INDUSTRY STANDARD

NON-DESTRUCTIVE CONTROL.

WELDED PIPELINE JOINTS

Ultrasound method

OST 36-75-83

INDUSTRY STANDARD

This standard applies to butt ring welded joints of process pipelines at a pressure of no more than 10 MPa (100 kgf/cm 2), with a diameter of 200 mm or more and a wall thickness of 6 mm or more from low-carbon and low-alloy steels, made by all types of fusion welding and establishes requirements for non-destructive testing using ultrasonic methods. The standard was developed taking into account the requirements of GOST 14782-76, GOST 20415-75, as well as the recommendations of CMEA PC 4099-73 and PC 5246-75. The need to use an ultrasonic control method, its volume and quality requirements for welded joints are established by regulations -technical documentation to pipelines. APPROVED AND ENTERED INTO EFFECT BY ORDER OF THE Ministry of Installation and Special Construction Works of the USSR dated February 22, 1983 No. 57 EXECUTORS: VNIImontazhspetsstroy Popov Yu.V., Ph.D. tech. Sciences (topic leader), Grigoriev V.M., Art. n. With. (responsible executive), Kornienko A. M., art. engineer (executor) CO-PERFORMERS: UkrPTKImontazhspetsstroy Tsechal V.A., head of the basic welding laboratory (responsible executor) VNIKTIstalkonstruktsiya (Chelyabinsk branch) Vlasov L.A., head. sector (responsible executor), Neustroeva N.S., art. engineer (executor) Central Welding Laboratory of the Trust "Belpromnaladka" Vorontsov V.P., group leader (executor in charge) AGREED BY: Ministry of Food Industry of the USSR A.G. Ageev Ministry of Health of the RSFSR R.I. Khalitov Ministry of Installation and Special Construction Works of the USSR Soyuzstalkonstruktsiya V.M. Vorobyov V/O "Soyuzspetslegkonstruktsiya" A.N. Secrets of Glavstalkonstruktsiya B. C. Konopatov Glavmetallurgmontazh F.B. Trubetskoy Glavkhimmontazh V.Ya. Kurdyumov Glavneftemontazh K.I. Persecutor Glavtekhmontazh D.S. Korelin Glavlegprodmontazh A.Z. Medvedev Main Technical Directorate G.A. Sukalsky Deputy Director of the Institute for scientific work, Ph.D. Yu.V. Sokolov I.o. head Department of Standardization, Ph.D. V.A. Karasik Topic leader, head. laboratory, Ph.D. Yu. B. Popov Responsible executor, Art. Researcher, acting head sector V.M. Grigoriev Performer, Art. engineer A.M. Kornienko CO-PERFORMERS: Director of the Institute UkrPTKIMontazhspetsstroy V.F. Nazarenko Head of the Welding and Pipelines Department N.V. Vygovsky Chief designer of the project G.D. Shkuratovsky Responsible executive, head of the basic welding laboratory V.A. Tsechal Director of the Institute VNIKTIstalkonstruktsiya (Chelyabinsk branch) M.F. Chernyshev Executive Officer, Head. sector of L.A. Vlasov Head of the central laboratory of the Belpromnaladka trust L.S. Denisov Responsible executive, group leader V.P. Vorontsov

1. PURPOSE OF THE METHOD

2. REQUIREMENTS FOR DEFECTOSCOPISTS AND ULTRASONIC INSPECTION SITE

3. SAFETY REQUIREMENTS

4. REQUIREMENTS FOR EQUIPMENT AND MATERIALS

Standard sample No. 3

1 - maximum amplitude of the reflected signal; 2 - exit point of the ultrasonic beam; n - finder's arrow

Standard sample No. 2

1 - scale; 2 - block of steel grade 20 GOST 1050-74 in a normalized state with a grain size of 7 points or more according to GOST 5839-65; 3 - screw; 4 - hole for determining the angle of beam entry; 5 - hole for checking dead zone.

5. PREPARATION FOR CONTROL

B 1 = d × tan a -l/2+d+m (1)

When sounded directly

B 2 =2 d × tan a +d+m (2)

When sounded by a direct and once reflected beam

B 3 =3 d × tan a -l/2+d+m (3)

When sounded by a once and twice reflected beam

Table 1

Ultrasonic testing parameters

Scheme for determining surface cleaning zones near the seam of a welded joint

D - thickness of welded elements, mm; a - input angle, degrees; d - distance from the insertion point to the rear edge of the finder, mm; - half the width of the seam reinforcement bead, mm; B 1 , B 2 , B 3 , - zones of surface cleaning when sounding with a direct, once and twice reflected beam, mm; m =20 mm

Marking the circular welded joint of the pipeline into sections and their numbering

1. The welded joint must be divided into 12 equal sections around the circumference of the elements being welded. 2. The boundaries of the sections are numbered from 1 to 12 in a clockwise direction with the indicated direction of movement of the product in the pipeline. 3. Plots are numbered with two numbers: 1-2, 2-3, etc. 4. The boundary between sections 11-12 and 12-1 should pass through the welder’s mark, perpendicular to the seam.

5.6. The frequency and angle of the finder prism are selected based on the thickness of the elements being welded and the sounding method according to the table. 1. 5.7. Sounding the seams should be done by transversely and longitudinally moving the finder along the prepared in accordance with paragraphs. 5.5.2, 5.5.3, 5.5.5 surface with simultaneous rotation of it at an angle of 3-5 ° in both directions from the direction of transverse movement. The size of the step of movement of the finder should be no more than half the diameter of the piezoelectric plate of the transducer (Table 2). 5.8. Checking basic control parameters. 5.8.1. Before setting up a flaw detector to test a specific product, the following basic control parameters must be checked in accordance with the requirements of GOST 14782-76: finder boom; angle of entry of the ultrasonic beam into the metal; dead zone; extreme sensitivity; resolution. 5.8.2. The finder arm and the angle of entry of the ultrasonic beam are checked at least once per shift. 5.8.3. The finder arrow is determined according to standard sample No. 3 according to GOST 14782-76 and it should not be less than the values ​​​​specified in the table. 2. 5.8.4. The angle of entry of the ultrasonic beam is determined according to standard sample No. 2 according to GOST 14782-76 and it should not differ from the nominal value by more than ± 1°. The nominal values ​​of the input angle for finders with different prism angles are given in Table 2.

table 2

FINDER PARAMETERS

4.0>h/b>0.5,

And the areas S p of the flat bottom of the hole (or segment) and S 1 of the vertical face of the corner reflector are related by the relation:

S p = NS 1, where

N is the coefficient determined from the graph (Fig. 6). 5.8.7. The maximum sensitivity is checked on test samples with artificial reflectors, the area of ​​which is selected from the table. 1 depending on the thickness of the elements being welded and the type of finder selected.

