STATE STANDARD OF THE USSR UNION

NON-DESTRUCTIVE TESTING

WELDED CONNECTIONS

ULTRASONIC METHODS

GOST 14782-86

STATE COMMITTEE OF THE USSR
ON PRODUCT QUALITY MANAGEMENT AND STANDARDS

Moscow

STATE STANDARD OF THE USSR UNION

Date of introduction 01.01.88

This standard establishes methods for ultrasonic testing of butt, corner, lap and T-joints made by arc, electroslag, gas, gas press, electron beam and flash butt welding in welded structures made of metals and alloys to identify cracks, lack of fusion, pores, non-metallic and metallic inclusions .The standard does not establish methods for ultrasonic testing of surfacing. The need for ultrasonic testing, the scope of control and the size of unacceptable defects are established in standards or technical specifications for products. Explanations of the terms used in this standard are given in Reference Appendix 1.

1. CONTROLS

1.1. During testing, the following should be used: an ultrasonic pulse flaw detector (hereinafter referred to as the flaw detector) in accordance with GOST 23049-84 of at least the second group with piezoelectric transducers; standard samples for setting up the flaw detector; auxiliary devices and devices for observing scanning parameters and measuring the characteristics of identified defects. Flaw detectors and standard samples used for control must be certified and verified in accordance with the established procedure. It is allowed to use a flaw detector with electromagnetoacoustic transducers. 1.2. For testing, flaw detectors should be used, equipped with direct and inclined transducers, having an attenuator, which allows you to determine the coordinates of the location of the reflecting surface. The value of the attenuation stage of the attenuator should be no more than 1 dB. It is allowed to use flaw detectors with an attenuator, the value of the attenuation stage of which is 2 dB, flaw detectors without an attenuator with an automatic signal amplitude measurement system. 1.3. Piezoelectric transducers with a frequency of more than 0.16 MHz - in accordance with GOST 26266-84. The use of non-standardized transducers in accordance with GOST 8.326-89.1.3.1 is allowed. Piezoelectric transducers are selected taking into account: the shape and dimensions of the electroacoustic transducer; the material of the prism and the speed of propagation of the longitudinal ultrasonic wave at a temperature of (20 ± 5) °C; the average path of ultrasound in the prism. 1.3.2. The frequency of ultrasonic vibrations emitted by inclined transducers should not differ from the nominal value by more than 10% in the light range. 1.25 MHz, more than 20% in the range up to 1.25 MHz.1.3.3. The position of the mark corresponding to the beam exit point should not differ from the actual one by more than ± 1 mm.1.3.4. The working surface of the transducer when testing welded joints of products of cylindrical or other curved shape must comply with the requirements of technical documentation for testing, approved in the prescribed manner. 1.4. Standard samples SO-1 (Diagram 1), SO-2 (Diagram 2) and SO-3 (Diagram 4) should be used to measure and check the basic parameters of equipment and control using the pulse-echo method and a combined circuit for switching on a piezoelectric transducer with a flat working surface at a frequency of 1.25 MHz or more, provided that the width of the converter does not exceed 20 mm. In other cases, industry (enterprise) standard samples should be used to check the basic parameters of equipment and control. 1.4.1. Standard sample SO-1 (see Figure 1) is used to determine the conditional sensitivity, check the resolution and error of the depth gauge of the flaw detector.

Notes: 1. Maximum deviations of the linear dimensions of the sample are not lower than 14th quality according to GOST 25346-82. 2. The maximum deviations of the diameter of the holes in the standard sample must be no lower than the 14th quality according to GOST 25346-82. Sample SO-1 must be made of organic glass of the TOSP brand according to GOST 17622-72. The propagation speed of a longitudinal ultrasonic wave at a frequency of (2.5 ± 0.2) MHz at a temperature of (20 ± 5) °C should be equal to (2670 ± 133) m/s. The velocity value measured with an error of no worse than 0.5% must be indicated in the passport for the sample. The amplitude of the third bottom pulse across the thickness of the sample at a frequency of (2.5 ± 0.2) MHz and temperature (20 ± 5) °C should not differ more than ± 2 dB from the amplitude of the third bottom pulse in the corresponding original sample, certified by the state metrological service. The attenuation coefficient of the longitudinal ultrasonic wave in the original sample should be in the range from 0.026 to 0.034 mm -1. It is allowed to use samples made of organic glass according to the drawing. 1, in which the amplitude of the third bottom pulse along the thickness of the sample differs from the amplitude of the corresponding pulse in the original sample by more than ± 2 dB. In this case, as well as in the absence of the original sample, the certified sample must be accompanied by a certificate schedule in accordance with the mandatory Appendix 2 or a table of corrections taking into account the spread of the attenuation coefficient and the influence of temperature. 1.4.2. The standard sample SO-2 (see Fig. 2) is used to determine the conditional sensitivity, dead zone, depth gauge error, beam entry angle a, width of the main lobe of the radiation pattern, pulse conversion coefficient when testing connections made of low-carbon and low-alloy steels, as well as for determining the maximum sensitivity.

1 - hole for determining the beam input angle, the width of the main lobe of the radiation pattern, conditional and maximum sensitivity; 2 - hole for checking the dead zone; 3- converter; 4 - block made of steel grade 20 or steel grade 3.

Sample CO-2 must be made of steel grade 20 according to GOST 1050-88 or steel grade 3 according to GOST 14637-79. The speed of propagation of a longitudinal wave in a sample at a temperature of (20 ± 5) °C should be equal to (5900 ± 59) m/s. The speed value measured with an error of no worse than 0.5% must be indicated in the sample passport. When testing connections made of metals that differ in acoustic characteristics from low-carbon and low-alloy steels, the standard SO-2A sample should be used to determine the beam entry angle, the width of the main lobe of the radiation pattern, the dead zone, and the maximum sensitivity (Fig. 3). Requirements for sample material, number of holes 2 and distances l 1, which determines the center of holes 2 in sample SO-2A, must be indicated in the technical documentation for control.

1 - hole for determining the beam input angle, the width of the main lobe of the radiation pattern, conditional and maximum sensitivity; 2 - hole for checking the dead zone; 3 - converter; 4 - block of controlled metal; 5 - scale; 6 - screw.

The beam entry angle scales for standard samples CO-2 and CO-2A are calibrated in accordance with the equation

l = H tg a,

Where N- depth of location of the center of the hole 1. The zero of the scale must coincide with the axis passing through the center of the hole with a diameter of (6 + 0.3) mm perpendicular to the working surfaces of the sample, with an accuracy of ± 0.1 mm.1.4.3. The propagation time of ultrasonic vibrations in the forward and reverse directions, indicated on standard samples SO-1 and SO-2, should be (20 ± 1) μs. 1.4.4. Standard sample CO-3 (see Fig. 4) should be used to determine the exit point 0 of the ultrasonic beam, arrow n transducer. It is allowed to use a standard sample CO-3 to determine the propagation time of ultrasonic vibrations in the prism of the transducer according to reference Appendix 3. The standard sample CO-3 is made of steel grade 20 according to GOST 1050-88 or steel grade 3 according to GOST 14637-89. The speed of propagation of a longitudinal wave in a sample at a temperature of (20 ± 5) °C should be (5900 ± 59) m/s. The speed value measured with an error of no worse than 0.5% must be indicated in the sample passport. Marks must be engraved on the side and working surfaces of the sample, passing through the center of the semicircle and along the axis of the working surface. On both sides of the marks, scales are applied to the side surfaces. The scale zero must coincide with the center of the sample with an accuracy of ± 0.1 mm. When testing connections made of metal, the speed of propagation of the shear wave in which is less than the speed of propagation of the shear wave from steel grade 20, and when using a transducer with a wave incidence angle close to the second critical angle in steel grade 20, the transducer should be used to determine the exit point and boom of the transducer standard sample of the enterprise SO-3A, made of controlled metal according to drawing. 4.

Requirements for metal sample SO-3A must be specified in the technical documentation for control, approved in the prescribed manner. 1.5. It is allowed to use sample SO-2R in accordance with GOST 18576-85 or a composition of samples SO-2 and SO-2R with the introduction of additional holes with a diameter of 6 mm to determine the conditional sensitivity, depth gauge error, location of the exit point and input angle, width of the main lobe of the radiation pattern.1.6 . The flaw detector for mechanized testing must be equipped with devices that provide systematic testing of the parameters that determine the performance of the equipment. The list of parameters and the procedure for checking them must be specified in the technical documentation for control, approved in the prescribed manner. It is allowed to use standard samples or CO-1, or CO-2, or standard samples of the enterprise specified in the technical documentation for control, to check conditional sensitivity, approved in accordance with the established procedure.1.7. It is allowed to use equipment without auxiliary devices and devices to comply with scanning parameters when moving the transducer manually and to measure the characteristics of detected defects.

2. PREPARATION FOR CONTROL

2.1. The welded joint is prepared for ultrasonic testing if there are no external defects in the joint. The shape and dimensions of the heat-affected zone must allow the transducer to be moved within limits that ensure that the acoustic axis of the transducer can sound the welded joint or its part to be tested.2.2. The surface of the connection along which the converter is moved must not have dents or irregularities; metal splashes, flaking scale and paint, and contamination must be removed from the surface. When machining the connection provided for in the technological process for the manufacture of a welded structure, the surface must be no lower than Rz 40 microns according to GOST 2789-73. Requirements for permissible waviness and surface preparation are indicated in the technical documentation for control, approved in accordance with the established procedure. The permissibility of the presence of non-flaking scale, paint and contamination when testing with EMA converters is indicated in the technical documentation for control, approved in in the prescribed manner.2.3. Inspection of the heat-affected zone of the base metal within the range of movement of the converter for the absence of delaminations should be carried out in accordance with the technical documentation for inspection, approved in the prescribed manner, if metal inspection was not carried out before welding. 2.4. The welded joint should be marked and divided into sections so as to unambiguously determine the location of the defect along the length of the seam.2.5. Pipes and tanks must be free of liquid before testing with a reflected beam. It is allowed to control pipes and tanks with liquid according to the method specified in the technical documentation for control, approved in the prescribed manner.2.6. The angle of entry of the beam and the limits of movement of the transducer should be selected in such a way as to ensure sounding of the seam section with direct and once reflected beams or only with a direct beam. Direct and once reflected beams should be used to control seams whose width or leg dimensions allow sounding of the section under test with the acoustic axis of the transducer. Allowed control welded joints with a repeatedly reflected beam. 2.7. The scan duration should be set so that the largest part of the scan on the screen of the cathode ray tube corresponds to the path of the ultrasonic pulse in the metal of the controlled part of the welded joint. 2.8. Main control parameters: 1) wavelength or frequency of ultrasonic vibrations (flaw detector); 2) sensitivity; 3) position of the beam exit point (transducer boom); 4) angle of entry of the ultrasonic beam into the metal; 5) depth gauge error (coordinate measurement error); 6) dead zone; 7) range and (or) front resolution; 8) characteristics of the electroacoustic transducer; 9) minimum conditional size of a defect detected at a given scanning speed; 10) flaw detector pulse duration. List of parameters to be checked, numerical values , the methodology and frequency of their inspection must be specified in the technical documentation for control.2.9. The main parameters in accordance with clause 2.8, listings 1 - 6, should be checked against standard samples CO-1 (Fig. 1) SO-2 (or SO-2A) (drawings 2 and 3), SO-3 (drawing 4), SO-4 (Appendix 4) and a standard sample of the enterprise (drawings 5 - 8). Requirements for standard samples of the enterprise, as well as the methodology for checking the main control parameters must be specified in the technical documentation for control, approved in the prescribed manner. 2.9.1. The frequency of ultrasonic oscillations should be measured by radio engineering methods by analyzing the spectrum of the echo signal on a transducer from the concave cylindrical surface of a standard CO-3 sample or by measuring the duration of the oscillation period in the echo pulse using a broadband oscilloscope. It is possible to determine the wavelength and frequency of ultrasonic oscillations emitted by an inclined transducer, interference method according to the CO-4 sample in accordance with the recommended Appendix 4 of this standard and according to GOST 18576-85 (recommended Appendix 3). 2.9.2. Conditional sensitivity when testing using the echo method should be measured using a standard sample CO-1 in millimeters or using a standard sample CO-2 in decibels. Measurement of conditional sensitivity using a standard sample CO-1 is carried out at the temperature established in the technical documentation for control, approved in the established ok.

1 - bottom of the hole; 2 - converter; 3 - block of controlled metal; 4 - acoustic axis.

Conditional sensitivity when testing by shadow and mirror-shadow methods is measured on a defect-free section of the welded joint or on a standard sample of the enterprise in accordance with GOST 18576-85.2.9.3. The maximum sensitivity of a flaw detector with a transducer should be measured in square millimeters over the area of the bottom of 1 hole in a standard plant sample (see Figure 5) or determined from ARD (or SKH) diagrams. It is allowed to use standard samples instead of a standard plant sample with a hole with a flat bottom enterprises with segment reflectors (see Fig. 6) or standard enterprise samples with corner reflectors (see Fig. 7), or standard enterprise samples with a cylindrical hole (see Fig. 8).

1 - plane of the segment reflector; 2 - converter; 3 - block of controlled metal; 4 - acoustic axis.

The angle between the plane of the bottom of 1 hole or the plane of 1 segment and the contact surface of the sample should be (a ± 1)° (see Fig. 5 and Fig. 6).

1 - plane of the corner reflector; 2 - converter; 3 - block of controlled metal; 4 - acoustic axis.

Maximum deviations of the hole diameter in the standard sample of the enterprise according to drawing. 5 must be ± according to GOST 25347-82. Height h the segment reflector must be greater than the ultrasonic wavelength; attitude h/b segment reflector should be more than 0.4. Width b and height h the corner reflector must be longer than the ultrasonic length; attitude h/b should be more than 0.5 and less than 4.0 (see Fig. 7). Limit sensitivity ( S p) in square millimeters, measured according to a standard sample with an angular reflector of area S 1 = hb, calculated by the formula

S p = N.S. 1 ,

Where N- coefficient for steel, aluminum and its alloys, titanium and its alloys, depending on the angle e, is specified in the technical documentation for control, approved in the prescribed manner, taking into account reference Appendix 5. Cylindrical hole 1 diameter D= 6 mm for setting the maximum sensitivity must be done with a tolerance of + 0.3 mm at depth H= (44 ± 0.25) mm (see drawing 8). The maximum sensitivity of a flaw detector using a sample with a cylindrical hole should be determined in accordance with reference Appendix 6.

1 - cylindrical hole; 2 - converter; 3 - block of controlled metal; 4 - acoustic axis.

