RU2702408C1 - Method and device for scanning flaw detection of internal protective-insulating coatings of pipelines - Google Patents

Abstract

FIELD: defectoscopy.

SUBSTANCE: use: for flaw detection of inner protective-insulating coatings, to avoid uncontrolled opening of protective coatings and damage to pipe wall. Essence of the invention consists in the fact that the method of scanning flaw detection of internal protective-insulating coatings of pipelines consists in measurement of leakage currents between an internal medium of the surveyed pipeline and a pipe wall, when voltage is supplied to corresponding electrodes of measuring device of in-tube device from built-in voltage source, in order to localize defects along pipeline section, sensitive elements of measuring device of in-pipe instrument are distributed along measuring sectors, and are as close as possible to internal surface of surveyed pipeline.

EFFECT: technical result is possibility of accurate assessment of dimensions of detected defects.

7 cl, 12 dwg

Description

The technical field to which the invention relates: diagnostics of the technical condition of pipelines.

The proposed solution relates to the field of diagnostics of the technical condition of pipelines, and can be used for flaw detection of internal protective and insulating coatings, in order to avoid uncontrolled opening of protective coatings and damage to the pipe wall.

State of the art

1. Known "In-tube ultrasonic inspection device" "UZVIP" from the company LLC "INTRON VTD" (http://intron-vtd.ru/3.html).

The device allows you to:

- Measure the wall thickness of the studied pipe;

- Measure the internal profile of the pipe;

- Detect delamination in the pipe wall;

- Identify pipe defects and anomalies, including unauthorized taps;

- Diagnose pipes from non-magnetic materials, including polyethylene and stainless steel.

Including the device has the ability to measure the thickness of the inner protective coating.

But the device is not intended to search for minor defects of the internal protective and insulating coating, which lead to leaks of the aggressive working medium of the pipeline to the metal wall and are the cause of its active destruction.

2. Known electrospark method for the diagnosis of insulation coatings.

One of the versions: “Electro-spark flaw detector KORONA 1B (Digital)” from the company “ANK”, Perm (http://ank-ndt.m/produkcziya/kontrol-izolyaczii/elektroiskrovyie-defektoskopyi/korona-lv.html) .

“The device is designed to control cracks, porosity, unacceptable thinning and other violations of the integrity of the protective coatings inside the pipes.

Features:

- high safety due to the pulse mode of operation;

- a specialized disk electrode with support wheels, which allows you to control pipes of a given size with a large variation in bore diameter;

- a specialized prefabricated system for feeding and moving a disk electrode inside a pipe with support wheels;

- the ability to control the continuity of coatings of structures after assembly (welding) to a length of 14 m. "

The method is applicable only in a dry short pipe. If the pipeline is in operation and is filled with any kind of liquid, the method is not applicable in principle.

3. In the article "Method for the diagnosis of internal anti-corrosion coating of pipelines", A.A. Kundik (Gazpromneft-Orenburg LLC) PROneft Magazine (http://ntc.gazprom-neft.ru/research-and-development/proneft/1236/20535/) offers:

3.1. “The proposed method for determining the place of violation of the integrity of the pipe insulation is based on the ability of produced water to conduct electric current. An open circuit is created with a “plus” on a highly sensitive device, which is connected to the pipe metal in the zone of the most vulnerable place (weld), “minus” on the electrolyte - bottom water. After supplying current to the weld in the event of violation of the integrity of the insulation, the circuit will close and the device will indicate the presence of current. If the dielectric (insulating) layer is not broken, the circuit remains open, and the device indicates the absence of current. The main disadvantage of this method is the local nature of the control of the pipeline section. It is applicable only to detect defects in the installation of bushings that insulate the welded joints of the pipeline. At the same time, the problem of determining the breakdown of the internal insulation coating along the pipeline route remains unresolved. ”

In the same place (“Method for the diagnosis of internal anti-corrosion coating of pipelines”, A.A. Kundik (Gazpromneft-Orenburg LLC) RROneft magazine):