Dependence of coefficientNfrom the cornerabeam input

5.8.8. The material of the test samples must be similar in terms of acoustic properties and surface cleanliness to the product being tested. The test samples must be free of defects (except for artificial reflectors) detected by the pulse echo method. 5.8.9. A reflector of the “hole with a flat bottom” type is made in the test sample in such a way that the center of the reflective surface of the bottom of the hole is located at a depth d equal to the thickness of the elements being welded (Fig. 7). 5.8.10. Test samples with corner or segment reflectors must have the same radius of curvature as the product being tested if the internal diameter of the elements being welded is less than 200 mm. When the internal diameter of the welded elements is 200 mm or more, test samples with plane-parallel surfaces are used (Fig. 8, 9). The method for manufacturing segmental reflectors is given in reference Appendix 6. The corner reflector in the test sample is made using a device from the KOU-2 kit. 5.8.11. The results of testing the maximum sensitivity are considered satisfactory if the signal amplitude from the artificial reflector is at least 30 mm across the CRT screen. 5.8.12. Resolution is checked using standard sample No. 1 according to GOST 14782-76. The resolution is considered satisfactory if the signals from three concentrically located cylindrical reflectors with diameters 15A 7, 20A 7, 30A 7, made in standard sample No. 1 (Fig. 1), are clearly distinguishable on the CRT screen.

Sample with a reflector type: “hole with a flat bottom” for adjusting the sensitivity of the flaw detector

Test sample with an angular reflector for adjusting sensitivity, determining the coordinates of defects and setting the control zone of the flaw detector

Where n is the number of reflections

Test sample with a segmented reflector for adjusting sensitivity, determining the coordinates of defects and setting the control zone of the flaw detector

The length of the test sample is determined by the formula:

L ¢ =(n+1) d × tg a +d+m+25; m=20,

Where n is the number of reflections

5.9. Setting up a flaw detector for inspection. 5.9.1. Connect a finder to the flaw detector with the parameters selected according to the table. 1 in accordance with the thickness of the elements being welded, the acoustic properties of the metal and the geometry of the welded joint. 5.9.2. Prepare the flaw detector for operation in accordance with the requirements of the operating instructions, and then configure it for testing a specific product in the following sequence (basic operations): set the sweep duration; adjust the depth measuring device; set the maximum sensitivity (first rejection level); sensitivity is equalized using a temporary sensitivity adjustment system (TSC); set search sensitivity; set the duration and position of the strobe pulse. 5.9.3. The sweep duration is set in such a way as to ensure the possibility of observing the signal from the most distant reflector on the CRT screen in accordance with the selected control parameters. 5.9.4. The strobe pulse is installed so that its leading edge is located near the probing pulse, and its rear edge is at the end of the CRT screen along the scan line. 5.9.5. Adjust the depth measuring device of the flaw detector according to the operating instructions. If the flaw detector does not have a depth-measuring device, then it is necessary to calibrate the scale of the CRT screen in accordance with the thickness of the product being tested. The method for determining coordinates on the CRT screen scale for the "ECHO" set is given in recommended appendix 7. The method for checking the depth gauge scale of the DUK-66P flaw detector is given in recommended appendix 8. 5.9.6. To set up the depth-measuring device, it is recommended to use test samples with artificial reflectors of the “side drilling” type in the case of testing welded joints with a wall thickness of more than 15 mm (recommended Appendix 8) and samples with segment or corner reflectors for welded joints with a wall thickness of 15 mm or less ( drawings 8 and 9). 5.9.7. Set the maximum sensitivity (first rejection level). The values ​​of the reflector area corresponding to the first rejection level for a specific controlled product are determined according to table. 1. 5.9.8. The flaw detector is adjusted to the first rejection level using the “attenuation” or “sensitivity”, “cut-off”, “power” and VRF regulators so that the height of the echo signal from the artificial reflector is equal to 30 mm, regardless of the control circuit in the absence of noise in the working section of the sweep . 5.9.9. Set the level of operation of the automatic defective alarm system (ADS). 5.9.10. The values ​​of the second rejection level of maximum sensitivity are set higher than the first by 3 dB. 5.9.11. To set the flaw detector to the second rejection level, turn the “weakening” control (for flaw detectors with an attenuator) 3 dB to the left (counterclockwise) or the “sensitivity” control (for flaw detectors without an attenuator) 1 division to the right clockwise relative to the first rejection level . 5.9.12. Set search sensitivity. The search sensitivity level values ​​are set above the first rejection level by 6 dB. 5.9.13. To adjust the flaw detector to search sensitivity, turn the “attenuation” knob 6 dB to the left (counterclockwise) or the “sensitivity” knob 2 notches to the right (clockwise) relative to the value of the first rejection level. 5.9.14. Set the duration and position of the strobe pulse in accordance with the controlled thickness and method of sounding according to the method outlined in the recommended Appendix 9.