When determining the maximum sensitivity, a correction should be introduced that takes into account the difference in the cleanliness of the processing and the curvature of the surfaces of the standard sample and the controlled connection. When using diagrams, echo signals from reflectors in standard samples or CO-1, or CO-2, or CO- are used as a reference signal. 2A, or CO-3, as well as from the bottom surface or dihedral angle in the tested product or in a standard sample of the enterprise. When testing welded joints with a thickness of less than 25 mm, the orientation and dimensions of the cylindrical hole in the standard sample of the enterprise used to adjust the sensitivity are indicated in the technical control documentation approved in accordance with the established procedure. 2.9.4. The beam entry angle should be measured using standard samples SO-2 or SO-2A, or according to a standard sample of the enterprise (see Fig. 8). An insertion angle of more than 70° is measured at the control temperature. The beam insertion angle when testing welded joints with a thickness of more than 100 mm is determined in accordance with the technical documentation for testing, approved in the prescribed manner. 2.10. The characteristics of the electroacoustic transducer should be checked against the normative and technical documentation for the equipment, approved in the prescribed manner. 2.11. The minimum conditional size of a defect recorded at a given inspection speed should be determined on a standard sample of the enterprise in accordance with the technical documentation for inspection, approved in the prescribed manner. When determining the minimum conventional size, it is allowed to use radio equipment that simulates signals from defects of a given size. 2.12. The duration of the flaw detector pulse is determined using a wideband oscilloscope by measuring the duration of the echo signal at a level of 0.1.

3. CONTROL

3.1. When inspecting welded joints, pulse-echo, shadow (mirror-shadow) or shadow-echo methods should be used. When using the pulse-echo method, combined (Fig. 9), separate (Fig. 10 and 11) and separate-combined (Fig. 12 and 13) circuit diagrams for connecting the converters.

With the shadow method, a separate (Fig. 14) circuit for switching on the converters is used.

With the echo-shadow method, a separate-combined (Fig. 15) circuit for switching on the transducers is used.

Note. Fuck it. 9 - 15; G- output to the ultrasonic vibration generator; P- output to the receiver.3.2. Butt welded joints should be made according to the diagrams shown in Fig. 16 - 19, T-joints - according to the diagrams shown in Fig. 20 - 22, and overlap connections - according to the diagrams shown in Fig. 23 and 24. It is allowed to use other schemes given in the technical documentation for control, approved in the prescribed manner. 3.3. Acoustic contact of the piezoelectric transducer with the controlled metal should be created by contact or immersion (slit) methods of introducing ultrasonic vibrations. 3.4. When searching for defects, sensitivity (conditional or limiting) must exceed the specified value established in the technical documentation for control, approved in the prescribed manner. 3.5. Sounding of a welded joint is performed using the method of longitudinal and (or) transverse movement of the transducer at a constant or changing angle of beam entry. The scanning method must be established in the technical documentation for control, approved in accordance with the established procedure. 3.6. Scanning steps (longitudinal D cl or transverse D ct) are determined taking into account the specified excess of search sensitivity over evaluation sensitivity, the transducer radiation pattern and the thickness of the controlled welded joint. The method for determining the maximum scanning steps is given in recommended Appendix 7. The nominal value of the scanning step during manual testing, which must be observed during the control process, should be taken as follows:

D cl= - 1 mm; D ct= - 1 mm.

3.7. The method, basic parameters, circuits for switching on the transducers, the method of introducing ultrasonic vibrations, the sounding circuit, as well as recommendations for separating false signals and signals from defects must be specified in the technical documentation for testing, approved in the prescribed manner.

4. ASSESSMENT AND REGISTRATION OF CONTROL RESULTS

4.1. Evaluation of control results4.1.1. Assessment of the quality of welded joints based on ultrasonic testing data should be carried out in accordance with the regulatory and technical documentation for the product, approved in the prescribed manner. 4.1.2. The main measured characteristics of the identified defect are: 1) equivalent defect area S e or amplitude U d echo signal from the defect, taking into account the measured distance to it; 2) coordinates of the defect in the welded joint; 3) conditional dimensions of the defect; 4) conditional distance between defects; 5) number of defects at a certain length of the connection. Measured characteristics used to assess the quality of specific connections must be indicated in the technical documentation for control, approved in the prescribed manner. 4.1.3. The equivalent defect area should be determined from the amplitude of the echo signal by comparing it with the amplitude of the echo signal from the reflector in the sample or by using calculated diagrams, provided that their convergence with experimental data is at least 20%. 4.1.4. The conventional dimensions of the identified defect are (Fig. 25): 1) conventional length D L;2) conditional width D X;3) conditional height D H.Conventional length D L in millimeters, measured along the length of the zone between the extreme positions of the transducer, moved along the seam, oriented perpendicular to the axis of the seam. Conditional width D X in millimeters, measured along the length of the zone between the extreme positions of the transducer moved in the plane of incidence of the beam. Conditional height D H in millimeters or microseconds, measured as the difference in the depth of the defect in the extreme positions of the transducer moved in the plane of incidence of the beam. 4.1.5. When measuring conventional dimensions D L, D X, D H the extreme positions of the transducer are taken to be those at which the amplitude of the echo signal from the detected defect is either 0.5 of the maximum value, or decreases to a level corresponding to the specified sensitivity value.

It is allowed to take as extreme positions those in which the amplitude of the echo signal from the detected defect is a specified part from 0.8 to 0.2 of the maximum value. Accepted level values must be indicated when reporting control results. Conditional width D X and conditional height D H defect is measured in the cross section of the connection, where the echo signal from the defect has the greatest amplitude, at the same extreme positions of the transducer. 4.1.6. Conditional distance D l(see drawing 25) between defects, measure the distance between the extreme positions of the transducer, at which the conditional length of two adjacent defects was determined. 4.1.7. An additional characteristic of the identified defect is its configuration and orientation. To assess the orientation and configuration of the identified defect, use: 1) comparison of conditional dimensions D L and D X identified defect with calculated or measured values of conventional dimensions D L 0 and D X 0 non-directional reflector located at the same depth as the detected defect. When measuring conventional dimensions D L, D L 0 and D X, D X 0 the extreme positions of the transducer are taken to be those at which the amplitude of the echo signal is a specified part from 0.8 to 0.2 of the maximum value, specified in the technical documentation for control, approved in the prescribed manner; 2) comparison of the amplitude of the echo signal U 1 reflected from the identified defect back to the transducer closest to the seam, with the amplitude of the echo signal U 2, which has undergone mirror reflection from the inner surface of the connection and is received by two transducers (see Fig. 12); 3) comparison of the ratio of the conditional sizes of the identified defect D X/D N with the ratio of the nominal dimensions of the cylindrical reflector D X 0/D N 0 .4) comparison of the second central moments of the conventional dimensions of the identified defect and a cylindrical reflector located at the same depth as the identified defect; 5) amplitude-time parameters of wave signals diffracted at the defect; 6) spectrum of signals reflected from the defect; 7 ) determination of the coordinates of the reflecting points of the defect surface; 8) comparison of the amplitudes of the received signals from the defect and from a non-directional reflector when sounding the defect at different angles. The need, possibility and methodology for assessing the configuration and orientation of the identified defect for connections of each type and size must be specified in the technical documentation for control approved in accordance with the established procedure.4.2. Registration of control results4.2.1. The results of the control must be recorded in a journal or conclusion, or on a diagram of the welded joint, or in another document, which must indicate: the type of the inspected joint, the indices assigned to this product and the welded joint, and the length of the inspected section; technical documentation, in accordance with which inspection was performed; type of flaw detector; uninspected or incompletely inspected areas of welded joints subject to ultrasonic testing; inspection results; date of inspection; surname of the flaw detector. Additional information to be recorded, as well as the procedure for drawing up and storing the log (conclusions) must be specified in the technical documentation for control, approved in accordance with the established procedure. 4.2.2. Classification of butt welded joints based on the results of ultrasonic testing is carried out according to the mandatory Appendix 8. The need for classification is specified in the technical documentation for testing, approved in the prescribed manner. 4.2.3. In an abbreviated description of the inspection results, each defect or group of defects should be indicated separately and designated: by a letter that determines the qualitative assessment of the admissibility of the defect based on the equivalent area (echo signal amplitude) and conditional length (A, or D, or B, or DB); a letter, defining the qualitatively conditional extent of the defect, if it is measured in accordance with clause 4.7, listing 1 (D or E); a letter defining the configuration of the defect, if installed; a number defining the equivalent area of the identified defect, mm 2, if it was measured; a number , which determines the greatest depth of the defect, mm; a number that determines the conditional length of the defect, mm; a number that determines the conditional width of the defect, mm; a number that determines the conditional height of the defect, mm or μs. 4.2.4. For the abbreviated recording, the following designations should be used: A - defect, the equivalent area (echo signal amplitude) and the conditional extent of which are equal to or less than the permissible values; D - defect, the equivalent area (echo signal amplitude) of which exceeds the permissible value; B - defect , the conditional length of which exceeds the permissible value; Г - defects, the conditional length of which is D L£ D L 0 ;E - defects, the nominal length of which is D L> D L 0 ;B - group of defects spaced from each other at distances D l£ D L 0 ;T - defects that are detected when the transducer is positioned at an angle to the weld axis and are not detected when the transducer is positioned perpendicular to the weld axis. The conditional length for defects of types G and T is not indicated. In the abbreviated notation, numerical values are separated from each other and from letter ones designations with a hyphen. The need for abbreviated notation, the designations used and the order of their recording are specified in the technical documentation for control, approved in the prescribed manner.

5. SAFETY REQUIREMENTS

5.1. When carrying out work on ultrasonic testing of products, the flaw detector must be guided by GOST 12.1.001-83, GOST 12.2.003-74, GOST 12.3.002-75, rules for the technical operation of consumer electrical installations and technical safety rules for the operation of consumer electrical installations, approved by Gosenergonadzor.5.2. When performing control, the requirements of “Sanitary norms and rules for working with equipment that creates ultrasound transmitted by contact to the hands of workers” No. 2282-80, approved by the USSR Ministry of Health, and the safety requirements set out in the technical documentation for the equipment used, approved in the established ok.5.3. The noise levels generated at the flaw detector's workplace should not exceed those allowed according to GOST 12.1.003-83.5.4. When organizing control work, fire safety requirements in accordance with GOST 12.1.004-85 must be observed.

ANNEX 1
Information

EXPLANATION OF TERMS USED IN THE STANDARD

	Definition
Defect	One discontinuity or a group of concentrated discontinuities, not provided for in the design and technological documentation and independent in its impact on the object from other discontinuities
Maximum sensitivity of control using the echo method	Sensitivity, characterized by the minimum equivalent area (in mm2) of the reflector that is still detectable at a given depth in the product for a given equipment setting
Conditional sensitivity of control using the echo method	Sensitivity, characterized by the size and depth of detected artificial reflectors made in a sample from a material with certain acoustic properties. When ultrasonic testing of welded joints, conditional sensitivity is determined using standard sample SO-1, or standard sample SO-2, or standard sample SO-2R. Conditional sensitivity according to the standard sample SO-1 is expressed by the greatest depth (in millimeters) of the location of the cylindrical reflector, fixed by flaw detector indicators. Conditional sensitivity according to the standard sample SO-2 (or SO-2R) is expressed by the difference in decibels between the attenuator reading at a given flaw detector setting and the reading corresponding to the maximum attenuation at which a cylindrical hole with a diameter of 6 mm at a depth of 44 mm is recorded by flaw detector indicators
Acoustic axis	According to GOST 23829-85
Exit point	According to GOST 23829-85
Converter boom	According to GOST 23829-85
Entry angle	The angle between the normal to the surface on which the transducer is installed and the line connecting the center of the cylindrical reflector with the exit point when the transducer is installed in the position at which the amplitude of the echo signal from the reflector is greatest
Dead zone	According to GOST 23829-85
Range resolution (beam)	According to GOST 23829-85
Front resolution	According to GOST 23829-85
Enterprise standard sample	According to GOST 8.315-78
Industry standard sample	According to GOST 8.315-78
Input surface	According to GOST 23829-85
Contact method	According to GOST 23829-85
Immersion method	According to GOST 23829-85
Depth gauge error	Error in measuring the known distance to the reflector Where s 2 is the central moment; T- scanning path on which the moment is determined; x- coordinate along the trajectory T; U (x) - signal amplitude at a point x $ x 0 - average coordinate value for the dependence U (x): For symmetric dependencies U (x) dot x 0 coincides with the point corresponding to the maximum amplitude U (x)
The second central normalized moment s 2н of the conditional size of the defect located at depth H

APPENDIX 2
Mandatory

METHOD FOR CONSTRUCTING A CERTIFICATE GRAPH FOR A STANDARD SAMPLE FROM ORGANIC GLASS

The certification schedule establishes the connection between the conditional sensitivity () in millimeters according to the original standard sample SO-1 with the conditional sensitivity () in decibels according to the standard sample SO-2 (or SO-2R according to GOST 18576-85) and the number of the reflector with a diameter of 2 mm in the certified sample SO-1 at ultrasonic vibration frequency (2.5 ± 0.2) MHz, temperature (20 ± 5) °C and prism angles b = (40 ± 1)° or b = (50 ± 1)° for specific transducers type. In the drawing, the dots indicate the graph for the original sample CO-1.

To construct the appropriate graph for a specific certified sample SO-1, which does not meet the requirements of clause 1.4.1 of this standard, under the above conditions, determine in decibels the differences in amplitudes from reflectors No. 20 and 50 with a diameter of 2 mm in the certified sample and the amplitudes N 0 from a reflector with a diameter of 6 mm at a depth of 44 mm in sample SO-2 (or SO-2R):

Where N 0 - attenuator reading corresponding to the attenuation of the echo signal from a hole with a diameter of 6 mm in the sample CO-2 (or CO-2R) to the level at which the conditional sensitivity is assessed, dB; - attenuator reading at which the amplitude of the echo signal from the test hole with number i in the certified sample reaches the level at which the conditional sensitivity is assessed, dB. The calculated values are marked with dots on the graph field and connected by a straight line (for an example of construction, see the drawing).

EXAMPLES OF APPLICATION OF THE CERTIFICATE SCHEDULE

Inspection is carried out using a flaw detector with a transducer at a frequency of 2.5 MHz with a prism angle b = 40° and the radius of the piezoelectric plate A= 6 mm, manufactured in accordance with technical specifications approved in the prescribed manner. The flaw detector is equipped with sample SO-1, serial number, with a certificate schedule (see drawing). 1. The technical documentation for control specifies a conditional sensitivity of 40 mm. The specified sensitivity will be reproduced if the flaw detector is adjusted to hole No. 45 in sample CO-1, serial number ________. 2. The technical documentation for monitoring specifies a conditional sensitivity of 13 dB. The specified sensitivity will be reproduced if the flaw detector is adjusted to hole No. 35 in sample CO-1, serial number ________.

