The instruction applies to butt girth welded joints of pipes with a diameter of 200 mm and more, wall thickness from 4 to 20 mm, with a pressure of less than 10 MPa from low-carbon steels Art. 10 and steel 20 (GOST 1050-88), made by fusion welding, and sets requirements for non-destructive testing by ultrasonic method.

JSC NIICHIMMASH

CONTROL NON-DESTRUCTIVE
RING SEAMS OF BUTT WELDED PIPE CONNECTIONS

ULTRASONIC CONTROL TECHNIQUE

(Topic No. 923176)

RDI 26-11-65-96

AGREED:
Deputy quality director	Head of department number 23
Bugulma Mechanical Plant	N.V. Khimchenko
VC. Konkin	Head of Sector
"__" ________________ 1997	V.A. Bobrov
	Executor
	V.V. Volokitin

Moscow 1997

INTRODUCTION

This instruction applies to butt ring welded joints of pipes with a diameter of 200 mm and more, wall thickness from 4 to 20 mm, with a pressure of less than 10 MPa from low-carbon steels Art. 10 and steel 20 (GOST 1050-88), made by fusion welding, and sets requirements for non-destructive testing by ultrasonic method.

The standard was developed taking into account the requirements of GOST 14782-86 “Non-destructive testing of welded joints. Ultrasonic methods ", OST 26-2044-83" Seams of butt and fillet welded joints of vessels and devices operating under pressure ", OST 36-75-83" Non-destructive testing. Welded joints of pipelines. Ultrasonic method ", SNiP 3.05.05-84, as well as the experience of JSC NIIkhimmash on ultrasonic testing of the mentioned pipes.

After gaining experience in ultrasonic testing of pipes by the specialists of your enterprise, in 6 - 12 months, according to your materials, OJSC NIIkhimmash can agree on changes and additions to this method.

The need to use the ultrasonic method of control and its scope are established by the normative and technical documentation.

1. PURPOSE OF THE METHOD

1.1. Ultrasonic testing is designed to detect cracks, lack of penetration, lack of fusion, pores, slag inclusions and other types of defects in welded seams and near-weld zones without decoding their nature, but indicating the coordinates, nominal dimensions and the number of detected defects.

1.2. Ultrasonic testing is carried out at an ambient temperature of 5 to 40 ° C. In cases of heating the controlled item in the zone of movement of the finder to temperatures from 5 to 40 ° C, it is allowed to carry out the control at an ambient temperature of up to minus 10 ° C. In this case, flaw detectors and transducers should be used that remain operational (according to passport data) at temperatures up to minus 10 ° C and below.

1.3. Ultrasonic testing is carried out at any spatial position of the welded joint.

2. REQUIREMENTS FOR FLAW DETECTORS AND ULTRASONIC CONTROL SECTION

2.1. Requirements for NDT inspectors for ultrasonic testing.

2.1.1. Ultrasonic testing should be carried out by a team of two NDT inspectors.

2.1.2. Persons who have undergone theoretical and practical training in accordance with " Rules for the certification of non-destructive testing specialists, "Approved by the Gosgortekhnadzor of Russia, having a second level certificate for the right to control and issue an opinion on the quality of welds based on the results of ultrasonic testing.

Non-destructive inspectors of the first and second levels must undergo recertification after three years, as well as during a break in work for more than 1 year and when the place of work is changed.

Certification and recertification of specialists is carried out in special certification centers that are licensed.

2.1.3. The management of ultrasonic testing should be carried out by engineers and technicians or NDT inspectors with the second or third qualification levels.

2.2. Requirements for the ultrasonic testing area.

2.2.1. The ultrasonic testing section must have production sites that provide accommodation for the workplaces of NDT inspectors, equipment and accessories.

2.2.2. The ultrasonic testing area should be provided with:

Ultrasonic flaw detectors with a set of standard and special transducers;

Distribution board from an alternating current with a frequency of 50 Hz, a voltage of 220 V ± 10%, 36 V ± 10%, portable power supply blocks, grounding buses;

Standard and test samples, auxiliary devices for checking and adjusting flaw detectors with transducers;

Sets of locksmith, electrical and measuring tools, accessories (chalk, colored pencils, paper, paints);

Contact liquid, oiler, cleaning material, seam brush;

Work tables and workbenches;

Racks and cabinets for storing flaw detectors with a set of transducers, samples, materials and documentation.

3. SAFETY REQUIREMENTS

3.1. When working with ultrasonic flaw detectors, it is necessary to comply with safety and industrial sanitation requirements in accordance with GOST 12.2.007-75, SNiP III-4-80, " Rules for the technical operation of electrical installations of consumers and safety rules for the operation of electrical installations of consumers", Approved by the USSR State Energy Supervision Service on 04/12/1969, with the additions and amendments made, and" Sanitary norms and rules when working with equipment that creates ultrasound transmitted by contact to the hands of workers "No. 2282-80, approved by the Ministry of Health.

3.2. When powered from an alternating current network, ultrasonic flaw detectors must be grounded with a copper wire with a cross section of at least 2.5 mm 2.

3.3. Flaw detectors are connected to the alternating current network through sockets installed by an electrician at specially equipped posts.

3.4. Inspectors are prohibited from opening the flaw detector connected to the power supply and repairing it due to the presence of a high-voltage unit.

3.5. It is forbidden to carry out control near the places where welding works are performed without fencing with light shields.

3.6. It is forbidden to use oil as a couplant when carrying out ultrasonic testing near oxygen cutting and welding places, as well as in rooms for storing oxygen cylinders.

3.7. When working at a height, in cramped conditions, workplaces must provide the NDT inspector with convenient access to the welded joint, subject to safety conditions (construction of scaffolding, scaffolding, use of helmets, assembly belts, overalls). It is forbidden to carry out testing without protective devices against the impact of atmospheric precipitation on the inspector, equipment and place of testing.

3.8. Flaw detectors must undergo medical examinations at least once a year in accordance with the order of the Ministry of Health of the USSR No. 555 dated September 29, 1989 (Appendix 1, clause 4.5) and order No. 280/88 dated 05.10.95 of the Ministry of Health and Medical Industry RF (Appendix No. 1, clause 5.5).

3.9. To work on ultrasonic flaw detection are allowed persons at the age of at least 18 years, who have undergone safety training with registration in the journal in the prescribed form. The briefing should be carried out periodically within the time frame established by the order for the organization (plant, combine, etc.).

3.10. The administration of the organization conducting ultrasonic testing is obliged to ensure that safety requirements are met.

3.11. If safety rules are violated, the inspector must be removed from work and re-admitted to it after additional instruction.

4. PREPARATION FOR CONTROL

4.1. Butt welded joints with a thickness of 4 - 9 mm are inspected from one surface of the product on both sides of the welded seam in one pass by a direct and one-time reflected beam.

4.2. The main control parameters are set according to the specifications for pipes. In the absence of technical conditions, be guided by table No. 1 OST 26-2044-83.

4.6. The limiting sensitivity of the ultrasonic flaw detector is adjusted using defects such as segment reflectors or an angular reflector.

When adjusting the sensitivity, the increased sensitivity mode is set at the beginning. Receive an echo signal from a reflector on direct and reflected beams. The echoes are then equalized in height and the sensitivity is decreased until the amplitude reaches 30 mm for the direct and reflected beams.

SETTING THE CONTROL ZONE IN THE "SOFT SCAN" MODE

Heck. 1

If the device does not allow leveling the signals, then the sensitivity should be adjusted separately for the direct and reflected beams and the control should be carried out in two passes.

4.7. When searching for defects, the sensitivity increases by 4 - 6 dB, while the level of noise on the screen in height should not exceed 5 ÷ 10 mm.

4.8. The DN coordinate for welded seams with a thickness of 4 to 9 mm is determined if it is necessary to distinguish interference from a defect signal.

5. CONTROL

5.1. The inspection includes the operations of sounding the weld metal and the heat-affected zone and determination of the measured characteristics of defects. The control is carried out with transducers having a memorial frequency of 5.0 MHz and an angle of entry on steel of 70 degrees. (see p.).

5.2. The sounding of the seams is performed by the method of transverse-longitudinal movement of the transducer. The speed of the transducer movement should be approximately no more than 30 mm / s.

5.3. Acoustic contact of the transducer with the surface on which it moves is ensured through the couplant by lightly pressing the transducer. The stability of the acoustic contact is evidenced by a decrease in the signal amplitudes at the trailing edge of the probing pulse, created by the acoustic noise of the transducer, in comparison with their level when the acoustic contact of the transducer with the product surface deteriorates or is absent. Use contact liquids in accordance with OST 26-2044-83.

5.4. Sounding of welded joints and analysis of echo signals in a strobe pulse are carried out at the search sensitivity, and the determination of the characteristics of the detected defects - at rejection levels. Only those echoes observed in the strobe are analyzed.

5.5. During the inspection process, it is necessary to check the flaw detector setting to the rejection level at least twice a shift.

5.6. At the rejection level, the signal amplitude, conditional length, conditional distance between defects and the number of defects are estimated.

5.7. The seams of welded joints sound with direct and single-beam reflected rays from both sides (Fig.).

When echo signals appear near the trailing or leading edges of the strobe pulse, it should be clarified whether they are the result of the reflection of the ultrasonic beam from the amplification bead or sagging at the root of the seam (Fig.). To do this, measure distances L 1 and L 2 - the position of the transducers II at which the echo signal from the reflector has the maximum amplitude, and then the transducer is placed on the other side of the seam at the same distances L 1 and L 2 from reflector - position of transducers I.

The method of transillumination of welded joints

a - a direct beam; b - reflected beam.

Heck. 2

False echo decoding circuit

a - from sagging at the root of the seam, b - from the seam reinforcement bead

Heck. 3

If there are no defects under the surface of the gain bead or at the root of the weld, echo signals at the edges of the strobe pulse will not be observed. The signals from the gain roller will be observed strictly at the gate-pulse boundary.

If the echo is caused by reflection from the reinforcement bead, then when touched with a swab soaked in contact liquid, the amplitude of the echo will change in time with the touch of the swab.

5.8. In welded joints with a backing ring and backing, defects such as cracks and lack of penetration are more often observed in the root part of the weld, and slag and gas inclusions can be located in any layer of the deposited metal. Signal from lack of penetration at the root of the seam when sounding with a direct and one-time reflected beam (Fig.). The defect coordinate Д У corresponds to the wall thickness, and Д У indicates the location of the reflector in the half of the seam reinforcement closest to the transducer or in the middle of the reinforcement. In this case, the transducer is usually somewhat distant from the seam.

5.9. When inspecting welded joints with a backing ring or a lock, "false" signals may appear (Fig.):

From the gap between the wall of the welded joint and the backing ring or "whisker" when joining in a lock (echo 1);

From the float of metal or slag under the backing ring or "mustache" (echo 2);

From the corners of the backing ring or "mustache" (echo 3);

From the border of the seam reinforcement bead (echo 4).

5.10. Echo signals 1 and 2 from the gap or float of metal (slag) when measuring the coordinate D X corresponds to half of the seam reinforcement farthest from the transducer, and the transducer is located close to the weld reinforcement. In this case, the Du coordinate corresponds to the wall thickness or slightly more (by 1 - 2 mm). The presence of reflectors is not confirmed when sounding from the opposite side of the seam reinforcement, which distinguishes them from cracks and lack of penetration at the root of the seam.

5.11. Echo signal 3 from the corners of the backing ring or "mustache", as a rule, appears when the weld is sounded along the entire length of the joint and is located at a certain place of the strobe pulse (in the control zone by a single-reflected beam), while the coordinate D X corresponds to the reflector, located in the area farthest from the transducer border of the seam reinforcement.

In the presence of lack of penetration (lack of fusion) at the root of the seam, the signal from the backing ring sharply decreases or is completely absent.

5.12. Echo signal 4 from the seam amplification boundary appears in the region of the trailing edge of the strobe pulse (mark 2b) when the upper part of the seam is sounded by a single reflected beam, and the DY coordinate corresponds to the double wall thickness or slightly more than it, and the DX coordinate indicates the far amplification boundary seam. When sounding from the opposite side of the reinforcement of the seam, the location of the reflector is not confirmed and it is fixed as a false one.

SCHEME OF REFLECTION OF ULTRASONIC VIBRATIONS FROM NON-FAULT IN THE ROOT OF THE WELD (a) AND THE CORRESPONDING Oscillogram (b)

Heck. 4

SCHEME ULTRASONICINSPECTION OF WELD SEAMS WITH PAD RING (a) LOCK CONNECTIONS (b) AND CORRESPONDING Oscillogram (c)

Heck. 5

6. PRODUCTION OF CONTROL SAMPLES

Control samples should be made from pipe sections 20 mm wide and at least 120 mm long. Artificial reflectors should be applied on the inner and outer sides of the specified samples with a special device for applying a defect such as an angular reflector. It is advisable to choose a tool with a width of 1.5 - 2.0 mm.

7. REFUSAL RULES

Based on the results of ultrasound control welded joints pipelines with a pressure of less than 10 MPa (100 kgf / cm 2) are considered to be of high quality if there are no:

a) extended planar defects;

b) bulk non-extended defects with an amplitude of the reflected signal corresponding to an equivalent area of ​​1 mm 2 for thicknesses of 4 - 10 mm and 2 mm 2 for thicknesses of 11 - 20 mm.

8. REGISTRATION OF CONTROL RESULTS

8.1. Registration of control results is carried out in accordance with OST 26-2044-83.

8.2. For abbreviated designation of defects, use GOST 14782-86.

APPENDIX No. 1

TECHNOLOGY FOR RECOVERY OF PCN PC TYPE INVERTERS

Due to the fact that the prisms of the transducer are made of organic glass and are subject to abrasion, it is desirable for the process of their subsequent restoration not to bring the tread wear to the level of the probe body, i.e. the maximum wear from the nominal level is 1.3 - 1.4 mm (the remainder is not less than 0.2 mm to the body).

