General requirements

Respectivelymethodological provisions of this section on pipe systems and pipelinescarry out ultrasonic testing onfeetwelded joints,completedin any wayelectric arcwelding and gas welding:

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

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

c) lock welded connections of bottoms with collectors.

Ultrasonic testing of welded joints according to 6.1.1 is performed with a direct and one-time beating beam or only a straight beam.

If, during testing with a one-time reflected beam, a direct beam hits the conical part of the internal boring of a pipe, the quality of the welded joint is assessed only based on the results of direct beam testing, about which a corresponding entry should be made in the “Final Conclusions”.

To ensure the possibility of ultrasonic testing of welded joints along the entire intersection, the length of the cylindrical part for 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 is the width of the adjacent zone, which is subject to control

would be the angle of insertion.

The cleanliness of boring processing should be no 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 converters for control

welded joints with backing rings

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

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

Drawing6.1 - SZP for control of butt welded joints

with nominal wall thickness up to 20 mm with backing rings

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

with a wall thickness of 65 mm or more when testing with a direct beam;

D - diameter; S - stand thickness

Drawing6.2 - Unfold the SZP to adjust the speed

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

with backing rings

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

The sensitivity of the flaw detector is adjusted according to 5.5.6-5.5.8.

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

To adjust the sensitivity during ultrasonic testing of welded joints with a thickness of 8 mm and more, the technology of high pressure diagrams (Addendum I) is used.

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

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

To separate these signals and avoid errors when assessing the quality of the welded joint, it is necessary to measure with a ruler the distances Xk, X1 and X2 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 welded joint and the transducer than the signal from the non-integrity located above the root of the welded joint. During the control process, it is necessary to periodically compare these distances with the measurement data at the SWP.

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

A sign of non-integrity is the appearance on the screen of the flaw detector of pulses in the area 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 a signal from the reinforcement of the welded joint or from the backing ring may be mistaken for a signal from non-integrity. Therefore, before testing, it is necessary to measure the actual wall thickness of each pipe, compare them with the thickness of the SZP and make appropriate adjustments to the sweep speed setting.

If the thickness of the pipe wall is greater than the thickness of the SPS, then when monitoring from the side of this pipe, the signal from the backing ring will shift to the right compared to the same signal received at the SPS. If the pipe is thinner compared to the SZP, then the signal from the pipe backing ring will shift to the left.

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

The location of irregularities in depth is determined using a depth gauge or by comparison with the coordinates of signals from artificial reflectors or corners in the NWS.

To determine which of the pipes is closest to the non-integrity at the root of the welded joint, we are guided by the following signs:

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

b) during 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. Simultaneous appearance of signals is also possible.

The measured characteristics of non-essentialities are determined accordingly 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, identified by direct or

one-time reflected beam; Xk, XI and X2 - distances between the middle

welded joint and the point of insertion of the transducer

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

lack of integrity

During monitoring, a number of special qualitative signs should be taken into account, which help determine the nature of some non-essentialities.

Cracks in the root of a seam in a Y-shaped structure, as a rule, begin from the gap formed by the edge of the pipe and the backing ring. As cracks propagate, they extend into 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 shield the signal from the backing ring only during testing from 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 passes through it freely. Two signals appear on the flaw detector screen - from the backing ring and from the crack. The signal from the backing ring has approximately the same amplitude and range across the screen as in areas where there is no discontinuity. Cracks from this side turn out to be much worse, and at a low height they may not appear at all. Figure 6.4 shows a diagram for identifying a root crack with a height of more than 3 mm

Lack of penetration, located higher than the root layer of the welded joint, does not shield the signal from the backing ring to a small extent or at all. During inspection, signals from the backing ring and non-integrity appear on the screen on both sides of the welded joint. The distance between these signals is slightly greater than in the case when imperfections are located at the root of the welded joint. In some cases, several signals are observed on the screen due to the lack of integrity and the backing ring.

Slag inclusions or pores are characterized by the appearance of pulses on the flaw detector screen, which quickly disappear and appear again with slight movements of the transducer in the longitudinal or transverse directions. An accumulation of small slag inclusions or pores in the deposited metal produces one signal or a group of closely spaced signals on the screen.

a - crack detection diagram; would - display on the screen in position I

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

D - signal from non-integrity; K - signal from the backing ring

Drawing6.4 - Scheme for identifying a crack at the root of a welded joint

The missing backing ring has some characteristic signs, namely: the signal from the missing backing ring appears on the flaw detector screen on the left side of the signal from the backing ring. In this case, the amplitude of the echo signal from a ring with a burn-through is less than from a ring without a burn-through. When moving the transducer of the forming pipe, one signal with two tips or two signals in close proximity to one another appears on the flaw detector screen in the area where the signal from the backing ring is located. This differs from failure in the deposited metal. During testing from different sides of the welded joint, the shape and nature of the changes in signals from the missing one are similar. If the burn turns into non-penetration of the deposited metal, then it turns out to be non-penetration.

The gap between the backing ring and the base metal of the pipe is accompanied by the appearance of a signal on the flaw detector screen in the same place as the signal from non-integrity at the root of the welded joint (poor penetration, crack) and therefore can cause erroneous rejection of the welded joint. The characteristic signs of the gap are the following. When the transducer of the forming pipe moves smoothly towards the seam, a signal first appears from the backing ring, and

then from the gap. In this case, the signal from the backing ring has the same amplitude as at the welded joint, where there is no gap. It should also be taken into account that gaps up to 0.5 mm, as a rule, are not found, and gaps up to 1 mm give echo signals, less or levels to the first level of the rejector.

