Bars and blanks of round and rectangular section. Methods of ultrasonic flaw detection

GOST 21120-75*
Group B09

STATE STANDARD OF THE UNION OF THE SSR

RODS AND BLANKS OF ROUND AND RECTANGULAR SECTION

Methods of ultrasonic flaw detection

Round and rectangular bars and billets. ultrasonic testing

Introduction date 1977-01-01

By the Decree of the State Committee of Standards of the Council of Ministers of the USSR dated August 29, 1975 N 2282, the introduction period was set from 01.01.77

Checked in 1986. By the Decree of the State Standard of 07.22.86 N 2199, the validity period was extended until 01.01.94 **
________________
** The limitation of the validity period was removed according to the protocol N 3-93 of the Interstate Council for Standardization, Metrology and Certification (IUS N 5/6, 1993). — Database manufacturer's note.

* REPUBLICATION (December 1988) with Amendments No. 1, 2, approved in November 1981, July 1986 (IUS 2-82, 10-86).

This standard applies to rolled bars of round and square section, swaged blanks, blanks for pipes and for rolling with a diameter or side of a square from 30 to 300 mm from carbon, alloy and high-alloy steels and alloys and establishes echo-pulse, shadow and mirror-shadow methods ultrasonic testing of the metal, or a combination of them in order to identify internal defects that lie within the sensitivity of the method.

General requirements for ultrasonic testing methods - according to GOST 12503-75 and GOST 20415-82.

Terms and definitions - in accordance with GOST 23829-85 and the reference appendix.

1. SAMPLING METHOD

1.1. The control sample for adjusting the sensitivity of the flaw detector is a piece of workpiece that does not have defects according to the results of ultrasonic testing. The control sample is made in cross section equal to or with a deviation of no more than 10% from the dimensions of the controlled product, and in terms of configuration, structure and surface quality - similar to the controlled product.

1.2. To adjust the sensitivity of the flaw detector during ultrasonic testing using direct transducers, control samples are used, the artificial reflectors of which are the side surface (Fig. 1 and 3) or the flat bottom (Fig. 2 and 4) of the hole.

Hole diameter, if not specified in the standards or specifications, when ultrasonic waves are reflected from the side surface of the hole, it should be no more than 2.5 mm and from the flat bottom of the hole no more than 3.0 mm. The drilling depth for the case when the artificial reflector is the side surface of the hole must be at least 50 mm.

1.3. Diameters of artificial reflectors should be chosen from the range: 1; 1.5; 2; 2.5; 3; 3.5; four; 5; 6; 7; 8 mm.

1.4. The depth of artificial reflectors from the input surface of ultrasonic vibrations should be ¾ of the diameter or thickness of the metal being tested, unless this is specified in the regulatory and technical documentation.

1.5. Accuracy and manufacturing technology of artificial reflectors in control samples for a direct transducer - according to GOST 21397-81, for an inclined transducer - according to GOST 14782-86.

Section 1.

2. PREPARATION FOR TESTS

2.1. On the surface of the rolled products there should be no dirt, flaking scale, captivity and splashes of molten metal. The surface quality must comply with the normative and technical documentation for the controlled metal.

2.2. The sensitivity of the ultrasonic flaw detector is adjusted according to the control sample. The sensitivity of the automated ultrasonic unit is adjusted by passing a control sample through the unit 5 times. In this case, there should be 100% registration of artificial reflectors.

Adjusting the sensitivity of the flaw detector when using inclined transducers is carried out in accordance with GOST 14782-86.

Section 2. (Changed edition, Rev. N 2).

3. TESTING

3.1. Control is carried out using longitudinal and (or) transverse waves. The introduction of ultrasonic vibrations into the metal is carried out by non-contact, contact, immersion or slot methods.

3.2. When checking the round section of workpieces by contact or slot methods, the working surface of the transducer must be identical in shape to the surface of the workpiece. It is allowed to use nozzles and supports when inspecting round workpieces with a transducer with a flat working surface.

