RU2794338C2 - Method for pipeline control using electromagnetic-acoustic technology - Google Patents

Abstract

FIELD: non-destructive testing of oil and gas pipelines.

SUBSTANCE: invention relates to the field of non-destructive testing of the technical condition of oil and gas pipelines and oil product pipelines using the ultrasonic method using electromagnetic-acoustic transducers. The essence of the invention lies in the fact that when moving along the magnetized wall of the pipeline, an electromagnetic-acoustic transducer periodically emits ultrasonic waves, while at least two electromagnetic-acoustic transducers operating only for reception are moved along with it, located at an angle to the radiating and displaced relative to the axis directed along the propagation of ultrasonic waves and passing through its middle, and these electromagnetic-acoustic transducers receive ultrasonic waves reflected from crack-like defects located at angles to the direction perpendicular to the direction of propagation of the emitted ultrasonic waves.

EFFECT: improving the quality of ultrasonic testing of the pipeline without additional increase in energy consumption.

5 cl, 8 dwg

Description

The invention relates to the field of non-destructive testing of the technical condition of oil and gas pipelines and oil product pipelines by the ultrasonic method using electromagnetic acoustic transducers (EMAT) and can be used in flaw detectors of various designs, the operation of which is based on technologies using direct and inverse electromagnetic acoustic conversion.

As a rule, the known methods for testing pipelines by the ultrasonic method using electromagnetic-acoustic transducers are implemented in devices containing an EMAT layout, in which the EMAT generates and receives ultrasonic waves propagating at an angle to the surface of the body under study, as well as surface or normal (resonant) ultrasonic waves, while:

- these EMATs work each for radiation and reception;

- these EMATs work in pairs, one works only for radiation, and the other only for reception.

The disadvantage of such methods is that when using such EMAT arrangements, it is possible to detect crack-like defects located at small angles with respect to the direction perpendicular to the propagation of the ultrasonic wave. The value of this angle can be from -10 to 10°.

The principle of operation of these devices is described below, which underlies the known methods of non-destructive testing of pipelines using EMAT.

With the help of EMAT, an ultrasonic wave is formed in the wall of a pipe magnetized in a given direction of magnetic induction. This wave can be directed at an angle to the surface. It can also be a normal or surface wave. Such waves can be formed, for example, using an EMAT with a meander-shaped inductor. The type and parameters of waves directed at an angle to the surface, as well as surface waves, are determined by the ratio of the geometric parameters of the inductor and the frequency of the applied electrical signal to the radiating EMAT. The type and parameters of normal waves are determined by the ratio of the geometric parameters of the inductor, the frequency of the applied electrical signal to the radiating EMAT, and the thickness of the pipe wall. The type and parameters of the waves emitted by the EMAT are also affected by the parameters of the magnetic field introduced into the pipe wall. This type of EMAT emits an ultrasonic wave propagating in a certain direction along the pipe body.

In the case of a “crack” type defect, the ultrasonic wave is reflected from it and enters the receiving EMAT (echo method).

Due to the fact that the ultrasonic wave is reflected in accordance with the laws of geometric optics, i.e. the angle of incidence is equal to the angle of reflection; when the defect is oriented at a sufficiently large angle to the direction perpendicular to the direction of propagation of the ultrasonic wave, the ultrasonic wave reflected from the defect may not enter the receiving inductor, and, therefore, will not be registered.

Flaw detectors using a control method similar to the one described above are not able to see crack-like defects located at sufficiently large angles relative to the direction perpendicular to the direction of propagation of the ultrasonic wave (exceeding 10° in absolute value). In this case, the introduction of additional sensors operating on radiation, forming an ultrasonic wave directed at different angles, will lead to a significant increase in energy consumption, which is a problem for flaw detection. Thus, some crack-like defects may not be detected, and additional control methods will be required to identify them. To increase the number of detection of crack-like defects, the question arises of increasing the angles of location of defects at which their detection is possible.