6. CONTROL

Patterns for sounding seams with symmetrical cutting of edges

A - with a bevel of two edges, b - with a curved bevel of two edges

Scheme for decoding false echoes

A - from sagging at the root of the seam; b - from the seam reinforcement roller

6.8. Butt joints with a bevel of one edge with a wall thickness of more than 18 mm are recommended, in addition to sounding on both sides according to the method for symmetrical cutting, to additionally sound with finders with a prism angle of 54° (53°) on the side of the edge without the bevel (Fig. 12). In this case, the searcher movement zone and the stripping zone are calculated using the formulas in clause 5.5.2, and the maximum sensitivity (the first rejection level) is set equal to 6 mm 2. 6.9. When half the width of the seam reinforcement l /2 does not exceed the distance L 1 from the front edge of the finder to the projection of the supposed defect at the root of the weld on the surface of the welded joint, sounding the lower part of the weld is performed with a direct beam (Fig. 13a), and when l /2 exceeds L 1 the lower part of the seam is sounded by a doubly reflected beam (Fig. 13b). 6.10. To compare the values ​​of quantities l /2 and L 1 it is recommended to experimentally determine the distance L 1 (Fig. 14). The finder is installed at the end of the tested pipe or test sample used to adjust the flaw detector to the first rejection level. By moving the finder perpendicular to the end, fix the position of the finder at which the echo signal from the lower corner will be maximum, and then measure the distance L 1. 6.11. With unilateral access to the seam, it is sounded only on one side (Fig. 15). If the thickness of the welded elements is no more than 18 mm, the seam should be additionally sounded with finders with a prism angle of 54° (53°) according to the method described in clause 6.8. In the conclusion and in the control log, an appropriate entry must be made that the sounding was carried out only on one side of the seam.

Patterns for sounding seams with asymmetrical cutting of edges

A - with a bevel of one edge; b - with a curved bevel of one edge; c - with a stepped bevel of one edge; a 2 > a 1 ; a 2 =54°(53°)

Scheme of sounding the lower part of the seam.

A - size l /2 less than L 1 by such an amount that the searcher movement area equal to L 1 - l /2 allows you to fully sound the root of the seam with a direct beam; b - area of ​​movement of the finder equal to L 1 - l /2 allows you to sound only part of the root of the seam with a direct beam, and the rest with a doubly reflected beam

Scheme of experimental determination of distance

Scheme of sounding a seam with unilateral access

Scheme of sounding a seam with different wall thicknesses of joined elements

6.12. If the joined elements have different thicknesses without bevelling a wall of greater thickness, then sounding should be performed in accordance with clause 6.7. When a signal appears near the trailing edge of the strobe pulse, it is necessary to take into account that when the finder is located on the side of the thicker wall of the element at a distance L 1 = tg a from the weld axis, the signal is from the lower corner of the wall and the signal from the defect in the root of the seam (Fig. 16) can be observed as a single signal. To determine from which reflector the signal is observed, it is necessary to install the finder on the side of the thinner wall thickness of the element at a distance L 1 from the axis of the seam. In this case, if the signal is not observed near the trailing edge of the strobe pulse, there is no defect, but if the signal is observed, then a defect is detected in the root of the weld. 6.13. If the joined elements have different thicknesses with a bevel of a wall of greater thickness, then on the side of the smaller thickness the sounding is performed according to clause 6.7, and on the side of the greater wall thickness of the element - according to the diagrams shown in Fig. 17, 18. The thickness of the walls of the joined pipes and the actual boundary (length) of the bevel are determined with a direct finder in accordance with the recommended Appendix 10. 6.14. The main measured characteristics of identified defects are: amplitude of the echo signal from the defect; defect coordinates; conditional length of the defect; conditional distance between defects; the number of defects in any section of a 100 mm long seam. 6.15. The amplitude in dB of the echo signal from the defect is determined by the readings of the “attenuation” regulator (attenuator).

Schemes for sounding seams with a direct and once reflected beam from the side of an element of greater thickness

Intervals of movement of the finder when sounding a seam: a - with a straight beam from L "to L", where L "= l /2 +n; L "= d × tg a; b - once reflected beam from to , where =5(d 1 - d)+10+ d 1 × tg a, =2 d 1 × tg a + l /2 ; L =5(d 1 - d).

Scheme of sounding seams with a doubly reflected beam from the side of an element of greater thickness

The interval of movement of the finder from to , where =2 d 1 × tg a + l /2 ; =(2 d 1 + d) tg a

6.16. The coordinates of the defect - the distance L from the beam entry point to the projection of the defect onto the surface of the welded joint and the depth H - are determined in accordance with the requirements of the operating instructions for flaw detectors (Figure 19) 6.17. The coordinates of the defect are determined at the maximum amplitude of the reflected signal. If the echo signal goes beyond the screen, then the “attenuation” or “sensitivity” controls reduce its amplitude so that the maximum signal is in the range from 30 to 40 mm. 6.18. The conditional length of the defect and the conditional distance between defects are determined according to GOST 14782-76. When measuring these characteristics, the extreme positions of the finder should be considered those at which the amplitude of the echo signal from the defect is 0.2 of the vertical size of the working field of the CRT screen.

7. PROCESSING AND REGISTRATION OF CONTROL RESULTS

Determination of defect coordinates

Table 3

MAXIMUM ALLOWABLE VALUES OF MEASURED CHARACTERISTICS AND NUMBER OF DEFECTS IN WELDED JOINTS

ANNEX 1

Operating frequencies, MHz

Attenuator dynamic range, dB

Maximum sounding depth (for steel), mm

Availability of depth gauge

Dimensions of the working part of the CRT screen, mm

Operating temperature range, ° K (° C).

Dimensions, mm

Weight, kg

Supply voltage, V

Power type

0,80; 1,80; 2,50; 5,00

70 diameter

278-303 (from +5 to +30)

220 × 335 × 423

0,60; 1,80; 2,50; 5,00

125; 2,50; 5,00; 10,00

(from minus 10 to +40)

260×160×425

260 × 170 × 435

220, 127, 36, 24

0,60; 1,25; 2,50; 5,00

50 (in steps of 2dB)

278-323 (from +5 to +50)

345 × 195 × 470

40 (smooth)

1,25; 2,50; 5,00; 10,00

263-323 (from minus 10 to +50)

130 × 255 × 295

500 (for aluminum)

278-424 (from +5 to +50)

520 × 490 × 210

258-313 (from minus 15 to +40)

140 × 240 × 397

APPENDIX 2

METHOD FOR DETERMINING THE LINEARITY OF THE SPECIALIZED "ECHO" KIT

APPENDIX 3

APPENDIX 4

APPLICATION REGISTRATION JOURNAL FORM

APPENDIX 5

CONTACT LIQUIDS

Contact fluid of the Taganrog plant "Krasny Kotelshchik"

The easily washable inhibitor contact fluid has the following composition: water, l.................................................... ........................................................ ........................... 8 sodium nitrite (technical), kg................ ........................................................ ..... 1.6 starch (potato), kg.................................... ........................................... 0.24 glycerin (technical) , kg........................................ ........................... 0.45 soda ash (technical), kg......... ........................................... 0.048

Cooking method

Soda and sodium nitrite are dissolved in 5 liters of cold water and boiled in a clean container. Starch is dissolved in 3 liters of cold water and poured into a boiling solution of sodium nitrite and soda. The solution is boiled for 3-4 minutes, after which glycerin is poured into it, then the solution is cooled. Contact liquid is used at temperatures from +3 to +38 º C.