3.3. The billet sounding scheme is set in such a way that the entire volume of the metal is checked, with the exception of uncontrolled zones inherent in the ultrasonic testing method. In this case, square-section blanks are sounded from two mutually perpendicular faces, round blanks - along the generators. When using inclined transducers, scanning is performed in two directions, perpendicular to the generatrix of a round workpiece and the length of a rectangular one.

3.4. The method of relative movement of the finder and the controlled metal surface (type of scanning) should ensure the detection of defects specified in the standards and specifications for products, and the scanning speed should ensure the fixation of these defects.

3.5. The main measured characteristic of these defects is the amplitude of the signal from the artificial reflector in the control sample.

3.6. When setting the sensitivity of the flaw detector, the amplitude of the signal reflected from the artificial reflector in the control sample must be at least ½ of the screen height of the cathode ray tube of the flaw detector.

3.8. When using manual and mechanized control methods, the search sensitivity level of the flaw detector and the fixation level are set. The fixation level corresponds to the value of the amplitude of the signal reflected from the artificial reflector in the control sample, the size and location of which is indicated in the regulatory and technical documentation approved in in due course. The search sensitivity level is set 6 dB above the hold level. When using the automatic control method, only the fixation level is set.

3.9. The search for defects is carried out on search sensitivity, and sections of the workpiece in which at least one of the following signs of a defect is observed are subject to fixation:

a reflected signal whose amplitude is equal to or greater than the fixation level;

attenuation of a given signal, or attenuation of a transmitted signal to or below the clamp level.

3.10. Checking the correct setting of the flaw detector is carried out using control samples at least after 4 hours of operation.

3.11. The boundaries of defective areas are determined by the position of the transducer. The conditional length of the defect is determined by the transducer displacement interval, within which the signal from the defect is perceived at a given sensitivity of the flaw detector.

3.12. The method, basic parameters, transducer switching circuit, ultrasonic vibration input method, scanning circuit, methods for separating false signals and signals from defects are established in the regulatory and technical documentation for a specific metal product.

3.13. It is allowed to combine the echo-pulse and mirror-shadow methods of control if the amplitude of the bottom signal in areas that do not contain discontinuities exceeds the amplitude of the echo signal from the reflector of the control sample by at least 6 dB.

Section 3. (Changed edition, Rev. N 2).

4. PROCESSING THE RESULTS

4.1. The damage of the controlled metal with internal defects at a given control sensitivity is characterized by quality groups in accordance with the table.

Note. If the distance between the boundaries of the identified defective areas does not exceed 15 mm, their conditional length is summed up and the defect belongs to the corresponding quality group.

(Changed edition, Rev. N 2).

4.1a. A rejection sign for all quality groups during control by different methods are the following parameters established in the regulatory and technical documentation:

in the echo-pulse method - the magnitude of the amplitude of the signal reflected from the discontinuity, equal to or greater than the amplitude of the signal from the control reflector;

with the mirror-shadow method - the magnitude of the attenuation of the amplitude of the bottom signal;

in the shadow method - the magnitude of the attenuation of the amplitude of the transmitted signal.

4.2. The permissible quality group and sensitivity of metal control is set depending on its purpose and is indicated in the standards and technical specifications or other regulatory and technical documentation for products.

(Changed edition, Rev. N 2).

4.3. Registration and registration of control results are carried out in accordance with GOST 12503-75.

APPENDIX (reference). Explanation of terms used in the standard

APPENDIX
Reference

(Introduced additionally, Rev. N 2).

Electronic text of the document
prepared by CJSC Kodeks and checked against:

official publication
M.: Publishing house of standards, 1989

This standard applies to rolled bars of round and square section, swaged blanks, blanks for pipes and for rolling with a diameter or side of a square from 30 to 300 mm from carbon, alloy and high-alloy steels and alloys and establishes echo-pulse, shadow and mirror-shadow methods ultrasonic testing of the metal, or a combination of them in order to identify internal defects that lie within the sensitivity of the method.