APPENDIX 3

Information

DETERMINATION OF THE PROPAGATION TIME OF ULTRASONIC OSCILLATIONS IN THE TRANSVERTER PRISM

Time 2 tn in microseconds of propagation of ultrasonic vibrations in the transducer prism is equal to

Where t 1 - total time between the probing pulse and the echo signal from the concave cylindrical surface in the standard CO-3 sample when the transducer is installed in the position corresponding to the maximum amplitude of the echo signal; 33.7 μs is the time of propagation of ultrasonic vibrations in a standard sample, calculated for the following parameters: sample radius - 55 mm, speed of transverse wave propagation in the sample material - 3.26 mm/μs.

APPENDIX 4 Sample SO-4 for measuring the wavelength and frequency of ultrasonic vibrations of transducers

1 - grooves; 2 - ruler; 3 - converter; 4 - block made of steel grade 20 according to GOST 1050-74 or steel grade 3 according to GOST 14637-79; the difference in the depth of the grooves at the ends of the sample ( h); sample width ( l).

The standard sample SO-4 is used to measure the wavelength (frequency) excited by converters with input angles a from 40 to 65° and a frequency from 1.25 to 5.00 MHz. Wavelength l (frequency f) are determined by the interference method based on the average value of distances D L between the four extrema of the echo signal amplitude closest to the center of the sample from parallel grooves with smoothly varying depth

Where g is the angle between the reflective surfaces of the grooves, equal to (see drawing)

Frequency f determined by the formula

f = c t/l,

Where c t- speed of propagation of a transverse wave in the sample material, m/s.

APPENDIX 5

Information

Addiction N = f(e) for steel, aluminum and its alloys, titanium and its alloys

APPENDIX 6 METHOD FOR DETERMINING THE LIMITING SENSITIVITY OF A Flaw Detector and the EQUIVALENT AREA OF A DETECTED DEFECT USING A SAMPLE WITH A CYLINDRICAL HOLE

Maximum sensitivity ( S n) in square millimeters of a flaw detector with an inclined transducer (or equivalent area Suh identified defect) is determined by a standard sample of the enterprise with a cylindrical hole or by a standard sample SO-2A or SO-2 in accordance with the expression

Where N 0 - attenuator reading corresponding to the attenuation of the echo signal from the side cylindrical hole in the standard sample of the enterprise or in the standard sample SO-2A, or SO-2 to the level at which the maximum sensitivity is assessed, dB; Nx- attenuator reading at which the maximum sensitivity of the flaw detector is assessed S n or at which the amplitude of the echo signal from the defect under study reaches the level at which the maximum sensitivity is assessed, dB; D N- the difference between the transparency coefficients of the transducer prism boundary - metal of the controlled connection and the transparency coefficient of the transducer prism boundary - metal of the enterprise standard sample or standard sample SO-2A (or SO-2), dB (D N£0). When standardizing sensitivity against a standard factory sample having the same shape and surface finish as the test compound, D N = 0;b 0 - radius of a cylindrical hole, mm; - shear wave speed in the material of the sample and the controlled connection, m/s; f- ultrasound frequency, MHz; r 1 - average path of ultrasound in the transducer prism, mm; - longitudinal wave speed in the prism material, m/s; a and b are the angle of entry of the ultrasonic beam into the metal and the angle of the transducer prism, respectively, degrees; H- depth for which the maximum sensitivity is assessed or at which the detected defect is located, mm; N 0 - depth of location of the cylindrical hole in the sample, mm; d t- transverse wave attenuation coefficient in the metal of the controlled connection and sample, mm -1. To simplify the determination of the maximum sensitivity and equivalent area, it is recommended to calculate and construct a diagram (SKH diagram) relating the maximum sensitivity S n(equivalent area Suh), conditional coefficient TO defect detectability and depth N, for which the maximum sensitivity is assessed (adjusted) or at which the identified defect is located. Convergence of calculated and experimental values S n at a = (50 ± 5)° no worse than 20%.

Construction exampleSKH -diagrams and definitions of limiting sensitivityS n and equivalent areaS uh

EXAMPLES

Inspection of seams in butt welded joints of sheets 50 mm thick made of low-carbon steel is carried out using an inclined transducer with known parameters: b, r 1 , . The frequency of ultrasonic vibrations excited by the transducer lies within the range of 26.5 MHz ± 10%. Attenuation coefficient d t= 0.001 mm -1. When measuring using a standard CO-2 sample, it was found that a = 50°. SKH diagram calculated for the stated conditions and b= 3 mm, H 0 = 44 mm according to the formula given above is shown in the drawing. Example 1. It has been determined by measurement that f= 2.5 MHz. Standardization is carried out according to a standard enterprise sample with a cylindrical hole with a diameter of 6 mm located at a depth H 0 = 44 mm; the shape and cleanliness of the sample surface corresponds to the shape and cleanliness of the surface of the controlled connection. The attenuator reading corresponding to the maximum attenuation at which an echo signal from a cylindrical hole in the sample is still registered by an audio indicator is N 0 = 38 dB. It is required to determine the maximum sensitivity for a given flaw detector setting ( Nx = N 0 =38 dB) and searching for defects at depth H= 30 mm. The desired value of the limiting sensitivity on the SKH diagram corresponds to the ordinate intersection point H= 30 mm with line K = Nx - N 0 = 0 and is S n» 5 mm 2 . It is necessary to adjust the flaw detector to maximum sensitivity S n= 7 mm 2 for the depth of the desired defects H= 65 mm, N 0 = 38 dB. Set values S n And H according to the SKH diagram corresponds K = Nx - N 0 = - 9 dB. Then Nx = K + N 0 = - 9 + 38 = 29 dB. Example 2. Measurements have shown that f= 2.2 MHz. The setting is carried out according to the standard CO-2 sample ( H 0 = 44 mm). By comparing the amplitudes of echo signals from identical cylindrical holes in the sheets of the controlled connection and in the standard CO-2 sample, it was established that D N= - 6 dB. The attenuator reading corresponding to the maximum attenuation, at which the echo signal from the cylindrical hole in CO-2 is still recorded by an audio indicator, is N 0 = 43 dB. It is required to determine the equivalent area of the identified defect. According to measurements, the depth of the defect is located H= 50 mm, and the attenuator reading, at which the echo signal from the defect is still recorded, Nx= 37 dB. The required value of the equivalent area Suh, the identified defect on the SKH diagram corresponds to the point of intersection of the ordinate H= 50 mm with line TO = Nx - (N 0+D N) = 37 - (43 - 6) = 0 dB and is Suh» 14 mm 2 .

APPENDIX 7 METHOD FOR DETERMINING THE MAXIMUM SCAN STEP

Scanning step during transverse-longitudinal movement of the transducer with parameters n£15mm and af= 15 mm MHz is determined by the nomogram shown in the drawing ( m- way of sounding).

1 - a 0 = 65°, d = 20 mm and a 0 = 50°, d = 30 mm; 2 - a 0 = 50°, d = 40 mm; 3 - a 0 = 65°, d = 30 mm; 4 - a 0 = 50°, d = 50 mm; 5 - a 0 = 50°, d = 60 mm.

Examples: 1. Given Snn /S n 0 = 6 dB, m= 0, a = 50°. According to the nomogram = 3 mm. 2. Given a = 50°, d = 40 mm, m= 1, = 4 mm. According to the nomogram Snn /S n 0 » 2 dB. The scanning step during longitudinal-transverse movement of the transducer is determined by the formula

Where i- 1, 2, 3, etc. - sequence number of the step; L i- distance from the exit point to the scanned section normal to the contact surface of the controlled object. Parameter Y determined experimentally by a cylindrical hole in a sample SO-2 or SO-2A, or by a standard sample of the enterprise. To do this, measure the nominal width of the cylindrical hole D X with a weakening of the maximum amplitude equal to Snn /S n 0 and minimum distance Lmin from the projection of the center of the reflector onto the working surface of the sample to the insertion point of the transducer located in the position at which the conditional width D was determined X. Meaning Y i calculated by the formula

Where - reduced distance from the emitter to the beam exit point in the converter.

APPENDIX 8

Mandatory

CLASSIFICATION OF DEFECTIVENESS OF BUTT WELDS ACCORDING TO THE RESULTS OF ULTRASONIC CONTROL

1. This annex applies to butt welds of main pipelines and building structures and establishes a classification of defects in butt welds of metals and their alloys with a thickness of 4 mm or more based on the results of ultrasonic testing. The appendix is a unified section of the USSR standard and the GDR standard according to the following main features: designation and name of weld defects; assignment of defects to one of the types; establishing stages of defect size; establishing defect frequency levels; establishing the length of the assessment section; establishing a defect class depending on the type of defects, size level and frequency level of defects. 2. The main measured characteristics of the identified defects are: diameter D equivalent disk reflector; defect coordinates ( H , X) in cross section (Fig. 1); conditional dimensions of the defect (see Fig. 1); echo amplitude ratio U 1 reflected from the detected defect and the echo signal U 2, which has undergone mirror reflection from the inner surface (Fig. 2); the angle g of rotation of the transducer between the extreme positions at which the maximum amplitude of the echo signal from the edge of the identified defect is reduced by half in relation to the maximum amplitude of the echo signal when the transducer is positioned perpendicular to the axis of the seam (Fig. 3).

The characteristics used to assess the quality of specific welds, the procedure and accuracy of their measurements must be established in the technical documentation for control. 3. Diameter D the equivalent disk reflector is determined using a diagram or standard (test) samples based on the maximum amplitude of the echo signal from the detected defect. 4. The conventional dimensions of the identified defect are (see Figure 1): conventional length D L; nominal width D X; nominal height D H. 5. Conditional length D L in millimeters, measured along the length of the zone between the extreme positions of the transducer, moved along the seam, oriented perpendicular to the axis of the seam. Conditional width D X in millimeters, measured along the length of the zone between the extreme positions of the transducer, moved perpendicular to the seam. Conditional height D N in millimeters (or microseconds) measured as the difference in depth values ( H 2 , N 1) location of the defect in the extreme positions of the transducer, moved perpendicular to the seam. The extreme positions of the transducer are considered to be those at which the amplitude of the echo signal from the detected defect decreases to a level that is a specified part of the maximum value and established in the technical documentation for testing, approved in the prescribed manner. Conditional width D X and conditional height D N defect is measured in the seam section, where the echo signal from the defect has the greatest amplitude at the same positions of the transducer. 6. Based on the results of ultrasonic testing, defects are classified into one of the following types: non-extended volumetric; volumetric extended; planar. 7. To determine whether a defect belongs to one of the types (Table 1), use: comparison of the conditional length D L identified defect with calculated or measured values of the conditional length D L 0 non-directional reflector at the same depth as the detected defect;

Table 1

Types of defects	Signs
Volumetric non-extended	D L£D L 0 ; U 1 > U 2 D L£D L 0 ; g ³ g 0
Volumetric extended	D L> D L 0 ; U 1 > U 2 D L> D L 0 ; g ³ g 0
Planar	U 1 < U 2

comparison of the amplitudes of the echo signal reflected from the identified defect back to the transducer closest to the seam ( U 1), with echo amplitude ( U 2), which has undergone mirror reflection from the inner surface (see Fig. 2); comparison of the ratio of the conditional sizes of the identified defect D X/D H with the ratio of the conventional dimensions of the non-directional reflector D X 0/D H 0 ; comparison of the angle g between the extreme positions of the transducer, corresponding to a decrease in the maximum amplitude of the echo signal from the edge of the defect U m twice, with the value g 0 established by the technical documentation for control. 8. Depending on the equivalent diameter ratio D identified defect to thickness s metal being welded, there are four stages of defect size, which are determined according to the drawing. 4. 9. Depending on the ratio of the total length of defects L S on the assessment section to the length of the assessment section l Four levels of defect frequency have been established, which are determined by the drawing. 5. The total length is calculated for defects of each type separately; at the same time, for volumetric extended and planar ones, their conditional extensions D are summed up L, and for volumetric non-extended ones, their equivalent diameters are summed up D .

10. The length of the evaluation section is determined depending on the thickness of the metal being welded. At s> 10 mm the evaluation area is taken equal to 10 s, but not more than 300 mm, with s £ 10 mm - equal to 100 mm. The selection of this area on the weld is made in accordance with the requirements of technical documentation for control, approved in the prescribed manner.

If the length of the controlled weld is less than the calculated length of the evaluation section, then the length of the evaluation section is taken as the length of the weld. 11. The tested sections of the seams, depending on the type of defects, their location along the cross-section, the level of defect size (first digit) and the level of defect frequency (second digit), are assigned to one of five classes in accordance with Table. 2. By agreement between the manufacturer and the consumer, it is allowed to divide the first class into subclasses. If defects of various types are detected at the evaluation site, each type is classified separately and the weld is assigned to a class with a higher number.

table 2

Types of defects	Defect classes	Defect size steps and defect frequency steps
Volumetric non-extended		11
		12; 21
		l 3; 22; 31
		23; 32
		14; 24; 33; 41; 42; 43; 44
Volumetric extended subsurface and reaching the surface		-
		-
		11
		12; 21
		13; 14; 22; 23; 24; 31; 32; 33; 34; 41; 42; 43; 44
Volumetric extended in the seam section		-
		11
		12; 21
		13; 22
		14; 23; 24; 31; 32; 33; 34; 41; 42; 43; 44
Planar		-
		-
		-
		-
		11; 12; 13; 14; 21; 22; 23; 24; 31; 32; 33; 34; 41; 42; 43; 44

If two types of defects in the evaluation area are assigned to the same class, then the weld is assigned to a class whose serial number is greater by one. The results of classifying welds by defects can be compared provided that the control is performed using the same basic parameters of ultrasonic flaw detection, and the measured characteristics of defects are determined using the same methods.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the USSR Ministry of Railways.2. PERFORMERS:A. K. Gurvich, Dr. Tech. sciences, prof.; L. I. Kuzmina(topic leaders); M. S. Melnikova; I. N. Ermolov, Dr. Tech. sciences, prof.; V. G. Shcherbinsky, Dr. Tech. sciences; V. A; Troitsky, Dr. Tech. sciences, prof.; Yu. K. Bondarenko; N.V. Khimchenko, Ph.D. tech. sciences; V. A. Bobrov, Ph.D. tech. sciences; L. M. Yablonik, Ph.D. tech. sciences; V. S. Grebennik, Ph.D. tech. sciences; Yu. A. Petnikov; N. P. Aleshin, Dr. Tech. sciences, prof.; A. K. Voshchanov, Ph.D. tech. sciences; N. A. Kusakin, Ph.D. tech. sciences; E. I. Seregin, Ph.D. tech. sciences.3. APPROVED AND ENTERED INTO EFFECT BY RESOLUTION OF THE USSR State Committee on Standards dated December 17, 1986 No. 3926. 4. Instead of GOST 14782-76, GOST 22368-77.5. The date of the first inspection is the fourth quarter of 1991, and the inspection frequency is 5 years.6. The standard takes into account the requirements of ST CMEA 2857-81 and the CMEA RecommendationsPC 5246-75.7. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