Echo signals from a gap or influx of metal (slag) under the ring when measuring the Dx coordinate correspond to the half of the weld joint reinforcement that is more distant from the transducer, while the transducer is located adjacent to the weld joint reinforcement. The value of the coordinate DN 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 lack of penetration at the root of the welded joint.

Welded joints are assessed based on the following criteria:

a) score 1 - non-integrity has been identified, the measured characteristics or the number of which are greater, and the shape coefficient is less than the values ​​​​given in Table 6.2.

b) score 2 - non-integrity has been identified, the measured characteristics or the number of which is equal to or less, and the shape coefficient is greater than the values ​​​​given in Table 6.2.

Inspection of welded joints of pipes on heat exchange surfaces

Thissubsection is devoted to the presentation of the procedure and methodology for monitoring butt ring welded pipe joints of heat transfer surfaces of boilers manufactured electric arc, combined and gas welding.

These provisions should be followed during ultrasonic testing:

a) butt ring welded joints with a wall thickness from 2 to 8 mm from pearlite class steels;

b) butt circumferential welded joints with a wall thickness of 4 to 8 mm from austenitic steel grades X18N12T, X18N10T, X18N9T.

c) butt circumferential welded joints of elements made from steels of all listed structural classes.

When inspecting welded joints of pipes on heat exchange surfaces, imperfections may be located in hard-to-reach areas, for which the converter must be installed between two closely spaced pipes. To be able to control these zones, the pipes should be “separated” to the required distance, if the design allows it.

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

Table 6.3. – Characteristics of converters for testing welded joints

heat exchange surface pipes

Before setting up the flaw detector, it is necessary to make sure that it is possible to control the root of the welded joint with a direct beam using the lines on the welded joint (Figure 6.5). The front face of the transducer should be shifted to the right of the line in the transducer position, which corresponds to the maximum amplitude of the echo signal from the lower corner reflector.

The scan speed is adjusted using the lower and upper corner 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 corner reflector on the flaw detector screen is set to the upper horizontal line (the first level of the rejector). The area where an echo signal from non-integrity appears is determined by the position of the echo signal from the corresponding notch on the screen of the flaw detector when moving the transducer along the surface of the SZP (Figure 6.6).

To adjust the sensitivity, the SEP is used (Figure 6.5).

After setting up the flaw detector, control should be carried out in accordance with the provisions of section 5.6.

During testing, the possible appearance on the left side of the screen of echo signals of a surface wave reflected from the reinforcement of the welded joint. A sign that this signal belongs to a surface wave is a sharp decrease in the height of the signal on the screen when a finger is applied to the surface of the welded joint in front of the transducer.

Displacement of the edges of the pipes being connected can be mistakenly taken for non-integrity at the root of the welded joint.

Table 6.2- Limit permissible values ​​of measured characteristics and quantities

defects in welded joints of pipelines with backing rings

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 control from the second side with

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

1 - a piece of pipe; 2 and 3 - notches for adjusting sensitivity and speed

sweeps; 4 - dashes that correspond to the limits of welded reinforcement

Drawing 6.5- Enterprise standard sample for control

welded joints of heat exchange surfaces

When inspecting welded joints of pipes made of austenitic steels, one should be guided by the following characteristic signs of failures, which allow them to be distinguished from obstacles:

a) long range across the screen, close to the range from an artificial reflector;

b) imperfections appear on both sides of the welded joint;

c) the positions of the maxima of echo signals from non-integrity on the screen of the flaw detector when testing from two sides of the welded joint practically coincide;

d) echo signals from abnormalities turn out to be without complications, that is, with repeated measurements, the results are confirmed.

When testing welded joints made of austenitic steels, to obtain insertion angles similar to those used during testing pearlitic steels, the angles of inclination of the transducer prism should be 3-60 higher (53-60 instead of 50-550). This is due to the difference in the speed of propagation of ultrasound in steels of the noted classes.

Drawing 6.6- Determining the displacement of connected pipes

Inspection of butt circumferential 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 monitoring the welded joints of pearlite class pipes, and from the side of the austenite class pipe by a converter and by the method of monitoring the welded joints of 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 size and grade of steel of the controlled welded joint for pearlitic and austenitic steels, respectively.

Welded joints of heat exchange surfaces are assessed based on the following criteria.

a) score 1 - non-integrity was detected with an echo signal amplitude that exceeds the control level of sensitivity.

b) score 2 - no abnormalities were detected with an echo signal amplitude that exceeds the control level of sensitivity.

Inspection of welded joints of pipelines with wall thicknessless20 mm without washers

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

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

In welded joints, the main part of the unacceptable imperfections is located at the root of the welded joint. Therefore, when inspecting marked welded joints, the main attention should be paid to the root part. In addition, it should be borne in mind that during inspection, the most dangerous planar imperfections at the root of the welded joint - cracks, lack of welding - are more reliable, and less reliably rounded ones - 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 - the metal sags and the edges are displaced. The signals reflected from inequalities during control by a direct beam coincide in time with the signals reflected from super-root inconsistencies identified by a one-time reflected beam.

Before setting up the flaw detector, it is necessary to make sure that it is possible to control the root of the welded joint with a direct beam along the lines on the welded joint (Figure 6.7). The front edge of the transducer should be on the right side of the dash in a position of the transducer that corresponds to the maximum amplitude of the echo signal from the artificial reflector.