1. SAMPLING METHOD

1.1. The control sample for adjusting the sensitivity of the flaw detector is a piece of workpiece that does not have defects according to the results of ultrasonic testing. The control sample is made in cross section equal to or with a deviation of no more than 10% from the dimensions of the controlled product, and in terms of configuration, structure and surface quality - similar to the controlled product.
1.2. To adjust the sensitivity of the flaw detector during ultrasonic testing using direct transducers, control samples are used, the artificial reflectors of which are the side surface (Fig. 1 and 3) or the flat bottom (Fig. 2 and 4) of the hole. The diameter of the hole d, if it is not specified in the standards or technical specifications, when reflecting ultrasonic waves from the side surface of the hole, should be no more than 2.5 mm and from the flat bottom of the hole no more than 3.0 mm. drilling depth; for the case when the lateral surface of the hole is an artificial reflector, it must be at least 50 mm.
1.3. Diameters of artificial reflectors should be chosen from the range: 1; 1.5; 2; 2.5; 3; 3.5; four; 5; 6; 7; 8 mm.
1.4. The depth of artificial reflectors from the input surface of ultrasonic vibrations should be 3/4 of the diameter or thickness of the metal being tested, unless this is specified in the regulatory and technical documentation.
1.5. Accuracy and manufacturing technology of artificial reflectors in control samples for a direct transducer - according to GOST 21397-81, for an inclined transducer - according to GOST 14782-86.

2. PREPARATION FOR TESTS

2.1. On the surface of the rolled products there should be no dirt, flaking scale, captivity and splashes of molten metal. The surface quality must comply with the normative and technical documentation for the controlled metal.
2.2. The sensitivity of the ultrasonic flaw detector is adjusted according to the control sample. The sensitivity of the automated ultrasonic unit is adjusted by passing a control sample through the unit 5 times. In this case, there should be 100% registration of artificial reflectors. Adjusting the sensitivity of the flaw detector when using inclined transducers is carried out in accordance with GOST 14782-86.

3. TESTING

3.1. Control is carried out using longitudinal and (or) transverse waves. The introduction of ultrasonic vibrations into the metal is carried out by non-contact, contact, immersion or slot methods.
3.2. When checking the round section of workpieces by contact or slot methods, the working surface of the transducer must be identical in shape to the surface of the workpiece. It is allowed to use nozzles and supports when inspecting round workpieces with a transducer with a flat working surface.
3.3. The billet sounding scheme is set in such a way that the entire volume of the metal is checked, with the exception of uncontrolled zones inherent in the ultrasonic testing method. In this case, square-section blanks are sounded from two mutually perpendicular faces, round blanks - along the generators. When using inclined transducers, scanning is performed in two directions, perpendicular to the generatrix of a round workpiece and the length of a rectangular one.
3.4. The method of relative movement of the finder and the controlled metal surface (type of scanning) should ensure the detection of defects specified in the standards and specifications for products, and the scanning speed should fix these defects.
3.5. The main measured characteristic of these defects is the amplitude of the signal from the artificial reflector in the control sample.
3.6. When setting the sensitivity of the flaw detector, the amplitude of the signal reflected from the artificial reflector in the control sample must be at least 1/2 of the screen height of the cathode ray tube of the flaw detector.
3.7. The recommended frequency of ultrasonic vibrations is set from 0.5 to 5 MHz.
3.8. When using manual and mechanized control methods, the search sensitivity level of the flaw detector and the fixation level are set. The level of fixation corresponds to the value of the amplitude of the signal reflected from the artificial reflector in the control sample, the size and location of which is indicated in the normative and technical documentation approved in the prescribed manner. The search sensitivity level is set 6 dB above the hold level. When using the automatic control method, only the fixation level is set.
3.9. The search for defects is carried out on the search sensitivity, and sections of the workpiece are subject to fixation, in which at least one of the following signs of a defect is observed: a reflected signal whose amplitude is equal to or greater than the fixation level; attenuation of a given signal, or attenuation of a transmitted signal to or below the clamp level.
3.10. Checking the correct setting of the flaw detector is carried out using control samples at least after 4 hours of operation.
3.11. The boundaries of defective areas are determined by the position of the transducer. The conditional length of the defect is determined by the transducer displacement interval, within which the signal from the defect is perceived at a given sensitivity of the flaw detector.
3.12. The method, basic parameters, transducer switching circuit, ultrasonic vibration input method, scanning circuit, methods for separating false signals and signals from defects are established in the regulatory and technical documentation for a specific metal product.
3.13. It is allowed to combine the echo-pulse and mirror-and-shadow methods of control if the amplitude of the bottom signal in areas that do not contain discontinuities exceeds the amplitude of the echo signal from the reflector of the control sample by at least 6 dB.