The restoration of the probe is carried out as follows: stripping. The probe is installed on the cover (upside down) in the vice of a milling machine, clamped (not tightly, without using a knob, otherwise piezo plates may come off the prisms) and with a sharp-edged cutter "ballerina" with a minimum feed in depth, level (clean) the remnants of the tread to flat state.

Protector blanks with a size of 20 × 22 mm are cut out of sheet plexiglass 3 mm thick, on which noise-absorbing teeth are applied on one side (size 20 mm) (pitch 0.8 mm; angle 45 ° - 50 °, depth 0.8 mm), similar available on the prism.

The protectors made from one side are smoothed on fine emery paper until a matte surface is obtained.

The surfaces of the transducers treated in this way (see above) and the protectors are degreased with acetone or alcohol. Next, gluing is performed.

Bonding of the probe with the protector is carried out either with a very liquid solution of "Acryloxide" (dental filling material), the powder-liquid ratio is about 5-10% powder - 95-90% liquid, or sold in stalls and households. stores "Japanese" acrylate superglue. Gluing is done with a clamp. It is desirable to align the sound-absorbing teeth on the front edge of the tread with the existing ones on the prisms; remove the excess glue (in a liquid state) from the teeth and from the side surfaces of the finder.

Drying for about 10 minutes. Under a lamp with a power not exceeding 60 W (distance to the lamp - 10 cm). After gluing and drying, the probe is installed on a milling machine (for the installation and clamping procedure, see above), and the ballerina makes a longitudinal selection of the required radius.

The depth of the sampling, in its thin part (the center of the finder), is chosen such that the remainder of the prism from the edge of the body to the center of curvature of the machine being machined in the total was 1.5 - 1.65 mm.

Accordingly, if the remainder of the prisms before the cut-off of the probe body after stripping was 0.1 ÷ 0.2 mm, the depth of the radius cut is, (with a protector thickness of 3 mm) - 1.6 ÷ 1.7 mm.

After making the curvature with a disc cutter 0.85 - 1.0 mm thick, a longitudinal cut is made in the middle of the obtained recess to insert the acoustic screen of the protector that is missing from the glued protector.

The cut must reach the remainder of the screen remaining on the probe when cleaning the prism (cutting depth 1.6 ÷ 1.7 mm) with "Japanese" superglue. The screen, 0.85 - 1.0 mm thick (along the thickness of the cutter), is cut from an oil-resistant cork-compound gasket from the engine of the Moskvich -407 car; 408 (Cylinder block pusher hatch gasket).

After drying, the remainder of the screen to the level of the new prism is cut with a scalpel.

A mass of the following composition is applied to the groove remaining in the sound-absorbing teeth as sound insulation: 3 parts of automotive polyester putty (any brand of colomix, hempropol, etc.), 1 part - powder, cork (by volume).

After drying, the excess sound-insulating mass is cut off with a scalpel. Then the protector is sanded with fine emery cloth to remove the marks after the "ballerina" and other roughness. If the described operations are observed, and the foreman has the necessary qualifications, the converter after restoration according to the RSHH is practically indistinguishable from the new one.

APPENDIX 2

PASSPORT
5.0 70 ° Æ 89 No. 1, 2 TSNIITMASH

Main technical data:

f 0, MHz 5 ± 10 %

f

f, MHz 4.6 ± 0.1

7. Calculated center value

Focal spot in depth, mm 6.5

Notes Æ

The converter complies with the requirements for non-destructive testing equipment in accordance with GOST 26266-90, and is recognized as suitable for operation.

PASSPORT
on the transducer ultrasonic inclined separate-combined general purpose type PKN PC 5.0 70 ° Æ 114 No. 3, 4 TSNIITMASH

Main technical data:

1. Rated value of operating frequencyf 0, MHz 5 ± 10 %

* the deviation of the operating frequency of the converter can reach forf- over 5 MHz, large values, without deterioration of the RSHH PEP (GOST 26266-90)

2. Actual value of operating frequencyf, MHz 4.6 ± 0.1

3. Angle of entry (on steel), deg. 70 °

4. Piezo plate size, mm 2 × 5 × 5

5. Boom of the transducer, mm 6 ± 0.5

6. Duration of the echo pulse, μs 1.2 ± 0.1

7. Calculated center value

focal spot in depth, mm 6.5

8. Range of sounding thicknesses, mm 2 - 10

9. Working temperature range, deg. C -10 ÷ +30

10. Overall dimensions of the converter, mm 20 × 22 × 19

Note: the measurement of the duration of the echo pulse is carried out on a standard CO-2 standard in accordance with GOST 14762-76 at a level of 12 dB from the maximum, from cylindrical drilling Æ 6 mm from the near side, with the UD2-12 device. Measurements are taken prior to fabrication of the tread curvature.

PASSPORT
on the transducer ultrasonic inclined separate-combined general purpose type PKN PC 5.0 70 ° Æ 159 No. 5, 6 TSNIITMASH

Main technical data:

1. Rated value of operating frequencyf 0, MHz 5 ± 10 %

* the deviation of the operating frequency of the converter can reach forf- over 5 MHz, large values, without deterioration of the RSHH PEP (GOST 26266-90)

2. Actual value of operating frequencyf, MHz 4.6 ± 0.1

3. Angle of entry (on steel), deg. 70 °

4. Piezo plate size, mm 2 × 5 × 5

5. Boom of the transducer, mm 6 ± 0.5

6. Duration of the echo pulse, μs 1.2 ± 0.1

7. The calculated value of the center of the focal

spots in depth, mm 6.5

8. Range of sounding thicknesses, mm 2 - 10

9. Working temperature range, deg. C -10 ÷ +30

10. Overall dimensions of the converter, mm 20 × 22 × 19

Note: measurement of the duration of the echo pulse is carried out on a standard CO-2 standard in accordance with GOST 14762-76 at a level of 12 dB from the maximum, from cylindrical drilling Æ 6 mm from the near side, with the UD2-12 device. Measurements are taken prior to fabrication of the tread curvature.

The converter complies with the requirements for non-destructive testing equipment in accordance with GOST 26266-90, and is recognized as suitable for operation.

General requirements

Respectivelythe methodological provisions of this section on pipe systems and pipelinescarry out ultrasonic testing onfeetwelded joints,completedany wayelectric arcwelding and gas welding:

a) butt girth welded joints of pipes, fittings or branch pipes with a nominal wall thickness of 4 mm or more on steel backing rings;

b) butt girth welded joints of pipes with a nominal wall thickness of 2 mm or more without backing rings;

c) lock welded joints of the bottoms with the collectors.

Ultrasonic inspection of welded joints in accordance with 6.1.1 is performed with a straight and one-time beaten off or only with a straight beam.

If, during the inspection with a one-time beaten off beam, a straight beam hits the tapered part of the internal bore of the pipe, the quality of the welded joint is assessed only based on the results of the inspection with a straight beam, about which an appropriate entry must be made in the "Final conclusions".

To ensure the possibility of ultrasonic testing of welded joints along the entire intersection, the length of the cylinder part of boring elements of pipe systems and pipelines must be at least 2Stgb + b + a

where S is the wall thickness in the boring zone

b - gain width

a - the width of the adjacent zone, which is subject to control

would be the angle of introduction.

The finish of boring processing should not be worse than Rz = 40 µm.

Inspection of welded joints with backing rings

During ultrasonic testing of welded joints with backing rings, sloping transducers with the characteristics noted in Table 6.1 are used.

Table 6.1- Characteristics of transducers for control

welded joints with backing rings

Wall thickness, mm		Introduction angle, degrees		transducer when monitoring
		Control	Control one-time
From 4 to 5 incl.
Over 5 to 8 incl.
"70" 120 "
Note. In the presence of a groove under the backing ring, the flaw detector settings and the assessment of inconsistencies are carried out for the thickness of the welded elements in the groove zone marked in the drawing.

1 - notches for adjusting the sweep speed and flaw detector sensitivity;

D is the diameter of the welded joint; S- wall thickness

Drawing6.1 - SZP for inspection of butt welded joints

with nominal wall thickness up to 20 mm with backing rings

1 - unfold a hole with a depth of at least 15 mm to adjust the speed

with a wall thickness of 65 mm and more when controlled by a direct beam;

D is the diameter; S - rack thickness

Drawing6.2 - unfold the FFP to adjust the speed

when inspecting welded joints of products with a thickness of 20 mm and more

with backing rings

When using AED-diagrams to control thickness of 8-20 mm, you can use (if available) the SZP shown in Figure 6.1 to adjust the speed of unroll. In this case, you can use any reflectors, including the ends of the samples. When setting the sweep speed for inspection of welded joints with a thickness of more than 20 mm, it is allowed to use SZ No. 2, 2a, etc.

The flaw detector sensitivity is adjusted accordingly 5.5.6-5.5.8.

To adjust the sensitivity during ultrasonic inspection of welded joints with a thickness of less than 8 mm, notches are used.

To adjust the sensitivity during ultrasonic inspection of welded joints with a thickness of 8 mm and more, the AED diagram technology is used (appendix I).

After setting up the flaw detector, the control is carried out in accordance with the requirements of 5.6.

Non-integers located above the root layer (Figure 6.3) can be detected by a direct or one-time beaten beam. In the latter case, there is a possible coincidence of signals from the backing ring and non-integrality.

In order to separate these signals and avoid errors during the evaluation of the quality of the welded joint, it is necessary to measure the distances Xk, X1 and X2 with a ruler from the point of introduction of the beam to the middle of the reinforcement of the welded joint. The signal from the backing ring appears at a smaller distance between the weld joint and the transducer than the signal from the non-integrality located above the root of the welded joint. In the process of control, it is necessary to periodically compare these distances with the measurement data on the SZP.

Non-pointness above the root of the seam is determined not only by the coordinates, but also through the order in which the echo appears. When approaching the welded joint, the signal from the ring appears first, and then from the non-integer.

A sign of non-integrity is the appearance on the flaw detector screen of pulses in the zone limited by the coordinates of signals 1 or 2 (Figure 5.3) for welded joints with a thickness of less than 65 mm and signals 2 or 3 for welded joints of elements with a thickness of 65 mm and more.

It should be remembered that as a result of the possible difference between the thickness of the pipe walls and the SZP, there is a possibility that the signal from the non-integrity of the signal will be mistakenly received from the reinforcement of the welded joint or from the backing ring. Therefore, before testing, it is necessary to measure the real wall thickness of each pipe, compare them with the thickness of the WSP and make the appropriate adjustments to the sweep speed setting.

If the pipe wall thickness is greater than the FSC thickness, then when monitoring from the side of this pipe, the signal from the backing ring will shift to the right in comparison with the same signal received at the FSC. If the pipe is thinner compared to the FFP, then the signal from the pipe washer will shift to the left.

The difference in the thickness of the FFP and the element that is controlled should be no more than ± 10% of the wall thickness.

The location of inconsistencies in depth is determined by means of a depth gauge or by comparison with the coordinates of signals from artificial reflectors or corners in the NWP.

To determine which of the pipes is the closer located non-integrity at the root of the welded joint, they are guided by the following signs:

a) if the non-integrity at the root of the welded joint is located closer to the fusion line with the pipe on the side of which the inspection is being carried out, then when the transducer slowly approaches the welded joint, a signal from non-integrity appears on the flaw detector screen first, and then, when the ultrasonic beam passes over the non-integrity, which partially shields the ring, a signal from the ring appears on the screen;

b) during the inspection of this section of the welded joint from the side of the second pipe, a signal from the backing ring first appears on the screen, and then from non-integrity. The simultaneous appearance of signals is also possible.

The measurable characteristics of non-sufficiency are determined in accordance with 5.6.10-5.6.16.

1 and 2 - coordinates of signals from notches; K - signal from the backing ring;

D1 and D2 - signals from super-root non-integrity, revealed by direct or

one-time beaten off beam; Xk, XI and X2 - the distance between the middle

welded joint and the point of insertion of the transducer

Drawing6.3- Schemes for the identification of the backing ring and the super-root

non-wholeness

During the control, a number of special qualitative signs should be taken into account, which help to determine the nature of some inconsistencies.

Cracks in the root of the seam with a Y-shaped structure, as a rule, start from the gap formed by the edge of the pipe and the backing ring. In the process of propagation, the cracks enter the middle zone of the deposited metal. In this regard, a characteristic feature of cracks in the root of a welded joint is that they partially or completely screen the signal from the backing ring only during inspection from the side of the pipe from which they originate. During inspection of the welded joint from the opposite side, the crack does not shield the backing ring and the ultrasonic beam freely passes through it. Two signals appear on the flaw detector screen - from the backing ring and from a crack. The signal from the backing ring has approximately the same amplitude and range across the screen as in areas where there is no inoperability. Cracks from this side turn out to be much worse, and at a low height they may by no means appear. Figure 6.4 shows the scheme for detecting a root crack with a height of more than 3 mm

Lack of fusion, located higher than the root layer of the welded joint, insignificantly or does not screen the signal from the backing ring. On the screen during inspection, signals from the backing ring and non-integrity appear on both sides of the welded joint. The distance between these signals is slightly larger than in the case when the non-integers are located at the root of the welded joint. In some cases, there are several signals on the screen from non-integrity and washer ring.

For slag inclusions or pores, impulses appear on the flaw detector screen, which quickly disappear and appear again with minor movements of the transducer in the longitudinal or transverse directions. The accumulation of small slag inclusions or pores in the weld metal gives on the screen one signal or a group of closely spaced signals.

a - crack detection scheme; would - display on the screen at position AND

converter; c - display on the screen at position II of the transducer;

D - signal from lack of wholeness; K - signal from the backing ring

Drawing6.4 - Scheme for detecting a crack in the root of a welded joint

The missing backing ring has some characteristic features, namely: on the flaw detector screen, on the left side of the signal from the backing ring, a signal from the missing one appears. In this case, the amplitude of the echo signal from the rushing ring is less than that from the ring without burn-through. When the transducer of the forming pipe is moved, one signal with two tops or two signals in close proximity to each other appears on the flaw detector screen in the area of ​​the signal from the backing ring. This is the difference between the disappearance and the inconsistencies in the weld metal. During control from different sides of the welded joint, the shape and nature of the change in signals from the missing are similar. If the burn-through turns into a non-penetration of the deposited metal, then it turns out to be as a non-penetration.