The flaw detector scanning speed setting should correspond to the position 5.5.1-5.5.4, and the sensitivity - accordingly 5.5.6-5.5.8, 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 paragraph 6.4.7. When new SZP 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 diagram for setting the scanning speed of the flaw detector, as well as the diagram for identifying super-root inconsistencies and inequalities in the root of a welded joint such as sags during inspection of welded joints of pipes with a thickness of less than 20 mm. The scan area “a” is the zone of appearance of echo signals from imperfections located in the root . Section “x” is the zone where echo signals appear both from imperfections located directly above the root of the welded joint and from sags. Section “b” is the zone of appearance of echo signals reflected from imperfections in the upper part of the welded joint. It is also possible that signals from non-essentialities will appear on the left side of the D1 signal in the immediate vicinity of it.

Table 6.4- Characteristics of converters for monitoring welded joints

pipelines less than 20 mm thick without backing rings

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

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

connection, to check the maximum value of the transducer boom

Drawing 6.7 - SZP for monitoring welded joints of pipelines

with a thickness of less than 20 mm without washers

The echo signal from displacement of pipes can be distinguished from the echo signal from non-integrity at the root of the welded joint by the following signs:

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

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

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

a - turn up the speed setting:

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

would - identifying the signal from super-root non-susceptibility and sagging:

D - signal from non-integrity, P - signal coinciding with it in coordinates

from sags; c - scan the screen after setting the speed, expand

Drawing 6.8- Scheme for monitoring welded joints of pipes less than 20 mm thick

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

a) the echo signal from the sag is located on the screen in the “x” zone;

b) sagging usually occurs at a smaller distance between the transducer and the welded joint than when identifying super-root failures. The formation sags most likely in areas welded in the lower position. In horizontal joints, sags are located more evenly and form less frequently than in vertical joints;

c) echo signals from the sags have both different coordinates on the screen and different amplitudes during control from different sides.

Welded joints of sector bends are controlled under the same parameters as butt welded joints rub. A feature of such connections is that the axis of the welded joint is not perpendicular to the forming pipe and the variable width of the reinforcement. When testing 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, the transducer should be moved parallel to the forming pipe.

Welded connections of pipelines are assessed for the following characteristics:

a) score 1 - the identified imperfections have no signs of displacement and sag according to 6.4.8 and 6.4.9, the measured characteristics or the number of identified imperfections exceed the values ​​​​given in Table 6.5;

b) score 2 - the identified imperfections have no signs of displacement and sag according to 6.4.8 and 6.4.9, the measured characteristics or the number of identified imperfections are equal to or lower than the values ​​​​given in Table 6.5.

Table 6.5 - Limit permissible values ​​of measured characteristics and number of failures in welded joints of pipelines less than 20 mm thick without backing rings

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

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

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

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

Ultrasonic testing of welded joints of pipelines with a bored root part or using backing rings that are removed is carried out in accordance with 6.2.

The speed and sensitivity settings should correspond to 5.5.1-5.5.4 and 5.5.6-5.5.11.

To adjust the scan speed, use the SZP manufactured in Figure 6.2.

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

A peculiarity of welded joints without backing rings is the presence of inequalities at the root of the welded joint (mainly, the metal sags), which leads to the appearance of signals reflected from them when testing with a direct beam.

Sagging metal is distinguished from non-integrity at the root of the welded joint by the following feature: when sounded from one side of the welded joint, the echo signal from the sagging has an amplitude that 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 insertion angle of 65°.

Welded joints are assessed in the following way:

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

b) score 2 - non-integrity has been identified, the measured characteristics or the number of which are equal to or less, and the shape coefficient is equal to or greater than the values ​​​​given in Table 6.7.

Inspection of welded joints between bottoms and collectors

This subsection of the ND regulates the procedure and methodology for ultrasonic inspection of lock 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 kept in mind that:

the design of the welded joint may not include grooves;

control by the collector with a one-time reflected beam is not always possible.

Bottom welding joints are controlled using 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 direct beam from the side of the collector pipe and from the bottom side, if there is a sufficient area on its surface for the operation of the converter. The other part of the welded joint is controlled from the side of the collector pipe with a one-time reflected beam, if the design allows it.

If, during testing of welded joints with a thickness of less than 65 mm, the inaccessibility and design features of the collector (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 - different options for welded joints

Drawing 6.9 - Control of welded joints for welding bottoms

to the collectors

The flaw detector deployment speed setting 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 imperfections and assessing their measured characteristics, you should be guided by the provisions of 5.5.5-5.5.8, 6.2.5-6.2.9.

The quality assessment must comply with 6.2.13.

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

pipelines 20 mm and more without washers

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

Before inspecting such welded joints, it is necessary to ensure that the existing joint design corresponds to the drawing, for which:

a) through the holes for welding the cap to the fitting or the bottom to the manifold, visually 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 unbroken part and in the area of ​​possible location of the groove.

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

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

To carry out inspection of 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 options of which is shown in Figure 6.10.

To do this you need:

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

b) by sounding a direct beam at a frequency of 5 MHz, measure the thickness and plot the internal structure of the product on the drawing, while the thickness of the bottom should be measured closer to its middle (item 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 (items 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 (item 5), which is included in the boring of the pipe element (chamber, manifold);

e) remove the reinforcement in one of the sections of the welded joint and, by measuring the thickness of the surface prepared in this place in the area from the middle of the welded joint in the direction of the pipe element, determine the presence of a groove in it, measure its dimensions and the thickness of the welded joint (items 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 to a distance of 80-100 mm from the edge of the tubular element.

Figure 6.10 – Design of the welded joint

Control of the welded joint from the cylindrical surface of the bottom is carried out by a small-sized converter at a frequency of 5 MHz. The cylindrical surface of the bottom (the end of the bottom) 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 using a flat-bottomed 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 the displays of the glibinovimiryuvac.