3.2. “However, it is possible to solve the problem, based on the nature of the electromagnetic field. An insulated section of the pipeline filled with electrolyte is a conductor of electric current, therefore, when a current is applied to the in-tube space around the electrolyte, a magnetic field will inevitably form. In a longitudinal section of the pipeline, the magnetic field propagates in the form of a sinusoid. In the place of violation of isolation of the sinusoid will go beyond the reference values. Thus, when fixing the value of the magnetic field with a special device, it becomes possible to determine the places of insulation damage along the entire length of the mounted pipeline. ”

The method also did not find wide application due to the ambiguity of the results, the complexity of measurements on rough terrain, in conditions of significant deepening of the studied pipeline, as well as the impact of environmental noise factors.

4. One of the closest in technical essence to the claimed invention is a measurement method for lateral logging with a three-electrode probe (see, for example, SS Itenberg, TD Dakhkilgov. Geophysical studies in wells. M .: "Nedra", 1982 S. 108, 131, 132), in which a supply alternating current is supplied to the central and screen electrodes of the probe, interconnected to equalize their potentials with an electric shunt of low (≈0.01 Ohm), measure the current I _{0 of the} central electrode and potential ΔU of the shield electrodes relative to the electrode comparisons and determine the apparent resistivity P _to rocks. (Fig. 1).

Physical basis of the method.

“Lateral logging refers to measurements of apparent resistance along a borehole with a three-electrode lateral logging probe with automatic focusing of current. The probe has a central electrode Ao (Fig. 2), symmetrically with respect to which elongated shield electrodes (A 1-0 and A1-1) are interconnected.

When measuring the apparent resistance, the same potential of all electrodes is provided. Thus, the screen electrodes prevent the spreading of the current of the central electrode through the borehole and direct it directly into the studied formation (Fig. 3). "

This measurement method is designed to measure rock resistance in wells, and of course is not intended to diagnose the technical condition of pipes.

5. The closest in technical essence to the claimed invention is the measurement method described in the Application for invention No. 2017123805/06 (041330) "Method and device for flaw detection of internal protective and insulating coatings of existing field pipelines":

“The problem is solved by measuring the leakage of electric current arising from a violation of the internal insulation coating of the steel pipeline.

Method and device for defectoscopy of internal protective-insulating coatings of pipelines, consisting in the emission of sounding voltage pulses with a generator and measuring the parameters of a current pulse through an internal protective-insulating coating of a pipeline arising in a section bounded by two insulating cuffs tightly fixed on the body of the in-tube device.

The measuring system contains a measuring electrode “A0”, as well as an electrode “B1” at the rear of the in-tube device and an electrode “B2” at the front of which alternate pulse measurements are made, and the measuring electrode is connected through a low-impedance shunt to measure the parameters of the pulse flowing through it current.

In order to eliminate the influence of leakage of electric current in the gap between the insulating cuffs and the inner wall of the examined pipe, the in-tube device contains screen electrodes "AE1" and "AE2" on both sides of the measuring electrode, which have an equal electric potential with it. "

Method and device for scanning flaw detection of internal protective-insulating coatings of pipelines

This measurement method is high-tech and has good prospects for development, but does not provide localization of defects along the pipeline cross section.

SUMMARY OF THE INVENTION

1. The objective of the invention is to identify small-sized damage to the protective insulating coating of the pipeline, causing leakage of pumped aggressive liquids to the steel wall of the pipe, causing its active corrosion damage, with the localization of defects along the cross section of the pipeline.

2. The problem is solved by measuring the leakage of electric current arising from a violation of the internal insulation coating of the steel pipe.

3. The localization of defects along the pipeline section is provided by dividing the measuring part of the probe installation of the in-tube device into N sectors. Physically, this is achieved by dividing the measuring electrode "A0" into a group of electrodes "A01 ÷ A0N", or by placing between the measuring electrode "A0" and the inner surface of the examined pipeline N measuring inductors "K1 ÷ KN", which will be described in more detail below.