The gap between the backing ring and the base metal of the pipe is accompanied by a signal on the flaw detector screen in the same place as the signal from non-integrity at the root of the welded joint (not penetration, crack) and therefore can cause erroneous rejection of the welded joint. The characteristic features of the gap are as follows. When the transducer is smoothly moved up and down the forming pipe to the seam, the signal from the backing ring first appears, and

then from the gap. In this case, the signal from the backing ring has the same amplitude as in the place of the welded joint, where there is no gap. It should also be borne in mind that gaps of up to 0.5 mm, as a rule, do not appear, and gaps of up to 1 mm give echoes that are less than or levels to the first level of the referee.

The echo signals from the gap or the influx of metal (slag) under the ring when measuring the Dx coordinate correspond to the half of the welded joint gain that is more distant from the transducer, while the transducer is close to the reinforcement of the welded joint. In this case, the value of the Du coordinate is equal to or 2-3 mm greater than the wall thickness. The location of the marked reflectors is not confirmed during inspection from the opposite side of the reinforcement of the welded joint, which distinguishes them from cracks and no penetrations in the root of the welded joint.

Welded joints are evaluated according to the following criteria:

a) point 1 - non-integrity was revealed, the measured characteristics or the number of which are greater, and the form factor is less than the values ​​given in table 6.2.

b) score 2 - non-wholeness was revealed, the measured characteristics or the number of which is equal or less, and the form factor is greater than the values ​​given in table 6.2.

Inspection of welded joints on pipes of heat exchange surfaces

Thissubsection is devoted to the presentation of the order and method of control of butt girth welded joints of pipes of heat exchange surfaces of boilers manufactured electric arc, combinable and gas welding.

These provisions should be guided by during ultrasonic inspection:

a) butt girth welded joints with a wall thickness of 2 to 8 mm made of steels of the pearlite class;

b) butt girth welded joints with a wall thickness of 4 to 8 mm made of steels of the austenite class of grades Х18Н12Т, Х18Н10Т, Х18Н9Т.

c) butt girth welded joints of elements with steels of all listed structural classes.

During inspection of welded joints of pipes of heat transfer surfaces, non-integral parts can be located in hard-to-reach areas, for the control of which the transducer must be installed between two closely spaced pipes. To be able to control these zones, the pipes should be "spread" to the required distance, if the design allows it.

To control welded joints of heat transfer surfaces, converters are used in accordance with Table 6.3.

Table 6.3. - Characteristics of transducers for inspection of welded joints

pipes of heat exchange surfaces

Pipe wall thickness	Working hour Tota, MHz	Angle of introduction of re-creative, degrees		Maximum not met converter, mm
		Perlitney	Austenitni
From 2 to 4 incl. Over 4 to 6 inclusive
Note. When inspecting welded joints with a thickness of 2-3.5 m, it is recommended to use separately-aligned PEP at a frequency of 4-10 MHz.

Before adjusting the flaw detector, it is necessary to make sure that it is possible to inspect the root of the welded joint with a straight beam using the dashes on the SZP (Figure 6.5). The front face of the transducer should be offset to the right of the dash in the transducer position, which corresponds to the maximum echo amplitude from the lower corner reflector.

The sweep speed is adjusted using the lower and upper angular cylindrical reflectors of the SZP, the design of which is shown in Figure 6.5. In this case, the height of the echo signal from the angular reflector on the flaw detector screen is set to the upper horizontal line (the first rejection level). The zone of occurrence of the echo signal from non-integrity is determined by the position of the echo signal from the corresponding notch on the flaw detector screen when the transducer is moved along the surface of the SZP (Figure 6.6).

To adjust the sensitivity, use the PDS (Figure 6.5).

After adjusting the flaw detector, control should be carried out in accordance with the provisions of Section 5.6.

During the inspection, the possible appearance on the left side of the screen of echo signals of a surface wave bounced off the reinforcement of the welded joint. A sign that this signal belongs to a surface wave is a sharp decrease in the signal height on the screen when the surface of the welded joint is smeared with a finger in front of the transducer.

Offset of the edges of the pipes to be joined can be mistaken for non-integrality at the root of the welded joint.

Table 6.2- Limiting permissible values ​​of the measured characteristics and quantities

defects in welded joints of pipelines with backing rings

Nominal wall thickness, mm

Echo amplitude

Conditional length of a defect (MM) located at a depth, mm

Form factor Kf

Special signs of defects

Number of permissible defects for any 100mm of seam length, pcs

The total loss of permissible defects (MM), located at the same depth, per 100 mm of the seam length, at a depth of occurrence of defects (mm)

Kf measurement

3 by Kf measurement

and more

Small and large in general

referee

not measured same

According

5 to 20 incl.

Over 20 to 40 incl.

"65" 100 "

referee level

"100" 120 "

Note 1 Small ones include point defects (5.6.21) Large ones include defects whose conditional length is greater than that established for point defects, but does not exceed the values ​​given in columns 4-6 (permissible lengths), as well as all defects with a positive aspect ratio and with the amplitude of the moon signal is less than the first rejection level. Note 2. When using the data in columns 4, 5, 6, 11 and 12, it should be borne in mind that when testing with a straight beam, the depth of the defect is determined as the distance from the outer surface of the welded joint, and when testing with a one-time beaten off beam - as the sum of the wall thickness and the distance from the inner surface of the welded joint. connections to the defect. Note 3 ... If the defects turn out to be straight and one-off beams, then the assessment of their conditional length and total length is made according to the results of the control with a straight beam.

The displacement of the pipes can be determined by the appearance of a signal on one side of the welded joint (Figure 6.6, position of the transducer 3), provided that during the inspection from the second side with

at the diametrically opposite point (position 2), a signal will also appear, and there are no signals at transducer positions 1 and 4.

1 - pipe section; 2 and 3 - notches for adjusting sensitivity and speed

sweep; 4 - dashes that correspond to the boundaries of the reinforcement of the welded

Drawing 6.5- Enterprise standard sample for control

welded joints of heat transfer surfaces

During the inspection of welded joints of pipes with austenitic steels, one should be guided by the following characteristic signs of inconsistencies, which make it possible to distinguish them from obstacles:

a) a large run across the screen, close to the run from an artificial reflector;

b) non-integers appear from both sides of the welded joint;

c) the positions of the maxima of echo signals from non-integrity on the flaw detector screen during inspection from both sides of the welded joint practically coincide;

d) echoes from inconsistencies turn out to be without complications, that is, with multiple measurements, the results are confirmed.

During the inspection of welded joints made of steels of the austenite class, to obtain angles of introduction similar to those used during the inspection of steels of the pearlite class, the tilt angles of the transducer prism should be used higher by 3-60 (53-60 instead of 50-550). This is due to the difference in the speed of propagation of ultrasound in the steels of the indicated classes.

Drawing 6.6- Defining the offset of the pipes to be connected

Control of butt ring welded joints of pipes made of steels of different structural classes (composite joints) is carried out from the side of the pearlite class pipe by a transducer and by the method of control of the welded joints of the pearlite class pipes, and from the side of the austenite class pipe by the converter and by the method of control of the welded joints of the austenite class pipes.

The SZP for adjusting the sweep speed and sensitivity of control of austenitic and composite joints must have a welded joint and correspond to the standard size and steel grade of the inspected welded joint for pearlite and austenite steels, respectively.

Welded joints of heat transfer surfaces are evaluated according to such criteria.

a) point 1 - non-integrity was revealed with the amplitude of the echo signal, which exceeds the control level of sensitivity.

b) point 2 - no inconsistencies were found with an echo signal amplitude that exceeds the control sensitivity level.

Inspection of welded joints of pipelines with wall thicknessless20 mm without washer rings

In accordance with the methodological instructions of this subsection, butt circular welded joints of pipes and sector bends with a wall thickness of 2 to 20 mm from steels of the pearlite class are controlled, regardless of the method of electric arc welding.

Welded joints are controlled by sloping transducers, the characteristics of which must comply with the data in Table 6.4.

In welded joints, most of the unacceptable inconsistencies are located at the root of the welded joint. Therefore, during inspection of the marked welded joints, the main attention should be paid to the root part. In addition, it should be borne in mind that during the inspection, the most dangerous planar non-integralities in the root of the welded joint are more reliable - cracks, lack of penetration, and less reliably rounded - pores, fistulas.

Note. The root part of the welded joint should be considered a layer 1/3 of the wall thickness from the inner surface of the welded joint.

A feature of welded joints is the presence of inequalities at the root - sagging of the metal and displacement of the edges. The signals repulsed from inequalities during the control with a direct beam coincide in time with the signals repulsed from super-root inconsistencies identified by a one-time repulsed beam.

Before adjusting the flaw detector, it is necessary to make sure that it is possible to inspect the root of the welded joint with a straight beam using the dashes on the SZP (Figure 6.7). The front face of the transducer should be on the right side of the dash in such a position of the transducer that corresponds to the maximum amplitude of the echo signal from the artificial reflector.

The setting of the sweep speed of the flaw detector should correspond to the position 5.5.1-5.5.4, and the sensitivity - 5.5.6-5.5.8, respectively, the design of the SZP of which is shown in Figure 6.7. Features of setting the sweep speed during inspection of welded joints with a thickness of less than 20 mm are given in clause 6.4.7. When new FFPs are manufactured in accordance with Figure 6.7, notches should be provided for samples with a thickness of up to 8 mm

In Figure 6.8, the provided scheme for setting the sweep speed of the flaw detector, as well as the scheme for detecting super-root inconsistencies and inequalities in the root of a welded joint sags during inspection of welded joints of pipes with a thickness of less than 20 mm. ... Section "x" is the zone where echoes appear both from inconsistencies located directly above the root of the welded joint and from sagging. Section "b" is the zone of occurrence of echo signals, repulsed from inconsistencies in the upper part of the welded joint. It is also possible the appearance of signals from nonsciences from the left side of the D1 signal in the immediate vicinity of it.

Table 6.4- Characteristics of transducers for inspection of welded joints

pipelines less than 20 mm thick without backing rings

Wall thickness	Working hours stota, MHz	Insertion angle	Maximum boom converter at controls direct beam, mm
Over 5 to 8 incl.
Note. When inspecting welded joints with a thickness of 2-3.5 mm, it is recommended to use separately-combined PEP per frequency 5thMHz.

1 - pipe section; 2 and 3 - notches for adjusting sensitivity and speed

unfold; 4 - dashes that correspond to the boundaries of the reinforcement of the welded

connection, for checking the maximum value of the boom of the transducer

Drawing 6.7 - SZP for inspection of welded joints of pipelines

less than 20 mm thick without washer rings

Displacement echoes can be distinguished from non-intact echoes at the root of the weld by:

a) the echo signal from the displacement is located on the screen in the zone "a";

b) displacement through different pipe thicknesses is characterized by the presence of a signal during inspection only from one side of the welded joint along the entire perimeter or on most of it. In this case, the pipe wall thickness should be measured;

c) the displacement of the pipes to be connected is characterized by the appearance of signals during inspection from different sides of the welded joint at diametrically opposite points (6.3.10);

a - expand the speed setting:

D1 - signal from the lower control reflector, D2 - signal from the upper;

would - revealing a signal from super-root inconsistencies and sag:

D - signal from non-wholeness, P - signal coinciding with it on the coordinate

from sagging; c - unroll the screen after setting the speed, unroll

Drawing 6.8- Scheme of inspection of welded joints of pipes with a thickness of less than 20 mm

Sagging metal at the root of the welded joint is distinguished from non-integrity by the following features:

a) the echo signal from the slack is located on the screen in the zone "x";

b) sagging usually turns out to be at a smaller distance between the transducer and the welded joint than when detecting super-root inconsistencies. Sagging is most likely to occur in down-welded areas. In horizontal joints, sagging is more even and less frequent than in vertical joints;

c) the echoes from the sag have both different coordinates on the screen and different amplitudes during control from different sides.

Welded joints of sector bends are controlled with the same parameters as butt welded joints rub. A feature of such joints is the non-perpendicularity of the axis of the welded joint to the forming pipe and the variable width of the reinforcement. During inspection of welded joints of bends with a diameter of more than 160 mm, the transducer should be moved perpendicular to the axis of the welded joint. When checking the connection of sector bends of smaller diameters, move the transducer parallel to the forming pipe.

Welded joints of pipelines are assessed for the following features:

a) point 1 - the identified non-integers do not have any signs of displacement and sag according to 6.4.8 and 6.4.9, the measured characteristics or the number of identified non-completeness exceed the values ​​given in Table 6.5;

b) score 2 - the identified non-integers do not have any signs of displacement and sag according to 6.4.8 and 6.4.9, the measured characteristics or the number of identified non-completeness are equal or lower than the values ​​given in Table 6.5.

Table 6.5 - Maximum permissible values ​​of the measured characteristics and the number of inconsistencies in welded joints of pipelines with a thickness of less than 20 mm without backing rings

walls, mm	Amplitude moon- signal	Conditional length of non-integrity (mm), located at the depth (mm)		Special signs of non-wholeness	The number of permissible inconsistencies at a point 100mm length of the welded joint		The total conditional length of the admissible non-conformities located on one depth at whatever 100 mm length of the welded joint, mm
					Small and large, in total
	The first level of the referee			According to 6.4.8 and 6.4.9.
Note 1. Small ones include point non-integers (5.6.13). Inconsistencies are considered large, the conditional length of which is greater than the values ​​established for point inconsistencies, but does not exceed the values ​​given in columns 3.4 of the table (permissible lingering). Note 2. If the non-integers turn out to be straight and one-off beams, then the assessment of their conditional length and total conditional length is carried out according to the results of the control of the straight beam.