Schemes for identifying defects in the root of a welded joint using 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 conventional length.

Drawing 6.11 - schemes for identifying non-essentialities

Inspection for transverse cracks

This subsection deals with the procedure and methodology for ultrasonic inspection of welded joints of pipelines with a diameter of 465 mm or 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.

Testing for transverse cracks is carried out by moving the transducer along the welded joint directly along the surface of the deposited metal. The reinforcement of the seam is then removed.

Drawing 6.12 - Schemes for identifying root failures when inspecting welded joints

welding bottoms with sloping converters

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

The converters must be rubbed against the surface of the pipe. Grinding in of the converter is done according to the markings (Figure 6.13). The working surface of the transducer is ground in by moving the transducer along sandpaper placed on the controlled pipe.

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

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

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

Drawing 6.13 - Marking of the transducer for checking for transverse cracks

The coordinates of identified non-essentialities are determined in the following way:

a) if an echo signal from a non-integrity appears in the zone of an echo signal from a notch, then such non-integrity is located near the outer surface and their location is determined by “promatsuvannyam”, as shown in Figure 6.14. It should be borne in mind that the place where the signal from the subsurface non-integrity is “palpated” does not correspond to its actual location along the perimeter. This is explained by the fact that the rays reflected from the non-integrity fall on the adjacent

the section of the welded joint (point B, Figure 6.14), which lends itself to “matzing”;

b) if the imperfection is not “palpable”, only its location along the perimeter of the welded joint is determined. To do this, fix the position of the transducer, 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 the non-integrity.

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 next to the welded joint, along which the transducer can move during ultrasonic testing, must be at least 500 mm, with the exception of ring welded joints, which can be controlled with radii of curvature of at least 200 mm

Before starting testing, the amplitude of the signal that passed through the deposited metal of the welded joint and through the base metal of the product is determined in 2-3 places, 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, b) 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 adjusted when assessing the admissibility of inconsistencies.

SZP for ultrasonic inspection of austenitic welded joints must involve welding of plates or sections of welded pipes. The material, size and welding technology of the FWS must be the same

themselves, which are used for the controlled product. The use of metal plates without welded joints as FPS is not allowed.

1 - receiver; 2 – emitter

Drawing 6.15 - Signal amplitude measurement circuits

ultrasonic vibrations when sounding the welded joint (a)

and base metal (b) with separate and combined converters

The dimensions of the welding joint in the direction perpendicular to the axis of the weld must allow the transducer to move in order to fully sound the metal of the welded joint.

In the SZP metal for ultrasonic inspection of austenitic welds, there must be no imperfections, which are revealed by radiography or ultrasound to be smooth and sensitive.

As an artificial reflector in the SZP, a side hole is made at the ends of the seam (Figure 6.16). The 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 controlled welded joint is d=10-20 mm, a side hole is made along the axis of the welded joint at a depth of h=0.55. With a thickness d=20-40 mm - along the axis of the welded joint at a depth h=10 mm. Hole length 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 monitoring, specially manufactured transducers with parameters that meet the requirements of this ND are used, or a block of two serial transducers with an insertion angle of 40°, 45°, 50°, 60°, 65°, 70°, in which the angle of inclination of the organic glass prism should be reduced to 24° by removing part of the prism (Figure 6.17) so that the angle of introduction of longitudinal waves is in the range of 60-70°.

The ascension 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 manufacturing the transducers are shown in Figure 6.18. It is recommended to take the diameter of the transducer element equal to 10-12 mm

Simultaneously with the longitudinal wave signal from non-integrity, a transverse wave signal may appear on the flaw detector screen, reflected from the surface once or twice. When scanning, they move synchronously across the flaw detector screen.

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

a) adjust the converter using templates (Figure 6.18), and use the SZP (Figure 6.16) to adjust the flaw detector to the signal reflected from the side hole. The operating frequency of the flaw detector is set at exactly 2.5 MHz;

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

Table 6.8 - Dependence of hole diameter on product thickness

Drawing 6.17 – Separate-combined converter

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

Drawing 6.18- Template for customization

Monitoring of austenitic welds is carried out using a separate circuit using a separate-combined transducer using 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 plate.

Two equal sensitivities are set: a sound 6 dB above that which ensures detection of side holes, and a rejector - the signal amplitude is set according to

visible 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-integral joints in the following ways:

a) increased penetration usually occurs at a smaller distance between the converter and the welded joint than when identifying super-root failures. The occurrence 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 based on the following criteria:

a) signal amplitude;

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

c) 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 assessed with a score of 1 as unsuitable if at least one of the following signs is present:

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

b) the amplitude of the signal from the 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 permissible (6.8.20);

c) the amplitude of the signal from the non-integrity exceeds 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 smaller, but the number of defects exceeds 3 over a length of 100 mm of the welded joint.

The value of the permissible conditional length of non-integrity is:

for d<15мм L<20мм;

for d=15...25mm L<30 мм;

for d=25...40mm L<40 мм

The width of the scanning area is:

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

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

Monitoring the technical condition of gas pipelines is an important and responsible task. Their damage and breakthroughs can lead to man-made disasters with serious environmental consequences, financial losses and disruptions in industrial activities.

Welds at the joints of steel sections in pipelines are the most vulnerable point of the structure. Moreover, their strength does not depend on the age or novelty of the connection. They require constant monitoring of tightness.

The walls of the pipes are less vulnerable, but during operation they are subject to pressure and aggressive effects from the distilled substances from the inside and adverse external influences from the outside. As a result, even durable materials and reliable protective coatings can become damaged, deformed, deteriorate and collapse over time.