Contact fluid of Chernivtsi Machinery Plant

The contact liquid is an aqueous solution of polyacrylamide and sodium nitrite in the following ratio: polyacrylamide in % ................................... ........................................................ .......... from 0.8 to 2 sodium nitrite in% .................................... ........................................................ ............... from 0.4 to 1% water .............................. ........................................................ ................................ from 98.8 to 97

Cooking method

500 g of technical (8%) polyacrylamide and 1.3 liters of water are loaded into a steel tank with a capacity of 3 liters, equipped with a stirrer at a speed of 800-900 rpm, and stirred for 10-15 minutes. until a homogeneous solution of sodium nitrite is obtained. The appropriate amount of polyacrylamide, sodium nitrite solution and water is loaded into the hopper. Then the motor and the contents of the hopper are turned on for 5-10 minutes. pumped repeatedly until a homogeneous mass is obtained. When using a pump with a capacity of 12.5 l/min. An electric motor with a power of 1 kW is used.

APPENDIX 6

Information

METHOD FOR MANUFACTURING SEGMENTAL REFLECTORS

Method for manufacturing segment reflectors

Graph of the dependence of the milling depth "H" on the segment area "S" for finders with different prism angles (cutter diameter 3 mm)

Graph of the dependence of the milling depth "H" on the area "S" for finders with different prism angles (cutter diameter 6 mm)

APPENDIX 7

METHOD FOR DETERMINING THE COORDINATES OF DEFECTS WITH THE "ECHO" SET WHEN INSPECTION OF WELDED JOINTS SEAMS

1. General instructions

1.1. The coordinates "H" and "L" are determined directly from the scale of the CRT screen. 1.2. To determine coordinates on a scale, perform the following operations: select the working sweep range; the position and duration of the strobe pulse are set in accordance with the seam control zone of the welded joint and the scale is calibrated in relation to the thickness of the elements being welded, and the scale factors KH and KL are calculated. 1.3. The ECHO set is configured using a test sample, which is used to adjust the sensitivity during testing. 1.4. For convenience of calculations, the value of the small horizontal scale division is taken to be 0.2. 1.5. The "Y" regulator aligns the scan line with the lower horizontal scale line, and the "X" regulator aligns the maximum amplitude of the probing pulse with the first left vertical scale line of the screen. 1.6. Set the “coarse sweep” switch to position “5” and the “ ” knob to the extreme right position. 1.7. Use the " " regulator to set the leading edge of the strobe pulse near the trailing edge of the probing pulse (PS), and use the " " regulator to set the duration of the strobe pulse such that its trailing edge is located at the end of the scale.

2. Methodology for determining the coordinates of defects when sounding the seams of welded joints with a direct beam

2.1. In accordance with the thickness of 6 welded elements according to table. 1 determine the scale factor K N.

Table 1

An example of scale graduation when sounding the seams of welded joints with a direct beam

2.5. Using the " " regulator, combine the leading edge of the strobe pulse with the position of the leading edge of the signal (1). 2.6. Use the " " regulator to align the trailing edge of the strobe pulse with the position of the leading edge of the signal (2). 2.7. To determine the coordinates of the defect, set the maximum amplitude of the signal from the reflector detected in the control zone (for example, signal (3) from reflector 3, Fig. 1). Then count the number of divisions N i from the trailing edge of the strobe pulse to the leading edge of the signal from the defect in the control zone and determine the depth (H) of the defect using the formula:

H= δ -N i K N;

In the example of hell. 1 N i = 2.6. 2.8. Distance L is determined by the formula:

3. Methodology for determining the coordinates of defects when sounding the seams of welded joints with a direct and once reflected beam

3.1. In accordance with the thickness δ of the welded elements according to table. 2 determine the scale factor K H .

table 2

N p = δ / K H .

3.3. The number of divisions is determined, which is set between the positions of the leading edges of signals (1) and (2) from reflectors 1 and 2 when sounded by a direct beam (Fig. 2) according to the formula:

N l = δ "/ K H.

3.4. By moving the finder along the test sample, they achieve the maximum amplitude of the signal (4) from the reflector 4 (Fig. 2), located at the maximum distance from the beam entry point when sounded by a single reflected beam. 3.5. Set the "scan coarse" switch and the "" regulator signal (4) between 8 and 9 large divisions of the horizontal scale. 3.6. Using the " " and " " controls, using the method of successive approximations, the leading edge of the maximum signal amplitude (2) from reflector 2 is aligned with the middle of the scale, and the leading edge of the maximum signal amplitude (4) from reflector 4 is located at a distance equal to N n divisions (clause 3.2.) from the middle of the scale to the right. 3.7. Using the " " regulator, set the leading edge of the strobe pulse at a distance equal to N l divisions (clause 3.3.) from the middle of the scale to the left, corresponding to the position of the leading edge of the maximum amplitude of the signal (1) from reflector 1. 3.8. Use the " " regulator to align the trailing edge of the strobe pulse with the position of the leading edge of the maximum amplitude of the signal (4) from reflector 4 (clause 3.6.).