4. Since the measuring electrodes (or measuring coils of 'inductance) are close to the surface being examined, the results of measurements by sectors will be quite differentiated. This will allow not only to determine in which sector the defect is located, but also to evaluate its dimensions.

5. Depending on the selected physical principle of measurements in sectors, it is possible to measure both in direct current (usually connected briefly) and in a pulsed mode, analyzing the parameters of transients.

In FIG. 4 shows an in-line device for defectoscopy of internal protective-insulating coatings (hereinafter referred to as the “In-pipe device”), placed in the examined pipeline.

The standard equipment of the in-tube device includes 3 components:

• measuring section;

• a beacon to track the passage of the in-tube device over a distance;

• odometric wheels, for exact reference of the received data.

In FIG. 5 shows the design of the measuring installation of the in-tube device.

In this embodiment, the measuring electrode is divided into N sectors, and each of the electrodes “A01 ÷ A0N” is approximated to the inner surface of the examined pipeline using elastic elements.

In the future, for definiteness with terminology, the sections of the measuring device of the in-tube device, separated by insulating cuffs, will be called the "Section":

• Section of measuring electrodes;

• Sections of screen electrodes.

The sections of the cross section of the inner surface of the examined pipeline, corresponding to the measuring electrodes "A01 ÷ A0N", or measuring coils "K0 ÷ KN", will be called "Sector".

In FIG. 6. - The electric circuit of the measuring installation of the in-tube device with measuring electrodes "A01 ÷ A0N".

I do not provide equivalent measurement schemes and corresponding processing algorithms in this description. Equivalent electrical measurement circuits were discussed in detail in the Prototype.

With scanning measurements, the circuit will become even more complicated. When developing data processing algorithms, this scheme will need to be reasonably simplified, etc.

In this case, this is not the purpose of the invention, therefore, do not complicate.

In FIG. 7. - Distribution of current lines in the studied pipeline during measurements when the measuring electrode is divided into N sectors.

Since the measuring electrodes are close to the surface being examined, the results of measurements by sectors will be quite differentiated. This will allow not only to determine in which sector the defect is located, but also to evaluate its dimensions.

Such a constructive solution for dividing measurements by sectors is, of course, an order of magnitude more informative than "integral" measurements.

But, like any solution, it has its own advantages and disadvantages.

Therefore, the Application proposes a second constructive solution for measurements in N sectors.

And only the experience of a specific implementation and testing of these structures will show which of these solutions will be more practical for mass use.

In FIG. 9 shows the design of the measuring installation of the in-tube device with measuring coils "K0 ÷ KN".

In this embodiment, N measuring coils “K1 ÷ KN” are placed between the measuring electrode A0 of the measuring device of the in-tube device and the inner surface of the examined pipe, and they are distributed across the measuring sectors in the cross section of the examined pipe and are as close as possible to the inner surface of the examined pipe.

In FIG. 10. - The electric circuit of the measuring installation of the in-tube device, in which N measuring inductors "K1 ÷ KN".

The circuit differs significantly from the circuit with electrodes "A01 ÷ A0N", primarily in that it, in principle, does not work from a constant voltage. Only a change in the electric current through the internal conducting medium of the pipeline passing through the circuits of the measuring inductors will lead to the appearance of voltage at the terminals of the coils.

This measurement option unambiguously assumes an analysis of transients with pulsed signals supplied from the built-in generator to the electrodes of the measuring device of the in-tube device.

In FIG. 11. - Distribution of current lines in the studied pipeline during measurements with measuring inductors "K1 ÷ KN".

6. As we already know from the analysis of "integrated" measuring circuits described in the Prototype, the results of such saturated circuits cannot be calculated from one measurement.

With scanning measurements, it is similar, except for the main measurements, to do without auxiliary measurements.

For example, it is possible to measure leakage currents between the sectors of a measuring installation of an in-tube device. In FIG. 12 (a, c), diagrams of such auxiliary measurements are presented, in this case, for measuring leakage between the sectors of the measuring electrode and the sectors of the screen electrodes.