A known system of ultrasonic flaw detection of the pipeline [see. utility model patent No. RU 102810 dated March 10, 2011], which implements a method of ultrasonic flaw detection, in which two bidirectional EMATs are placed symmetrically on both sides of the pipeline generatrix in the zone from 3 to 9 hours and move along the pipeline. They emit ultrasonic waves directed along the circumference and register them. Determination of the position of a defect on a circle occurs when processing the signals obtained during the registration of an ultrasonic wave reflected from defects, by the EPAM that generated it, and the wave reflected from the defect, generated by another EMAT.

The disadvantage of this method is that with this method it is possible to detect only defects located at small angles relative to the pipe generatrix. In addition, this sounding scheme obviously assumes that the diagnostics are carried out by normal or surface waves. If diagnostics are carried out with normal (resonant) waves, for example, Lamb waves, there will be limitations associated with the thickness of the pipe wall, in particular, its possible changes during the diagnostics. If the diagnostics is carried out by surface waves, for example, Rayleigh waves, then only defects that appear on one surface of the pipe will be detected.

A known system of ultrasonic flaw detection of the pipeline [see. utility model patent No. RU 108627 dated September 20, 2011], which implements a method of ultrasonic flaw detection, in which a bidirectional EMAT sensor emits Rayleigh ultrasonic waves around the circumference of the pipeline. The defect is detected by the echo method, the ultrasonic wave reflected from the defect is recorded by the same EMAT.

The disadvantage of this method is that during its implementation it is possible to detect only defects located at small angles relative to the pipe generatrix. In addition, since the diagnostics are carried out by surface Rayleigh waves, only defects that appear on one surface of the pipe will be detected. Also, the disadvantages of this method include the fact that this system does not provide an accurate determination of the location of the defect along the circumference of the pipeline, but is able to determine only the defective section.

The set of features closest to the set of essential features of the claimed invention is inherent in the method implemented in a known device for non-destructive testing of the walls of ferromagnetic structural elements [see. patent for invention No. RU 2413214 dated February 27, 2011].

In this method, taken as a prototype, ultrasonic waves (primarily normal shear waves) are excited by a high-frequency inductive coil on a wall section magnetized in a given direction of magnetic induction, propagate along a trajectory specified by the orientation of the inductive coil, which is a transmitter-converter and received at a distance from the transmitter-converter of at least one inductive coil, which is the receiver-converter, and the direction of the propagation path of ultrasonic waves is oriented at an acute angle to the direction of magnetic induction. The value of this angle can be from 10 to 60°, and the receiver-converter is placed on the side of the path of propagation of ultrasonic waves and is directed to the given controlled area located on it.

This method has the following disadvantages.

Firstly, the orientation of the magnetic field and the EMAT transmitting inductor is made in such a way that there is a certain angle different from 0° between the direction of the magnetic field and the direction of propagation of the ultrasonic wave, which leads to a decrease in the coefficient of direct electromagnetic-acoustic conversion, therefore, reduces the amplitude of the emitted ultrasonic wave.

Secondly, there is a limitation in the diagnostics of pipelines associated with their thickness, and above all with a possible change in the thickness of the pipe wall during the diagnostics of the pipeline. This is due to the mechanism of formation of normal waves. Different modes of normal waves are formed only at a certain combination of the pipe wall thickness and the frequency of the generated signal. If the thickness of the pipe wall changes, the conditions for the formation of the originally used modes of normal waves change, and, consequently, there are significant difficulties for their generation.

Thirdly, this method is applicable only with the use of magnetic systems that form a tangentially directed magnetic field (the magnetic induction vector is directed mainly in the direction of the generatrix or guide wall of the pipe) and is not possible when using magnetic systems that create a normal magnetic field (the magnetic induction vector is directed predominantly perpendicular to the pipe wall). Thus, the diagnostic method used is not universal. Sometimes it is more convenient to use magnetic systems for normal input, as a rule, their design is more compact and lighter, for example, this can be used in hand-held flaw detectors.

Fourthly, this method of control, as well as the fact that the transducer emitting an ultrasonic wave operates only on radiation, makes it possible to detect defects of only a certain orientation, while a large spread of angles relative to this direction is not allowed.