An example of scale graduation when sounding the seams of welded joints with a direct and once reflected beam

3.9. All signals detected within the duration of the set strobe pulse from its leading edge to the middle of the scale are considered to be detected by a direct beam, and from the middle of the scale to the trailing edge - by a single reflected beam. 3.10. Depths (N l, N p) of detected defects in the area of ​​direct beam sounding are determined by the formula:

N l = δ - N l i K N;

Where N l i is the number of scale divisions, counted from the middle to the leading edge of the signal from the defect, and in the sound zone of a single reflected beam is determined by the formula:

N p = δ - N p i K N;

Where N p i is the number of scale divisions, counted from the trailing edge of the strobe pulse to the leading edge of the signal from the defect. 3.11. Determine the distance L l in the sounding area with a direct beam using the formula:

L l =N l · tg α ;

A once reflected beam according to the formula:

L p =(2 δ -Н p) · tg α ;

3.12. The method for setting up the "ECHO" kit to determine the coordinates of defects while simultaneously sounding the seams of welded joints with single- and double-reflected beams is similar to the above. In this case, the coordinates H and L are determined by the formulas:

N= N l i K N;

Where KH increases 3 times compared to the values ​​in the table. 1.

L p = [(n +1) δ -Н p ] · tg α .

APPENDIX 8

METHOD FOR CHECKING THE ERROR OF THE DEPTH GAUGE OF THE DUK-66P FEFECTOSCOPE

Test sample with "side drilling" type reflectors for checking and adjusting the depth gauge scale of a flaw detector type DUK-66P

APPENDIX 9

METHOD FOR SETTING THE DURATION AND POSITION OF THE STROBE PULSE

Scheme for determining the duration and position of a strobe pulse when sounding a seam with a direct and once reflected beam

L "is calculated depending on δ, α and the sound pattern using the formula: L "=(n +1) d × tg a + d + m +25, where n is the number of reflections

1.6. When sounding the seam of a welded joint with a double and once reflected beam, the leading edge of the strobe pulse is set along the leading edge of the signal with maximum amplitude reflected from the upper reflector, and the trailing edge of the strobe pulse is set along the trailing edge of the maximum signal with maximum amplitude reflected from the lower reflector . With this setting, echo signals at the beginning of the strobe pulse indicate the presence of defects in the upper part of the seam, and echo signals at the end of the strobe pulse indicate the presence of defects in the lower part of the seam (Fig. 2) 1.7. The position of the strobe pulse is set using the “X offset” regulator symmetrically relative to the middle of the CRT screen scale for all flaw detectors with the exception of the “ECHO” set.

Scheme for determining the duration and position of a strobe pulse when sounding a seam with a single and double reflected beam

APPENDIX 10

DETERMINATION OF THE WALL THICKNESS OF WELDED ELEMENTS AND THE ACTUAL BOUNDARY (LENGTH) OF THE BEvel USING A DIRECT FINDER

Scheme of sounding the walls of welded elements with a direct finder to determine their thickness and bevel length

SI - probing pulse; 1,2,3... signals reflected from the opposite side of the wall of the elements being welded

APPENDIX 11

JOURNAL OF ULTRASONIC TESTING

APPENDIX 12

APPENDIX 13

DEFECTOGRAM No. 6 OF WELDED JOINT No. 30 ENTRY No. 21 IN THE ULTRASONIC TESTING JOURNAL

(filling example)

Note: the "+" arrow indicates the direction of movement of the product away from us perpendicular to the drawing plane

Ultrasonic testing is carried out on process pipelines (to the extent according to the category of the pipeline), pipelines of heating networks (depending on the conditions of laying the pipeline and the requirements of the operating organization), fire pipelines, gas pipelines, steam pipelines, drill pipe and pump-compressor pipe, etc.

Ultrasonic testing pipe inspection is a pipeline diagnostics for the presence of internal defects. Both the pipe body itself and the weld seam can be inspected. This type of flaw detection can be carried out both in a specially equipped laboratory on the territory of our enterprise (if the dimensions of the product do not exceed 2000 mm in length and 500 mm in diameter and the weight of the product does not exceed 150 kg), and at the actual location of the object.

If the pipeline is operational, ultrasonic testing is carried out after drainage (removal) of the transported medium. Ultrasonic testing is possible without stopping technological process, without stopping production (unlike X-ray inspection).

Ultrasonic testing must be carried out not only when putting pipelines into operation, during the pipe certification procedure, but also on a regular basis in order to prevent premature wear of pipes and the occurrence of emergency situations.

The procedure for ultrasonic flaw detection of pipelines consists of the following activities:

preparing welded joints for inspection (cleaning). Carried out by the customer or by the laboratory by agreement.

weld marking

direct inspection of the pipeline - inspection of welds or continuous inspection of the pipeline metal, thickness gauging if necessary.

marking defective areas if repairs are possible

drawing up a pipeline diagram and conclusions based on inspection results

As you have already seen, ultrasonic inspection of pipes is very effective method flaw detection. Besides, this type control has also proven itself to be the most accurate, efficient, low-cost and safe for humans.

Contact us and we will organize for you the full range of works on ultrasonic testing of pipelines, we will identify weak spots objects, existing defects, we will provide complete information about their size and location relative to the surface of the product, we will examine welds and joints also in order to control their quality. It is thanks to such checks that you ensure long-term uninterrupted, and most importantly safe work equipment.

In construction, pipes with Ø from 28 to 1420 mm with a wall thickness from 3 to 30 mm are used. The entire range of diameters according to flaw detection can be divided into 3 groups:

1. Ø from 28 to 100 mm and H from 3 to 7 mm
2. Ø from 108 to 920 mm and H from 4 to 25 mm
3. Ø from 1020 to 1420 mm and H from 12 to 30 mm

According to studies that were carried out at MSTU. N.E. Bauman for Lately, in the process of developing methods for ultrasonic testing of welded pipe joints, this very important factor, as anisotropy of the elastic characteristics of the pipe material.

Anisotropy of pipe steel, its features

Anisotropy- this is the difference in the properties of a medium (for example, physical: thermal conductivity, elasticity, electrical conductivity, etc.) in different directions within a given medium.

In the process of ultrasonic testing of welded joints of main gas pipelines assembled from pipes of domestic and foreign production, the omission of serious root defects, inaccurate assessment of their coordinates, and a significant level of acoustic noise were discovered.

It turned out that if optimal control parameters are observed and during its implementation, the main reason for missing a defect is the presence of significant anisotropy in the elastic properties of the base material. It affects the speed, attenuation and deviation from straightness of the ultrasonic beam.