Inspection of welded joints of pipelines with a wall thickness of 20 mm and more without washer rings

Ultrasonic inspection of welded joints of pipelines with a wall thickness of 20 mm and more without backingrings differs from ultrasonic testing of similar joints on backing ringsonlyin partcontrol of the root of the welded joint. Control and quality assessment of the other part of the welded jointmeets the requirements of section 6.2.

To control the root of the welded joint, transducers with the characteristics given in Table 6.6 are used.

Table 6.6- Characteristics of transducers for root control of welded joints of pipelines with a thickness of 20 mm and more without backing rings

Ultrasonic inspection of welded joints of pipelines with a bored root part or using backing rings, which are removed, is performed in accordance with 6.2.

Unroll speed and sensitivity settings must comply with 5.5.1-5.5.4 and 5.5.6-5.5.11.

To adjust the sweep speed, use the SZP made according to Figure 6.2.

After adjusting the flaw detector, the welded joint is inspected in accordance with the provisions of 5.6.

A feature of welded joints without backing rings is the presence of inequalities in the root of the welded joint (mainly sagging of the metal), which leads to the appearance of signals bounced off them when controlled by a direct beam.

Sagging metal is distinguished from non-integrity at the root of the welded joint due to the following feature: when sounded from one side of the welded joint, the echo signal from sagging has an amplitude, which differs from the amplitude of the echo signal when sounded from the other side of the welded joint by at least 3 dB for the transducer with an angle of introduction of 65 °.

Welded joints are assessed in this way:

a) point 1 - non-integrations were revealed, the measured characteristics of which are greater, and the shape factor is equal to or less than the values ​​given in Table 6.7, provided that the identified non-integers do not have signs of metal sagging according to 6.5.5.

b) score 2 - non-wholeness was revealed, the measured characteristics or the number of which are equal or less, and the form factor is equal to or greater than the values ​​given in table 6.7.

Inspection of welded joints of bottoms with collectors

This subsection of the normative document regulates the procedure and methodology for ultrasonic testing of interlocking welded joints of collectors with a thickness of 4 mm and more. The connection design and control circuits are shown in Figures 6.9 and 6.10. The length and quality of the machined part (dimension "a" in Figure 6.9) must meet the requirements of 6.1.3.

At the same time, it should be borne in mind that:

the design of the welded joint may not provide for grooves;

control from the side of the collector with a single-shot beam is not always possible.

The welded joints of the bottom welding are controlled by sloping transducers, the characteristics of which are given in Table 6.1.

Inspection of the root part of the welded joint is carried out with a straight beam from the side of the collector pipe and from the side of the bottom, if there is a sufficient area on its surface for the operation of the transducer. The other part of the welded joint is inspected from the side of the collector pipe with a one-time beaten beam, if the design allows it.

If, during the inspection of welded joints with a thickness of less than 65 mm, the inaccessibility and design features of the collector (the presence of fittings located near the bottom, short boring length, etc.) do not make it possible to control the middle and upper parts of the welded joint with a broken beam, then the reinforcement of the welded joint should be removed.

but also would - different options for welded joints

Drawing 6.9 - Inspection of welded joints of bottom welding

to collectors

The unrolling speed setting of the flaw detector must meet the requirements of 5.5.1-5.5.4 and 6.2.3.

When adjusting the sensitivity of the flaw detector, searching for inconsistencies and evaluating their measured characteristics, one should be guided by the provisions 5.5.5-5.5.8, 6.2.5-6.2.9.

The quality assessment should be in accordance with 6.2.13.

Table 6.7 - Maximum permissible values ​​of the measured characteristics and the number of defects in welded joints

pipelines 20 mm and more without backing rings

Nominal wall thickness, mm

Echo amplitude

Conditional length of a defect (mm) located at a depth, mm

Form factor Kf

Special signs of defects

The number of permissible defects for any 100mm of the seam length, mm

The total loss of permissible defects (mm) located at the same depth, per 100mm of the seam length, at the depth of the defects (mm)

Without Kf measurement

With Kf measurement

20 to 65

65 and more

Small and large in general

65 and more

The first level of the referee

Not measured

> 65 – 100

Second level of the referee

Note 1 ... Small ones include point defects (5.6.21). Large ones include defects, the conditional length of which is greater than that established for point defects, but does not exceed the values ​​given in columns 4-6 (permissible lingering), as well as all defects with a positive aspect ratio. Note 2. When using the data of columns 4, 5, 6, 11 and 12, it should be borne in mind that when monitoring with a direct beam, the depth the occurrence of a defect is defined as the distance from the outer surface of the welded joint, and when inspecting with a one-time beaten off beam - as the sum of the wall thickness and the distance from the inner surface of the welded joint to the defect. Note 3. If the defects turn out to be straight and one-off beams, then the assessment of their conditional length and total length is made according to the results of testing with a straight beam.

The designs of welded joints, made with a deviation from the current standards, have a number of peculiarities, without taking into account which the possible erroneous rejection of the welded joint or the omission of inconsistencies.

Before carrying out control of such welded joints, it is necessary to make sure that the existing joint design complies with the drawing, for which:

a) through the holes for welding the cap to the fitting or the bottom to the manifold, visually and "for prominence" inspect the inner surface of the welded joint;

b) in order to determine the configuration, depth and length of the groove, measure the thickness of the collector wall in the non-grooved part and in the area of ​​the possible location of the groove.

If, after carrying out the noted operations, the structure of the welded joint could not be established, control should be carried out with a direct transducer from the side of the end surface of the bottom. If this is not enough, it is recommended to cut out and inspect one of the bottoms, which gives a typical picture of echo signals on the flaw detector screen during testing.

Inspection of welded joints of flat bottoms of collectors (chambers) designwhichdoes not meet the requirements of modern regulatory documents

To control such welded joints, it is necessary to first establish the actual design of the welded joint and, on this basis, draw up a drawing, one of the probable variants of which is shown in Figure 6.10.

This requires:

a) measure the external dimensions of the product, wall thickness and form the basis of a drawing with a welded joint in a section;

b) by sounding with a direct beam at a frequency of 5 MHz, measure the thickness and apply the internal structure of the product to the drawing, while the thickness of the bottom should be measured closer to its middle (pos. 1);

c) by moving the transducer along the radius of the bottom from the center to the edge, determine the presence of a relief groove and its dimensions (pos. 2-4);

d) by subsequent movement of the transducer from the middle to the edge of the bottom, fix the end of the protruding part of the inner surface of the bottom (pos. 5), which is included in the boring of the pipe element (chamber, collector);

e) remove the reinforcement in one of the sections of the welded joint and by measuring the thickness from the surface prepared in this place in the section from the middle of the welded joint in the direction of the pipe element, establish the presence of a groove in it, measure its dimensions and the thickness of the welded joint (pos. 6-8 );

f) it should be remembered that between the groove and the inner surface of the tubular element, the structure can provide a transition in the form of a cone, which is determined by moving the transducer at a distance of 80-100 mm from the edge of the tubular element.

Figure 6.10 - The structure of the welded

The control of the welded joint from the cylindrical surface of the bottom is carried out by a small-sized transducer at a frequency of 5 MHz. The bottom cylinder surface (bottom end face) must be prepared for inspection. In this case, the width of the cleaned surface should be 10-15 mm greater than the thickness of the welded joint.

The sensitivity level is adjusted along a flat-bottom hole with a diameter of 3 mm in the NW at a depth that is equal to the distance from the middle of the intersection of the welded joint to the end of the bottom. If a defect is detected, its location is determined outside the position of the transducer and glybinovimiruvach displays.

Diagrams for detecting inconsistencies in the root of a welded joint with a prismatic transducer are shown in Figure 6.11.

The quality of the welded joint is assessed by the amplitude of the echo signal and the nominal length.

Drawing 6.11 - schemes for identifying inconsistencies

Check for transverse cracks

This subsection deals with the procedure and methodology for ultrasonic testing of welded joints of pipelines with a diameter of 465 mm and less with a wall thickness of 25 mm or more in order to identify transverse cracks located in the upper third of the welded joint.

Control for transverse cracks is carried out by moving the transducer along the welded joint directly over the surface of the deposited metal. In this case, the reinforcement of the seam is removed.

Drawing 6.12 - Schemes for detecting root inconsistencies during the inspection of welded joints

bottom welding with sloping transducers

For control, converters are used for an operating frequency of 1.25-2 MHz. With a wall thickness of more than 40 mm and a diameter of 325 mm or less, transducers with an insertion angle of 50 ° should be used, and with a wall thickness of less than 40 mm or a diameter of more than 325 mm, transducers with an insertion angle of 65 °.

The transducers must be rubbed over the pipe surface. The grinding of the transducer is done according to the marking (Figure 6.13). The working surface of the transducer is rubbed in by moving the transducer over emery paper placed on the controlled pipe.

The sweep speed and sensitivity (the first level of the referee according to 5.5.7) are adjusted according to the cut with a height of 10% of the thickness, but not more than 2 mm

The edge of the cut that beats off must be located in the plane formed by the radius and forming the pipe.

From the non-integer "a" located in the upper part of the welded joint, you can get an echo signal at two positions of the transducer - 1 and 2 (Figure 6.13). At position 1, the signal on the screen will be located in the right half of the sweep (D (), and in position 2 to the left (D2) Non-integers are better when the transducer is in position 1 and echoes are located on the right side of the sweep.

Drawing 6.13 - Marking of the transducer for transverse cracks control

The coordinates of the identified inconsistencies are determined in this way:

a) if an echo from a non-wholeness appears in the echo zone from a notch, then such non-integers are near the outer surface and their location is determined by "promotions", as shown in figure 6.14. It should be borne in mind that the place where the signal from under the surface non-integrity is "felt" does not correspond to its actual location along the perimeter. This is due to the fact that the rays, repulsed from non-wholeness, fall on the adjacent

the section of the welded joint (point B, Figure 6.14), which lends itself to "industrialization";

b) if non-integrity is not "felt", only its location along the perimeter of the welded joint is determined. For this, the position of the transducer is fixed, which corresponds to the maximum echo signals from non-integrity when sounded from opposite sides. The middle of the section between the two marked positions of the transducer corresponds to the location of non-integer.

Drawing 6.14 - Adjustment of sweep speed and control scheme for transverse cracks

Inspection of butt welded jointsausteniticsteelswith element thickness 10-40 mm

This specialized technique contains technological recommendations regarding ultrasonic testing of welded joints of austenitic steels without structural lack of penetration with the same thickness of the welded elements.

For 100% sounding of the deposited metal, it is advisable to remove the reinforcement bead. The minimum radius of curvature of the surface near the welded joint, along which the transducer can move during ultrasonic inspection, must be at least 500 mm, with the exception of circular welded joints, which can be controlled at radii of curvature of at least 200 mm

Before the start of testing, in 2-3 places, the amplitude of the signal is determined, which passed through the deposited metal of the welded joint and through the base metal of the product, according to the diagram in Figure 6.15. Ultrasonic testing is possible if the signal amplitude in the welded joint (Figure 6.15, a) differs from the signal amplitude in the base metal of the product (Figure 6.15, would) by no more than 20 dB.

If the difference in signal amplitudes in the welded joints of the product and the SZP is more than 3 dB, the sensitivity should be corrected when assessing the admissibility of inconsistencies.

SZP for ultrasonic testing of austenitic welded joints, plates or sections of welded pipes should be welded. The material, size and welding technology of the SZP should be the same

by themselves, which are used for the controlled item. The use of metal plates without welded joints as an SZP is not allowed.

1 - receiver; 2 - emitter

Drawing 6.15 - Circuits for measuring signal amplitude

ultrasonic vibrations with sounding of the welded joint (a)

and base metal (b) separately-combined transducers

The dimensions of the SZP in the direction perpendicular to the weld axis should provide the ability to move the transducer in order to completely sound the welded joint metal.

In the metal of the NWP for ultrasonic inspection of austenitic seams, there should be no non-integralities, which turn out to be radiography or ultrasound on the search even chutli-east.

As an artificial reflector in the SZP, a side hole is made at the ends of the seam (Figure 6.16). Side hole diameters are shown in Table 6.8.

Drawing 6.16- SZP for adjusting the sensitivity of the flaw detector

When the thickness of the tested welded joint is d = 10-20 mm, the side hole is made along the axis of the welded joint at a depth of h = 0.55. With a thickness of d = 20-40 mm - along the axis of the welded joint at a depth of h = 10 mm The length of the hole L must be at least 50 mm

The depth of the side hole must be at least 25 mm, its surface must be made with a surface finish of at least Rz = 80 µm.

For control, specially made transducers with parameters that meet the requirements of this ND are used, or a block of two serial transducers with an introduction angle of 40 °, 45 °, 50 °, 60 °, 65 °, 70 °, in which the angle of inclination of the prism is made of organic glass should be reduced to 24 ° by removing a part of the prism (Figure 6.17) so that the angle of introduction of longitudinal waves was in the range of 60-70 °.

The ascent angle of the acoustic beams of the emitter and receiver is 14 °, and the distance between the centers of the transducers is 21 mm. The dimensions of the templates for the manufacture of transducers are shown in Figure 6.18. It is recommended to take the diameter n "of the transducer's microelement even 10-12 mm.

Simultaneously with the signal of a longitudinal wave from non-integrity, a signal of a shear wave may appear on the flaw detector screen, bounced off the surface once or twice. When scanning, they move along the flaw detector screen synchronously.

Before carrying out ultrasonic testing of austenitic welded joints, it is necessary:

a) adjust the transducer by means of templates (Figure 6.18), and use the SZP (Figure 6.16) to adjust the flaw detector to the signal bounced off the side hole. The operating frequency of the flaw detector is set equal to 2.5 MHz;

b) determine the zone of transducer movement in the direction perpendicular to the axis of the welded joint, and select on the flaw detector screen the zone of appearance of the expected non-integrity by means of a strobe pulse.