Ultrasonic testing of pipelines is used for monitoring and timely detection of defects. With its help, you can detect even the smallest or hidden imperfections in seam joints or pipe walls.

What is this technology based on?

The ultrasonic diagnostic method is based on acoustic wave vibrations, indistinguishable to human hearing, their registration and instrumental analysis. These waves travel through the metal at a certain speed. If it contains voids, the speed changes and is determined by instruments, as well as deviations in the movement of the wave flow due to encountered obstacles or places of structural heterogeneity of the material. The characteristics of acoustic waves can also be used to understand the shape and size of defects and their location.

How is ultrasonic testing of gas pipelines carried out?

When carrying out monitoring in automatic mode, infrasound systems are used that operate on the basis of hardware and software methods. Devices for collecting acoustic information, installed in groups along the pipeline at a certain distance from each other, transmit it via communication channels to control centers for integration, processing and analysis. The number, coordinates and parameters of detected flaws or leaks are recorded. The signal results are monitored by specialists on the monitor.

An automated infrasound monitoring system for pipelines allows for continuous remote verification of their operation, monitoring and control in real time with the ability to diagnose hard-to-reach areas and gas distribution compartments, using a combination of several monitoring methods simultaneously for greater accuracy of the result and prompt detection of defects and leaks. This is modern high-class equipment.

Pressure and temperature sensors, flow meters and meters of other parameters can also be connected to the system to obtain information about the technological processes occurring in the pipeline.

Advantages of the method:

• Ultrasonic inspection is a gentle and non-destructive inspection of pipelines,
• has high sensitivity and diagnostic accuracy,
• minimum time to detect leaks of gas or other substances,
• possibility of remote monitoring,
• safety,
• convenience and ease of installation and operation of the system,
• the inspection does not stop or affect the process of technical operation of the pipeline,
• suitable for all types of materials from which pipes are made,
• can be used for above-ground and underground pipe laying,
• can be carried out in any climatic conditions,
• beneficial in terms of economic costs.

Our company's proposals for pipeline monitoring.

High-quality monitoring of the condition of pipelines is a guarantee of their safe operation, reliable operation and insurance against damage. It is ensured thanks to the reliability and efficiency of the equipment used.

The SMIS Expert company develops diagnostic instruments and monitoring systems using modern scientific knowledge and innovative technologies. The use of such systems in practice ensures a high level and accuracy of monitoring the integrity of main pipelines, timely detection of any types of defects and prevention of emergency situations.

Take advantage of our services for the professional organization of ultrasonic testing of gas pipelines and other objects of increased importance when you need experience, a responsible approach and an impeccable result.

We are waiting for your applications!

Seams in structures with welded joints must be constantly monitored. And this does not depend on when the connection was made. For this, various methods are used, one of which is ultrasonic flaw detection (USD). In terms of the accuracy of the studies performed, it surpasses fluoroscopy, radio flaw detection, and gamma flaw detection.

It should be noted that this technique is not new. It has been used since the thirties of the last century, and today ultrasonic testing of welded joints is popular because it can help identify the smallest defects inside the weld. And, as practice shows, it is hidden defects that are the main serious reasons for the unreliability of the welded structure.

Ultrasonic flaw detection technology. (On the left there is no defect, on the right there is a defect)

Ultrasonic vibrations are based on ordinary acoustic waves, which have a vibration frequency above 20 kHz. The person does not hear them. Penetrating into the metal, the waves fall between its particles, which are in equilibrium, that is, they oscillate in the same phase. The distance between them is equal to the ultrasonic wavelength. This indicator depends on the speed of passage through the metal seam and the frequency of the vibrations themselves. The dependence is determined by the formula:

• L is the wavelength;
• c is the speed of its movement;
• f – oscillation frequency.

The speed depends on the density of the material. For example, ultrasonic waves move faster in the longitudinal direction than in the transverse direction. That is, if there are voids (another medium) in the path of the wave, then its speed also changes. At the same time, encountering various defects along the way, waves are reflected from the walls of shells, cracks and voids. And, accordingly, deviation from the directional flow. The operator sees the change in movement on the monitor of the ultrasonic instrument and, based on certain characteristics, determines which defect stands in the way of the movement of acoustic waves.

For example, attention is paid to the amplitude of the reflected wave, thereby determining the size of the defect in the weld. Or by the time of propagation of an ultrasonic wave in the metal, which determines the distance to the defect.

Types of ultrasonic testing

Currently, several methods of ultrasonic flaw detection of welds are used in industry. Let's look at each of them.

1. Shadow diagnostic method. This technique is based on the use of two transducers at once, which are installed on opposite sides of the object under study. One of them is an emitter, the second is a receiver. The installation location is strictly perpendicular to the plane of the weld being examined. The emitter directs a stream of ultrasonic waves to the seam, and the receiver receives them on the other side. If a blind zone is formed in the flow of waves, this indicates that a section with a different medium has come across its path, that is, a defect is detected.
2. Pulse echo method. For this, one ultrasonic flaw detector is used, which both emits waves and receives them. In this case, the technology of ultrasound reflection from the walls of defective areas is used. If the waves passed through the metal of the weld and were not reflected on the receiving device, then there are no defects in it. If there is a reflection, it means there is some kind of flaw inside the seam.
3. Echo-mirror. This ultrasonic testing of welds is a subtype of the previous one. It uses two devices: an emitter and a receiver. They are only installed on one side of the metal being tested. The emitter sends waves at an angle, they hit defects and are reflected. These reflected vibrations are received by the receiver. Usually, in this way, vertical defects inside the weld seam are recorded - cracks.
4. Mirror-shadow. This ultrasonic testing method is a symbiosis of shadow and mirror. Both devices are installed on one side of the metal being tested. The emitter sends oblique waves, they are reflected from the wall of the base metal and received by the receiver. If no flaws in the weld seam are encountered on the path of the reflected waves, then they pass without changes. If a blind zone is reflected on the receiver, then it means there is a flaw inside the seam.
5. Delta method. This method of ultrasonic testing of welded joints is based on the re-emission of directed acoustic vibrations by a defect into the welded joint. In fact, reflected waves are divided into mirror waves, transformed in the longitudinal direction and re-emitted. The receiver may not pick up all the waves, mostly reflected and moving directly towards it. The size of the defect and its shape will depend on the number of waves received. Not the best test, because it involves fine-tuning the equipment, and it is difficult to decipher the results obtained, especially when a welding seam more than 15 mm wide is checked. When carrying out ultrasonic quality control of metal using this method, strict requirements are imposed on the cleanliness of the weld seam.