During the sounding of metal, more than 200 pieces of pipes according to the scheme shown in Fig. 1, it turned out that the standard deviation of the wave speed with this direction of motion and polarization is equal to 2 m/s (for transverse waves). Deviations of velocities from the table values ​​of 100 m/s or more are not random and are probably associated with the production technology of rolled products and pipes. Such deviations have a strong influence on the propagation of polarized waves. In addition to the indicated anisotropy, inhomogeneity of the speed of sound across the thickness of the pipe wall was also discovered.

Rice. 1. Designations of deposits in the pipe metal: X, Y, Z. - directions of ultrasound propagation: x. y.z: - polarization directions; Y - rolling direction: Z - perpendicular to the plane of the pipe

The structure of rolled sheets is layered, consisting of metal fibers and other inclusions elongated during deformation. In addition, due to the effect of the thermomechanical rolling cycle on the metal, sections of the sheet that are uneven in thickness are subject to various deformations. These features cause the speed of sound to additionally depend on the depth of the sound layer.

Features of control of welded seams of pipes of various diameters

Pipes Ø from 28 to 100 mm

A distinctive feature of welded seams of pipes Ø from 28 to 100 mm with H from 3 to 7 mm is the occurrence of sagging inside the pipe. This causes false echo signals from them to appear on the screen of the flaw detector during testing with a direct beam, which coincide in time with the echo signals reflected from the root defects found by a single reflected beam. Due to the fact that the effective width of the beam is comparable to the thickness of the pipe wall, it is extremely difficult to identify the reflector by the location of the finder relative to the reinforcement roller. There is also an uncontrolled zone in the center of the seam due to the large width of the seam bead. All this is the reason for the low probability (10-12%) of detecting unacceptable volumetric defects, although unacceptable planar defects are detected much better (~ 85%). The main characteristics of sagging - depth, width and angle of contact with the surface of the object - are random variables for this standard size of pipe; the average values ​​are respectively 2.7 mm; 6.5 mm and 56°30".

Rolled steel behaves as an anisotropic and inhomogeneous medium with rather complex dependences of the velocities of elastic waves on the direction of polarization and sounding. The speed of sound changes approximately symmetrically with respect to the middle of the sheet section, and in the region of this middle the transverse wave speed can greatly (up to 10%) decrease compared to the surrounding areas. The shear wave speed in the controlled objects varies in the range from 3070 to 3420 m/s. At a depth of up to 3 mm from the surface of the rolled product, the speed of the transverse wave may increase slightly (up to 1%).

Noise immunity of control increases significantly in the case of using inclined separate-combined probes of the RSN type (Fig. 2), which are called chordal. They were designed at MSTU. N.E. Bauman. A special feature of the inspection is that there is no need for cross scanning when searching for defects. It is performed only along the perimeter of the pipe at the moment the front face of the converter is pressed against the seam.

Rice. 2. Inclined chord RSN-PEP: 1 - emitter: 2 - receiver

Pipes Ø from 108 to 920 mm

Pipes with Ø from 108 to 920 mm with H from 4 to 25 mm are also connected by one-sided welding without back welding. Until recently, the control of these connections was carried out using combined probes according to a method developed for pipes with Ø from 28 to 100 mm. But such a control technique requires the presence of a fairly large zone of coincidence (zone of uncertainty). This significantly reduces the accuracy of connection quality assessment. In addition, combined probes are characterized by a high level of reverberation noise, which makes it difficult to decipher signals, as well as uneven sensitivity, which cannot always be compensated by available means. The use of chordal separate-combined probes for the purpose of monitoring this standard size of welded joints is impractical, since due to the limited values ​​of the input angles of ultrasonic vibrations from the surface of the welded joint, the dimensions of the transducers increase significantly, and the area of ​​acoustic contact becomes larger.

At MSTU. N. E. Bauman created inclined probes with leveled sensitivity to perform inspection of welded joints with a diameter of 100 mm or more. Sensitivity equalization ensures that the rotation angle 2 is selected in such a way that the upper part and middle of the seam are sounded by the central once reflected beam, and the lower part by direct peripheral rays that fall on the defect at an angle Y from the central one. In Fig. Figure 3 shows a graph of the dependence of the angle of introduction of the transverse wave on the angle of rotation and opening of the directional pattern Y. In such probes, the incident and reflected waves from the defect are horizontally polarized (SH-wave).

Rice. 3. Changing the input angle alpha, within the limit of half the opening angle of the RSN-PEP radiation pattern, depending on the rotation angle delta.

It is clear from the graphs that when testing objects with a wall thickness of 25 mm, the uneven sensitivity of the RS-probe reaches 5 dB, while for a combined probe it can reach 25 dB. RS-PEP is characterized by an increased signal-to-interference level and, therefore, increased absolute sensitivity. For example, the RS-PEP easily detects a defect with an area of ​​0.5 mm2 during the inspection of a welded joint 10 mm thick with both direct and once reflected beams with a useful signal/interference ratio of 10 dB. The procedure for performing control with probe data is the same as for a combined probe.

Pipes Ø from 1020 to 1420 mm

Welded joints of pipes Ø from 1020 to 1420 mm with H from 12 to 30 mm are performed by double-sided welding or with back welding of the seam bead. In seams that are made by double-sided welding, usually, false signals from the trailing edge of the reinforcement roller do not cause as much interference as in single-sided seams. Their amplitude is not so great due to the smoother contours of the roller. In addition, they are further along the scan. For this reason, this is the most suitable pipe size for flaw detection. But the results of research conducted at MSTU named after. N. E. Bauman show that the metal of these pipes is characterized by the greatest anisotropy. To reduce the effect of anisotropy on defect detection, you should use a 2.5 MHz probe with a prism angle of 45°, and not 50°, as indicated in most regulatory documents. Most high accuracy control was achieved using a probe of the RSM-N12 type. Unlike the methodology compiled for pipes with Ø from 28 to 100 mm, there is no zone of uncertainty when monitoring these connections. The rest of the control method is similar. When using an RS-PET, it is also recommended to adjust the scanning speed and sensitivity for vertical drilling. The scanning speed and sensitivity of inclined combined probes should be adjusted using corner reflectors of the appropriate size.