	Number of paragraph, subparagraph. transfers, applications
GOST 8.315-78	Annex 1
GOST 8.326-89	clause 1.3
GOST 12.1.001-83	clause 6.1
GOST 12.1.003-83	clause 6.4
GOST 12.1.004-85	clause 6.4
GOST 12.2.003-74	clause 6.1
GOST 12.3.002-75	clause 6.1
GOST 1050-88	clause 1.4.2, clause 1.4.4
GOST 14637-89	clause 1.4.4
GOST 17622-72	clause 1.4.1
GOST 18576-85	clause 1.5, clause 2.9.1, clause 2.9.2, appendix 2
GOST 23049-84	clause 1.1
GOST 23829-85	Annex 1
GOST 25347-82	clause 2.9.2
GOST 26266-84	clause 1.3

8. Reissue. October 1990

1. Controls. 1

2. Preparation for control. 5

3. Carrying out control. 8

4. Evaluation and registration of control results. eleven

5. Safety requirements. 13

Annex 1 Explanations of terms used in the standard. 13

Appendix 2 Methodology for constructing a certificate schedule for a standard sample of organic edema. 14

Appendix 3 Determination of the propagation time of ultrasonic vibrations in the transducer prism. 15

Appendix 4 Sample co-4 for measuring the wavelength and frequency of ultrasonic vibrations of transducers. 15

Appendix 5 Addiction n = f (e) for steel, aluminum and its alloys, titanium and its alloys. 16

Appendix 6 Methodology for determining the maximum sensitivity of a flaw detector and the equivalent area of a detected defect using a sample with a cylindrical hole. 16

Appendix 7 Method for determining the maximum scanning step. 18

Appendix 8 Classification of defects in butt welds based on the results of ultrasonic testing. 19

To ensure safe operating conditions for various objects with welded joints, all seams must be regularly inspected. Regardless of their newness or long service life, metal connections are checked by various flaw detection methods. The most effective method is ultrasound - ultrasonic diagnostics, which is superior in the accuracy of the results obtained to X-ray flaw detection, gamma flaw detection, radio flaw detection, etc.

This is far from a new method (ultrasound testing was first carried out in 1930), but it is very popular and is used almost everywhere. This is due to the fact that the presence of even small ones leads to the inevitable loss of physical properties, such as strength, and over time to the destruction of the connection and the unsuitability of the entire structure.

Theory of acoustic technology

The ultrasound wave is not perceived by the human ear, but it is the basis for many diagnostic methods. Not only flaw detection, but also other diagnostic industries use various techniques based on the penetration and reflection of ultrasonic waves. They are especially important for those industries in which the main requirement is the inadmissibility of causing harm to the object under study during the diagnostic process (for example, in diagnostic medicine). Thus, the ultrasonic method of monitoring welds is a non-destructive method of quality control and identifying the location of certain defects (GOST 14782-86).

The quality of ultrasonic testing depends on many factors, such as the sensitivity of instruments, setup and calibration, the choice of a more appropriate diagnostic method, the operator’s experience and others. Control of seams for suitability (GOST 14782-86) and approval of an object for operation is not possible without determining the quality of all types of joints and eliminating even the smallest defect.

Definition

Ultrasonic testing of welds is a non-destructive method of monitoring and searching for hidden and internal mechanical defects of unacceptable magnitude and chemical deviations from a given standard. The method of ultrasonic flaw detection (USD) is used to diagnose various welded joints. Ultrasonic testing is effective in identifying air voids, chemically non-uniform composition (slag investments in) and identifying the presence of non-metallic elements.

Principle of operation

Ultrasonic testing technology is based on the ability of high-frequency vibrations (about 20,000 Hz) to penetrate metal and be reflected from the surface of scratches, voids and other irregularities. An artificially created, directed diagnostic wave penetrates the connection being tested and, if a defect is detected, deviates from its normal propagation. The ultrasound operator sees this deviation on the instrument screens and, based on certain data readings, can characterize the identified defect. For example:

distance to the defect - based on the time of propagation of the ultrasonic wave in the material;
the relative size of the defect is based on the amplitude of the reflected pulse.

Today, industry uses five main methods of ultrasonic testing (GOST 23829 - 79), which differ only in the way they record and evaluate data:

Shadow method. It consists of controlling the reduction in the amplitude of ultrasonic vibrations of transmitted and reflected pulses.
Mirror-shadow method. Detects seam defects based on the attenuation coefficient of the reflected vibration.
Echo-mirror method or "Tandem" . It consists of using two devices that overlap in operation and approach the defect from different sides.
Delta method. It is based on monitoring ultrasonic energy re-emitted from the defect.
Echo method. Based on recording a signal reflected from a defect.

Where do the wave oscillations come from?

We carry out control

Almost all devices for diagnostics using the ultrasonic wave method are designed according to a similar principle. The main working element is a piezoelectric sensor plate made of quartz or barium titanite. The piezoelectric sensor of the ultrasound device is located in the prismatic search head (in the probe). The probe is placed along the seams and moved slowly, imparting a reciprocating movement. At this time, a high-frequency current (0.8-2.5 MHz) is supplied to the plate, as a result of which it begins to emit beams of ultrasonic vibrations perpendicular to its length.

The reflected waves are perceived by the same plate (another receiving probe), which converts them into alternating electric current and it immediately rejects the wave on the oscilloscope screen (an intermediate peak appears). During ultrasonic testing, the sensor sends alternating short pulses of elastic vibrations of different durations (adjustable value, μs) separating them with longer pauses (1-5 μs). This allows you to determine both the presence of a defect and the depth of its occurrence.

Flaw detection procedure

Paint is also removed from welding seams at a distance of 50 - 70 mm on both sides.
To obtain a more accurate ultrasound result, good transmission of ultrasonic vibrations is required. Therefore, the surface of the metal near the seam and the seam itself are treated with transformer, turbine, machine oil or grease, glycerin.
The device is pre-configured according to a certain standard, which is designed to solve a specific ultrasound problem. Control:
thicknesses up to 20 mm – standard settings (notches);
over 20 mm – DGS diagrams are adjusted;
connection quality – AVG or DGS diagrams are configured.
The finder is moved in a zigzag along the seam and at the same time they try to rotate it around its axis by 10-15 0.
When a stable signal appears on the device screen in the ultrasonic testing area, the finder is deployed as much as possible. It is necessary to search until a signal with maximum amplitude appears on the screen.
It should be clarified whether the presence of such vibration is caused by the reflection of the wave from the seams, which often happens with ultrasound.
If not, then the defect is recorded and the coordinates are recorded.
Inspection of welds is carried out in accordance with GOST in one or two passes.
T-seams (seams at 90 0) are checked using the echo method.
The flaw detector enters all the inspection results into a data table, from which it will be possible to easily re-detect the defect and eliminate it.

Sometimes, to determine the more accurate nature of the defect, the characteristics from ultrasound are not enough and it is necessary to apply more detailed studies using X-ray flaw detection or gamma flaw detection.

Scope of application of this technique when identifying defects

Ultrasound-based inspection of welds is quite clear. And with a correctly carried out weld testing method, it gives a completely comprehensive answer regarding the existing defect. But the scope of application of ultrasonic testing also has.

Using ultrasonic testing it is possible to identify the following defects:

Cracks in the heat-affected zone;
pores;
lack of weld penetration;
delamination of deposited metal;
discontinuity and lack of fusion of the seam;
fistulous defects;
sagging of the metal in the lower zone of the weld;
areas affected by corrosion,
areas with inappropriate chemical composition,
areas with distortion of geometric size.

Such ultrasonic testing can be carried out in the following metals:

copper;
austenitic steels;
and in metals that do not conduct ultrasound well.

Ultrasound is carried out within a geometric framework:

At the maximum depth of the seam – up to 10 meters.
At the minimum depth (metal thickness) - from 3 to 4 mm.
The minimum seam thickness (depending on the device) is from 8 to 10 mm.
The maximum metal thickness is from 500 to 800 mm.

The following types of seams are subject to inspection:

flat seams;
longitudinal seams;
circumferential seams;
welded joints;
T-joints;
welded

Main areas of use of this technique

Not only in industrial sectors the ultrasonic method of monitoring the integrity of seams is used. This service – ultrasound scanning – is also ordered privately during the construction or reconstruction of houses.

Ultrasound testing is most often used:

in the field of analytical diagnostics of components and assemblies;
when it is necessary to determine the wear of pipes in main pipelines;
in thermal and nuclear energy;
in mechanical engineering, oil and gas and chemical industries;
in welded joints of products with complex geometry;
in welded joints of metals with a coarse-grained structure;
when installing (connections) boilers and equipment components that are susceptible to high temperatures and pressure or the influence of various aggressive environments;
in laboratory and field conditions.

Field testing

The advantages of ultrasonic quality control of metals and welds include:

High accuracy and speed of research, as well as its low cost.
Safety for humans (unlike, for example, X-ray flaw detection).
Possibility of on-site diagnostics (due to the availability of portable ultrasonic flaw detectors).
During ultrasonic testing, it is not necessary to take the controlled part or the entire object out of service.
When performing an ultrasound scan, the object being tested is not damaged.

The main disadvantages of ultrasonic testing include:

Limited information received about the defect;
Some difficulties when working with metals with a coarse-grained structure, which arise due to strong scattering and attenuation of waves;
The need for preliminary preparation of the weld surface.

GOST R 55724-2013

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

NON-DESTRUCTIVE CONTROL. WELDED CONNECTIONS

Ultrasonic methods

Non-destructive testing. Welded joints. Ultrasonic methods

Date of introduction 2015-07-01

Preface

1 DEVELOPED by the Federal State Enterprise "Research Institute of Bridges and Flaw Detection of the Federal Agency of Railway Transport" (Research Institute of Bridges), the State Scientific Center of the Russian Federation "Open Joint Stock Company" Research and Production Association "Central Research Institute of Mechanical Engineering Technology" (JSC NPO "TsNIITMASH" "), Federal State Autonomous Institution "Research and Training Center "Welding and Control" at Moscow State Technical University named after N.E. Bauman"

2 INTRODUCED by the Technical Committee for Standardization TC 371 “Non-Destructive Testing”

3 APPROVED AND ENTERED INTO EFFECT by Order of the Federal Agency for Technical Regulation and Metrology dated November 8, 2013 N 1410-st

4 INTRODUCED FOR THE FIRST TIME

5 REPUBLICATION. April 2019

The rules for the application of this standard are established in Article 26 of the Federal Law of June 29, 2015 N 162-FZ "On Standardization in the Russian Federation" . Information about changes to this standard is published in the annual (as of January 1 of the current year) information index "National Standards", and the official text of changes and amendments is published in the monthly information index "National Standards". In case of revision (replacement) or cancellation of this standard, the corresponding notice will be published in the next issue of the monthly information index "National Standards". Relevant information, notices and texts are also posted in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet (www.gost.ru)

1 area of use

This standard establishes methods for ultrasonic testing of butt, corner, lap and T-joints with full penetration of the root of the weld, made by arc, electroslag, gas, gas press, electron beam, laser and flash butt welding or combinations thereof, in welded products made of metals and alloys for identifying the following discontinuities: cracks, lack of penetration, pores, non-metallic and metallic inclusions.

This standard does not regulate methods for determining the actual size, type and shape of identified discontinuities (defects) and does not apply to the control of anti-corrosion surfacing.

The need for and scope of ultrasonic testing, types and sizes of discontinuities (defects) to be detected are established in standards or design documentation for products.

2 Normative references

This standard uses normative references to the following standards:

GOST 12.1.001 System of occupational safety standards. Ultrasound. General safety requirements

GOST 12.1.003 System of occupational safety standards. Noise. General safety requirements

GOST 12.1.004 System of occupational safety standards. Fire safety. General requirements

GOST 12.2.003 System of occupational safety standards. Production equipment. General safety requirements

GOST 12.3.002 System of occupational safety standards. Production processes. General safety requirements

GOST 2789 Surface roughness. Parameters and characteristics

GOST 18353 * Non-destructive testing. Classification of types and methods
________________
* No longer valid. GOST R 56542-2015 is valid.

GOST 18576-96 Non-destructive testing. Railway rails. Ultrasonic methods

GOST R 55725 Non-destructive testing. Ultrasonic piezoelectric transducers. General technical requirements

GOST R 55808 Non-destructive testing. Ultrasonic transducers. Test methods

Note - When using this standard, it is advisable to check the validity of the reference standards in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or using the annual information index "National Standards", which was published as of January 1 of the current year, and on issues of the monthly information index "National Standards" for the current year. If an undated reference standard is replaced, it is recommended that the current version of that standard be used, taking into account any changes made to that version. If a dated reference standard is replaced, it is recommended to use the version of that standard with the year of approval (adoption) indicated above. If, after the approval of this standard, a change is made to the referenced standard to which a dated reference is made that affects the provision referred to, it is recommended that that provision be applied without regard to that change. If the reference standard is canceled without replacement, then the provision in which a reference to it is given is recommended to be applied in the part that does not affect this reference.

3 Terms and definitions

3.1 The following terms with corresponding definitions are used in this standard:

3.1.19 SKH diagram: Graphic representation of the dependence of the detection coefficient on the depth of a flat-bottomed artificial reflector, taking into account its size and type of transducer.

3.1.20 rejection sensitivity level: The level of sensitivity at which a decision is made to classify an identified discontinuity as a “defect”.

3.1.21 diffraction method: A method of ultrasonic testing using the reflection method, using separate transmitting and receiving transducers and based on receiving and analyzing the amplitude and/or time characteristics of wave signals diffracted by a discontinuity.

3.1.22 reference sensitivity level (fixation level): The level of sensitivity at which discontinuities are recorded and their acceptability is assessed based on their conventional size and quantity.

3.1.23 reference signal: A signal from an artificial or natural reflector in a sample of a material with specified properties or a signal that has passed through a controlled product, which is used in determining and adjusting the reference level of sensitivity and/or measured discontinuity characteristics.

3.1.24 reference sensitivity level: The sensitivity level at which the reference signal has a specified height on the flaw detector screen.

3.1.25 depth gauge error: The error in measuring the known distance to the reflector.

3.1.26 search sensitivity level: The level of sensitivity set when searching for discontinuities.

3.1.27 maximum sensitivity of control using the echo method: Sensitivity, characterized by the minimum equivalent area (in mm) of the reflector that can still be detected at a given depth in the product for a given equipment setting.