Table 6.8 - Dependence of the hole diameter on the thickness of the product

Thickness d of welded joint, mm	Side diameter holes, mm
From 10 to 15 incl.
Over 15 to 17 incl.

Drawing 6.17 - Separately combined transducer

1 - the point of intersection of the acoustic axes with the metal surface

Drawing 6.18- Customization templates

The control of austenitic seams is carried out in a separate scheme by a separately-aligned transducer by longitudinal waves, if possible, from both sides of the welded joint. The transducer must be moved along the scanning surface at a speed of 30-50 mm / s.

The step of transverse movement of the transducer should be no more than half the diameter of the n "zoplate.

Two equal sensitivities are set: 6 dB shouted above the one that ensures the detection of side holes, and the rejector - the signal amplitude is set by

valid until 6.8.19.

A feature of welded joints with a wall thickness of 10 to 20 mm is the presence of increased penetration (sagging) of the metal at the root of the welded joint, which differs from non-integrity by the following features:

a) increased penetration is usually found with a smaller distance between the transducer and the welded joint than when detecting over-root inconsistencies. The appearance of increased penetration is most likely in areas that were welded in the lower position. In horizontal welded joints, increased penetration occurs less frequently than in vertical ones;

b) signals from increased penetration have different coordinates and different amplitudes when sounded from different sides of the welded joint.

The quality of austenitic welded joints is assessed according to the following criteria:

a) signal amplitude;

b) the conditional height of non-integrity at the level of 6 dB (in amplitude);

c) the conditional width of non-integrity at the level of 6 dB (in amplitude);

d) conditional length of non-integrity at the level of 6 dB along the axis of the welded joint

Quality is assessed using a two-point system.

A welded joint is rated with a score of 1 as unsuitable if at least one of the following signs is present:

a) the amplitude of the signal from non-integrity exceeds the amplitude of the signal from the side hole (reference level) by more than 12 dB;

b) the amplitude of the signal from non-integrity exceeds the amplitude of the signal from the side hole by more than 6 dB, while the conditional width of the non-integrity is greater than the conditional width of the side hole or its conditional length is greater than the allowable one (6.8.20);

c) the amplitude of the signal from non-integrity is greater than the amplitude of the signal from the side hole or is equal to it, and the conditional height of the non-integrity is greater than the conditional height of the side hole;

d) the amplitude of the signal from non-integrity is 6-12 dB greater than the amplitude of the signal from the side hole, the nominal width and length are less, but the number of defects exceeds 3 at a length of 100 mm of the welded joint.

The value of the admissible conditional length of non-integer is:

for d<15мм L<20мм;

for d = 15 ... 25mm L<30 мм;

for d = 25 ... 40mm L<40 мм

The scanning area width is equal to:

for d = 10 ... 25mm 40-75 mm;

for d = 25 ... 40mm 80-90 mm

INDUSTRY STANDARD

CONTROL NON-DESTRUCTIVE.

WELDED PIPE CONNECTIONS

Ultrasonic method

OST 36-75-83

INDUSTRY STANDARD

By order of the Ministry of Assembly and Special Construction Works of the USSR dated February 22, 1983 No. 57, the date of introduction was established

This standard applies to butt girth welded joints of process pipelines for a pressure of not more than 10 MPa (100 kgf / cm 2), a diameter of 200 mm or more and a wall thickness of 6 mm or more from low-carbon and low-alloy steels, performed by all types of fusion welding and establishes requirements for non-destructive testing by ultrasonic method. The standard was developed taking into account the requirements of GOST 14782-76, GOST 20415-75, as well as the recommendations of the CMEA PC 4099-73 and PC 5246-75. The need to use an ultrasonic test method, its scope and requirements for the quality of welded joints are established by the regulatory and technical documentation for pipelines. APPROVED AND PUT INTO EFFECT BY ORDER of the Ministry of Assembly and Special Construction Works of the USSR No. 57 dated February 22, 1983 EXECUTORS: VNIIMontazhspetsstroy Y. Popov, Cand. tech. Sciences (topic leader), Grigoriev V.M., Art. n. with. (executive officer), Kornienko A. M., Art. engineer (executor) CONTRACTORS: UkrPTKImontazhspetsstroy V.A. sector (executive officer), N.S. Neustroeva, Art. engineer (executor) Central welding laboratory of the "Belpromnaladka" trust VP Vorontsov, head of the group (executive officer) AGREED: 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. Vorobiev 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 Head of the topic, head laboratory, Ph.D. Yu B. Popov Executive in charge, Art. researcher, acting head sector V.M. Grigoriev Performer, Art. engineer A.M. Kornienko CO-CONTRACTORS: Director of the Institute UkrPTKIMontazhspetsstroy V.F. Nazarenko Head of Welding and Pipeline Department N.V. Vygovskiy Chief designer of the project G.D. Shkuratovsky Executive Officer, Head of the Basic Welding Laboratory V.A. Tsechal Director of the Institute VNIKTistalkonstruktsiya (Chelyabinsk branch) M. F. Chernyshev Executive in charge, head. sector L.A. Vlasov Head of the central laboratory of the Belpromnaladka trust L.S. Denisov Executive in charge, group leader V.P. Vorontsov

1. PURPOSE OF THE METHOD

1.1. Ultrasonic testing is designed to detect cracks, lack of penetration, lack of fusion, pores, slag inclusions and other types of defects in welded seams and near-weld zone without decoding their nature, but indicating the coordinates, nominal dimensions and the number of detected defects. 1.2. Ultrasonic testing is carried out at an ambient temperature of + 5 ° C to + 40 ° C. In cases of heating the controlled item in the zone of movement of the finder to temperatures from + 5 ° C to + 40 ° C, it is allowed to carry out the control at ambient temperatures up to minus 10 ° C. In this case, flaw detectors and finders should be used that remain operational (according to passport data) at temperatures from minus 10 ° C and below. 1.3. Ultrasonic testing is carried out at any spatial position of the welded joint.

2. REQUIREMENTS FOR FLAW DETECTORS AND ULTRASONIC CONTROL SECTION

2.1. Requirements for NDT inspectors for ultrasonic testing. 2.1.1. Ultrasonic testing should be carried out by a team of two NDT inspectors. 2.1.2. Persons who have undergone theoretical and practical training in special courses (in a training center) in accordance with the program approved in accordance with the established procedure, who have a certificate for the right to control and issue an opinion on the quality of welds based on the results of ultrasonic testing, are allowed to carry out ultrasonic testing. Non-destructive inspectors must undergo recertification at least once a year, as well as during a break in work for more than 6 months and before being admitted to work after being temporarily suspended for poor quality of work. For re-certification at the place of work, the following composition of the certification commission is recommended: the chief welder of the trust, the head of the welding laboratory of the trust, the head of training courses, the head of the group or senior engineer for ultrasonic flaw detection, the safety engineer. The results of recertification are documented in protocols and recorded in the certificate of a defectoscopist. 2.1.3. Ultrasonic testing should be supervised by engineers and technicians or NDT inspectors of at least grade 5 with at least three years of work experience in this specialty. 2.2. Requirements for the ultrasonic testing area of ​​the welding laboratory. 2.2.1. The ultrasonic testing section must have production areas that provide accommodation for the workplaces of NDT inspectors, equipment and accessories. 2.2.2. At the ultrasonic testing site, the following are placed: ultrasonic flaw detectors with a set of standard finders; a distribution board from an alternating current with a frequency of 50 Hz with a voltage of 220 V ± 10%, 36 V ± 10%, portable power supply blocks, grounding buses; standard and test samples, auxiliary devices for checking and adjusting NDT inspectors with finders; sets of locksmith, electrical and measuring tools, accessories (chalk, colored pencils, paper, paints); couplant, oiler, cleaning material, folding brush; work tables and workbenches; racks and cabinets for storing flaw detectors with a set of finders, samples, materials and documentation.

3. SAFETY REQUIREMENTS

3.1. When working with ultrasonic flaw detectors, it is necessary to comply with safety and industrial sanitation requirements in accordance with GOST 12.2.007.0-75; SNiP III-4-80, "Rules for the technical operation of electrical installations of consumers and safety rules for the operation of electrical installations of consumers", approved by the State Energy Supervision Service of the USSR on April 12, 1969 with the additions and amendments made and "Sanitary norms and rules when working with equipment that creates ultrasound, transmitted by contact to the hands of workers No. 2282-80 ", approved by the USSR Ministry of Health. 3.2. When powered from an alternating current network, ultrasonic flaw detectors must be grounded with a copper wire with a cross section of at least 2.5 mm 2. 3.3. Flaw detectors are connected to an alternating current network through sockets installed by an electrician to specially equipped posts. 3.4. Inspectors are prohibited from opening the flaw detector connected to the power supply and making repairs, due to the presence of a high-voltage unit. 3.5. It is forbidden to carry out control near the places where welding works are performed without fencing with light shields. 3.6. It is forbidden to use oil as a couplant when carrying out ultrasonic testing near oxygen cutting and welding places, as well as in rooms for storing oxygen cylinders. 3.7. When working at height, in cramped conditions, workplaces should provide the NDT inspector with convenient access to the welded joint, subject to safety conditions (construction of scaffolding, scaffolding, use of helmets, assembly belts, overalls). It is forbidden to carry out testing without protective devices against the impact of atmospheric precipitation on the inspector, equipment and place of testing. 3.8. Non-defectoscopists must undergo medical examinations at least once a year in accordance with the order of the USSR Ministry of Health No. 400 dated May 30, 1969 and "Therapeutic and preventive measures to improve the health and working conditions of ultrasonic control operators" approved by the USSR Ministry of Health on March 15 1976 3.9. To work on ultrasonic flaw detection are allowed persons at the age of at least 18 years, who have undergone safety training with registration in the journal in the prescribed form. The briefing should be carried out periodically within the time frame established by the order of the organization (trust, installation department, plant). 3.10. The administration of the organization conducting ultrasonic testing is obliged to ensure that safety requirements are met. 3.11. If safety rules are violated, the inspector must be removed from work and re-admitted to it after additional instruction.

4. REQUIREMENTS FOR EQUIPMENT AND MATERIALS

4.1. For testing, it is recommended to use ultrasonic impulse flaw detectors UDM-1M and UDM-3, manufactured not earlier than 1975, DUK-66P (DUK-66PM), UD-10P, UD-10UA, UD-24, specialized set "ECHO" ("ECHO -2 ") or other flaw detectors that meet the requirements of GOST 14782-76. The main technical characteristics of flaw detectors are given in reference Appendix 1. 4.2. To control the quality of welded seams in hard-to-reach places (in a confined space, at a height) at construction or assembly sites, it is recommended to use lightweight small-sized flaw detectors: ECHO (ECHO-2) kit or other similar devices. 4.3. Flaw detectors should be equipped with standard or special inclined finders with prism angles for plexiglass 30 °, 40 °, 50 °, 53 °, 54 ° (55 °) at frequencies of 1.25 (1.8); 2.5; 5.0 MHz and straight finders for 2.5 and 5.0 MHz. The use of other types of finders with prisms made of other materials is allowed. In this case, the angles of the seeker prisms are chosen such that the corresponding entry angles are equal to the entry angles of the searchers with plexiglass prisms. 4.4. To check the main parameters of flaw detectors and finders, as well as control parameters, the equipment set should include standard samples Nos. 1, 2, 3 - according to GOST 14782-76 or a set of control samples and auxiliary devices (KOU-2) according to TU 25- 06.1847-78. In addition, test samples with artificial reflectors should be made for adjusting flaw detectors. 4.5. To assess the performance of flaw detectors and finders at the ultrasonic testing site, their basic parameters should be periodically checked for compliance with the passport data, which is recorded in the documentation for the device. Newly received flaw detectors and finders for which the parameters have not been verified are not allowed to be used for testing. 4.6. Conditional sensitivity, depth gauge error and sweep linearity, if the coordinates are determined by the CRT screen scale, are checked for compliance with their values ​​with the passport data at least twice a year. 4.7. Conditional sensitivity and depth gauge error are checked according to standard samples Nos. 1, 2 (Fig. 1, 3). The linearity of the sweep is checked according to the method described in the recommended Appendix 2. 4.8. In the finders, at least once a week, check the compliance of the mark on the lateral surface of the prism with the exit point "O" of the ultrasonic beam according to the standard sample No. 3 (Fig. 2), and the angle of the prism according to the standard sample No. 1 (Fig. 1). 4.9. Flaw detectors are considered suitable for operation if the values ​​of the checked parameters (clause 4.6.) Correspond to the values ​​specified in the passport for the device. 4.10. Seekers should be considered fit for work if the values ​​of the checked parameters (clause 4.8.) Do not exceed the permissible deviations specified in section 1 of GOST 14782-76. 4.11. Flaw detectors and finders for which the results of checking the parameter values ​​turned out to be unsatisfactory must be repaired or replaced with new ones. Repair of flaw detectors, with the exception of malfunctions specified in the operating instructions for the device, must be carried out by the specialists of the manufacturer or in specialized workshops.