When inspecting welds, it must be remembered that in the heat-affected zone there are metal delaminations, which make it difficult to determine the coordinates of the defect. The area in which the defect was found by an inclined probe must be additionally checked by a direct probe in order to clarify the nature of the defect and identify the exact value of the depth of the defect.

In the nuclear, petrochemical industry and nuclear energy Clad steels are often used in the manufacture of pipelines, apparatus and vessels. For cladding the inner wall of these structures, austenitic steels are used, which are applied by surfacing, rolling or explosion in a layer of 5 to 15 mm.

The process of monitoring these welded joints involves analyzing the continuity of the pearlite part of the weld, as well as the fusion zone with restorative anti-corrosion surfacing. In this case, the continuity of the body of the surfacing itself is not controlled.

But due to the difference in the acoustic characteristics of the base metal and austenitic steel, echo signals appear from the interface during ultrasonic testing, preventing the detection of defects, for example, cladding delaminations and sub-cladding cracks. In addition, the presence of cladding and its characteristics have a significant impact on the parameters of the acoustic path of the probe.

For this reason, standard technological solutions are ineffective in inspecting thick-walled welds of clad pipelines.

After many years of research, scientists have figured out the main features of the acoustic tract. Recommendations were received for optimizing its characteristics and a technology for performing ultrasonic analysis of welds with austenitic cladding was developed.

In particular, scientists have found that when a beam of ultrasonic waves is reflected from the boundary of pearlite-austenitic cladding, the radiation pattern almost does not change in the case of rolling cladding and changes significantly in the case of surfacing cladding. Its width increases significantly, and within the main lobe there are oscillations of 15-20 dB, depending on the surfacing method. There is a significant movement of the reflection exit point from the beam cladding boundary compared to its location, and the velocity of the shear waves in the transition zone also changes.

When developing technology for monitoring welded joints of clad pipelines, all this was taken into account. This technology provides for a preliminary mandatory determination of the thickness of the pearlite part (the depth of penetration of the anti-corrosion surfacing).

For more accurate detection of planar defects (lack of fusion and cracks), it is better to use a probe with an input angle of 45° and a frequency of 4 MHz. More accurate detection of vertically oriented defects at an input angle of 45°, in contrast to angles of 60 and 70°, is explained by the fact that during sounding of the latter, the angle at which the beam meets the defect is close to the third critical angle, at which the transverse wave reflection coefficient is minimal.
When the pipe is sounded outside at a frequency of 2 MHz, echo signals from defects are screened by an intense and long-lasting noise signal. The resistance to interference of the probe at a frequency of 4 MHz is on average 12 dB higher. For this reason, the useful signal from a defect located in close proximity to the deposit boundary will be better read against the background of noise. And vice versa, when sounding the pipe from the inside through the surfacing, better resistance to interference will be provided by a probe at a frequency of 2 MHz.

The technology for monitoring pipeline welds with surfacing is regulated by Gosatomnadzor document RFPNAEG-7-030-91.

). An expanded list of standards relating to ultrasound probes is given at the end of this page. Ultrasound probes can be conditionally classified according to the following criteria:

Based on the angle of vibration input, they are distinguished:

• Direct transducers introduce and (or) receive vibrations normal to the surface of the test object at the input point.
• Inclined transducers introduce and (or) receive vibrations in directions other than normal to the surface of the test object.

According to the method of placing the functions of emission and reception of the ultrasonic signal, they are distinguished:

• Combined probes where the same piezoelectric element operates in both emission and reception modes.
• Separate-combined converters where two or more piezoelements are placed in one housing, one of which operates only in the radiation mode, and the others in the reception mode.

By vibration frequency

• High-frequency ultrasonic probes can be conditionally limited to the range of 4-5 MHz; this frequency is usually used when testing fine-grained workpieces of small thickness (usually less than 100 mm) and welded joints less than 20 mm thick.
• Mid-frequency ultrasonic probes with a frequency range of 1.8-2.5 MHz. Converters with this frequency range are used to control products of greater thickness and larger particle sizes.
• Low-frequency ultrasonic probes with a frequency range of 0.5-1.8 MHz are used to control workpieces with a coarse-grained structure and a high attenuation coefficient, such as cast iron, concrete or plastic.

By acoustic contact method

• Contact probes where the working surface is in contact with the surface of the OC or is located from it at a distance of less than half the wavelength in the contact fluid.
• Immersion ones, which operate when there is a layer of liquid between the surfaces of the transducer and the OC with a thickness greater than the spatial extent of the acoustic pulse.

According to the type of wave excited in the test object:

• Longitudinal waves - vibrations of which occur along the axis of propagation;
• Shear (transverse) waves - oscillations of which occur perpendicular to the propagation axis;
• Surface waves (Relley waves) - propagating along the free (or lightly loaded) boundary of a solid body and quickly decaying with depth.
• Normal ultrasonic waves (Lamb waves) are ultrasonic waves that propagate in plates and rods. There are symmetric and antisymmetric waves.
• Head waves are a set of acoustic waves excited when a beam of longitudinal waves falls on the interface between 2 solid media at the first critical angle.

See also articles:

• Converters for TOFD testing

Selection of ultrasonic piezoelectric transducer

The choice of transducer depends on the parameters of the controlled object, such as material, thickness, shape and orientation of defects, etc.

Selection of probe by input angle(straight or oblique) are chosen based on the sound pattern of a particular object. Sounding schemes are contained in state and departmental standards, as well as technological control charts. In the general case, the input angle is chosen in such a way as to ensure that the section under test is intersected by the acoustic axis of the transducer (direct or single-reflected beam). Detection of defects emerging on the surface is most effectively ensured when a transverse wave is incident at an angle of 45 ° ± 5 ° to this surface.

Selecting a probe according to the connection diagram(combined or PC) is selected depending on the thickness of the product or the distance of the control zone from the input surface. Direct combined probes are usually used when monitoring products with a thickness of more than 50 mm, and direct RS probes are used for monitoring products up to 50 mm thick inclusive, or a near-surface layer up to 50 mm.