3.1.28 entry angle: The angle between the normal to the surface on which the transducer is installed and the line connecting the center of the cylindrical reflector to the beam exit point when the transducer is installed in the position at which the amplitude of the echo signal from the reflector is greatest.

3.1.29 conditional size (length, width, height) of the defect: The size in millimeters corresponding to the zone between the extreme positions of the transducer, within which the signal from a discontinuity is recorded at a given sensitivity level.

3.1.30 conventional distance between discontinuities: The minimum distance between transducer positions at which the amplitudes of echo signals from discontinuities are fixed at a given sensitivity level.

3.1.31 conditional sensitivity of control using the echo method: Sensitivity, which is determined by the CO-2 (or CO-3P) measure and is expressed by the difference in decibels between the reading of the attenuator (calibrated amplifier) at a given flaw detector setting and the reading corresponding to the maximum attenuation (gain) at which a cylindrical hole with a diameter of 6 mm at a depth 44 mm is fixed by flaw detector indicators.

3.1.32 scanning step: The distance between adjacent trajectories of movement of the transducer beam exit point on the surface of the controlled object.

3.1.33 equivalent discontinuity area: The area of a flat-bottomed artificial reflector oriented perpendicular to the acoustic axis of the transducer and located at the same distance from the input surface as the discontinuity, at which the signal values of the acoustic device from the discontinuity and the reflector are equal.

3.1.34 equivalent sensitivity: Sensitivity, expressed by the difference in decibels between the gain value at a given flaw detector setting and the gain value at which the amplitude of the echo signal from the reference reflector reaches a specified value along the y-axis of the Type A scan.

4 Symbols and abbreviations

4.1 The following symbols are used in this standard:

I - emitter;

P - receiver;

Conditional height of the defect;

Conditional length of the defect;

Conditional distance between defects;

Conditional defect width;

Sensitivity is extreme;

Transverse scanning step;

Longitudinal scanning step.

4.2 The following abbreviations are used in this standard:

BCO - side cylindrical hole;

BUT - tuning sample;

PET - piezoelectric transducer;

Ultrasound - ultrasound (ultrasonic);

UZK - ultrasonic testing;

EMAT - electromagnetoacoustic transducer.

5 General provisions

5.1 When ultrasonic testing of welded joints, methods of reflected radiation and transmitted radiation are used in accordance with GOST 18353, as well as their combinations, implemented by methods (variants of methods), sounding schemes regulated by this standard.

5.2 When ultrasonic testing of welded joints, the following types of ultrasonic waves are used: longitudinal, transverse, surface, longitudinal subsurface (head).

5.3 For ultrasonic inspection of welded joints, the following inspection means are used:

- Ultrasonic pulse flaw detector or hardware-software complex (hereinafter referred to as flaw detector);

- converters (PEP, EMAP) in accordance with GOST R 55725 or non-standardized converters (including multi-element ones), certified (calibrated) taking into account the requirements of GOST R 55725;

- measures and/or BUT for setting up and checking flaw detector parameters.

Additionally, auxiliary devices and devices can be used to maintain scanning parameters, measure the characteristics of identified defects, evaluate roughness, etc.

5.4 Flaw detectors with transducers, measures, NO, auxiliary devices and devices used for ultrasonic testing of welded joints must provide the ability to implement ultrasonic testing methods and techniques from those contained in this standard.

5.5 Measuring instruments (flaw detectors with transducers, measures, etc.) used for ultrasonic testing of welded joints are subject to metrological support (control) in accordance with current legislation.

5.6 Technological documentation for ultrasonic testing of welded joints should regulate: types of controlled welded joints and requirements for their testability; requirements for the qualifications of personnel performing ultrasonic testing and quality assessment; the need for ultrasonic testing of the heat-affected zone, its dimensions, control methods and quality requirements; control zones, types and characteristics of defects to be detected; control methods, types of means and auxiliary equipment used for control; values of the main control parameters and methods for setting them; sequence of operations; ways to interpret and record results; criteria for assessing the quality of objects based on ultrasonic inspection results.

6 Control methods, sound patterns and methods of scanning welded joints

6.1 Control methods

When ultrasonic testing of welded joints, the following testing methods (variants of methods) are used: pulse-echo, mirror-shadow, echo-shadow, echo-mirror, diffraction, delta (Figures 1-6).

It is allowed to use other methods of ultrasonic testing of welded joints, the reliability of which has been confirmed theoretically and experimentally

Ultrasound testing methods are implemented using converters connected in combined or separate circuits.

Figure 1 - Pulse echo

Figure 2 - Mirror-shadow

Figure 3 - Echo-shadow straight (a) and inclined (b) probe

Figure 4 - Echo-mirror

Figure 5 - Diffraction

Figure 6 - Variants of the delta method

6.2 Sounding diagrams for various types of welded joints

6.2.1 Ultrasonic testing of butt welded joints is performed with straight and inclined transducers using sounding schemes with direct, single-reflected, double-reflected beams (Figures 7-9).

It is allowed to use other sounding schemes given in the technological documentation for control.

Figure 7 - Scheme of sounding a butt welded joint with a direct beam

Figure 8 - Scheme of sounding a butt welded joint with a single-reflected beam

Figure 9 - Scheme of sounding a butt welded joint with a doubly reflected beam

6.2.2 Ultrasonic testing of T-weld joints is performed with direct and inclined transducers using direct and (or) single-reflected beam sounding schemes (Figures 10-12).

Note - In the figures, the symbol indicates the direction of sounding by the inclined probe “from the observer”. With these schemes, sounding is performed in the same way in the direction “towards the observer”.

Figure 10 - Schemes for sounding a T-weld joint with direct (a) and single-reflected (b) beams

Figure 11 - Schemes for sounding a T-weld joint with a direct beam

Figure 12 - Scheme of sounding a T-weld joint with inclined transducers according to a separate scheme (H-lack of penetration)

6.2.3 Ultrasonic testing of corner welded joints is performed with straight and inclined transducers using direct and (or) single-reflected beam sounding schemes (Figures 13-15).

It is allowed to use other schemes given in the technological control documentation.

Figure 13 - Scheme of sounding a fillet welded joint using combined inclined and direct transducers

Figure 14 - Scheme of sounding a fillet welded joint with double-sided access using combined inclined and direct transducers, subsurface (head) wave transducers

Figure 15 - Scheme of sounding a fillet welded joint with one-sided access using combined inclined and direct transducers, subsurface (head) wave transducers

6.2.4 Ultrasonic inspection of lap welded joints is performed with inclined transducers using the sounding circuits shown in Figure 16.

Figure 16 - Scheme for sounding a lap welded joint using combined (a) or separate (b) schemes

6.2.5 Ultrasonic inspection of welded joints in order to detect transverse cracks (including in joints with a removed weld bead) is performed with inclined transducers using the sounding circuits shown in Figures 13, 14, 17.

Figure 17 - Scheme of sounding butt welded joints during inspection to search for transverse cracks: a) - with the weld bead removed; b) - with the seam bead not removed

6.2.6 Ultrasonic testing of welded joints in order to identify discontinuities located near the surface along which scanning is performed is performed using longitudinal subsurface (head) waves or surface waves (for example, Figures 14, 15).

6.2.7 Ultrasonic inspection of butt welded joints at the intersections of seams is performed with inclined transducers using the sounding circuits shown in Figure 18.

Figure 18 - Schemes for sounding the intersections of butt welded joints

6.3 Scanning methods

6.3.1 Scanning of a welded joint is performed using the method of longitudinal and (or) transverse movement of the transducer at constant or changing angles of beam entry and rotation. The scanning method, the direction of sounding, the surfaces from which sounding is carried out must be established taking into account the purpose and testability of the connection in the technological documentation for testing.

6.3.2 When ultrasonic testing of welded joints, transverse-longitudinal (Figure 19) or longitudinal-transverse (Figure 20) scanning methods are used. It is also possible to use the swing beam scanning method (Figure 21).

Figure 19 - Options for the transverse-longitudinal scanning method

Figure 20 - Transverse-longitudinal scanning method

Figure 21 - Swinging beam scanning method

7 Requirements for controls

7.1 Flaw detectors used for ultrasonic testing of welded joints must provide adjustment of the gain (attenuation) of signal amplitudes, measurement of the ratio of signal amplitudes throughout the entire range of gain (attenuation) adjustment, measurement of the distance traveled by the ultrasonic pulse in the test object to the reflecting surface, and the coordinates of the location of the reflecting surface relative to the beam exit point.

7.2 Transducers used in conjunction with flaw detectors for ultrasonic testing of welded joints must provide:

- deviation of the operating frequency of ultrasonic oscillations emitted by the transducers from the nominal value - no more than 20% (for frequencies no more than 1.25 MHz), no more than 10% (for frequencies above 1.25 MHz);

- deviation of the beam input angle from the nominal value - no more than ±2°;

- deviation of the beam exit point from the position of the corresponding mark on the transducer is no more than ±1 mm.

The shape and dimensions of the transducer, the values of the inclined transducer boom and the average ultrasonic path in the prism (protector) must comply with the requirements of the technological documentation for control.

7.3 Measures and settings

7.3.1 When ultrasonic testing of welded joints, measures and/or ND are used, the scope of application and verification (calibration) conditions of which are specified in the technological documentation for ultrasonic testing.

7.3.2 Measures (calibration samples) used for ultrasonic testing of welded joints must have metrological characteristics that ensure repeatability and reproducibility of measurements of echo signal amplitudes and time intervals between echo signals, according to which the basic parameters of ultrasonic testing, regulated by technological documentation, are adjusted and checked at UZK.

As measures for setting up and checking the basic parameters of ultrasonic testing with transducers with a flat working surface at a frequency of 1.25 MHz and more, you can use samples SO-2, SO-3, or SO-3R in accordance with GOST 18576, the requirements for which are given in Appendix A.

7.3.3 NO used for ultrasonic testing of welded joints must provide the ability to configure time intervals and sensitivity values specified in the technological documentation for ultrasonic testing, and have a passport containing the values of geometric parameters and ratios of the amplitudes of echo signals from reflectors in the NO and measures, and also identification data of the measures used in the certification.

As a reference for setting up and checking the basic parameters of ultrasonic testing, samples with flat-bottomed reflectors, as well as samples with BCO, segment or corner reflectors are used.

It is also allowed to use calibration samples V1 according to ISO 2400:2012, V2 according to ISO 7963:2006 (Appendix B) or their modifications, as well as samples made from test objects with structural reflectors or alternative reflectors of arbitrary shape, as ND.

8 Preparation for control

8.1 The welded joint is prepared for ultrasonic inspection if there are no external defects in the joint. The shape and dimensions of the heat-affected zone must allow the transducer to be moved within the limits determined by the degree of testability of the connection (Appendix B).

8.2 The surface of the connection on which the converter is moved must not have dents or irregularities; splashes of metal, flaking scale and paint, and dirt must be removed from the surface.

When machining a joint as provided for in the technological process for manufacturing a welded structure, the surface roughness must be no worse than 40 microns according to GOST 2789.

Requirements for surface preparation, permissible roughness and waviness, methods for measuring them (if necessary), as well as the presence of non-flaking scale, paint and surface contamination of the test object are indicated in the technological documentation for control.

8.3 Non-destructive testing of the heat-affected zone of the base metal for the absence of delaminations that impede ultrasonic testing with an inclined transducer is carried out in accordance with the requirements of the technological documentation.

8.4 The welded joint should be marked and divided into sections so as to unambiguously determine the location of the defect along the length of the seam.

8.5 Pipes and tanks must be free of liquid before testing with a reflected beam.

It is allowed to control pipes, tanks, ship hulls with liquid under the bottom surface using methods regulated by technological control documentation.

8.6 Basic control parameters:

a) frequency of ultrasonic vibrations;

b) sensitivity;

c) position of the beam exit point (boom) of the transducer;

d) angle of beam entry into the metal;

e) coordinate measurement error or depth gauge error;

e) dead zone;

g) resolution;

i) the opening angle of the radiation pattern in the plane of wave incidence;

j) scanning step.

8.7 The frequency of ultrasonic vibrations should be measured as the effective frequency of the echo pulse in accordance with GOST R 55808.

8.8 The main parameters for items b)-i) 8.6 should be configured (checked) using measures or BUT.

8.8.1 Conditional sensitivity for echo-pulse ultrasonic testing should be adjusted according to CO-2 or CO-3P measures in decibels.

The conditional sensitivity for mirror-shadow ultrasonic testing should be adjusted on a defect-free area of the welded joint or on the NO in accordance with GOST 18576.

8.8.2 The maximum sensitivity for echo-pulse ultrasonic testing should be adjusted according to the area of the flat-bottomed reflector in the NO or according to the ARD, SKH - diagrams.

It is allowed, instead of a non-reflective device with a flat-bottomed reflector, to use a non-reflective device with segmental, corner reflectors, BCO or other reflectors. The method for setting the maximum sensitivity for such samples should be regulated in the technological documentation for ultrasonic testing. Moreover, for a NO with a segmented reflector

where is the area of the segment reflector;

and for NO with a corner reflector

where is the area of the corner reflector;

- coefficient, the values of which for steel, aluminum and its alloys, titanium and its alloys are shown in Figure 22.

When using ARD and SKH diagrams, echo signals from reflectors in measures CO-2, CO-3, as well as from the bottom surface or dihedral angle in the controlled product or in the NO are used as a reference signal.

Figure 22 - Graph for determining the correction to the maximum sensitivity when using a corner reflector

8.8.3 The equivalent sensitivity for echo-pulse ultrasonic testing should be adjusted according to the NO, taking into account the requirements of 7.3.3.

8.8.4 When adjusting the sensitivity, a correction should be introduced that takes into account the difference in the state of the surfaces of the measure or reference and the controlled connection (roughness, presence of coatings, curvature). Methods for determining corrections must be indicated in the technological documentation for control.

8.8.5 The beam entry angle should be measured according to measures or BUT at an ambient temperature corresponding to the control temperature.

The angle of beam entry when testing welded joints with a thickness of more than 100 mm is determined in accordance with the technological documentation for testing.

8.8.6 The coordinate measurement error or the depth gauge error, the dead zone, the opening angle of the radiation pattern in the plane of wave incidence should be measured using SO-2, SO-3R or HO measures.

9 Carrying out control

9.1 Sounding of a welded joint is performed according to the diagrams and methods given in Section 6.

9.2 Acoustic contact of the probe with the controlled metal should be created by contact, or immersion, or slot methods of introducing ultrasonic vibrations.

9.3 Scanning steps are determined taking into account the specified excess of the search sensitivity level over the control sensitivity level, the directional pattern of the transducer and the thickness of the controlled welded joint, while the scanning step should be no more than half the size of the active element of the probe in the direction of the step.

9.4 When carrying out ultrasonic testing, the following sensitivity levels are used: reference level; reference level; rejection level; search level.