GOST 21120-75*

Group B09

STATE STANDARD OF THE UNION OF THE SSR

RODS AND BLANKS OF ROUND AND RECTANGULAR SECTION

Methods of ultrasonic flaw detection

Round and rectangular bars and billets. ultrasonic testing

Introduction date 1977-01-01

By the Decree of the State Committee of Standards of the Council of Ministers of the USSR dated August 29, 1975 N 2282, the introduction period was set from 01.01.77

Checked in 1986. By the Decree of the State Standard of 07.22.86 N 2199, the validity period was extended until 01.01.94 **
________________
** The limitation of the validity period was removed according to protocol N 3-93 of the Interstate Council for Standardization, Metrology and Certification (IUS N 5/6, 1993). - Database manufacturer's note.

* REPUBLICATION (December 1988) with Amendments No. 1, 2, approved in November 1981, July 1986 (IUS 2-82, 10-86).


This standard applies to rolled bars of round and square section, swaged blanks, blanks for pipes and for rolling with a diameter or side of a square from 30 to 300 mm from carbon, alloy and high-alloy steels and alloys and establishes echo-pulse, shadow and mirror-shadow methods ultrasonic testing of the metal, or a combination of them in order to identify internal defects that lie within the sensitivity of the method.

General requirements for ultrasonic testing methods - according to GOST 12503-75 and GOST 20415-82.

Terms and definitions - according to GOST 23829-85 and reference appendix.

1. SAMPLING METHOD

1. SAMPLING METHOD

1.1. The control sample for adjusting the sensitivity of the flaw detector is a piece of workpiece that does not have defects according to the results of ultrasonic testing. The control sample is made in cross section equal to or with a deviation of no more than 10% from the dimensions of the controlled product, and in terms of configuration, structure and surface quality - similar to the controlled product.

1.2. To adjust the sensitivity of the flaw detector during ultrasonic testing using direct transducers, control samples are used, the artificial reflectors of which are the side surface (Fig. 1 and 3) or the flat bottom (Fig. 2 and 4) of the hole.

Hole diameter, if it is not specified in the standards or technical conditions, when ultrasonic waves are reflected from the side surface of the hole, it should be no more than 2.5 mm and from the flat bottom of the hole no more than 3.0 mm. The drilling depth for the case when the artificial reflector is the side surface of the hole must be at least 50 mm.

1.3. Diameters of artificial reflectors should be chosen from the range: 1; 1.5; 2; 2.5; 3; 3.5; four; 5; 6; 7; 8 mm.

Damn.4

1.4. The depth of artificial reflectors from the input surface of ultrasonic vibrations should be 3/4 of the diameter or thickness of the metal being tested, unless this is specified in the regulatory and technical documentation.

1.5. Accuracy and manufacturing technology of artificial reflectors in control samples for a direct transducer - according to GOST 21397-81, for an inclined transducer - according to GOST 14782-86.

Section 1.

2. PREPARATION FOR TESTS

2.1. On the surface of the rolled products there should be no dirt, flaking scale, captivity and splashes of molten metal. The surface quality must comply with the normative and technical documentation for the controlled metal.