Inclined RS probes are mainly used in a combined connection scheme. Inclined RS probes with a transverse wave are used primarily for testing welded joints of thin-walled (up to 9 mm) pipes with a diameter of no more than 400 mm (chord transducers). Inclined RS probes with a longitudinal wave are used to control joints with a coarse-grained structure and a high noise level (austenitic welds).

Selection of probe by oscillation frequency, is selected mainly based on the thickness of the OC and the required sensitivity of control. Due to their shorter wavelength, high-frequency transducers make it possible to find smaller defects, while the ultrasonic waves of low-frequency probes penetrate deeper into the material, because the attenuation coefficient decreases with frequency. Low-frequency probes are used for testing coarse-grained materials and materials with a high attenuation coefficient.

When choosing a frequency, it must be taken into account that increasing it causes:

• near field increase
• reduction of the dead zone associated with a decrease in the duration of free oscillations of the piezoelectric element;
• improvement of beam and frontal resolution;
• narrowing of the directional characteristics;
• an increase in the attenuation coefficient and an associated decrease in sensitivity at large thicknesses
• increase in the level of structural noise in coarse-grained materials; reduction in the level of intrinsic noise of the probe, associated with an increase in the attenuation of the sound wave in the elements of the probe with increasing frequency;

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P111 - Direct combined converters

Converters type P111 used for flaw detection and thickness gauging of products using longitudinal waves. In practice, direct combined transducers are used to control sheets, plates, shafts, castings, forgings, as well as to search for local thinning in the walls of products. P111 transducers are used to detect volumetric and planar defects - pores, hairlines, delaminations, etc. The characteristics of P111 type probes are given in the table:

P112 - direct separate-combined converters

Contact separate-combined converters, type P112, are usually used to determine the residual wall thickness of products and to search for defects located at relatively small depths below the surface. The thickness of the controlled P 112 objects, as a rule, is in the range from 1 to 30 mm. The characteristics of P112 are given in the table:

P121 inclined combined transducers

Slope transducers, type P121, are widely used in testing welded joints, sheets, stampings, forgings and other objects. P121 transducers allow you to detect cracks, volumetric defects, such as non-metallic inclusions, pores, lack of fusion, shrinkage cavities, etc. Using P121 type transducers, as a rule, the characteristics of vertically oriented defects are determined. The characteristics and possible markings of P 121 from one of the manufacturers are shown in the table:

P122 – inclined separate-combined transducers

Chord transducers type P122 mainly used for testing circumferential welds of pipe elements made of steel and polyethylene with a diameter of 14 to 219 mm. with a wall thickness from 2 to 6 mm., contact separate-combined chord transducers are used. The use of chord type transducers is especially effective for testing thin-walled welds from 2 to 4 mm.

P122 type transducers are designed for monitoring thin-walled welds, usually made of stainless steel, low-carbon steel and aluminum alloys Feature PEP – minimum dead zone and focusing of the ultrasonic field in a certain thickness range. The characteristics of P 121 are presented in the table:

A number of standards have been introduced for industrial engineering communications, which require fairly stringent testing of connections. These techniques are being transferred to privately owned systems. The use of methods allows you to avoid emergency situations and carry out external and hidden installations with the required level of quality.

Incoming control

Incoming inspection of pipes is carried out for all types of materials, including metal-plastic, polyethylene and polypropylene after purchasing the products.

The standards mentioned involve testing pipes, regardless of the material from which they are made. Input controlling implies rules for checking the received batch. Inspection of welded joints is carried out as part of the acceptance of communications installation work. The described methods are mandatory for use by construction and installation organizations when delivering residential, commercial and industrial facilities with water supply and heating systems. Similar methods are used where quality control of pipes in industrial communications operating as part of equipment is necessary.

Sequence of implementation and methods

Acceptance of products after delivery is an important process, subsequently ensuring that there are no wasteful costs for replacing pipe products and no accidents. Both the quantity of products and their features are subject to careful verification. Quantitative verification allows you to take into account the entire consumption of products and avoid unnecessary costs associated with inflated standards and irrational use. The influence of the human factor should not be overlooked.

The work is carried out in accordance with section No. 9 of standard SP 42-101-96.

The sequence of input events is as follows:

• Checking the certificate and marking compliance;
• Random testing of samples is carried out if there is any doubt about the quality. The magnitude of the yield strength in tension and elongation during mechanical rupture is studied;
• Even if there is no doubt about the supply, a small number of samples are selected for testing, within 0.25-2% of the batch, but not less than 5 pieces. When using products in coils, cut off 2 m;
• The surface is inspected;
• Inspected for swelling and cracks;
• Measure typical dimensions of thicknesses and walls with a micrometer or caliper.

During an official inspection of a commercial or government organization A protocol is drawn up upon the completion of the procedure.

Non-destructive testing - features

Non-destructive methods are used in functioning utility systems. Particular attention is paid to the actual state of the metal and welded joints. Operational safety is determined by the quality of seam welding. During long-term operation, the degree of structural damage between connections is examined. They can be damaged by rust, which leads to thinning of the walls, and clogging of the cavity can lead to increased pressure and a pipeline rupture.

For these purposes, specialized equipment has been proposed - flaw detectors (for example, ultrasonic), which can be used to carry out work in private and commercial purposes.

In pipeline studies, pipe inspection methods are used:

By using this equipment The development of cracks or loss of integrity is monitored. Moreover, the main advantage is the identification of hidden defects. It is obvious that each of these methods shows high effectiveness on certain types of damage. The eddy current flaw detector is to some extent universal and cost-effective.

Ultrasonic inspection of pipes is more expensive and demanding, but it is very popular among specialists due to the established stereotype. Many plumbers use the capillary and magnetic particle method, which is applicable to all types of pipe products, including polyethylene and polypropylene. Testex is a popular tool among specialists for checking the tightness of welds.

Conclusion

Of the proposed methods of non-destructive testing, all 4 options are successfully used in practice, but do not have absolute universality. The pipe inspection system includes all types of flaw detectors for carrying out work. The ultrasonic method, as well as the technique based on eddy currents, has a certain degree of versatility. Moreover, the vortex version of the equipment is much cheaper.