The described disadvantages are eliminated by the claimed invention.

The technical result of the invention is to improve the quality of ultrasonic testing of the pipeline without additional increase in energy consumption. This result is achieved by providing the possibility of detecting crack-like defects located in a wide range of angles relative to the direction perpendicular to the direction of propagation of the ultrasonic wave, without the introduction of additional EMAT operating on radiation, and therefore without an additional increase in energy consumption.

The specified technical result is achieved in the proposed pipeline control method, according to which at least one electromagnetic-acoustic transducer is moved along the pipeline wall, magnetized in a given direction of the magnetic induction vector, emitting ultrasonic waves within the controlled area of the pipeline wall surface, propagating along its given orientation trajectories. Ultrasonic waves reflected from defects located at a distance from the radiating electromagnetic-acoustic transducer and at least two electromagnetic-acoustic transducers are received, and the presence of defects in the pipeline walls is determined. In addition, ultrasonic waves reflected from crack-like defects located at angles to the direction perpendicular to the direction of propagation of radiated ultrasonic waves are received by at least two electromagnetic-acoustic transducers operating only for receiving ultrasonic waves, located at an angle to the radiating electromagnetic-acoustic transducer and displaced relative to the axis directed along the propagation of ultrasonic waves and passing through its middle.

In special cases, according to the method:

- move at least one electromagnetic-acoustic transducer, emitting ultrasonic waves within the controlled area of the inner or outer surface of the pipe wall, propagating along a trajectory specified by its orientation;

- radiation of ultrasonic waves is carried out by an electromagnetic-acoustic transducer, which can be unidirectional or bidirectional;

- the radiation of ultrasonic waves is carried out by a unidirectional electromagnetic-acoustic transducer, while at least two electromagnetic-acoustic transducers operating only to receive ultrasonic waves are moved along with it;

- the radiation of ultrasonic waves is carried out by a bidirectional electromagnetic-acoustic transducer, while at least four electromagnetic-acoustic transducers operating only to receive ultrasonic waves are moved along with it;

- ultrasonic waves reflected from crack-like defects are received simultaneously by electromagnetic-acoustic transducers operating only for reception, and by radiating electromagnetic-acoustic transducer or only by electromagnetic-acoustic transducers operating only for reception;

- at least one electromagnetic-acoustic transducer is moved, emitting ultrasonic waves within the controlled area of the pipeline wall surface, propagating along a trajectory specified by its orientation, while the emitted ultrasonic waves can be directed at an angle to the surface, or normal, or surface;

- magnetization of the pipeline wall is carried out by the magnetic system of the diagnostic device, which can be made using permanent magnets or electromagnets and move along with a radiating electromagnetic-acoustic transducer;

- magnetization of the pipeline wall is carried out by normal or tangential magnetization;

- along the pipeline wall, magnetized tangentially, at least one electromagnetic-acoustic transducer is moved, emitting ultrasonic waves within the controlled area of the pipeline wall surface, propagating along the trajectory specified by its orientation, while the emitting electromagnetic-acoustic transducer is placed so that the direction of magnetization of the wall pipeline was parallel to the direction of propagation of ultrasonic waves.

The essence of the proposed method is illustrated by drawings.

In FIG. 1 shows an example of the method for diagnosing crack-like defects located at large angles with respect to the direction perpendicular to the direction of propagation of the ultrasonic wave, while the defects are located mainly in the direction of the longitudinal axis of the pipe. In this example, the method is carried out using a bi-directional EMAT, to which four receive-only EMATs are added, using a magnetic system that creates a tangential magnetic field in the pipe wall.

In FIG. Figure 2 shows an example of the method for diagnosing crack-like defects located at large angles with respect to the direction perpendicular to the direction of propagation of the ultrasonic wave, located mainly in the direction perpendicular to the longitudinal axis of the pipe. In this example, the method is carried out using a bi-directional EMAT, to which four receive-only EMATs are added, using a magnetic system that creates a tangential magnetic field in the pipe wall.