The quantitative difference between sensitivity levels should be regulated by technological documentation for control.

9.5 The scanning speed during manual ultrasonic testing should not exceed 150 mm/s.

9.6 To detect defects located at the ends of the connection, you should additionally sound the zone at each end, gradually turning the transducer towards the end at an angle of up to 45°.

9.7 When ultrasonic inspection of welded joints of products with a diameter of less than 800 mm, the control zone should be adjusted using artificial reflectors made in NO, having the same thickness and radius of curvature as the product being tested. The permissible deviation along the radius of the sample is no more than 10% of the nominal value. When scanning along an external or internal surface with a radius of curvature of less than 400 mm, the prisms of the inclined probes must correspond to the surface (be ground in). When monitoring RS probes and direct probes, special attachments should be used to ensure constant orientation of the probe perpendicular to the scanning surface.

Processing (grinding) of the probe must be carried out in a device that prevents the probe from being skewed relative to the normal to the input surface.

Features of setting the main parameters and monitoring cylindrical products are indicated in the technological documentation for ultrasonic testing.

9.8 The scanning stage during mechanized or automated ultrasonic testing using special scanning devices should be performed taking into account the recommendations of the equipment operating manuals.

10 Measurement of defect characteristics and quality assessment

10.1 The main measured characteristics of the identified discontinuity are:

- the ratio of the amplitude and/or time characteristics of the received signal and the corresponding characteristics of the reference signal;

- equivalent discontinuity area;

- coordinates of discontinuity in the welded joint;

- conventional dimensions of discontinuity;

- conventional distance between discontinuities;

- the number of discontinuities at a certain length of the connection.

The measured characteristics used to assess the quality of specific compounds must be regulated by technological control documentation.

10.2 The equivalent area is determined by the maximum amplitude of the echo signal from the discontinuity by comparing it with the amplitude of the echo signal from the reflector in the NO or by using calculated diagrams, provided that their convergence with experimental data is at least 20%.

10.3 The following can be used as conditional dimensions of the identified discontinuity: conditional length; conditional width ; conditional height (Figure 23).

The conditional length is measured by the length of the zone between the extreme positions of the transducer, moved along the seam and oriented perpendicular to the axis of the seam.

The conventional width is measured by the length of the zone between the extreme positions of the transducer moved in the plane of incidence of the beam.

The conditional height is determined as the difference in the measured values of the depth of the discontinuity in the extreme positions of the transducer moved in the plane of incidence of the beam.

10.4 When measuring conventional dimensions , , the extreme positions of the transducer are taken to be those at which the amplitude of the echo signal from the detected discontinuity is either 0.5 of the maximum value (relative measurement level - 0.5), or corresponds to a given sensitivity level.

It is allowed to measure the conventional sizes of discontinuities at values of the relative measurement level from 0.8 to 0.1, if this is indicated in the technological documentation for the ultrasonic testing.

The conditional width and conditional height of an extended discontinuity are measured in the section of the connection where the echo signal from the discontinuity has the greatest amplitude, as well as in sections located at distances specified in the technological documentation for control.

Figure 23 - Measurement of conventional sizes of defects

10.5 The conventional distance between discontinuities is measured by the distance between the extreme positions of the transducer. In this case, the extreme positions are set depending on the length of the discontinuities:

- for a compact discontinuity (, where is the conditional length of a non-directional reflector located at the same depth as the discontinuity), the position of the transducer at which the amplitude of the echo signal is maximum is taken as the extreme position;

- for an extended discontinuity (), the position of the transducer at which the amplitude of the echo signal corresponds to the specified level of sensitivity is taken as the extreme position.

10.6 Welded joints in which the measured value of at least one characteristic of the identified defect is greater than the rejection value of this characteristic specified in the technological documentation do not meet the requirements of ultrasonic testing.

11 Registration of control results

11.1 The results of the ultrasonic testing must be reflected in the working, accounting and acceptance documentation, the list and forms of which are accepted in the prescribed manner. The documentation must contain information:

- about the type of joint being monitored, the indices assigned to the product and the welded joint, the location and length of the section subject to ultrasonic testing;

- technological documentation in accordance with which ultrasonic testing is performed and its results are evaluated;

- date of control;

- identification data of the flaw detector;

- type and serial number of the flaw detector, converters, measures, NO;

- uncontrolled or incompletely controlled areas subject to ultrasonic testing;

- results of ultrasonic testing.

11.2 Additional information to be recorded, the procedure for preparing and storing the journal (conclusions, as well as the form for presenting control results to the customer) must be regulated by the technological documentation for the ultrasonic testing facility.

11.3 The need for an abbreviated recording of inspection results, the designations used and the order of their recording must be regulated by the technological documentation for ultrasonic testing. For abbreviated notation, the notation according to Appendix D may be used.

12 Safety requirements

12.1 When carrying out work on ultrasonic testing of products, the flaw detector must be guided by GOST 12.1.001, GOST 12.2.003, GOST 12.3.002, rules for the technical operation of consumer electrical installations and technical safety rules for the operation of consumer electrical installations, approved by Rostechnadzor.

12.2 When performing monitoring, the requirements and safety requirements set out in the technical documentation for the equipment used, approved in the prescribed manner, must be observed.

12.3 The noise levels generated at the flaw detector’s workplace must not exceed those permitted by GOST 12.1.003.

12.4 When organizing control work, fire safety requirements in accordance with GOST 12.1.004 must be observed.

Appendix A (mandatory). Measures SO-2, SO-3, SO-3R for checking (adjusting) the basic parameters of ultrasonic testing

Appendix A
(required)

A.1 Measures SO-2 (Figure A.1), SO-3 (Figure A.2), SO-3R according to GOST 18576 (Figure A.3) should be made of grade 20 steel and used for measurement (adjustment) and checking the basic parameters of equipment and monitoring with converters with a flat working surface at a frequency of 1.25 MHz and more.

Figure A.1 - Sketch of CO-2 measure

Figure A.2 - Sketch of measure CO-3

Figure A.3 - Sketch of measure SO-3R

A.2 The CO-2 measure should be used to adjust the conditional sensitivity, as well as to check the dead zone, depth gauge error, beam entry angle, opening angle of the main lobe of the radiation pattern in the plane of incidence and determining the maximum sensitivity when inspecting steel joints.

A.3 When testing connections made of metals that differ in acoustic characteristics from carbon and low-alloy steels (in terms of longitudinal wave propagation speed by more than 5%) to determine the beam entry angle, the opening angle of the main lobe of the radiation pattern, the dead zone, as well as the maximum sensitivity NO SO-2A, made of controlled material, must be used.

A.4 The CO-3 measure should be used to determine the exit point of the transducer beam and boom.

A.5 Measure СО-3Р should be used to determine and configure the main parameters listed in 8.8 for measures СО-2 and СО-3.

Appendix B (for reference). Adjustment samples for checking (adjusting) the main parameters of ultrasonic testing

Appendix B
(informative)

B.1 NO with a flat-bottomed reflector is a metal block made of a controlled material, in which a flat-bottomed reflector is made, oriented perpendicular to the acoustic axis of the transducer. The depth of the flat-bottomed reflector must comply with the requirements of the technological documentation.

1 - bottom of the hole; 2 - converter; 3 - block made of controlled metal; 4 - acoustic axis

Figure B.1 - Sketch of a NO with a flat-bottomed reflector

B.2 HO V1 according to ISO 2400:2012 is a metal block (Figure B.1) made of carbon steel into which a 50 mm diameter cylinder made of plexiglass is pressed.

HO V1 is used to adjust the scanning parameters of the flaw detector and depth gauge, adjust sensitivity levels, as well as evaluate the dead zone, resolution, determine the exit point of the beam, the boom and the angle of entry of the transducer.

B.3 HO V2 according to ISO 7963:2006 is made of carbon steel (Figure B.2) and is used to adjust the depth gauge, adjust sensitivity levels, determine the beam exit point, boom and transducer entry angle.

Figure B.2 - Sketch of NO V1

Figure B.3 - Sketch of NO V2

Appendix B (recommended). Degrees of testability of welded joints

For seams of welded joints, the following degrees of testability are established in descending order:

1 - the acoustic axis intersects each element (point) of the controlled section from at least two directions, depending on the requirements of the technological documentation;

2 - the acoustic axis intersects each element (point) of the controlled section from one direction;

3 - there are elements of a controlled cross-section, which, with a regulated sound pattern, the acoustic axis of the directional pattern does not intersect in any direction. In this case, the area of non-sounding areas does not exceed 20% of the total area of the controlled section and they are located only in the subsurface part of the welded joint.

Directions are considered different if the angle between the acoustic axes is at least 15°.

Any degree of testability, except 1, is established in the technological documentation for control.

In an abbreviated description of the control results, each defect or group of defects should be indicated separately and designated by a letter:

- a letter that determines the qualitative assessment of the admissibility of a defect based on the equivalent area (amplitude of the echo signal - A or D) and conditional length (B);

- a letter defining the qualitatively conventional length of the defect, if it is measured in accordance with 10.3 (D or E);

- a letter defining the configuration (volumetric - W, planar - P) of the defect, if installed;

- a figure defining the equivalent area of the identified defect, mm, if it was measured;

- a number defining the greatest depth of the defect, mm;

- a number defining the conditional length of the defect, mm;

- a number defining the conditional width of the defect, mm;

- a number defining the conditional height of the defect, mm or µs*.
________________
* The text of the document corresponds to the original. - Database manufacturer's note.

For abbreviated notation the following notations should be used:

A - defect, the equivalent area (amplitude of the echo signal) and the conditional length of which are equal to or less than the permissible values;

D - defect, the equivalent area (echo signal amplitude) of which exceeds the permissible value;

B - defect, the conditional length of which exceeds the permissible value;

Г - defect, the conditional length of which is ;

E - defect, the nominal length of which is ;

B is a group of defects spaced apart from each other;

T is a defect that, when the transducer is positioned at an angle of less than 40° to the weld axis, causes the appearance of an echo signal that exceeds the amplitude of the echo signal when the transducer is positioned perpendicular to the weld axis by the amount specified in the technical documentation for testing, approved in the prescribed manner.

The conditional length for defects of types G and T is not indicated.

In abbreviated notation, numerical values are separated from each other and from letter designations by a hyphen.

Bibliography


UDC 621.791.053:620.169.16:006.354

Key words: non-destructive testing, welded seams, ultrasonic methods

Electronic document text
prepared by Kodeks JSC and verified against:
official publication
M.: Standartinform, 2019

STATE STANDARD OF THE USSR UNION

NON-DESTRUCTIVE TESTING

WELDED CONNECTIONS

ULTRASONIC METHODS

GOST 14782-86

STATE COMMITTEE OF THE USSR
ON PRODUCT QUALITY MANAGEMENT AND STANDARDS

Moscow

STATE STANDARD OF THE USSR UNION

Date of introduction 01.01.88

The standard does not specify methods for ultrasonic testing of surfacing.

The need for ultrasonic testing, the scope of control and the size of unacceptable defects are established in standards or technical specifications for products.

Explanations of terms used in this standard are given in the reference.

1. CONTROLS

standard samples for setting up a flaw detector;

auxiliary devices and devices for observing scanning parameters and measuring the characteristics of identified defects.

Flaw detectors and standard samples used for control must be certified and verified in the prescribed manner.

It is allowed to use a flaw detector with electromagnetoacoustic transducers.

1.2. For testing, flaw detectors should be used, equipped with straight and inclined transducers, having an attenuator, which allows determining the coordinates of the location of the reflecting surface.

The attenuation stage value of the attenuator should be no more than 1 dB.

It is allowed to use flaw detectors with an attenuator, the value of the attenuation stage of which is 2 dB, flaw detectors without an attenuator with a system for automatically measuring the signal amplitude.

The use of non-standardized converters in accordance with GOST 8.326-89 is allowed.

1.3.1. Piezoelectric transducers are selected taking into account:

shape and size of the electroacoustic transducer;

prism material and the speed of propagation of longitudinal ultrasonic waves at a temperature of (20 ± 5) °C;

the average path of ultrasound in a prism.

1.3.2. The frequency of ultrasonic vibrations emitted by inclined transducers should not differ from the nominal value by more than 10% in the light range. 1.25 MHz, more than 20% up to 1.25 MHz.

1.3.3. The position of the mark corresponding to the beam exit point should not differ from the actual one by more than ± 1 mm.

1.3.4. The working surface of the transducer when testing welded joints of products of cylindrical or other curved shape must comply with the requirements of technical documentation for testing, approved in the prescribed manner.

1.4. Standard samples SO-1 (), SO-2 () and SO-3 () should be used to measure and check the main parameters of equipment and control using the pulse-echo method and a combined circuit for connecting a piezoelectric transducer with a flat working surface at a frequency of 1.25 MHz or more, provided that the width of the converter does not exceed 20 mm. In other cases, industry (enterprise) standard samples should be used to check the basic parameters of equipment and control.

Standard sample CO-3 is made from steel grade 20 GOST 1050-88 or steel grade 3 GOST 14637-89. The speed of propagation of a longitudinal wave in a sample at a temperature of (20 ± 5) °C should be (5900 ± 59) m/s. The speed value measured with an error of no worse than 0.5% must be indicated in the sample passport.

Marks must be engraved on the side and working surfaces of the sample, passing through the center of the semicircle and along the axis of the working surface. On both sides of the marks, scales are applied to the side surfaces. The scale zero must coincide with the center of the sample with an accuracy of ± 0.1 mm.

When testing connections made of metal, the speed of propagation of the shear wave in which is less than the speed of propagation of the shear wave from steel grade 20, and when using a transducer with a wave incidence angle close to the second critical angle in steel grade 20, the transducer should be used to determine the exit point and boom of the transducer standard sample of the enterprise SO-3A, made of controlled metal according to .

Crap. 4.

Requirements for metal sample SO-3A must be specified in the technical documentation for control, approved in the prescribed manner.

1) wavelength or frequency of ultrasonic vibrations (flaw detector);

2) sensitivity;

3) position of the beam exit point (transducer boom);

4) angle of entry of the ultrasonic beam into the metal;

5) depth gauge error (coordinate measurement error);

6) dead zone;

7) range and (or) front resolution;

8) characteristics of the electroacoustic transducer;

9) the minimum conditional size of a defect detected at a given scanning speed;

10) flaw detector pulse duration.

The list of parameters to be checked, numerical values, methods and frequency of their checking must be specified in the technical documentation for control.

2.9. The main parameters in accordance with, listings 1 - 6, should be checked against standard samples CO-1 () CO-2 (or CO-2A) ( and ), CO-3 (), CO-4 () and a standard sample of the enterprise ( ).

Requirements for standard samples of the enterprise, as well as the methodology for checking the main control parameters must be specified in the technical documentation for control, approved in the prescribed manner.