2.2. The sensitivity of the ultrasonic flaw detector is adjusted according to the control sample. The sensitivity of the automated ultrasonic unit is adjusted by passing a control sample through the unit 5 times. In this case, there should be 100% registration of artificial reflectors.

Adjusting the sensitivity of the flaw detector when using inclined transducers is carried out in accordance with GOST 14782-86.

Section 2. (Changed edition, Rev. N 2).

3. TESTING

3.1. Control is carried out using longitudinal and (or) transverse waves. The introduction of ultrasonic vibrations into the metal is carried out by non-contact, contact, immersion or slot methods.

3.2. When checking the round section of workpieces by contact or slot methods, the working surface of the transducer must be identical in shape to the surface of the workpiece. It is allowed to use nozzles and supports when inspecting round workpieces with a transducer with a flat working surface.

3.3. The billet sounding scheme is set in such a way that the entire volume of the metal is checked, with the exception of uncontrolled zones inherent in the ultrasonic testing method. In this case, square-section blanks are sounded from two mutually perpendicular faces, round blanks - along the generators. When using inclined transducers, scanning is performed in two directions, perpendicular to the generatrix of a round workpiece and the length of a rectangular one.

3.4. The method of relative movement of the finder and the controlled metal surface (type of scanning) should ensure the detection of defects specified in the standards and specifications for products, and the scanning speed should fix these defects.

3.5. The main measured characteristic of these defects is the amplitude of the signal from the artificial reflector in the control sample.

3.6. When setting the sensitivity of the flaw detector, the amplitude of the signal reflected from the artificial reflector in the control sample must be at least 1/2 of the screen height of the cathode ray tube of the flaw detector.

3.8. When using manual and mechanized control methods, the search sensitivity level of the flaw detector and the fixation level are set. The level of fixation corresponds to the value of the amplitude of the signal reflected from the artificial reflector in the control sample, the size and location of which is indicated in the normative and technical documentation approved in the prescribed manner. The search sensitivity level is set 6 dB above the hold level. When using the automatic control method, only the fixation level is set.

3.9. The search for defects is carried out on search sensitivity, and sections of the workpiece in which at least one of the following signs of a defect is observed are subject to fixation:

a reflected signal whose amplitude is equal to or greater than the fixation level;

attenuation of a given signal, or attenuation of a transmitted signal to or below the clamp level.

3.10. Checking the correct setting of the flaw detector is carried out using control samples at least after 4 hours of operation.

3.11. The boundaries of defective areas are determined by the position of the transducer. The conditional length of the defect is determined by the transducer displacement interval, within which the signal from the defect is perceived at a given sensitivity of the flaw detector.

3.12. The method, basic parameters, transducer switching circuit, ultrasonic vibration input method, scanning circuit, methods for separating false signals and signals from defects are established in the regulatory and technical documentation for a specific metal product.

3.13. It is allowed to combine the echo-pulse and mirror-shadow methods of control if the amplitude of the bottom signal in areas that do not contain discontinuities exceeds the amplitude of the echo signal from the reflector of the control sample by at least 6 dB.

Section 3. (Changed edition, Rev. N 2).

4. PROCESSING THE RESULTS

4.1. The damage of the controlled metal with internal defects at a given control sensitivity is characterized by quality groups in accordance with the table.

Note. If the distance between the boundaries of the identified defective areas does not exceed 15 mm, their conditional length is summed up and the defect belongs to the corresponding quality group.


(Changed edition, Rev. N 2).

4.1a. A rejection sign for all quality groups during control by different methods are the following parameters established in the regulatory and technical documentation:

with the echo-pulse method - the magnitude of the amplitude of the signal reflected from the discontinuity, equal to or more than the amplitude of the signal from the control reflector;

with the mirror-shadow method - the magnitude of the attenuation of the amplitude of the bottom signal;

with the shadow method - the magnitude of the attenuation of the amplitude of the transmitted signal.

