be used as the final level.
5.6 Enlarged inspection
For welds inspected by proportional inspection, if one or both ends of the film show that the hazardous defects (cracks, lack of fusion, lack of penetration) are extended, an enlarged inspection should be carried out at the extended end. The penetration length shall be in accordance with Article 9 of CB/T3177. 5.7 Treatment of welds below the acceptance level
When the quality of the weld is lower than the requirements of the corresponding acceptance level, it shall be treated in accordance with Article 9 of CB/T 3177. 5.8 Acceptance level of single-sided welding of circumferential butt welds for marine pressure channels without pads 5.8.1 This acceptance level instrument is applicable to the assessment of the root concave and lack of welds of pipe butt welds with a weld coefficient of less than or equal to 0.75 and an outer diameter of less than or equal to 89 mm.
5.8.2 The limit values ​​of the root lack of penetration of welds of various levels are shown in Table 14.Handle according to Appendix F (Supplement). 5.4 Assessment and classification of long defects.
5.4.1 Inclusions or long pores with a length-to-width ratio greater than 3 are defined as long defects. The measurement method is shown in Figure 5. 5.4.2 The size limits of single long defects in welds of all levels are shown in Table 12. Table 12 Limits of long defects
Original thickness of parent material T
Acceptance level
>12~48
Single long defect size
Defects greater than level
5.4.3 The distance between adjacent long defects (the shortest straight-line distance) is less than or equal to the longer dimension. The lengths of each defect should be added together for single long defect assessment
5.4.4 The total length limit of long defects in welds of all levels within any 12T weld length is shown in Table 13. Table 13 Acceptance level of the limit of long defects within any 12T weld length
Total length of long defects TL
Not more than
Not more than
More than 2T
Not more than 3T
More than N level
5. 4.5 When the length of the weld to be inspected is less than 12T, the total length of long defects shall be converted in proportion. If the converted allowable total length is less than the limit of a single long defect, the limit of a single long defect shall be used as the allowable total length. 5.5 Comprehensive assessment
In the circular defect assessment area, if there are both circular and long defects, the self-assessment level shall be determined first, and then the sum of the two defect levels minus 1 shall be used as the final level.
5.6 Enlarged inspection
For welds inspected by proportional inspection, if one or both ends of the film show that the hazardous defects (cracks, lack of fusion, lack of penetration) are extended, an enlarged inspection should be carried out at the extended end. The penetration length shall be in accordance with Article 9 of CB/T3177. 5.7 Treatment of welds below the acceptance level
When the quality of the weld is lower than the requirements of the corresponding acceptance level, it shall be treated in accordance with Article 9 of CB/T 3177. 5.8 Acceptance level of single-sided welding of circumferential butt welds for marine pressure channels without pads 5.8.1 This acceptance level instrument is applicable to the assessment of the root concave and lack of welds of pipe butt welds with a weld coefficient of less than or equal to 0.75 and an outer diameter of less than or equal to 89 mm.
5.8.2 The limit values ​​of the root lack of penetration of welds of various levels are shown in Table 14.
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