Standard sample No. 3

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

Standard sample No. 2

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

5. PREPARATION FOR CONTROL

5.1. The basis for the initial inspection, as well as repeated inspection after the elimination of defects in the welded seam, is an application signed by the customer. The application, the form of which is given in the recommended Appendix 3, is registered in the welding laboratory in the journal (Recommended Appendix 4). 5.2. Only welded joints accepted according to the results of external inspection and meeting the requirements of GOST 16037-80 are subject to control. 5.3. It is forbidden to inspect welded joints of pipelines filled with liquid. 5.4. Workplaces for performing ultrasonic testing should be prepared in advance. For work in hard-to-reach places and at heights, auxiliary personnel should be assigned to assist the NDT inspectors. 5.5. The choice of the sounding method, the type of the seeker, the couplant, the control scheme. 5.5.1. Depending on the thickness of the elements to be welded (GOST 16037-80), a method of sounding is chosen, which makes it possible to control the section of the entire deposited metal (Table 1). 5.5.2. The distance B, at which on both sides of the seam reinforcement bead the surface of the zone of movement of the IC type finder should be prepared, is selected according to table. 1 or in cases where other types of searchers are used, it is calculated by the formulas:

B 1 = d × tg a -l / 2 + d + m (1)

When sounding with a direct beam

B 2 = 2 d × tg a + d + m (2)

When sounding with a direct and one-time reflected beam

B 3 = 3 d × tg a -l / 2 + d + m (3)

When sounding once and twice with a reflected beam

Table 1

Ultrasonic testing parameters

Thickness of welded elements in accordance with GOST 16037-80, mm	Sounding method *)	Seeker prism angle, deg.	Seeker operating frequency, MHz	Finder movement area, mm	Stripping area B **, mm	Limiting sensitivity S p (first rejection level), mm 2	The area and linear dimensions of the vertical face of the corner reflector
							area S mm 2	width b mm	height h mm
from 6 to 7.5 incl.	Direct and once reflected beam
over 7.5 to 10 incl.

Notes: *) In case of impossibility of sounding the entire section of the seam with direct and once-reflected beams, sounding with single- and double-reflected beams is allowed. **) When sounding the seams with a double-reflected beam, the stripping zone B is calculated according to the formula (3) p. 5.5.2
A diagram explaining the indicated formulas for determining the stripping zone is shown in fig. 4. 5.5.3. Surfaces at distance B on both sides of the joint reinforcement must be free from metal splashes, peeling scale, rust, dirt and paint. The cleaned surfaces must be free of dents, irregularities and nicks. A highly correlated surface (corrosion depth greater than 1 mm) must be machined to a level and smooth surface. For cleaning it is recommended to use metal brushes, chisels and grinders with an abrasive wheel. After machining the surface, its roughness should be no more than R z = 40 microns in accordance with GOST 2789-73. 5.5.4. Cleaning the surface and removing the couplant after testing is not the responsibility of the NDT inspector. 5.5.5. After stripping, the welded joint is marked into sections and numbered so that it is possible to unambiguously establish the location of the defect along the length of the seam according to the diagram shown in Fig. 5 . 5.5.6. To create an acoustic contact, transformer oil is used in accordance with GOST 982-80, glycerin - in accordance with GOST 6259-75, liquids developed by the Taganrog plant "Krasny Kotelshchik" and the Chernivtsi machine-building plant (recommended Appendix 5). At temperatures above 25 ° C or diameters of welded elements less than 300 mm with a vertical arrangement, they are used as contact fluids autola 6, 10, 12, 18, solid oil - according to GOST 4366-76 or other mineral oils similar to those indicated in viscosity.

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

D - thickness of welded elements, mm; a - entry angle, degrees; d is the 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 cleaning the surface when sounding with a direct, once and twice reflected beam, mm; m = 20 mm

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

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

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

table 2

SEEKER PARAMETERS

Angle of the prism (b) of the seeker, deg.	Operating frequency (f), MHz	Transducer diameter, mm	Seeker arrow, mm	Input angle (a) of the ultrasonic beam (plexiglass-steel), deg.

Note: The parameters are given for IC type searchers (TU 25.06.1579-73 - collapsible searchers with plexiglass prisms). 5.8.5. The "dead zone" is checked according to the standard sample No. 2 GOST 14782-76 and when working with inclined finders with prism angles from 50 ° to 55 °, it should not exceed 3 mm, and when working with finders with prism angles of 30 ° and 40 °, it should not exceed 8 mm. Reflectors of the "side drilling" type with a diameter of 2 mm at a depth of 3 and 8 mm from the surface of movement of the seeker to the center of the hole should be made in the standard sample (Fig. 3). 5.8.6. The limiting sensitivity is determined by the area (mm 2) of the flat bottom of the hole, segment or corner reflectors. The flat bottom of the hole and the plane of the segment should be oriented perpendicular to the acoustic axis of the finder. The amplitudes of the echo signals from the segment reflector and the flat bottom of the hole with the same areas will be equal, provided that the height h of the segment is greater than the shear wavelength, and the ratio of the height h and width b of the segment is not less than 0.4. The amplitudes of echo signals from the corner reflector and the flat bottom of the hole (or segment reflector) will be equal provided that the width b and height h of the vertical face of the corner reflector are greater than the shear wavelength, the ratio h / b satisfies the inequality:

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 ratio:

S p = NS 1, where

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

Dependency ratioNfrom the cornerabeam input

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

Sample with reflector type: "flat bottom hole" for adjusting the sensitivity of the flaw detector

Test piece with an angled reflector for adjusting the sensitivity, determining the coordinates of defects and setting the inspection zone of the flaw detector

Where n is the number of reflections

Test piece with a segment reflector for adjusting the sensitivity, determining the coordinates of defects and setting the inspection zone of the flaw detector

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

L ¢ = (n + 1) d × tan a + d + m + 25; m = 20,

Where n is the number of reflections

5.9. Setting up a flaw detector for testing. 5.9.1. A finder with the parameters selected according to the table is connected to the flaw detector. 1 in accordance with the thickness of the elements to be welded, the acoustic properties of the metal and the geometry of the welded joint. 5.9.2. The flaw detector is prepared for operation in accordance with the requirements of the operating instructions, and then it is adjusted to control a specific product in the following sequence (basic operations): set the sweep duration; set up a depth-measuring device; set the limiting sensitivity (the first rejection level); equalize the sensitivity using a temporary sensitivity adjustment system (TSP); set the search sensitivity; set the duration and position of the strobe pulse. 5.9.3. The duration of the sweep 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 set so that its leading edge is near the probe pulse, and the rear one is at the end of the CRT screen along the scan line. 5.9.5. The depth-measuring device of the flaw detector is adjusted according to the instruction manual. If there is no depth-measuring device in the flaw detector, then it is necessary to calibrate the CRT screen scale in accordance with the thickness of the tested product. The method for determining the coordinates on the CRT screen scale for the "ECHO" set is given in the recommended Appendix 7. The method for checking the depth gauge scale of the DUK-66P flaw detector is given in the Recommended Appendix 8. 5.9.6. To adjust the depth gauge, it is recommended to use test specimens with artificial reflectors of the "side drilling" type in the case of inspection of welded joints with a wall thickness of more than 15 mm (recommended Appendix 8) and specimens with segment or corner reflectors for welded joints with a wall thickness of 15 mm or less ( Fig. 8 and 9). 5.9.7. The limiting sensitivity is set (the first rejection level). The values ​​of the reflector area corresponding to the first rejection level for a specific controlled product are determined from table. 1.5.9.8. The flaw detector is adjusted to the first rejection level using the "attenuation" or "sensitivity", "cutoff", "power" and TCG controls so that the height of the echo signal from the artificial reflector is equal to 30 mm regardless of the control scheme in the absence of noise in the working section of the sweep ... 5.9.9. Set the response level of the automatic defect alarm system (ASD). 5.9.10. The values ​​of the second rejection level of the limiting sensitivity are set higher than the first by 3 dB. 5.9.11. To adjust the flaw detector to the second rejection level, the "attenuation" knob (for flaw detectors with an attenuator) is turned by 3 dB to the left (counterclockwise) or the "sensitivity" knob (for flaw detectors without an attenuator) by 1 division to the right clockwise with respect to the first rejection level ... 5.9.12. Set the search sensitivity. The values ​​of the search sensitivity level are set above the first rejection level by 6 dB. 5.9.13. To adjust the flaw detector to the search sensitivity, the "attenuation" control is turned by 6 dB to the left (counterclockwise) or the "sensitivity" control by 2 divisions to the right (clockwise) with respect 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 sounding method according to the method described in the recommended Appendix 9.

6. CONTROL

6.1. The inspection includes the operations of sounding the weld metal and the heat-affected zone and determination of the measured characteristics of defects. 6.2. The sounding of the seams is performed by the method of transverse-longitudinal movement of the seeker, described in clause 5.7. The speed of movement of the seeker should be no more than 30 mm / s. 6.3. Acoustic contact of the seeker with the surface on which it moves is ensured through the couplant by lightly pressing the seeker. The stability of the acoustic contact is evidenced by a decrease in the levels of signal amplitudes at the trailing edge of the probing pulse, created by the acoustic noises of the seeker, in comparison with their level with the deterioration or absence of the acoustic contact of the seeker with the surface of the product. 6.4. The sounding of welded joints is carried out at the search sensitivity, and the determination of the characteristics of the detected defects - at the first and second rejection levels. Analyze only those echoes that are observed in the strobe pulse and have a height of at least 30 mm at the search sensitivity. 6.5. During the inspection process, it is necessary to check the flaw detector setting to the first rejection level at least twice a shift. 6.6. At the first rejection level, the defects are assessed by their amplitude, and at the second rejection level, the conditional length, the conditional distance between the defects and the number of defects are estimated. 6.7. The seams of welded joints sound with direct and single-beam reflected beams from both sides (Fig. 10). When echo signals appear near the trailing or leading edges of the strobe pulse, it should be clarified whether they are the result of the reflection of the ultrasonic beam from the amplification or sagging at the root of the seam (Fig. 11). To do this, measure the distances L 1 and L 2 - the position of the searchers (I), at which the echo signal from the reflector has a maximum amplitude, and then the finder is placed on the other side of the seam at the same distances L 1 and L 2 from the reflector, - the position of the seekers (II). If there are no defects under the surface of the gain bead or at the root of the weld, echo signals at the edges of the strobe pulse will not be observed. If the echo is caused by reflection from the reinforcement of the seam, then when you touch it with a swab soaked in contact liquid, the amplitude of the echo will change in time with the touch of the swab. Please note that acceptable undercuts can also cause false echoes. In this case, it is recommended to clean the reflective weld section flush with the base metal surface and then retest. In the absence of defects, echoes at the edges of the strobe pulse will not be observed.

Sounding schemes for seams with symmetrical grooving

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

False echo decoding circuit

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

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 from both sides according to the method for symmetric groove, to sound additionally with finders with a prism angle of 54 ° (53 °) from the side of the edge without bevel (Fig. 12). In this case, the zone of movement of the seeker and the zone of stripping are calculated according to the formulas of clause 5.5.2, and the limiting 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 alleged defect at the root of the seam on the surface of the welded joint, the sounding of the lower part of the seam is performed with a straight 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 the 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 controlled pipe or test specimen used to adjust the flaw detector to the first rejection level. Moving the finder perpendicular to the end face, 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 one-sided access to the seam, it is sounded only from one side (Fig. 15). If the thickness of the elements to be welded is not 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, a corresponding entry must be made that the sounding was performed only on one side of the seam.

Sounding schemes for seams with asymmetric grooving

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 °)

Sounding scheme for the bottom of the seam.

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

Experimental Distance Determination Scheme

Scheme of sounding the seam with unilateral access

Sounding scheme of a seam with different wall thicknesses of abutting elements

6.12. If the abutting elements have different thicknesses without a bevel of the 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 greater wall thickness of the element at a distance L 1 = tg a from the weld axis, the signal from the lower wall corner and the signal from the defect in the weld root (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 from the side of the smaller wall thickness of the element at a distance L 1 from the weld axis. In this case, if the signal near the trailing edge of the strobe pulse is not observed, the defect is absent, if the signal is observed, then a defect is found in the root of the weld. 6.13. If the abutting elements have different thicknesses with a beveled wall of greater thickness, then from the side of the smaller thickness, sounding is performed in accordance with clause 6.7, and from 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 pipes to be joined and the actual border (length) of the bevel are determined by a straight finder according to the recommended Appendix 10. 6.14. The main measurable characteristics of the detected defects are: the 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 the seam with a length of 100 mm. 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 single-beam reflected beam from the side of a thicker element

The intervals of movement of the seeker when sounding the seam: a - with a straight beam from L "to L", where L "= l /2 + n; L "= d × tan a; b - a single-time reflected beam from to, where = 5 (d 1 - d) +10+ d 1 × tan a, = 2 d 1 × tan a + l /2 ; L = 5 (d 1 - d).

Scheme of sounding seams with a double-reflected beam from the side of a thicker element

The interval of movement of the seeker 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 point of entry of the beam to the projection of the defect onto the surface of the welded joint and the depth of occurrence H - are determined in accordance with the requirements of the instructions for use of flaw detectors (Fig. 19) 6.17. The coordinates of the defect are determined at the maximum amplitude of the reflected signal. If the echo goes beyond the screen, 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 the defects are determined in accordance with 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

7.1. Assessment of the quality of welded joints. 7.1.1. The measured characteristics of defects in welded joints are assessed in accordance with the requirements of this standard and the current regulatory and technical documentation. The maximum permissible values ​​of the measured characteristics of defects established taking into account the requirements of SNiP III -31-78 are given in table. 3. 7.1.2. The quality of welded joints is assessed according to the results of control according to the principle: "good" - "bad". The term "good" is used to assess the seams of welded joints without defects or with defects, the measured characteristics of which do not exceed the standards specified in table. 3. The term "unfit" is used to assess the seams of welded joints if defects are found in them, the measured characteristics of which exceed the standards specified in table. 3.

Determination of coordinates of defects

Table 3

MAXIMUM PERMISSIBLE VALUES OF MEASURED CHARACTERISTICS AND NUMBER OF DEFECTS IN THE SEAMS OF WELDED CONNECTIONS

Nominal thickness of welded elements, mm	Amplitude estimation	Assessment by conditional length, conditional distance between defects and number of defects	Conditional length (mm) of a defect located at a depth, mm		The number of defects allowed by the measured characteristics for any 100 mm of the seam length	Total nominal length (mm) of permissible defects for any 100 mm of the seam length located at a depth, mm
from 6.0 to 20.0 incl.	First rejection level	Second rejection level
over 20.0 to 40.0 incl.
over 40.0 to 50.0 incl.