4.2. The permissible quality group and sensitivity of metal control is set depending on its purpose and is indicated in the standards and technical specifications or other regulatory and technical documentation for products.

(Changed edition, Rev. N 2).

4.3. Registration and registration of control results are carried out in accordance with GOST 12503-75.

APPENDIX (reference). Explanation of terms used in the standard

APPENDIX
Reference

(Introduced additionally, Rev. N 2).

Electronic text of the document
prepared by CJSC "Kodeks" and checked against:

official publication
M.: Publishing house of standards, 1989

GOST 21120-75*

Group B09

STATE STANDARD OF THE UNION OF THE SSR

RODS AND BLANKS OF ROUND AND RECTANGULAR SECTION

Methods of ultrasonic flaw detection

Round and rectangular bars and billets. ultrasonic testing

Introduction date 1977-01-01

By the Decree of the State Committee of Standards of the Council of Ministers of the USSR dated August 29, 1975 N 2282, the introduction period was set from 01.01.77

Checked in 1986. By the Decree of the State Standard of 07.22.86 N 2199, the validity period was extended until 01.01.94 **
________________
** The limitation of the validity period was removed according to protocol N 3-93 of the Interstate Council for Standardization, Metrology and Certification (IUS N 5/6, 1993). - Database manufacturer's note.

* REPUBLICATION (December 1988) with Amendments No. 1, 2, approved in November 1981, July 1986 (IUS 2-82, 10-86).

This standard applies to rolled bars of round and square section, swaged blanks, blanks for pipes and for rolling with a diameter or side of a square from 30 to 300 mm from carbon, alloy and high-alloy steels and alloys and establishes echo-pulse, shadow and mirror-shadow methods ultrasonic testing of the metal, or a combination of them in order to identify internal defects that lie within the sensitivity of the method.

General requirements for ultrasonic testing methods - according to GOST 12503-75 and GOST 20415-82.

Terms and definitions - according to GOST 23829-85 and reference appendix.

1. SAMPLING METHOD

1.1. The control sample for adjusting the sensitivity of the flaw detector is a piece of workpiece that does not have defects according to the results of ultrasonic testing. The control sample is made in cross section equal to or with a deviation of no more than 10% from the dimensions of the controlled product, and in terms of configuration, structure and surface quality - similar to the controlled product.

1.2. To adjust the sensitivity of the flaw detector during ultrasonic testing using direct transducers, control samples are used, the artificial reflectors of which are the side surface (Fig. 1 and 3) or the flat bottom (Fig. 2 and 4) of the hole.

Hole diameter, if it is not specified in the standards or technical conditions, when ultrasonic waves are reflected from the side surface of the hole, it should be no more than 2.5 mm and from the flat bottom of the hole no more than 3.0 mm. The drilling depth for the case when the artificial reflector is the side surface of the hole must be at least 50 mm.

1.3. Diameters of artificial reflectors should be chosen from the range: 1; 1.5; 2; 2.5; 3; 3.5; four; 5; 6; 7; 8 mm.

Damn.4

1.4. The depth of artificial reflectors from the input surface of ultrasonic vibrations should be 3/4 of the diameter or thickness of the metal being tested, unless this is specified in the regulatory and technical documentation.

1.5. Accuracy and manufacturing technology of artificial reflectors in control samples for a direct transducer - according to GOST 21397-81, for an inclined transducer - according to GOST 14782-86.

Section 1.

2. PREPARATION FOR TESTS

2.1. On the surface of the rolled products there should be no dirt, flaking scale, captivity and splashes of molten metal. The surface quality must comply with the normative and technical documentation for the controlled metal.

2.2. The sensitivity of the ultrasonic flaw detector is adjusted according to the control sample. The sensitivity of the automated ultrasonic unit is adjusted by passing a control sample through the unit 5 times. In this case, there should be 100% registration of artificial reflectors.

Adjusting the sensitivity of the flaw detector when using inclined transducers is carried out in accordance with GOST 14782-86.