In FIG. Figure 3 shows an example of the method for diagnosing crack-like defects located at large angles with respect to the direction perpendicular to the direction of propagation of the ultrasonic wave, located mainly in the direction of the longitudinal axis of the pipe. In this example, the method is carried out using a bidirectional EMAT, to which four receive-only EMATs are added, using a magnetic system that creates a normal magnetic field in the pipe wall.

In FIG. 4 shows an example of the implementation of the method for diagnosing crack-like defects located at large angles with respect to the direction perpendicular to the direction of propagation of the ultrasonic wave, located mainly in the direction perpendicular to the longitudinal axis of the pipe. In this example, the method is carried out using a bidirectional EMAT, to which four receive-only EMATs are added, using a magnetic system that creates a normal magnetic field in the pipe wall.

In FIG. 5 shows an example of the implementation of the method for diagnosing crack-like defects located at large angles with respect to the direction perpendicular to the direction of propagation of the ultrasonic wave, located mainly in the direction of the longitudinal axis of the pipe. In this example, the method is carried out using a unidirectional EMAT, to which two receive-only EMATs are added, using a magnetic system that creates a tangential magnetic field in the pipe wall.

In FIG. 6 shows an example of the implementation of the method for diagnosing crack-like defects located at large angles with respect to the direction perpendicular to the direction of propagation of the ultrasonic wave, located mainly in the direction perpendicular to the longitudinal axis of the pipe. In this example, the method is carried out using a unidirectional EMAT, to which two receive-only EMATs are added, using a magnetic system that creates a tangential magnetic field in the pipe wall.

In FIG. Figure 7 shows an example of the method for diagnosing crack-like defects located at large angles with respect to the direction perpendicular to the direction of propagation of the ultrasonic wave, located mainly in the direction of the longitudinal axis of the pipe. In this example, the method is carried out using a unidirectional EMAT, to which two receive-only EMATs are added, using a magnetic system that creates a normal magnetic field in the pipe wall.

In FIG. 8 shows an example of the method for diagnosing crack-like defects located at large angles with respect to the direction perpendicular to the direction of propagation of the ultrasonic wave, located mainly in the direction perpendicular to the longitudinal axis of the pipe. In this example, the method is carried out using a unidirectional EMAT, to which two receive-only EMATs are added, using a magnetic system that creates a normal magnetic field in the pipe wall.

The following designations are used in the drawings:

1 - EMAT emitting ultrasonic waves;

2 - EMAT, working only to receive ultrasonic waves;

3 - crack-like defect;

4 - direction of propagation of the emitted ultrasonic wave;

5 - the direction of propagation of the ultrasonic wave reflected from the defect;

6 - longitudinal axis of the pipe;

B is the direction of magnetization of the pipe wall.

The pipeline control method using electromagnetic-acoustic technology is carried out as follows.

Along the tangentially magnetized (the magnetic induction vector is directed mainly in the direction of the generatrix or guiding pipe wall) or normally (the magnetic induction vector is directed mainly perpendicular to the pipe wall) the pipe wall is moved along its outer surface or along its inner surface, forming an EMAT directed at an angle to the surface or normal or surface wave. This emitting EMAT can also be a receiver (combined type EMAT). In this case, the magnetic system can be formed using permanent magnets or electromagnets and move along with the movement of the EMAT. Moreover, when using tangential magnetization of the pipe wall, the EMAT, which forms the ultrasonic wave, is placed so that the direction of the pipe wall magnetization is parallel to the direction of propagation of the ultrasonic wave. Simultaneously with the EMAT emitting an ultrasonic wave (or emitting and receiving an ultrasonic wave), two or more EMATs are moved, which work only to receive an ultrasonic wave, which should be located at certain angles to the emitter and displaced relative to the axis directed along the propagation of the ultrasonic wave and passing through the middle of the EMAT emitting it. The value of the range of these angles for diagnostics using a tangential magnetic field is from 10 to 60°, for diagnostics using a normal magnetic field - from 10 to 90°.

Thus, when orienting a defect located at a sufficiently large angle to the direction perpendicular to the direction of propagation of the ultrasonic wave, the possibility of passing the ultrasonic wave reflected from the defect is excluded, in which case it may not enter the receiving inductor and, therefore, will not be registered.