These are the ultrasonic testing methods used today to determine the quality of welded joints. It should be noted that most often specialists use pulse-echo and shadow methods. The rest are less common. Both options are mainly used in ultrasonic inspection of pipes.

How is ultrasonic flaw detection performed?

All of the technologies described above belong to the category of ultrasonic non-destructive testing methods. They are convenient and easy to use. Let's look at how the shadow method is used in practice. All actions are carried out in accordance with GOST.

• The weld seam and adjacent areas are cleaned to a width of 50-70 mm on each side.
• To obtain more accurate results, a lubricant is applied to the connecting seam. For example, it could be solid oil, glycerin or any other technical oil.
• The device is configured according to GOST.
• The emitter is installed on one side and turned on.
• On the opposite side, the finder (receiver) makes zigzag movements along the weld joint. In this case, the device is slightly rotated back and forth around its axis by 10-15°.
• As soon as a signal with maximum amplitude appears on the monitor, it is likely that a defect has been detected in the weld metal. But you need to make sure that the reflective signal does not cause unevenness in the seam.
• If not confirmed, then the coordinates of the flaw are recorded.
• According to GOST, the test is carried out in two or three passes.
• All results are recorded in a special journal.

Attention! Quality control of welded corner joints (T-joints) is carried out only by the echo-pulse method; the shadow method is not suitable here.

Results Evaluation Options

The sensitivity of the device is the main factor in the quality of the work performed. How can you use it to recognize the parameters of a defect?

First, the number of flaws is determined. Even at the closest distances to each other, the echo method can determine: one defect in the weld or two (several). They are assessed according to the following criteria:

• acoustic wave amplitude;
• its length (conditional);
• size of the defect and its shape.

The length of the wave and the width of the flaw can be determined by moving the emitter along the weld joint. The height of a crack or hole can be determined based on the difference in time intervals between the reflected wave and the previously emitted one. The shape of the defect is determined by a special technique. It is based on the shape of the reflected signal appearing on the monitor.

The ultrasonic flaw detection method is complex, so the quality of the results obtained depends on the qualifications of the operator and the compliance of the obtained indicators, which are regulated by GOST.

Advantages and disadvantages of ultrasonic pipe inspection

The advantages of the method for monitoring welds include the following criteria.

• The examination goes quickly.
• The diagnostic result is high.
• The ultrasonic weld inspection method is the cheapest option.
• It is also the safest for humans.
• The device for seam quality control is a portable device, so the mobility of the technology is ensured.
• Ultrasonic diagnostics are carried out without damaging the part being examined.
• There is no need to stop the equipment or site in order to carry out welding inspection.
• You can check the joints of stainless metals, ferrous and non-ferrous.

There are also disadvantages.

• Inspection of welded joints of pipelines or other structures does not provide accuracy in the shape of the defect found. The thing is that air (gas) or slag may be present in the cracks or cavities of the weld. The two materials have different densities and therefore different reflectivities.
• It is difficult to identify defects in parts with complex configurations. The sent waves can be reflected on another section of the seam, and not on the one under study, due to curvature. And this will give incorrect information.
• It is difficult to carry out ultrasonic testing of pipes if the metal from which they are made has a coarse-grained structure. Inside the material, the directional flow will be dissipated and the reflected waves will be attenuated.
• It is important to take a responsible approach to cleaning the weld. Its waviness or contamination, rust or scale, drops of splashed metal or air seats and pores on the surface will create an obstacle to obtaining the correct indicators that comply with GOST.

Recently, government bodies of the Russian Federation have declared a “turn to the East” and potential close cooperation between Russian manufacturers/customers and Chinese ones. For high-quality collaboration with representatives of the PRC, it is necessary to speak the same language with them, and in particular, to navigate the terminology and standard regulatory documentation used by both parties. In this article, we would like to summarize our experience of interaction with colleagues from the People's Republic of China on one local issue - diagnosing casing strings, and, using its example, consider the similarities and differences in the regulatory documentation of the Russian Federation and the People's Republic of China.

Casing pipes are used to secure oil and gas wells during their construction and operation. The casing pipes are connected to each other using coupling or couplingless (integral) threaded connections. At the construction site, multi-stage construction quality control is always carried out, consisting of the following operations: control of the availability of accompanying documentation (certificate); checking compliance of certificate data with pipe markings; visual control; instrumental control; unbrakable control; mandrel control; hydraulic test.

All quality control activities shall be specified by the manufacturer's instructions, which shall include the appropriate procedure and quantitative or qualitative acceptance criteria. Non-destructive testing instructions must comply with the requirements of these specifications and the requirements of national and international standards selected by the manufacturer.