It is allowed to determine the wavelength and frequency of ultrasonic vibrations emitted by an inclined transducer using the interference method using the CO-4 sample in accordance with the recommendations of this standard and GOST 18576-85 (recommended).

Measurement of conditional sensitivity according to the standard sample SO-1 is carried out at the temperature established in the technical documentation for control, approved in the prescribed manner.

1 - bottom of the hole; 2 - converter; 3 - block of controlled metal; 4 - acoustic axis.

Crap. 5.

2.9.3. The maximum sensitivity of a flaw detector with a transducer should be measured in square millimeters over the area of the bottom of 1 hole in a standard enterprise sample (see) or determined from ARD (or SKH) diagrams.

It is allowed, instead of a standard enterprise sample with a hole with a flat bottom, to use standard enterprise samples with segment reflectors (see) or standard enterprise samples with corner reflectors (see), or a standard enterprise sample with a cylindrical hole (see).

1 - plane of the segment reflector; 2 - converter; 3 - block of controlled metal; 4 - acoustic axis.

Crap. 6.

The angle between the plane of the bottom of 1 hole or the plane of 1 segment and the contact surface of the sample should be ( a± 1)° (see and ).

1 - plane of the corner reflector; 2 - converter; 3 - block of controlled metal; 4 - acoustic axis.

Crap. 7.

Maximum deviations of hole diameter in standard volume The size of the enterprise must be ± according to GOST 25347-82.

Height h the segment reflector must be greater than the ultrasonic wavelength; attitude h/b segment reflector should be more than 0.4.

Width b and height h the corner reflector must be longer than the ultrasonic length; attitude h/b should be more than 0.5 and less than 4.0 (see).

Maximum sensitivity ( S p) in square millimeters, measured according to a standard sample with an angular reflector of area S 1 = hb, calculated by the formula

S p = N.S. 1 ,

Cylindrical hole 1 diameter D= 6 mm for setting the maximum sensitivity must be done with a tolerance of + 0.3 mm at depth H= (44 ± 0.25) mm (cm).

The maximum sensitivity of a flaw detector using a sample with a cylindrical hole should be determined in accordance with the reference.

1 - cylindrical hole; 2 - converter; 3 - block of controlled metal; 4 - acoustic axis.

Crap. 8.

When determining the limiting sensitivity, a correction should be introduced to take into account the difference in the cleanliness of processing and the curvature of the surfaces of the standard sample and the controlled connection.

When using diagrams, echo signals from reflectors in standard samples or CO-1, or CO-2, or CO-2A, or CO-3 are used as a reference signal, as well as from the bottom surface or dihedral angle in the controlled product or in the standard sample enterprise.

When testing welded joints with a thickness of less than 25 mm, the orientation and dimensions of the cylindrical hole in the standard sample of the enterprise used to adjust the sensitivity are indicated in the technical documentation for testing, approved in the prescribed manner.

2.9.4. The beam entry angle should be measured using standard samples SO-2 or SO-2A, or according to a standard sample of the enterprise (see). An insertion angle greater than 70° is measured at the control temperature.

The angle of beam entry when testing welded joints with a thickness of more than 100 mm is determined in accordance with the technical documentation for testing, approved in the prescribed manner.

2.10. The characteristics of the electroacoustic transducer should be checked against the normative and technical documentation for the equipment, approved in the prescribed manner.

2.11. The minimum conditional size of a defect recorded at a given inspection speed should be determined on a standard sample of the enterprise in accordance with the technical documentation for inspection, approved in the prescribed manner.

When determining the minimum conventional size, it is allowed to use radio equipment that simulates signals from defects of a given size.

2.12. The duration of the flaw detector pulse is determined using a wideband oscilloscope by measuring the duration of the echo signal at a level of 0.1.

3. CONTROL

3.1. When inspecting welded joints, pulse-echo, shadow (mirror-shadow) or echo-shadow methods should be used.

When using the pulse-echo method, combined (), separate ( and ) and separate-combined ( and ) circuits for connecting converters are used.

Crap. 10.

Crap. eleven.

Crap. 12.

Crap. 13.

With the shadow method, a separate () circuit for switching on the converters is used.

With the echo-shadow method, a separate-combined () circuit for switching on the converters is used.

Crap. 15.

Note . On ; G- output to the ultrasonic vibration generator; P- output to the receiver.

3.2. Butt welded joints should be made according to the diagrams given on, T-joints - according to the diagrams given on, and lap joints - according to the diagrams given on and.

It is allowed to use other schemes given in the technical documentation for control, approved in the prescribed manner.

3.3. Acoustic contact of the piezoelectric transducer with the controlled metal should be created by contact or immersion (slit) methods of introducing ultrasonic vibrations.

3.4. When searching for defects, the sensitivity (conditional or limiting) must exceed the specified value established in the technical documentation for testing, approved in the prescribed manner.

3.5. Sounding of a welded joint is performed using the method of longitudinal and (or) transverse movement of the transducer at a constant or changing angle of beam entry. The scanning method must be established in the technical documentation for control, approved in the prescribed manner.

3.6. Scanning steps (longitudinal Dcl or transverse Dct) are determined taking into account the specified excess of search sensitivity over evaluation sensitivity, the transducer radiation pattern and the thickness of the controlled welded joint. The method for determining the maximum scanning steps is given in the recommended one. The nominal value of the scanning step during manual testing, which must be observed during the control process, should be taken as follows:

Dcl= - 1 mm; Dct= - 1 mm.

Crap. 16 .

Crap. 17.

Crap. 18 .

Crap. 19 .

Crap. 20 .

Crap. 21.

Crap. 22.

Crap. 23.

Crap. 24.

4. ASSESSMENT AND REGISTRATION OF CONTROL RESULTS

4.1. Evaluation of control results

4.1.1. Assessment of the quality of welded joints based on ultrasonic testing data should be carried out in accordance with the regulatory and technical documentation for the product, approved in the prescribed manner.

4.1.2. The main measured characteristics of the identified defect are:

1) equivalent defect area S e or amplitude U d echo signal from the defect, taking into account the measured distance to it;

2) coordinates of the defect in the welded joint;

3) conditional dimensions of the defect;

4) conditional distance between defects;

5) the number of defects at a certain length of the connection.

The measured characteristics used to assess the quality of specific compounds must be indicated in the technical documentation for control, approved in the prescribed manner.

4.1.3. The equivalent defect area should be determined from the amplitude of the echo signal by comparing it with the amplitude of the echo signal from the reflector in the sample or by using calculated diagrams, provided that their convergence with experimental data is at least 20%.

4.1.4. The conventional dimensions of the identified defect are ():

1) conditional length DL;

2) conditional width DX;

3) conditional height DH.

Conditional length DL in millimeters, measured along the length of the zone between the extreme positions of the transducer, moved along the seam, oriented perpendicular to the axis of the seam.

Conditional width DX in millimeters, measured along the length of the zone between the extreme positions of the transducer moved in the plane of incidence of the beam.

Conditional height DH in millimeters or microseconds, measured as the difference in the depth of the defect in the extreme positions of the transducer moved in the plane of incidence of the beam.

4.1.5. When measuring conventional dimensions DL, DX, DH the extreme positions of the transducer are taken to be those at which the amplitude of the echo signal from the detected defect is either 0.5 of the maximum value, or decreases to a level corresponding to the specified sensitivity value.

Crap. 25.

Conditional width DX and conditional height DH defect is measured in the cross section of the connection, where the echo signal from the defect has the greatest amplitude, at the same extreme positions of the transducer.

4.1.6. Conditional distance Dl(see) between defects, the distance between the extreme positions of the transducer is measured, at which the conditional length of two adjacent defects was determined.

4.1.7. An additional characteristic of the identified defect is its configuration and orientation.

To assess the orientation and configuration of the identified defect, use:

1) comparison of conventional sizes DL And DX identified defect with calculated or measured values of conventional dimensions DL 0 and DX 0 non-directional reflector located at the same depth as the detected defect.

When measuring conventional dimensions DL, DL 0 and DX, DX 0 the extreme positions of the transducer are taken to be those at which the amplitude of the echo signal is a specified part from 0.8 to 0.2 of the maximum value, specified in the technical documentation for control, approved in the prescribed manner;

2) comparison of echo amplitude U 1 reflected from the identified defect back to the transducer closest to the seam, with the amplitude of the echo signal U 2, which has undergone mirror reflection from the inner surface of the connection and is received by two transducers (see);

3) comparison of the ratio of the conditional sizes of the identified defect DX/DN with the ratio of the conventional dimensions of the cylindrical reflector DX 0 /DN 0 .

4) comparison of the second central moments of the conventional dimensions of the identified defect and a cylindrical reflector located at the same depth as the identified defect;

5) amplitude-time parameters of wave signals diffracted at the defect;

6) spectrum of signals reflected from the defect;

7) determination of the coordinates of the reflecting points of the defect surface;

8) comparison of the amplitudes of the received signals from the defect and from a non-directional reflector when the defect is sounded at different angles.

The need, possibility and methodology for assessing the configuration and orientation of the identified defect for connections of each type and size must be specified in the technical documentation for control, approved in the prescribed manner.

4.2. Registration of control results

4.2.1. The results of the control must be recorded in a journal or conclusion, or on a welded joint diagram, or in another document, which must indicate:

type of inspected joint, indices assigned to this product and welded joint, and the length of the inspected section;

technical documentation in accordance with which the control was carried out;

flaw detector type;

uninspected or incompletely inspected areas of welded joints subject to ultrasonic testing;

control results;

control date;

surname of the flaw detector.

Additional information to be recorded, as well as the procedure for preparing and storing the log (conclusions) must be specified in the technical documentation for control, approved in the prescribed manner.

4.2.2. Classification of butt welded joints based on the results of ultrasonic testing is carried out according to mandatory requirements.

The need for classification is specified in the technical documentation for control, approved in the prescribed manner.

4.2.3. In an abbreviated description of the control results, each defect or group of defects should be indicated separately and designated:

a letter that determines the qualitative assessment of the admissibility of a defect based on the equivalent area (echo signal amplitude) and conditional length (A, or D, or B, or DB);

a letter defining the qualitatively conventional length of the defect, if it is measured in accordance with clause 4.7, item 1 (G or E);

a letter defining the defect configuration, if installed;

a figure defining the equivalent area of the identified defect, mm 2, if it was measured;

a number defining the greatest depth of the defect, mm;

a number defining the conditional length of the defect, mm;

a number defining the conditional width of the defect, mm;

a number defining the conditional height of the defect, mm or μs.

4.2.4. For abbreviated notation the following notations should be used:

A - defect, the equivalent area (echo signal amplitude) and conditional length of which are equal to or less than the permissible values;

D - defect, the equivalent area (echo signal amplitude) of which exceeds the permissible value;

B - defect, the conditional length of which exceeds the permissible value;

D - defects, the nominal length of which DL £ DL 0 ;

E - defects, the nominal length of which DL > DL 0 ;

B - a group of defects spaced apart from each other Dl £ DL 0 ;

T - defects that are detected when the transducer is positioned at an angle to the seam axis and are not detected when the transducer is positioned perpendicular to the seam axis.

The conditional length for defects of types G and T is not indicated.

In abbreviated notation, numerical values are separated from each other and from letter designations by a hyphen.

The need for abbreviated notation, the designations used and the order of their recording are stipulated by the technical documentation for control, approved in the prescribed manner.

5. SAFETY REQUIREMENTS

5.2. When performing control, the requirements of “Sanitary norms and rules for working with equipment that creates ultrasound transmitted by contact to the hands of workers” No. 2282-80, approved by the USSR Ministry of Health, and the safety requirements set out in the technical documentation for the equipment used, approved in the established ok.

5.3. The noise levels created at the flaw detector's workplace must not exceed the permissible limits. GOST 12.1.003-83.

5.4. When organizing control work, fire safety requirements in accordance with GOST 12.1.004-85 must be observed.

ANNEX 1
Information

EXPLANATION OF TERMS USED IN THE STANDARD

Term	Definition
Defect	One discontinuity or a group of concentrated discontinuities, not provided for in the design and technological documentation and independent in its impact on the object from other discontinuities
Maximum sensitivity of control using the echo method	Sensitivity, characterized by the minimum equivalent area (in mm2) of the reflector that is still detectable at a given depth in the product for a given equipment setting
Conditional sensitivity of control using the echo method	Sensitivity, characterized by the size and depth of detected artificial reflectors made in a sample from a material with certain acoustic properties. When ultrasonic testing of welded joints, conditional sensitivity is determined using standard sample SO-1, or standard sample SO-2, or standard sample SO-2R. Conditional sensitivity according to the standard sample SO-1 is expressed by the greatest depth (in millimeters) of the location of the cylindrical reflector, fixed by flaw detector indicators. Conditional sensitivity according to the standard sample SO-2 (or SO-2R) is expressed by the difference in decibels between the attenuator reading at a given flaw detector setting and the reading corresponding to the maximum attenuation at which a cylindrical hole with a diameter of 6 mm at a depth of 44 mm is recorded by flaw detector indicators
Acoustic axis	According to GOST 23829-85
Exit point	According to GOST 23829-85
Converter boom	According to GOST 23829-85
Entry angle	The angle between the normal to the surface on which the transducer is installed and the line connecting the center of the cylindrical reflector with the exit point when the transducer is installed in the position at which the amplitude of the echo signal from the reflector is greatest
Dead zone	According to GOST 23829-85
Range resolution (beam)	According to GOST 23829-85
Front resolution	According to GOST 23829-85
Enterprise standard sample	According to GOST 8.315-78
Industry standard sample	According to GOST 8.315-78
Input surface	According to GOST 23829-85
Contact method	According to GOST 23829-85
Immersion method	According to GOST 23829-85
Depth gauge error	Error in measuring the known distance to the reflector Where s 2 - central moment; T- scanning path on which the moment is determined;x- coordinate along the trajectory T; U(x) - signal amplitude at a pointx$ x 0 - average coordinate value for the dependenceU(x): For symmetric dependenciesU(x) dot x 0 coincides with the point corresponding to the maximum amplitudeU(x)
Second central normalized moments2n conditional size of the defect located at depth H

APPENDIX 2
Mandatory

METHOD FOR CONSTRUCTING A CERTIFICATE GRAPH FOR A STANDARD SAMPLE FROM ORGANIC GLASS

The certification schedule establishes the connection between the conditional sensitivity () in millimeters according to the original standard sample SO-1 with the conditional sensitivity () in decibels according to the standard sample SO-2 (or SO-2R according to GOST 18576-85) and the number of the reflector with a diameter of 2 mm in the certified sample SO-1 at ultrasonic vibration frequency (2.5 ± 0.2) MHz, temperature (20 ± 5) °C and prism anglesb= (40 ± 1)° or b= (50 ± 1)° for specific type of converters.