The more such auxiliary measurements can be implemented, the more accurate will be the data processing algorithms.

These auxiliary measurements clearly include:

• measurement of the electrical conductivity of the liquid filling the pipeline and which is the working medium for the measuring installation of the in-tube device;

• a group of auxiliary measurements, allowing to identify defects in various sectors of the measuring device of the in-tube device. This will not only duplicate the main measurements, but will clarify the results of processing the main measurements, and also in many cases will make it possible to judge the dimensions of the detected defects.

• a group of auxiliary measurements, allowing to identify defects in various sectors of the measuring device of the in-tube device.

7. In order to bind the data obtained as a result of measurements to the corresponding sectors of the cross-section of the examined pipeline, the measuring unit of the in-tube device contains a biaxial accelerometer.

Measurements are taken in a plane perpendicular to the axis of the pipeline being examined.

The technical result of the invention is a high-quality defectoscopy of internal protective-insulating coatings of pipelines, with the localization of defects along the cross-section of the pipeline, with a much more accurate assessment of the dimensions of the detected defects.

Brief Description of the Drawings

FIG. 1. Scheme of the side logging probe.

This, which has already become classic, the scheme of the side logging probe clearly demonstrates that the current of the measuring electrode is directed perpendicular to the vertical axis of the probe, due to the presence of screen electrodes. Since the potentials of the electrodes “A0”, “A1-0” and “A2-0” are equal, this does not allow the current of the measuring electrode to follow the shortest path through the drilling fluid, but directs it to the rock opposite the measuring electrode.

FIG. 2. The electrical circuit of the three-electrode lateral logging probe (BK-3).

1 - Screen electrode "A1-0";

2 - Insulator;

3 - Measuring electrode "A0";

4 - Insulator;

5 - Screen electrode "A1 -1";

6 - Shunt resistance (Rш≈0.01 Ohm);

7 - Jumper, electrical contact between the screen electrodes "A1-0" and "A1-1".

FIG. 3. The distribution pattern of the current lines of the lateral logging probes in a homogeneous medium for a three-electrode probe.

This circuit is very similar in essence to that shown in FIG. 1, but more clearly displays the studied interval.

FIG. 4. In-tube device located in the studied pipeline.

1 - device for launching an in-tube device into a pipe;

2 - the examined pipe;

3 - odometric wheels for measuring the distance traveled;

4 - measuring installation of the in-tube device;

5 - connecting hinge;

6 - a radio beacon;

7 - camera receiving in-tube device.

FIG. 5 Design of the measuring device of the in-tube device, with measuring electrodes “A01 ÷ A0N”.

8 - electrode "B1";

9 - screen electrode "AE1";

10 - measuring electrodes "A01 ÷ A0N";

11 - elastic elements that ensure the maximum proximity of the measuring electrodes "A01 ÷ A0N" to the inner wall of the examined pipeline, while not limiting the passage of the narrowing of the pipeline, bends, Celer couplings and other structural elements;

12 - screen electrode "AE2";

13 - electrode "B2";

14 - insulating cuffs;

15 - insulators on the body of the in-tube device.

FIG. 6. The electric circuit of the measuring installation of the in-tube device, with measuring electrodes "A01 ÷ A0N".

The power source "U" supplies voltage to the screen electrodes "AE1" and "Ae2", as well as to the measuring electrodes "A01 ÷ A0N". Moreover, voltage is applied to the measuring electrodes through low-resistance resistors "Rш1 ÷ RшN", for measuring currents.

All sections are separated by insulators, over each of which an insulating sleeve is installed. The cuffs are also centering and pulling, allowing fluid to push through the in-tube device. Moreover, the cuffs are installed on the insulators in such a way as to ensure tightness between the sections corresponding to each of the electrodes.

FIG. 7. Distribution of current lines of the measuring device of the in-tube device in the pipeline under study during measurements, with measuring electrodes “A01 ÷ A0N”.

The direction of the currents in each section of the measuring installation is clearly displayed here.

Particular attention is given to the currents of the measuring electrodes "A01 ÷ A0N".