On the territory of the Russian Federation, the main GOST 632-1980 and GOST 53366-2009 are currently in force (Cancelled, from 01/01/2015 use GOST 31446-2012. By order of the Federal Agency for Technical Regulation and Metrology dated 10/22/2014 No. 1377-st - restored on the territory of the Russian Federation from 01/01/2015 to 01/01/2017), regulating the requirements for non-destructive testing and control levels of seamless and electric-welded pipes. All casing pipes must be checked for defects along the entire length (from end to end) using non-destructive testing methods.

Casing pipes must not have defects that, according to GOST R 53366-2009, are considered unacceptable defects, and must meet the requirements established in this standard. Standard Methods for Non-Destructive Testing of Pipe are traditional, proven methods and provide non-destructive testing procedures that are widely used for the inspection of tubular products throughout the world. However, it is possible to use other non-destructive testing methods and procedures that can detect defects, for example, for the use of pipes in wells with special operating conditions. In such cases, it is recommended to use other non-destructive testing methods that make it possible to confirm the required quality of pipes and their suitability for lowering into the well.

Let's consider non-destructive testing methods for casing strings used in the Russian Federation and China:

1) Ultrasonic testing (ultrasonic method)

Ultrasound propagates throughout the entire circumference of the material. The acoustic characteristics of the material and internal structural changes are reflected in the propagation of ultrasonic waves. Signal recording and analysis gives an idea of ​​the degree of damage to the material. GOST 53366-2009 specifies only international standards, in accordance with which casing strings must be inspected: ISO 9303, ISO 9503 and ASTM E 213. However, GOST 13680-2011 for identifying delaminations, the projection area of ​​which on the outer surface is no more than 260 mm 2, it is proposed to act in accordance with ISO 10124:1994 (Table 1).

At the same time, standard methods of ultrasonic non-destructive testing are in effect in Russia: GOST R ISO 10332-99 “Seamless and welded steel pressure pipes (except for pipes made by submerged arc welding)”, GOST 12503-75 “Steel. Ultrasonic testing methods. General requirements", GOST 14782-86 "Non-destructive testing. Welded connections. Ultrasonic methods" (Repealed on the territory of the Russian Federation from July 1, 2015. Use GOST R 55724-2013), GOST R ISO 10893-12-2014 "Seamless and welded steel pipes. Part 12. Ultrasonic method for automated monitoring of wall thickness along the entire circumference,” however, they are not used to identify defects in casing strings. The international standards of the ultrasonic non-destructive testing method listed above are mainly used, while in the PRC the integrity of casing pipes is monitored in accordance with international and/or its own standards 1 .

Table 1 presents the most important standards for ultrasonic testing of casing strings, from the standard methods of non-destructive testing of pipes, used both in Russia and in China.

Table 1

2) Magnetic control (magnetic flux leakage method)

The next non-destructive testing method, which is recommended to be used in accordance with the requirements of GOST 53366-2009, is the magnetic flux scattering method.

Magnetic flaw detection of casing pipes using the leakage flux method is based on the detection of magnetic leakage fluxes in a ferromagnetic material with high magnetic permeability by measuring the variable characteristics after magnetization of the product. After magnetization, the magnetic flux, spreading through the object under study and encountering a defect on its way, bends around it due to the fact that the magnetic permeability of the defect is significantly lower than the magnetic permeability of the base metal. As a result, part of the magnetic field lines is displaced by the defect to the surface, forming a local magnetic leakage flux.

Magnetic testing methods cannot detect defects that cause disturbances in the distribution of magnetic flux lines without the formation of a local leakage flux. The flux disturbance depends on the size and shape of the defect, its depth and its orientation relative to the direction of the magnetic flux. Surface defects located perpendicular to the magnetic flux create significant leakage fluxes; defects oriented along the direction of magnetic field lines practically do not cause the appearance of stray fluxes. The presence of longitudinal and transverse defects leads to the need to carry out double testing using combined magnetization.

Table 2 presents the standards for magnetic flaw detection using the magnetic flux leakage method. Table 2 does not present standard non-destructive testing methods in force in the Russian Federation: GOST R 55680-2013 “Non-destructive testing. Fluxgate method" (valid from 07/01/2015, replacing GOST 21104-75); GOST R ISO 10893-3-2016 “Seamless and welded steel pipes. Part 3. Automated testing using the magnetic flux scattering method over the entire surface of ferromagnetic steel pipes to detect longitudinal and (or) transverse defects” (effective date 01.11.2016).

table 2

3) Eddy current testing (eddy current method)

Eddy current testing is a field of eddy currents generated by a ferromagnetic coil located near the surface of the tested object; analysis of changes in the electromagnetic field of eddy currents under the influence of certain defects. The method is only applicable to conductive material. Eddy current testing can be used to test pipes, welds and cracks in the surface layer of the deposit, and indirectly measure the length of the defect.

Table 3 presents testing standards using the eddy current method; there are no Russian and Chinese specialized standards for flaw detection of casing strings using this method. However, a number of standards are in force on the territory of the Russian Federation: GOST 24289-80 “Non-destructive eddy current testing. Terms and definitions", GOST R ISO 15549-2009 "Non-destructive testing. Eddy current testing. Basic provisions”, GOST R ISO 12718-2009 “Non-destructive testing. Eddy current testing. Terms and definitions", GOST R 55611-2013 "Non-destructive eddy current testing. Terms and Definitions". On the territory of the People's Republic of China, this method is standardized only for pipes of other classes (sizes).