In the drawing, the dots indicate the graph for the original sample CO-1.

To construct the appropriate graph for a specific certified sample SO-1, which does not meet the requirements of this standard, under the above conditions, the amplitude differences from reflectors No. 20 and 50 with a diameter of 2 mm in the certified sample and the amplitudes are determined in decibelsN 0 from a reflector with a diameter of 6 mm at a depth of 44 mm in sample SO-2 (or SO-2R):

Attenuator reading at which the amplitude of the echo signal from the test hole with numberiin the certified sample reaches the level at which the conditional sensitivity is assessed, dB.

The calculated values are marked with dots on the graph field and connected by a straight line (for an example of construction, see the drawing).

EXAMPLES OF APPLICATION OF THE CERTIFICATE SCHEDULE

Inspection is carried out using a flaw detector with a converter at a frequency of 2.5 MHz with a prism angleb= 40° and the radius of the piezoelectric plate A= 6 mm, manufactured in accordance with technical specifications approved in the prescribed manner.

The flaw detector is equipped with sample SO-1, serial number, with a certificate schedule (see drawing).

1. The technical documentation for control specifies a conditional sensitivity of 40 mm.

The specified sensitivity will be reproduced if the flaw detector is adjusted to hole No. 45 in sample CO-1, serial number ________.

2. The technical documentation for monitoring specifies a conditional sensitivity of 13 dB. The specified sensitivity will be reproduced if the flaw detector is adjusted to hole No. 35 in sample CO-1, serial number ________.

APPENDIX 3

Information

DETERMINATION OF THE PROPAGATION TIME OF ULTRASONIC OSCILLATIONS IN THE TRANSVERTER PRISM

Time 2 tnin microseconds of propagation of ultrasonic vibrations in the transducer prism is equal to

Where t 1 - the total time between the probing pulse and the echo signal from the concave cylindrical surface in the standard sample SO-3 when the transducer is installed in the position corresponding to the maximum amplitude of the echo signal; 33.7 μs is the time of propagation of ultrasonic vibrations in a standard sample, calculated for the following parameters: sample radius - 55 mm, speed of transverse wave propagation in the sample material - 3.26 mm/μs.

APPENDIX 4 Sample SO-4 for measuring the wavelength and frequency of ultrasonic vibrations of transducers

Standard sample CO-4 is used to measure the wavelength (frequency) excited by transducers with angles a input from 40 to 65° and frequency from 1.25 to 5.00 MHz.

Wavelength l(frequency f) is determined by the interference method based on the average value of the distances DL between the four extrema of the echo signal amplitude closest to the center of the sample from parallel grooves with smoothly varying depth

Where g- the angle between the reflective surfaces of the grooves is equal (see drawing)

Frequency fdetermined by the formula

f = c t/ l,

Where c t- speed of propagation of a transverse wave in the sample material, m/s.

APPENDIX 5

Information

Addiction N = f (e) for steel, aluminum and its alloys, titanium and its alloys

APPENDIX 6 METHOD FOR DETERMINING THE LIMITING SENSITIVITY OF A Flaw Detector and the EQUIVALENT AREA OF A DETECTED DEFECT USING A SAMPLE WITH A CYLINDRICAL HOLE

Maximum sensitivity (S n) in square millimeters of a flaw detector with an inclined transducer (or equivalent areaSuhidentified defect) is determined by a standard sample of the enterprise with a cylindrical hole or by a standard sample SO-2A or SO-2 in accordance with the expression

Nx- attenuator reading at which the maximum sensitivity of the flaw detector is assessedS nor at which the amplitude of the echo signal from the defect under study reaches the level at which the maximum sensitivity is assessed, dB;

DN- the difference between the transparency coefficients of the transducer prism boundary - the metal of the controlled connection and the transparency coefficient of the transducer prism boundary - the metal of the enterprise standard sample or the SO-2A (or SO-2) standard sample, dB (DN£ 0).

When standardizing sensitivity against a standard factory sample having the same shape and surface finish as the test compound,DN = 0;

b 0 - radius of the cylindrical hole, mm;

Shear wave speed in the material of the sample and the controlled connection, m/s;

f- ultrasound frequency, MHz;

r 1 - average path of ultrasound in the transducer prism, mm;

Longitudinal wave speed in the prism material, m/s;

a And b- angle of entry of the ultrasonic beam into the metal and angle of the transducer prism, respectively, degrees;

H- depth for which the maximum sensitivity is assessed or at which the detected defect is located, mm;

N 0 - depth of location of the cylindrical hole in the sample, mm;

dt- transverse wave attenuation coefficient in the metal of the controlled connection and sample, mm -1.

To simplify the determination of the maximum sensitivity and equivalent area, it is recommended to calculate and construct a diagram (SKH diagram) relating the maximum sensitivityS n(equivalent areaSuh), conditional coefficient TO defect detectability and depth N, for which the maximum sensitivity is assessed (adjusted) or at which the identified defect is located.

Convergence of calculated and experimental valuesS n at a= (50 ± 5)° not worse than 20%.

Construction example SKH -diagrams and definitions of limiting sensitivity S n and equivalent area S uh

EXAMPLES

When measuring using a standard CO-2 sample, it was found thata= 50°. SKH diagram calculated for the stated conditions andb= 3 mm, H 0 = 44 mm according to the formula above is shown in the drawing.

Example 1.

The measurements showed thatf= 2.5 MHz. Standardization is carried out according to a standard enterprise sample with a cylindrical hole with a diameter of 6 mm located at a depthH 0 = 44 mm; the shape and cleanliness of the sample surface corresponds to the shape and cleanliness of the surface of the controlled connection.

The attenuator reading corresponding to the maximum attenuation at which an echo signal from a cylindrical hole in the sample is still registered by an audio indicator isN 0 = 38 dB.

It is required to determine the maximum sensitivity for a given flaw detector setting (Nx = N 0 =38 dB) and searching for defects at depthH= 30 mm.

The desired value of the limiting sensitivity on the SKH diagram corresponds to the ordinate intersection pointH= 30 mm with line K = Nx - N 0 = 0 and is S n» 5 mm 2.

It is necessary to adjust the flaw detector to maximum sensitivityS n= 7 mm 2 for the depth of the desired defectsH= 65 mm, N 0 = 38 dB.

Set valuesS n And Haccording to the SKH diagram correspondsK = Nx - N 0 = - 9 dB.

Then Nx = K + N 0 = - 9 + 38 = 29 dB.

Example 2.

The measurements showed thatf= 2.2 MHz. The setting is carried out according to the standard CO-2 sample (H 0 = 44 mm). By comparing the amplitudes of echo signals from identical cylindrical holes in the sheets of the controlled connection and in the standard CO-2 sample, it was established thatDN= - 6 dB.

The attenuator reading corresponding to the maximum attenuation, at which the echo signal from the cylindrical hole in CO-2 is still recorded by an audio indicator, isN 0 = 43 dB.

It is required to determine the equivalent area of the identified defect. According to measurements, the depth of the defect is locatedH= 50 mm, and the attenuator reading, at which the echo signal from the defect is still recorded,Nx= 37 dB.

The required value of the equivalent areaSuh, detected defect on SKH -the diagram corresponds to the point of intersection of the ordinateH= 50 mm with line TO = Nx - (N 0 + DN) = 37 - (43 - 6) = 0 dB and isSuh» 14 mm 2.

APPENDIX 7 METHOD FOR DETERMINING THE MAXIMUM SCAN STEP

Scanning step during transverse-longitudinal movement of the transducer with parametersn£ 15 mm and af= 15 mm MHz is determined by the nomogram shown in the drawing (m- way of sounding).

1 - a 0 = 65°, d= 20 mm and a 0 = 50°, d= 30 mm; 2 - a 0 = 50°, d= 40 mm; 3 - a 0 = 65°, d= 30 mm; 4 - a 0 = 50°, d= 50 mm; 5 - a 0 = 50°, d= 60 mm.

Examples:

1. Given Snn/ S n 0 = 6 dB, m = 0, a= 50°. According to the nomogram = 3 mm.

2. Given a= 50°, d= 40 mm, m= 1, = 4 mm. According to the nomogramSnn/ S n 0 » 2 dB.

The scanning step during longitudinal-transverse movement of the transducer is determined by the formula

Where i- 1, 2, 3, etc. - sequence number of the step;

L i- distance from the exit point to the scanned section normal to the contact surface of the controlled object.

Parameter Ydetermined experimentally by a cylindrical hole in a sample SO-2 or SO-2A, or by a standard sample of the enterprise. To do this, measure the nominal width of the cylindrical holeDXwith a weakening of the maximum amplitude equal toSnn/ S n 0 and minimum distanceLminfrom the projection of the center of the reflector onto the working surface of the sample to the insertion point of the transducer located in the position at which the conditional width was determinedDX. Meaning Y icalculated by the formula

Where - reduced distance from the emitter to the beam exit point in the converter.

APPENDIX 8

Mandatory

CLASSIFICATION OF DEFECTIVENESS OF BUTT WELDS ACCORDING TO THE RESULTS OF ULTRASONIC CONTROL

The application is a unified section of the USSR standard and the GDR standard according to the following main features:

designation and name of weld defects;

assignment of defects to one of the types;

establishing stages of defect size;

establishing defect frequency levels;

establishing the length of the assessment section;

establishing a defect class depending on the type of defects, size level and frequency level of defects.

2. The main measurable characteristics of the identified defects are:

diameter Dequivalent disk reflector;

defect coordinates (H, X) insection();

conditional dimensions of the defect (see);

echo amplitude ratioU 1 , reflected from the detected defect, and the echo signalU 2 , which has undergone mirror reflection from the inner surface ();

corner gturning the transducer between extreme positions at which the maximum amplitude of the echo signal from the edge of the identified defect is reduced by half in relation to the maximum amplitude of the echo signal when the transducer is positioned perpendicular to the axis of the seam ().

Crap. 1 .

Crap. 2.

Crap. 3.

The characteristics used to assess the quality of specific welds, the procedure and accuracy of their measurements must be established in the technical documentation for control.

3. Diameter Dthe equivalent disk reflector is determined using a diagram or standard (test) samples based on the maximum amplitude of the echo signal from the detected defect.

4. The conventional dimensions of the identified defect are (see):

conditional lengthDL;

conventional width DX;

nominal height DH.

5. Conditional lengthDLin millimeters, measured along the length of the zone between the extreme positions of the transducer, moved along the seam, oriented perpendicular to the axis of the seam.

Conditional width DXin millimeters, measured along the length of the zone between the extreme positions of the transducer, moved perpendicular to the seam.

Conditional height DNin millimeters (or microseconds) measured as the difference in depth values (H 2 , N 1) location of the defect in the extreme positions of the transducer, moved perpendicular to the seam.

The extreme positions of the transducer are considered to be those at which the amplitude of the echo signal from the detected defect decreases to a level that is a specified part of the maximum value and established in the technical documentation for testing, approved in the prescribed manner.

1. CONTROLS

2. PREPARATION FOR CONTROL

3. CONTROL

4. ASSESSMENT AND REGISTRATION OF CONTROL RESULTS

5. SAFETY REQUIREMENTS

ANNEX 1 Information

EXPLANATION OF TERMS USED IN THE STANDARD

APPENDIX 2 Mandatory

METHOD FOR CONSTRUCTING A CERTIFICATE GRAPH FOR A STANDARD SAMPLE FROM ORGANIC GLASS

APPENDIX 3

DETERMINATION OF THE PROPAGATION TIME OF ULTRASONIC OSCILLATIONS IN THE TRANSVERTER PRISM

APPENDIX 4

Sample SO-4 for measuring the wavelength and frequency of ultrasonic vibrations of transducers

APPENDIX 5

Addiction N = f(e) for steel, aluminum and its alloys, titanium and its alloys

APPENDIX 6

METHOD FOR DETERMINING THE LIMITING SENSITIVITY OF A Flaw Detector and the EQUIVALENT AREA OF A DETECTED DEFECT USING A SAMPLE WITH A CYLINDRICAL HOLE

APPENDIX 7

METHOD FOR DETERMINING THE MAXIMUM SCAN STEP

APPENDIX 8

CLASSIFICATION OF DEFECTIVENESS OF BUTT WELDS ACCORDING TO THE RESULTS OF ULTRASONIC CONTROL

Theory of acoustic technology

Definition

Principle of operation

Where do the wave oscillations come from?

Flaw detection procedure

Scope of application of this technique when identifying defects

The advantages of ultrasonic quality control of metals and welds include:

The main disadvantages of ultrasonic testing include:

Preface

1 area of ​​use

2 Normative references

3 Terms and definitions

4 Symbols and abbreviations

5 General provisions

6 Control methods, sound patterns and methods of scanning welded joints

6.1 Control methods

6.2 Sounding diagrams for various types of welded joints

6.3 Scanning methods

7 Requirements for controls

8 Preparation for control

9 Carrying out control

10 Measurement of defect characteristics and quality assessment

11 Registration of control results

12 Safety requirements

Appendix A (mandatory). Measures SO-2, SO-3, SO-3R for checking (adjusting) the basic parameters of ultrasonic testing

Appendix B (for reference). Adjustment samples for checking (adjusting) the main parameters of ultrasonic testing

Appendix B (recommended). Degrees of testability of welded joints

Bibliography

1. CONTROLS

3. CONTROL

4. ASSESSMENT AND REGISTRATION OF CONTROL RESULTS

5. SAFETY REQUIREMENTS

ANNEX 1 Information

EXPLANATION OF TERMS USED IN THE STANDARD

APPENDIX 2 Mandatory

METHOD FOR CONSTRUCTING A CERTIFICATE GRAPH FOR A STANDARD SAMPLE FROM ORGANIC GLASS

APPENDIX 3

DETERMINATION OF THE PROPAGATION TIME OF ULTRASONIC OSCILLATIONS IN THE TRANSVERTER PRISM

APPENDIX 4

Sample SO-4 for measuring the wavelength and frequency of ultrasonic vibrations of transducers

APPENDIX 5

Addiction N = f (e) for steel, aluminum and its alloys, titanium and its alloys

APPENDIX 6

METHOD FOR DETERMINING THE LIMITING SENSITIVITY OF A Flaw Detector and the EQUIVALENT AREA OF A DETECTED DEFECT USING A SAMPLE WITH A CYLINDRICAL HOLE

APPENDIX 7

METHOD FOR DETERMINING THE MAXIMUM SCAN STEP

APPENDIX 8

CLASSIFICATION OF DEFECTIVENESS OF BUTT WELDS ACCORDING TO THE RESULTS OF ULTRASONIC CONTROL

ANNEX 1
Information

APPENDIX 2
Mandatory

1 area of use

ANNEX 1
Information

APPENDIX 2
Mandatory