FIG. 8. Timing chart of measurements. In autonomous equipment powered by batteries, voltage is usually not applied to the electrodes constantly, since sufficiently high currents in the measuring circuit are possible.

Constant voltage is turned on for a short time, but at the same time, certain rules must be observed, which are reflected in this time diagram:

1 - transient when voltage is applied;

2 - time interval to calm all kinds of fluctuations;

3 - time interval for measurements;

4 - transient when the voltage is turned off.

In reality, these time intervals are relatively short, but since such measurements are usually carried out at frequencies of tens or even hundreds of kilohertz, such nuances must already be calculated.

FIG. 9. The design of the measuring installation of the in-tube device, with measuring inductors "K1 ÷ KN".

8 - electrode "B1";

9 - screen electrode "AE1";

11 - elastic elements that provide the maximum approximation of the measuring inductance coils "K0 ÷ KN" to the inner wall of the examined pipeline, while not limiting the passage of the narrowing of the pipeline, bends, Celer couplings and other structural elements;

12 - screen electrode "AE2";

13 - electrode "B2";

14 - insulating cuffs;

15 - insulators on the body of the in-tube device;

16 - measuring electrode "A0";

17 - measuring coil inductance "K0 ÷ KN".

FIG. 10. The electric circuit of the measuring installation of the in-tube device, with measuring inductors "K1 ÷ KN".

The pulse generator "G" sends a signal to the screen electrodes "AE1" and "AE2", as well as to the measuring electrodes "A01 ÷ A0N". Moreover, the signal is fed to the measuring electrodes through low-resistance resistors "Rш1 ÷ RшN", for measuring currents.

All sections are separated by insulators, over each of which an insulating sleeve is installed. The cuffs are also centering and pulling, allowing fluid to push through the in-tube device. Moreover, the cuffs are installed on the insulators in such a way as to ensure tightness between the sections corresponding to each of the electrodes.

FIG. 11. Distribution of current lines of the measuring device of the in-tube device in the pipeline under study during measurements, with measuring inductors “K1 ÷ KN”.

The direction of the currents in each section of the measuring installation is clearly displayed here.

Particular attention is given to the currents of the measuring electrode “A0” passing inside the circuits of the measuring coils “K1 ÷ KN”.

Fig. 12. Equivalent electrical circuit of the measuring installation of the in-tube device in the studied pipeline, for auxiliary measurements, in this case, for measuring leakage between the sectors of the measuring electrode and the sectors of the screen electrodes.

The implementation of the invention

Like all in-line diagnostic shells operating over long distances (kilometers, tens of kilometers, and even hundreds of kilometers), this in-line device is pushed by the working medium of the pipeline under examination.

When pushing the in-tube device with the working medium of the pipeline under examination, certain reinforcement is required. We will not describe the whole complex; we will restrict ourselves to the main elements depicted in FIG. 4 .: Launcher and Reception Camera.

Initially, the in-tube device is placed in the Launcher, and is pushed by the working fluid into the test pipeline.

The speed of movement through the pipeline is determined by the performance of the pump, and is strictly specified in the statement of work for inspection of the pipeline.

In the process of movement, the actual position of the in-tube device is monitored by placing signal receivers emitted by the in-tube device transmitter in special “marker points”.

The in-tube device that has passed the entire distance enters the receiving chamber, as evidenced by a special “flag”.

The device is removed from the reception chamber, laundered. Recorded data is extracted from it (on a memory card, or through an interface cable), and the device is preserved until the next cycle of work.

Requirements for the working environment of the studied pipeline, unambiguously resulting from the measurement method:

1. The liquid must be well conductive and not contain viscous insulating fractions (fuel oil).

2. A minimum amount of gas is desirable. The air plug formed in the upper sector of the working area (Volume around the measuring electrode) excludes the corresponding sector from the examined area, since there is no electric current in this sector.