Table 3

4) Magnetic testing (magnetic particle method)

Magnetic particle testing - the use of magnetic powder, which is adsorbed in places of defects, forming a “magnetic mark” - rolls of black magnetic powder, control is carried out visually. The method reflects surface and internal defects, while the sensitivity of the method does not depend on the color and metallization of the surface. The magnetic particle method is preferable for ferromagnetic materials compared to the penetrating substance method, as it is more efficient and easier to use. The main disadvantage is limited access to ferromagnetic material; in order to fully examine the surface, special equipment and a power source are required. After testing, residual magnetization is observed, which is difficult to eliminate. Table 4 shows international standards for the magnetic particle method of inspection of casing strings, Chinese standards for inspection by this method, used in mechanical engineering: quality control of equipment under pressure using the magnetic particle method. Table 4 also does not include standards in force in Russia, because there were no references to them in the defining GOST 53366-2009: GOST R 56512-2015 “Non-destructive testing. Magnetic particle method. Typical technological processes" (date of implementation 01.11.2016), GOST R ISO 9934-1-2011 "Non-destructive testing. Magnetic particle method. Part 1. Basic requirements”, GOST R ISO 9934-2-2011 “Non-destructive testing. Magnetic particle method. Part 2. Flaw detection materials”, GOST 21105-87 “Non-destructive testing. Magnetic particle method”, GOST R ISO 10893-5-2016 “Seamless and welded steel pipes. Part 5. Magnetic particle testing of ferromagnetic steel pipes to detect surface defects” (effective date 11/01/2016).

Table 4

5) Inspection by penetrating substances (capillary flaw detection)

The penetrant method is based on the penetration of a special liquid - penetrant - into the cavities of surface and through discontinuities of the test object, with subsequent extraction of the penetrant from the defects. The most common method is the capillary method, which is suitable for diagnosing objects made of metals and ceramics. The duration of flaw detection depends on the physical properties of the liquid, the nature of the detected defects and the method of filling the defect cavities with liquid. Within half an hour, surface fatigue, stress corrosion cracking and weld defects can be detected, and the method can determine the size of the crack.

GOST 53366-2009 does not specify standards for the capillary testing method for identifying defects in the casing, but this standard allows the use of other methods and methods of non-destructive testing. At the same time, GOST R ISO 13680-2011 recommends using ISO 12095 or ASTM E 165, which are listed in Table 5. Internal Russian standards for non-destructive testing using the penetrating liquid method have been developed and are in force, but until now they have not been used for inspecting casing strings: GOST R ISO 3059-2015 “Non-destructive testing. Penetrating testing and magnetic particle method. Selection of inspection parameters" (date of implementation 06/01/2016), GOST R ISO 3452-1-2011 "Non-destructive testing. Penetrating control. Part 1. Basic requirements”, GOST R ISO 3452-2-2009 “Non-destructive testing. Penetrating control. Part 2. Testing of penetrants”, GOST R ISO 3452-3-2009 “Non-destructive testing. Penetrating control. Part 3. Test samples”, GOST R ISO 3452-4-2011 “Non-destructive testing. Penetrating control. Part 4. Equipment”, GOST R ISO 12706-2011 “Non-destructive testing. Penetrating control. Dictionary”, GOST 18442-80 “Non-destructive testing Capillary methods General requirements”.

Table 5 presents standards related to this casing diagnostic method. There are no domestic Chinese standards for casing penetrant testing.

Table 5

6) X-ray control (radiographic method)

The radiographic method involves the use of X-ray radiation passing through the weld metal and creating an image on a radiographic film that shows the presence of various defects. The degree of exposure of the film will be greater in areas where defects are located.

In accordance with GOST ISO 3183-2012 “Steel pipes for pipelines in the oil and gas industry. General technical conditions”, the welded seam of each pipe end must be subjected to radiographic testing at a distance of at least 200 mm from the end of the pipe. The following pipes are subjected to this control method:

• with one or two longitudinal seams or one spiral seam, obtained by combining gas metal arc welding and submerged arc welding;
• with one or two longitudinal seams or one spiral seam, obtained by submerged arc welding.

Table 6 presents the relevant standards related to radiographic inspection of casing welds. Some standards for inspection of pipe welds are not specified.

Table 6

1. In the Russian Federation and China, when inspecting casing pipes for defects using various non-destructive testing methods, they are mainly guided by international ISO and ASTM standards.
2. Non-destructive testing of casing pipes is carried out in accordance with at least the same international standard in both Russia and China.
3. The main methods of non-destructive testing of casing strings in accordance with GOST 632-1980 and GOST 53366-2009 are: ultrasonic method, magnetic flux scattering method, eddy current method and magnetic particle method.
4. On the territory of the Russian Federation and the People's Republic of China, internal standards for non-destructive testing have been developed, which are not used to identify defects in casing pipes, but are used in other industrial areas.
5. In current internal standards and newly adopted ones, you can find references to canceled or outdated (there are replacement) versions of international and internal standards.
6. The radiographic non-destructive testing method is used only for flaw detection of casing pipe welds.

XU Jin-long, CAO Biao, HONG Wu-xing, LU Shan-sheng, FENG Jun-han, HUA Bin, YANG Shu-jie Domestic and international standards for non-destructive testing methods for casing strings / “Non-destructive testing methods” 2014, Vol 36 , No. 10, pp. 72-77

Tags: eddy current testing, penetrant flaw detection, penetrant testing, magnetic testing, magnetic particle testing, magnetic flux dispersion method, non-destructive testing, non-destructive testing of casing pipes, casing pipe, radiographic testing, X-ray testing, ultrasonic testing