Note: Two adjacent defects with a conditional distance between them less than the conditional length of a smaller defect are considered one defect with a conditional length equal to the sum of the lengths of the first defect, the distance between the defects and the second defect. 7.2. Registration of control results. 7.2.1. The results of the inspection of each welded joint must be recorded in the journal and in the conclusion. 7.2.2. Registration of the inspection results in the log should be carried out by the defectoscopist who carried out the inspection, and the correctness of the registration of the specified data should be controlled by the person responsible for the preparation of the documentation. 7.2.3. Forms of the journal and conclusions, as well as examples of entries in them are given in the recommended annexes 11 and 12. 7.2.4. The control log and copies of the conclusions must be kept at the enterprise that carried out the control for at least 5 years after the facility was put into operation. 7.2.5. An abbreviated description of defects in the control log and in the conclusion should be carried out in accordance with GOST 14782-76. 7.2.6. For seams with unacceptable defects, in addition to the conclusion, defectograms must be drawn up. The form of the defectogram is given in the recommended Appendix 13.

ANNEX 1

Operating frequencies, MHz

Attenuator dynamic range, dB

Maximum sounding depth (on steel), mm

Depth gauge

Dimensions of the working part of the CRT screen, mm

Working temperature range, ° K (° C).

Dimensions, mm

Weight, kg

Supply voltage, V

Type of food

UDM-1M

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

70 diameter

278-303 (+5 to +30)

220 × 335 × 423

UDM-3

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

DUK-66P

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

(from minus 10 to +40)

260 × 160 × 425

DUK-66PM

260 × 170 × 435

220, 127, 36, 24

UD-10P

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

50 (in 2dB steps)

278-323 (+5 to +50)

345 × 195 × 470

From an alternating current with a frequency of 50 Hz; accumulators

40 (smoothly)

UD-24

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

263-323 (from minus 10 to +50)

130 × 255 × 295

Also UD-10UA

500 (for aluminum)

278-424 (+5 to +50)

520 × 490 × 210

From an alternating current with a frequency of 50 Hz Specialized ultrasonic kit "ECHO" ** ("ECHO-2" ***)

258-313 (from minus 15 to +40)

140 × 240 × 397

From an alternating current with a frequency of 50 Hz; accumulators Notes: * Determination of the coordinates of defects is carried out on the scale of the CRT screen. ** The set "ECHO" ("ECHO-2") is produced by the Sverdlovsk experimental plant Glavmontazhavtomatiki, the rest of the flaw detectors - by the plant "Electrotochpribor" PO "VOLNA", Chisinau. *** The set "EKHO-2" has a VRCH system and is equipped with a digital indicator IKD-1 for determining the coordinates of defects.

APPENDIX 2

METHODOLOGY FOR DETERMINING THE LINEARITY OF THE SCAN OF THE SPECIALIZED SET "ECHO"

The linearity of the scan line is determined as follows: 1. Connect the straight finder to socket 1 of the flaw detector. 2. The toggle switch of the "type of work" switch is set to position 1. 3. The attenuator switches "fine" and "rough" are set to position "0". 4. Using the "noise cutoff" regulator, if necessary, remove noise from the scan line. 5. Use the "" knob to remove the strobe pulse outside the screen. 6. The "sweep coarse" switch is set to position "5". 7. The "sweep smoothly" regulator is set to the extreme right position. 8. Install the finder on the surface of the standard sample No. 2 GOST 14782-76. 9. Achieve on the screen the maximum number of reflected back-ground signals so that they are distributed along the entire scan line. 10. Measure on a scale on the CRT screen the distance between the leading edges of the reflected signals. 11. Linearity is considered satisfactory if the distance between pulses does not differ from each other by more than 10%. 12. Check the linearity in the same way on the remaining ranges of the sweep.

APPENDIX 3

Name of the organization that issued the application APPLICATION No. for ultrasonic testing of welded joints 1. The application was made by ________________________________________________________ (initials and surname) 2. The name of the object __________________________________________________ 3. The name and brief characteristics of the controlled item ____________ ________________________________________________________________________ ________________________________________________________________________ (Т - temperature, º К (º С); Р - pressure (kgf / cm 2); ________________________________________________________________________ 4. Drawing number _________________________________________________________ 5. Scheme of the location of the controlled sections, their numbering, a sketch of the cross-section of the seam indicating the geometry of the groove, the thickness of the welded elements and the width of the seam reinforcement. 6. Number of the seam or joint section ____________________________________________ 7. Number of joints (pcs.) Subject to control ____________________________ 8. Inspection volume (%) of the joint perimeter ___________________________________ 9. Initial or repeated inspection ______________________________________ ________________________________________________________________________ (if control was previously carried out, then it is necessary to indicate ________________________________________________________________________ method and date of control) 10. Outer and inner diameter (mm) of welded elements ________________ 11. Type (method) of welding ___________________________________________________ ________________________________________________________________________ 12. Metal grade of welded elements ___________________________________ 13. Electrode grade ______________________________________________________ 14. Initials, surname and stamp of the welder __________________________________ 15. Welding date __________________________________________________________ 16. Degree the readiness of the workplace for control in accordance with the requirements of OST ________________________________________________________ ________________________________________________________________________ Application submitted "" 19

APPENDIX 4

APPLICATION REGISTRATION JOURNAL FORM

APPENDIX 5

CONTACT FLUIDS

Contact liquid 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 bowl. The 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. The contact liquid is used at temperatures from +3 to +38 º С.

Contact liquid of the Chernivtsi Machine-Building 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 in% .......................... .................................................. ................................ from 98.8 to 97

Cooking method

In a steel tank with a capacity of 3 liters, equipped with a stirrer at a speed of 800-900 rpm, 500 g of technical (8%) polyacrylamide and 1.3 liters of water are loaded, stirred for 10-15 minutes. until a homogeneous sodium nitrite solution is obtained. The hopper is loaded with the appropriate amount of polyacrylamide, sodium nitrite solution and water. Then the motor and the contents of the bunker are turned on for 5-10 minutes. It is pumped over and over again 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

Reference

METHOD FOR MANUFACTURING SEGMENT REFLECTORS

Segment reflectors are made on the surface of a test specimen by milling on a coordinate boring machine according to the scheme (Fig. 1). The cutter diameter is selected depending on the required area of ​​the segment reflector. The depth H of milling is selected according to the graphs (Fig. 2, 3). The angle α of inclination of the cutter is set equal to the angle of input of ultrasonic vibrations. It is allowed to manufacture segment reflectors on milling machines. The depth H of milling is measured with an indicator with a needle bore gauge.

Method of manufacturing segment reflectors

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

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

APPENDIX 7

PROCEDURE FOR DETERMINING THE COORDINATES OF DEFECTS BY THE "ECHO" SET WHEN INSPECTING THE SEAMS OF WELDED JOINTS

1. General instructions

1.1. Coordinates "H" and "L" are determined directly on the scale of the CRT screen. 1.2. To determine the coordinates on the scale, perform the following operations: select the working range of the sweep; set the position and duration of the strobe pulse in accordance with the control zone of the welded joint and carry out the graduation of the scale in relation to the thickness of the welded elements, calculate the scale factors K N and K L. 1.3. Adjustment of the "ECHO" set is carried out according to the test sample, which is used to adjust the sensitivity during testing. 1.4. For the convenience of calculations, the value of the small horizontal division of the scale is taken to be 0.2. 1.5. The "Y" regulator aligns the scan line with the lower horizontal line of the scale, and the "X" regulator aligns the maximum amplitude of the probing pulse with the first vertical line of the screen scale on the left. 1.6. Set the "sweep coarse" switch to the "5" position, and the "" knob to the extreme right position. 1.7. The "" regulator sets the leading edge of the strobe pulse near the trailing edge of the probing pulse (ZI), and the regulator "" makes the duration of the strobe pulse so that its trailing edge is located at the end of the scale.

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

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

Table 1

2.2. In accordance with the thickness δ "(part of the thickness) of the seam of the welded joint, the control of which is possible with a straight beam, equal to the distance from the center of reflector 1 (type" side drilling ") to the bottom of the test specimen (Fig. 1), the number of divisions that is necessary is determined by the formula set between the leading edges of signals (1) and (2). 2.3. Moving the finder over the surface of the test specimen (Fig. 1) successively achieve the maximum signal amplitudes (2) from reflector 2 located at the maximum depth and signal (1) from reflector 1 . 2.4. Regulators "rough sweep", "" and "" achieve the distance between the leading edges of the maximum signal amplitudes (2) and (1), equal to N large divisions, by the method of successive approximation, (in the example considered in Fig. 1, N = 4 ,4).

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

2.5. The "" regulator combines the leading edge of the strobe pulse with the position of the leading edge of the signal (1). 2.6. The "" regulator combines 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, the maximum amplitude of the signal from the reflector detected in the control zone is set (for example, the signal (3) from the reflector 3, Fig. 1). Then 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 is counted and the depth (H) of the defect is determined by the formula:

H = δ -N i K H;

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

3. Method for determining the coordinates of defects when sounding the seams of welded joints with a direct and one-time 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

3.2. Determine the number of divisions N p, which is set between the positions of the leading edges of the signals from reflectors 2 and 4 when sounding a single reflected beam (Fig. 2) according to the formula:

N p = δ / K H.

3.3. Determine the number of divisions, which is set between the positions of the leading edges of signals (1) and (2) from reflectors 1 and 2 when sounding with a straight beam (Fig. 2) according to the formula:

N l = δ "/ K H.

3.4. Moving the finder over the test piece, achieve the maximum amplitude of the signal (4) from the reflector 4 (Fig. 2), located at the maximum distance from the point of entry of the beam when sounding with a single reflected beam. 3.5. Set the switch "coarse sweep" and the knob "" signal (4) between 8 and 9 large divisions of the horizontal scale. 3.6. Using the "" and "" controls by the method of successive approximations, the leading edge of the maximum signal amplitude (2) from the reflector 2 is combined with the middle of the scale, and the leading edge of the maximum signal amplitude (4) from the reflector 4 is placed at a distance equal to N p divisions (Section 3.2.) from the middle of the scale to the right. 3.7. Set the regulator "" the leading edge of the strobe pulse at a distance equal to N l divisions (p. 3.3.) From the middle of the scale to the left, corresponding to the position of the leading edge of the maximum signal amplitude (1) from the reflector 1. 3.8. Combine the regulator "" the trailing edge of the strobe pulse with the position of the leading edge of the maximum signal amplitude (4) from reflector 4 (p. 3.6.).

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

3.9. Consider all signals detected within the duration of the exposed strobe pulse from its leading edge to the middle of the scale, identified by a straight beam, and from the middle of the scale to the trailing edge, by a single reflected beam. 3.10. The depth of occurrence (N l, N p) of the detected defects in the sounding zone by a straight beam is determined by the formula:

H l = δ - N l i K H;

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 sounding zone by a once reflected beam is determined by the formula:

H 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 zone with a straight beam using the formula:

L l = H l · tg α;

And a once reflected beam according to the formula:

L p = (2 δ -H p) · tan α;

3.12. The procedure for setting up the "ECHO" set for determining the coordinates of defects with simultaneous sounding of the seams of welded joints with single- and double-reflected beams is similar to the one described above. In this case, the coordinates H and L are determined by the formulas:

H = N l i K H;

Where K N increases by 3 times compared with the values ​​of the table. 1.

L p = [(n +1) δ -H p] · tan α.

APPENDIX 8

METHOD OF CHECKING THE ERROR OF DEPTH GAUGE OF DUK-66P FLAW DETECTOR

1.1. Set the scale selected in accordance with the operating frequency and angle of the finder prism. 1.2. Move the finder over the surface of the test specimen and when receiving a signal of maximum amplitude from each of the three holes (see drawing), measure the coordinates H and L using a depth gauge device. 1.3. The coordinates determined by the depth gauge are compared with the coordinates measured by metric means directly on the sample. 1.4. If the permissible error (according to the passport for the flaw detector), obtained from the results of the above comparison, is exceeded, it is recommended to send the device for verification.

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

APPENDIX 9

METHOD FOR ESTABLISHING THE DURATION AND POSITION OF THE STROBE PULSE

1.1. The duration and position of the strobe pulse are set in accordance with the selected sounding method (direct, single or double reflected beam). 1.2. The flaw detector is adjusted according to a test specimen with reflectors used to set the limiting sensitivity (the first rejection level). 1.3. In the flaw detectors UDM-1M, UDM-3, DUK-66P, DUK-66PM, with the exception of the "ECHO" set, the method of setting the strobe pulse is the same. 1.4. The method for setting the duration and position of the strobe pulse for the "ECHO" set is directly related to the method for determining the coordinates and is described in the recommended Appendix 7. 1.5. When sounding the seam of the welded joint with a direct and once-reflected beam, the leading edge of the strobe pulse is set along the leading edge of the signal with the maximum amplitude reflected from the lower reflector (angular or segment), and the trailing edge of the strobe pulse - along the trailing edge of the signal with the maximum amplitude reflected from the upper reflector - angular or segment (Fig. 1). With this setting, echoes at the start of the strobe indicate defects at the bottom of the weld, and echoes at the end of the strobe indicate defects at the top of the weld.

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

L "is calculated depending on δ, α and on the sounding scheme by the formula: L" = (n +1) d × tan a + d + m +25, where n is the number of reflections

1.6. When sounding the seam of the welded joint with a double and single reflected beam, the leading edge of the strobe pulse is set along the leading edge of the signal with the maximum amplitude reflected from the upper reflector, and the trailing edge of the strobe pulse - along the trailing edge of the maximum signal with the 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 by the "X offset" regulator symmetrically relative to the middle of the CRT screen scale for all flaw detectors, except for the "ECHO" set.