The optimal number of receive-only EMATs to add to an emitting bi-directional EMAT (radiating an ultrasonic wave in two opposite directions) is four. This is due to the fact that defects can be detected simultaneously using ultrasonic waves generated by a bidirectional EMAT in opposite directions, and for each of these directions, defects located at positive angles relative to the direction perpendicular to the direction of propagation of the emitted ultrasonic wave and defects located under negative angles relative to the direction perpendicular to the direction of propagation of the emitted ultrasonic wave are detected by two, differently located, EMAT, working only for reception (Fig. 1-4).

The optimal number of receive-only EMATs to add to an emitting unidirectional EMAT (radiating an ultrasonic wave in one direction) is two. This is due to the fact that defects located at positive angles relative to the direction perpendicular to the direction of propagation of the ultrasonic wave and defects located at negative angles relative to the direction perpendicular to the direction of propagation of the ultrasonic wave are detected by two differently located EMAT operating only for reception ( Fig. 5-8).

The parameters of the EMAT used for diagnostics should be selected based on the type and parameters of the wave used for diagnostics, taking into account the features of the formation of this wave in a magnetic field in the pipe wall (tangential or normal).

Claims (5)

1. A pipeline control method, which consists in moving at least one electromagnetic-acoustic transducer along the pipeline wall magnetized in a given direction of the magnetic induction vector, emitting ultrasonic waves within the controlled area of the pipeline wall surface, propagating along a trajectory specified by its orientation , wherein the magnetization of the pipeline wall is carried out by the magnetic system of the diagnostic device, which can be made using permanent magnets or electromagnets and which is moved together with a radiating electromagnetic-acoustic transducer, and the emitted ultrasonic waves can be directed at an angle to the surface, or normal, or surface, and receive ultrasonic waves reflected from crack-like defects located at a distance from the radiating electromagnetic-acoustic transducer and moved together with it by at least two electromagnetic-acoustic transducers operating only for reception, while ultrasonic waves reflected from crack-like defects are received simultaneously electromagnetic-acoustic transducers that work only for receiving, and a radiating electromagnetic-acoustic transducer or only electromagnetic-acoustic transducers that work only for receiving, then the presence of defects in the walls of the pipeline is determined, characterized in that the magnetization of the pipeline wall is carried out by normal or tangential magnetization, with tangential magnetization of the pipeline wall, the radiating electromagnetic-acoustic transducer is placed so that the direction of magnetization of the pipeline wall is parallel to the direction of propagation of ultrasonic waves, ultrasonic waves are received reflected from crack-like defects located at angles to the direction perpendicular to the direction of propagation of the emitted ultrasonic waves, at least two electromagnetic-acoustic transducers operating only to receive ultrasonic waves, located at an angle of 10 to 60° with tangential magnetization of the pipeline wall and from 10 to 90° with normal magnetization of the pipeline wall to the radiating electromagnetic-acoustic transducer and displaced relative to the axis directed along the propagation ultrasonic waves and passing through the middle of the radiating electromagnetic-acoustic transducer. 2. The pipeline control method according to claim 1, characterized in that at least one electromagnetic-acoustic transducer is moved, emitting ultrasonic waves within the controlled area of the inner or outer surface of the pipeline wall, propagating along a trajectory specified by its orientation. 3. The pipeline control method according to claim 1, characterized in that the radiation of ultrasonic waves is carried out by an electromagnetic-acoustic transducer, which can be unidirectional or bidirectional. 4. The method of monitoring the pipeline according to claim 3, characterized in that the radiation of ultrasonic waves is carried out by a unidirectional electromagnetic-acoustic transducer, while at least two electromagnetic-acoustic transducers operating only to receive ultrasonic waves are moved along with it. 5. The method of monitoring the pipeline according to claim 3, characterized in that the radiation of ultrasonic waves is carried out by a bidirectional electromagnetic-acoustic transducer, while at least four electromagnetic-acoustic transducers operating only to receive ultrasonic waves are moved along with it.

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