Linking the measured data to the distance along the studied pipeline can be made in various ways, for example:

• using odometric wheels, and recording their readings in the memory of the in-tube device;

• rigorous measurement of the volume of pumped liquid, with the recording of data in the memory of the measuring system at the pumping control point. After removing the in-tube device, its data is synchronized with the pumping data.

• Using a system of radio beacons and marker points;

• Etc.

The data obtained as a result of measurements are linked to the corresponding sectors of the cross-section of the pipeline under examination, based on the results of measurements of a biaxial accelerometer.

Claims (13)

1. The method of scanning flaw detection of internal protective-insulating coatings of pipelines, which consists in measuring leakage currents between the internal environment of the examined pipeline and the pipe wall, when voltage is applied to the corresponding electrodes of the measuring device of the in-tube device from the built-in voltage source, characterized in that in order to localize the defects by the cross-section of the pipeline, the sensitive elements of the measuring installation of the in-tube device are distributed across the measuring sectors, and the maximum close to the inner surface of the inspected pipeline. 2. The method of defectoscopy of internal protective-insulating coatings of pipelines according to claim 1, characterized in that, in order to improve the quality of measurements, the electrodes of the in-tube device can be supplied as a constant voltage supplied continuously or according to a specially calculated time diagram, when control is performed in a specific time window current through the measuring electrodes in each of the sectors of the measuring installation of the in-tube device, and the pulse voltage, when the measurement result is an analysis of Transient processes in various sectors of the in-tube instrument measuring system. 3. The method of flaw detection of internal protective-insulating coatings of pipelines according to claim 1, characterized in that in order to improve the quality of measurements, the measuring unit of the in-tube device provides a number of auxiliary measurements: • measurement of the electrical conductivity of the liquid filling the pipeline and which is the working medium for the measuring installation of the in-tube device; • a group of auxiliary measurements, allowing to measure the level of leakage between sections of the measuring installation of the in-tube device; • a group of auxiliary measurements, allowing to identify defects in various sections of the measuring unit of the in-tube device. 4. A device for scanning flaw detection of internal protective-insulating coatings of pipelines, comprising a measuring unit, odometer wheels and a beacon based on measuring leakage currents between the internal medium of the examined pipeline and the steel pipe wall, when voltage is applied to the corresponding electrodes of the measuring unit of the in-tube device from an integrated voltage source, characterized in that for the purpose of localizing defects along the pipeline section, the measuring electrode 0 of the measuring-tube installation device is divided into N electrode A01 ÷ A0N, wherein A01 ÷ A0N electrodes for measuring sectors distributed in the cross section of the subject of the pipeline, and as close to the inner surface of the inspected pipeline. 5. A device for scanning defectoscopy of internal protective-insulating coatings of pipelines according to claim 4, characterized in that in order to improve the quality of measurements, the measuring unit of the in-tube device provides a number of auxiliary measurements: • measurement of the electrical conductivity of the liquid filling the pipeline and which is the working medium for the measuring installation of the in-tube device; • a group of auxiliary measurements, which make it possible to measure the level of leaks between the sectors of the measuring unit of the in-tube device; • a group of auxiliary measurements, allowing to identify defects in various sectors of the measuring device of the in-tube device. 6. A device for scanning flaw detection of internal protective-insulating coatings of pipelines according to claim 4, characterized in that for the purpose of linking the data obtained as a result of the measurements to the corresponding sectors of the cross-section of the pipeline being examined, the measuring unit of the in-line device contains a two-axis accelerometer. 7. A device for scanning flaw detection of internal protective-insulating coatings of pipelines, comprising a measuring unit, odometric wheels and a beacon based on measuring leakage currents between the internal medium of the examined pipeline and the steel pipe wall, when a pulse voltage is applied to the corresponding electrodes of the in-tube measuring installation device from the built-in generator, characterized in that in order to localize defects along the pipeline section, between measuring ektrodom A0 measurement setup. N measuring coils K1 ÷ KN are placed in the in-tube device and the inner surface of the pipeline under examination, and they are distributed over the measuring sectors in the cross section of the pipeline under investigation, and are as close as possible to the inner surface of the pipeline under examination.

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