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

is calculated depending on δ, α and on the sounding scheme by the formula: = (n +1) d × tan a + d + m +25, where n is the number of reflections

APPENDIX 10

DETERMINATION OF WALL THICKNESS OF THE ELEMENTS TO BE WELDED AND THE ACTUAL BORDER (LENGTH) OF THE BEVEL WITH A DIRECT FINDER

1.1. The seeker is installed on the surface of the welded elements, previously prepared under control on both sides of the seam and covered with a contact liquid, at a distance of at least 40 mm from the line of transition of the seam to the base metal. When the diameter of the welded elements is less than 300 mm, the specified surface is cleaned to obtain a flat plane with a width greater than the diameter of the straight finder (see drawing). 1.2. The thickness of the walls of the elements to be welded is determined by the depth gauge device, configured for measurement with a straight finder according to the instructions for the flaw detector. 1.3. To determine the actual boundary (length L sk) of the bevel, the finder is moved over the surface of the element having a large thickness towards the seam until a sharp increase in the distance between the probe and the nearest reflected pulses appears in comparison with the distance between the rest of the multiple reflected signals. Having noted the position of the finder found in this way (see the explanatory diagram in the drawing), the distance L ck from the centerline of the seam to the position of the mark on the surface of the element is measured with a ruler.

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

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

APPENDIX 11

ULTRASONIC CONTROL LOG

Conclusion number and date of issue

Control date

The name of the controlled object and its address

Control scope

Characteristics of the welded joint

Control parameters

Control results

Assessment of the quality of the seam of the welded joint

Retest information

Surname of the inspector

Inspector's signature

Note

Connection type

Index (number) of the seam according to the drawing

Diameter and thickness of welded elements, mm

Steel grade

Welding method

Flaw detector type and number

Working frequency, MHz

Seeker prism type and head, degrees

The area of ​​the maximum permissible equivalent defect

Welded area number

Abbreviated description of detected defects

Number of detected defects per 100 mm of seam length

Conditional length of defects per 100 mm of weld length, mm

APPENDIX 12

(Object name)			(name of the organization that carried out the control
Line no.			installation department of the trust, laboratory)
CONCLUSION No. ___ for checking the quality of butt welded joints of pipelines by the ultrasonic method Drawing (form, wiring diagram) No. ____________________________________________________________________________ Surname, name, patronymic and number of the welder's mark ____________________________________________________________________ Type of flaw detector and its serial number ____________________________________________________________________________ Head of the laboratory _______________________________________________________ signature (last name, first name, patronymic) Ultrasonic inspection inspector from the last name ___________________________________, signature

Note: 1. The report number should be the serial number of the corresponding entry in the ultrasonic inspection log. 2. The control diagram is shown on the back.

APPENDIX 13

DEFECTOGRAM # 6 OF WELDED CONNECTION # 30 ENTRY # 21 IN THE ULTRASONIC CONTROL LOG

(example of filling)

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

1. Purpose of the method. 2 2. Requirements for NDT inspectors and ultrasonic testing area. 2 3. Safety requirements. 3 4. Requirements for equipment and materials .. 4 5. Preparation for testing .. 7 6. Testing. 14 7. Processing and presentation of control results. 19 Appendix 1 Recommended flaw detectors and their main technical characteristics. 21 Appendix 2 Methods for determining the linearity of the scan of a specialized set of "echo". 22 Appendix 3 Application for ultrasonic testing of welded joints. 22 Appendix 4 Application register form. 23 Appendix 5 Contact liquids. 23 Appendix 6 Method of manufacturing segment reflectors. 23 Appendix 7 Methods for determining the coordinates of defects using the "echo" set when inspecting the seams of welded joints. 25 Appendix 8 Method for checking the error of the depth gauge of the duk-66p flaw detector. 28 Appendix 9 Method for establishing the duration and position of the strobe pulse. 29 Appendix 10 Determination of the wall thickness of the welded elements and the actual boundary (length) of the bevel with a straight finder. 30 Appendix 11 Journal of ultrasonic testing. 32 Appendix 12 Conclusion on checking the quality of butt welded joints of pipelines by the ultrasonic method .. 32 Appendix 13 Defectogram No. 6 of welded joint No. 30 entry No. 21 in the ultrasonic inspection log. 33

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

This is not a new method (ultrasonic inspection was carried out for the first time 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 an inevitable loss of physical properties, such as strength, and over time to the destruction of the connection and the unsuitability of the entire structure.

Acoustic technology theory

The ultrasound wave during ultrasound is not perceived by the human ear, but it is the basis for many diagnostic methods. Not only non-destructive testing, 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 in the diagnostic process (for example, in diagnostic medicine). Thus, the ultrasonic method for testing welded seams belongs to non-destructive methods 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 the instruments, setting and calibration, the choice of a more appropriate diagnostic method, the experience of the operator, and others. Control of seams for suitability (GOST 14782-86) and admission of an object to operation is not possible without determining the quality of all types of joints and eliminating even the smallest defect.

Definition

Ultrasonic testing of welded seams is a non-destructive method of welded joints integrity control and search for hidden and internal mechanical defects of unacceptable size and chemical deviations from the specified norm. Diagnostics of various welded joints is carried out by the method of ultrasonic flaw detection (UZD). Ultrasonic testing is effective in detecting air voids, chemically inhomogeneous composition (slag deposits in) and detecting 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 the metal and reflect from the surface of scratches, voids and other irregularities. An artificially created, directed diagnostic wave penetrates the tested connection and, if a defect is detected, deviates from its normal propagation. The SPL operator sees this deviation on the instrument screens and, according to certain data readings, can characterize the detected defect. For example:

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

Today, the industry uses five main methods of ultrasonic testing (GOST 23829 - 79), which differ from each other only in the method of recording and evaluating data:

• Shadow method. It consists in controlling the decrease in the amplitude of ultrasonic vibrations of the transmitted and reflected pulses.
• Mirror-shadow method. Detects defects in seams by the attenuation coefficient of the reflected vibration.
• Echo mirroring method or "Tandem" ... It consists in the use of two devices that overlap in work and approach the defect from different sides.
• Delta method. It is based on the control of the ultrasonic energy re-emitted from the defect.
• Echo method. Based on the registration of a signal reflected from a defect.

Where does the wave oscillation come from?

We carry out control

Almost all devices for diagnostics by the method of ultrasonic waves are arranged 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 itself is located in the prismatic search head (in the probe). The probe is positioned along the seams and slowly moved, imparting a reciprocating motion. 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 deflects the wave on the oscilloscope screen (an intermediate peak appears). During ultrasonic testing, the sensor sends alternating short pulses of elastic vibrations of different duration (adjustable value, μs), separating them with longer pauses (1-5 μs). This makes it possible to determine both the presence of a defect and the depth of its occurrence.

Flaw detection procedure

1. The paint is removed from the welding seams and at a distance of 50 - 70 mm from both sides.
2. To obtain a more accurate ultrasound result, a 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.
3. The device is pre-configured according to a certain standard, which is designed to solve a specific SPL problem. Control:
4. thicknesses up to 20 mm - standard settings (notches);
5. over 20 mm - DGS diagrams are adjusted;
6. connection quality - AVG or DGS diagrams are configured.
7. The finder is moved in a zigzag manner along the seam and at the same time they try to turn it around the axis by 10-15 0.
8. When a stable signal appears on the screen of the device in the ultrasonic testing area, the finder is maximally deployed. It is necessary to search until the signal with the maximum amplitude appears on the screen.
9. It should be clarified: is the presence of such fluctuations caused by the reflection of the wave from the seams, which often happens with ultrasound.
10. If not, then the defect is fixed and the coordinates are recorded.
11. Inspection of welded seams is carried out in accordance with GOST in one or two passes.
12. Tee seams (seams under 90 0) are checked by the echo method.
13. The inspector enters all the results of the inspection into a data table, according to 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 ultrasonic scanning are not enough and it is required to apply more detailed studies using X-ray flaw detection or gamma flaw detection.

The scope of this technique when detecting defects

SPL-based weld control is quite clear. And with the correct method of testing the seam, it gives a completely exhaustive answer about the existing defect. But the scope of application of ultrasonic inspection also has.

With the help of ultrasonography, it is possible to identify the following defects:

• Cracks in the near-weld zone;
• pores;
• lack of penetration of the seam;
• delamination of the deposited metal;
• discontinuities and lack of fusion of the seam;
• defects of a fistulous nature;
• sagging of the metal in the lower zone of the weld;
• corroded areas
• areas with a mismatch in chemical composition,
• areas with distortion of the geometric size.

A similar ultrasound scan can be carried out in the following metals:

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

Ultrasonic scanning is carried out in a geometric framework:

• At the maximum seam depth - 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 checked:

• flat seams;
• longitudinal seams;
• circular seams;
• welded joints;
• T-joints;
• welded.

The 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 - UZD is also ordered privately during the construction or reconstruction of houses.

Ultrasonography 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 power engineering;
• in mechanical engineering, in the 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 units, which is subject to the influence of high temperatures and pressure or the influence of various aggressive media;
• in laboratory and field conditions.

Field testing

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

1. High accuracy and speed of research, as well as its low cost.
2. Human safety (as opposed to, for example, X-ray flaw detection).
3. Possibility of on-site diagnostics (due to the availability of portable ultrasonic flaw detectors).
4. During ultrasonic testing, it is not required to remove the controlled part or the entire object from operation.
5. When performing ultrasonic inspection, the inspected object is not damaged.

The main disadvantages of ultrasonography include:

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

Over a long period of use, pipelines come under negative external and internal environmental influences. As a result, the metal degrades, corrosive formations form on it, cracks and chips appear, and other types of defects. It would seem that when creating a pipeline project using modern technologies, full protection of trunk communications should be provided.

But, unfortunately, it is impossible to completely exclude the occurrence of damage. To prevent small defects from becoming a serious problem, various types of control are used.

One of them, which does not provide for the withdrawal of the main system for repair, is pipeline flaw detection.

This diagnostic method has become widespread. Its application allows you to identify the following types of defects:

• loss of tightness level;
• loss of control of the state of tension;
• violation of welded joints;
• depressurization of welded seams are other parameters that are responsible for the reliable functioning of the lines.

This way you can check:

• heating network;
• gas supply network;
• oil pipelines;
• water supply pipelines, etc.

Flaw detection is 100% capable of identifying deficiencies and preventing serious accidents. , and new models of flaw detectors are being tested. In addition to all this, various analyzes are carried out in order to subsequently improve the work of the funds.

Ultrasonic flaw detection

Ultrasonic pipeline inspection was first provided by S.Ya. Sokolov. in 1928. It was created based on the study of the movement of ultrasonic vibrations,
which were under the control of a flaw detector.

Describing the principle of operation of these devices, it should be noted that the sound wave does not change the direction of its movement in an environment with the same structure. When a medium is separated by a specific acoustic obstacle, a wave reflection is obtained.

The higher the number of such obstacles, the more waves will be reflected from the boundary that separates the environment. The ability to detect small defects separately from each other determines the length of the sound wave. And at the same time it is dependent on how frequent the sound vibrations are.

The many challenges faced in ultrasonic flaw detection have led to the emergence of great opportunities for this method of troubleshooting. Of these, five main options are distinguished:

1. Echo is a location.
2. Shadow method.
3. Mirror-shadow.
4. Mirror.
5. Delta is the way.

Modern devices for ultrasonic testing are equipped with several measuring possibilities at the same time. And they do it in different combinations.

These mechanisms are distinguished by very high accuracy, as a result, the residual spatial resolution and the reliability of the final conclusion about the defectiveness of the pipeline or its parts are obtained as true as possible.

Ultrasonic analysis does not cause damage investigated design, and makes it possible to carry out all work as quickly as possible and without harm to human health.

Ultrasonic flaw detection is a system for inspection of joints and seams available in all respects. The fact that this method is based on the high possibility of penetration of ultrasonic waves through the metal.

Analysis of welds

When they come into contact with liquid, they simply let it pass through them. This method makes it possible to detect the hiding of problem formations. This procedure is carried out in accordance with GOST 1844-80.

Often used for this type of verification magnetic flaw detection... It was based on such a phenomenon as electromagnetism. The mechanism generates a magnetic field near the tested area. Its lines pass freely through the metal, but when damage is present, the lines lose their evenness.

Video: Conducting in-line diagnostics of main pipelines

To fix the resulting image, magnetographic or magnetic particle flaw detection is used. If a powder is used, then it is applied dry or in the form of a wet mass (oil is added to it). The powder will accumulate only in problem areas.

In-line inspection

Intra-tube flaw detection of main pipelines is the most effective way of detecting problems, based on running special devices through the pipe system.

They are in-line flaw detectors with installed special devices. These mechanisms determine the configuration features of the cross-section, reveal dents, thinning and corrosive formations.

There are also in-line mechanisms that are created to solve specific tasks. For example, equipment with video and cameras inspects the interior of the highway and determines the degree of curvature and the profile of the structure. It also detects cracks.

These units move through the system in a stream and are equipped with a variety of sensors, they accumulate and store information.

In-line inspection of main pipelines has significant advantages. She does not set requirements to put devices that conduct systematic control.

To what has been said, it must be added that using this type of diagnostics, it is possible to carry out regular monitoring of deformation changes throughout the entire section of the existing structure with a high level of productivity.

In this way, you can timely establish a site that poses an emergency threat to the entire system, and timely carry out repair work to eliminate problems.

Speaking about this method, it is important to note that there are a number of technical difficulties in its implementation. The main thing is that it is expensive. And the second factor is the availability of devices only for trunk pipelines with large volumes.

For these reasons, this method is most often used for relatively new gas pipeline systems. It is possible to implement this method for other highways by performing reconstruction.

In addition to the specified technical difficulties, this method is distinguished by the most accurate indicators with the processing of verification data.

It is not necessary to complete all the procedures for examining the main pipelines to ensure that there are no problems. Each section of the highway can be checked in one way or another in the most suitable way.

To choose the best check option, you need to assess how important the responsibility of the joint is. And already, based on this, select a research method. For example, for home production, visual inspection or other budgetary checks are often sufficient.