Section 2. (Changed edition, Rev. N 2).

3. TESTING

3.1. Control is carried out using longitudinal and (or) transverse waves. The introduction of ultrasonic vibrations into the metal is carried out by non-contact, contact, immersion or slot methods.

3.2. When checking the round section of workpieces by contact or slot methods, the working surface of the transducer must be identical in shape to the surface of the workpiece. It is allowed to use nozzles and supports when inspecting round workpieces with a transducer with a flat working surface.

3.3. The billet sounding scheme is set in such a way that the entire volume of the metal is checked, with the exception of uncontrolled zones inherent in the ultrasonic testing method. In this case, square-section blanks are sounded from two mutually perpendicular faces, round blanks - along the generators. When using inclined transducers, scanning is performed in two directions, perpendicular to the generatrix of a round workpiece and the length of a rectangular one.

3.4. The method of relative movement of the finder and the controlled metal surface (type of scanning) should ensure the detection of defects specified in the standards and specifications for products, and the scanning speed should fix these defects.

3.5. The main measured characteristic of these defects is the amplitude of the signal from the artificial reflector in the control sample.

3.6. When setting the sensitivity of the flaw detector, the amplitude of the signal reflected from the artificial reflector in the control sample must be at least 1/2 of the screen height of the cathode ray tube of the flaw detector.

3.8. When using manual and mechanized control methods, the search sensitivity level of the flaw detector and the fixation level are set. The level of fixation corresponds to the value of the amplitude of the signal reflected from the artificial reflector in the control sample, the size and location of which is indicated in the normative and technical documentation approved in the prescribed manner. The search sensitivity level is set 6 dB above the hold level. When using the automatic control method, only the fixation level is set.

3.9. The search for defects is carried out on search sensitivity, and sections of the workpiece in which at least one of the following signs of a defect is observed are subject to fixation:

a reflected signal whose amplitude is equal to or greater than the fixation level;

Attenuation of a given signal or attenuation of a transmitted signal to or below the clamp level.

3.10. Checking the correct setting of the flaw detector is carried out using control samples at least after 4 hours of operation.

3.11. The boundaries of defective areas are determined by the position of the transducer. The conditional length of the defect is determined by the transducer displacement interval, within which the signal from the defect is perceived at a given sensitivity of the flaw detector.

3.12. The method, basic parameters, transducer switching circuit, ultrasonic vibration input method, scanning circuit, methods for separating false signals and signals from defects are established in the regulatory and technical documentation for a specific metal product.

3.13. It is allowed to combine the echo-pulse and mirror-shadow methods of control if the amplitude of the bottom signal in areas that do not contain discontinuities exceeds the amplitude of the echo signal from the reflector of the control sample by at least 6 dB.

Section 3. (Changed edition, Rev. N 2).

4. PROCESSING THE RESULTS

4.1. The damage of the controlled metal with internal defects at a given control sensitivity is characterized by quality groups in accordance with the table.

Note. If the distance between the boundaries of the identified defective areas does not exceed 15 mm, their conditional length is summed up and the defect belongs to the corresponding quality group.

(Changed edition, Rev. N 2).

4.1a. A rejection sign for all quality groups during control by different methods are the following parameters established in the regulatory and technical documentation:

With the echo-pulse method - the magnitude of the amplitude of the signal reflected from the discontinuity, equal to or more than the amplitude of the signal from the control reflector;

With the mirror-shadow method - the magnitude of the attenuation of the amplitude of the bottom signal;

With the shadow method - the magnitude of the attenuation of the amplitude of the transmitted signal.

4.2. The permissible quality group and sensitivity of metal control is set depending on its purpose and is indicated in the standards and technical specifications or other regulatory and technical documentation for products.

(Changed edition, Rev. N 2).

4.3. Registration and registration of control results are carried out in accordance with GOST 12503-75.

APPENDIX
Reference

Explanation of terms used in the standard

(Introduced additionally, Rev. N 2).