Pipeline stress internal detection probe

Abstract

The utility model discloses a pipeline stress internal detection probe which is characterized in that the pipeline stress internal detection probe comprises a pair of L-shaped magnetic cores, two excitation coils are respectively wound on the pair of L-shaped magnetic cores along the same direction, the excitation coils are connected with a driving circuit, and when current i in the same direction is conducted in the excitation coils through the driving circuit, the excitation coils are connected with the driving circuit. A uniform magnetic field area is formed near the distance l between the two magnet exciting coils, and a plurality of magnetic sensors are arranged in the uniform magnetic field area. According to the utility model, the pulse excitation coil is used as a low-frequency pulse magnetic field generating device to magnetize the ferromagnetic pipeline. After the pipeline is magnetized, if an external magnetic field disappears (is reduced to zero), the pipe wall still shows magnetism, and the residual magnetization intensity of the pipe wall at the moment is called residual magnetism. The stress can change the residual magnetization intensity of the ferromagnetic material, so that the internal magnetic conductivity of the material can be changed. Therefore, the residual magnetization is measured through the magnetic sensor integrated in the probe, the stress is represented, and stress detection and analysis are realized.

Description

Technical Field

[0001] The utility model relates to a pipeline stress internal detection probe, which is used for measuring the stress in the pipeline internal detection process and belongs to the field of pipeline internal detection. Background Art

[0002] Oil and gas pipelines are buried underground for a long time and are affected by medium pressure, soil and their own gravity. As time goes by, in the stress concentration area, mechanical damage, corrosion and cracks of the pipeline body are affected by internal and external stresses, resulting in yield failure and stress corrosion cracking in local areas, which brings huge risks to the safe operation of the pipeline. If the stress state of the pipeline cannot be predicted before the pipeline yields and transforms into plastic deformation and causes fatigue failure, the pipeline will be operated with problems for a long time, which is very likely to cause burst accidents.

[0003] Traditional pipeline magnetic leakage internal detection is only suitable for pipeline defect detection, not for stress internal detection, so it is necessary to study an internal detection method suitable for pipeline stress.

[0004] Ferromagnetic materials such as iron, nickel, cobalt and their alloys change size and shape after magnetization. This effect is called magnetostrictive effect. On the contrary, applying stress to magnetostrictive materials will change the magnetic conductivity of the material, especially the magnetic permeability. For example, applying stress to magnetostrictive materials will cause the magnetization intensity of the material to change. This phenomenon is called Villari effect, also known as inverse magnetostrictive effect. Utility Model Content

[0005] The purpose of the utility model is: based on the inverse magnetostrictive effect, the alloy material is firstly magnetized through the magnetic core, and then the residual magnetization intensity is measured through the magnetic sensor integrated in the probe, so as to characterize the stress size and realize stress detection and analysis.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the utility model is to provide a pipeline stress internal detection probe, which is characterized in that it includes a pair of L-shaped magnetic cores, two excitation coils are respectively wound on the pair of L-shaped magnetic cores in the same direction, the excitation coils are connected to the driving circuit, when the driving circuit passes the current i in the same direction through the excitation coils, a uniform magnetic field area is formed between the two excitation coils near the spacing l, and a plurality of magnetic sensors are arranged in the uniform magnetic field area.

[0007] Preferably, the two excitation coils are made of the same material and have the same number of turns, and are parallel and coaxial to each other.

[0008] Preferably, the distance l between the two excitation coils is equal to the radius R of any one of the excitation coils.

[0009] Preferably, all the magnetic sensors are arranged in parallel along the radial direction of the pipeline, covering the width of the L-shaped magnetic core.

[0010] Preferably, a plurality of groups of pipeline stress internal detection probes are arranged along the circumference of the pipeline, and all of the pipeline stress internal detection probes cover a circumference of the pipeline.

[0011] Preferably, the driving circuit includes a common-phase proportional operational amplifier circuit, the input end of the common-phase proportional operational amplifier circuit is connected to the square wave excitation signal VIN, the output end of the common-phase proportional operational amplifier circuit is connected to the input end 1 of the single-pole double-throw analog switch, the input end 2 of the single-pole double-throw analog switch is connected to the excitation coil and then grounded, the output end of the single-pole double-throw analog switch is grounded via the energy storage capacitor C1, and the control end S of the single-pole double-throw analog switch is connected to the Serlkct signal.

[0012] Preferably, the in-phase proportional operational amplifier circuit includes an operational amplifier U1, the inverting input terminal of the operational amplifier U1 is grounded via a resistor R2, the in-phase input terminal of the operational amplifier U1 is connected to the square wave excitation signal VIN, a resistor R1 is bridged between the inverting input terminal and the output terminal of the operational amplifier U1, and the output terminal of the operational amplifier U1 is connected to the input terminal 1 of the single-pole double-throw analog switch.

[0013] The utility model uses a pulse excitation coil as a low-frequency pulse magnetic field generating device to magnetize the ferromagnetic pipeline. After the pipeline is magnetized, if the external magnetic field disappears (reduced to zero), the pipe wall is still magnetic, and the residual magnetization intensity of the pipe wall at this time is called residual magnetism. Since stress will change the residual magnetization intensity of ferromagnetic materials, the internal magnetic permeability of the material will change. Therefore, the utility model measures the residual magnetization intensity through the magnetic sensor integrated in the probe, and then characterizes the stress size, realizing stress detection and analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a structural diagram of a pipeline stress internal detection probe disclosed in an embodiment of the utility model;

[0015] Figure 2 This is a layout diagram of a stress internal detection probe in a pipeline disclosed in an embodiment of the utility model;

[0016] Figure 3 It is a circuit diagram of an excitation signal of an excitation coil of a stress internal detection probe disclosed in an embodiment of the utility model;

[0017] Figure 4 A sampling timing diagram of a stress internal detection probe disclosed in an embodiment of the utility model. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

[0019] like Figure 1 As shown, the stress internal detection probe disclosed in the embodiment of the utility model comprises a steel plate 1 with a stress concentration area (used to replace Figure 2 The actual pipeline 6 in the middle is used to measure the performance of the probe), an excitation coil 2, an L-shaped magnetic core 3, a magnetic sensor 4 and a circuit board 5. The magnetic field generating device of the probe disclosed in the embodiment of the utility model is set as two parallel excitation coils 2. In this embodiment, two excitation coils 2 are wound on the L-shaped magnetic core 3 in the same direction. The L-shaped magnetic core 3 can be sintered by various iron oxide mixtures, such as manganese-zinc ferrite and nickel-zinc ferrite. In this embodiment, the two excitation coils 2 are made of the same material and the same number of turns, parallel to each other and coaxial. The spacing l between the two excitation coils 2 is set to be equal to the radius R of the excitation coil 2. When the current i in the same direction is passed through the excitation coil 2, a uniform magnetic field area is formed between the two excitation coils 2 near the spacing l. The main component of the magnetic field is parallel to the axes of the two excitation coils 2, which is the common result of the sum of the components of the magnetic field generated by the two excitation coils 2 in the direction parallel to the coil axis and the difference between the components perpendicular to the axis.

[0020] Combination Figure 2 , a plurality of magnetic sensors 4 are arranged in the uniform magnetic field region. Figure 2 In the figure: 6 represents a pipeline; the arrow of 7 represents the radial direction (diameter direction) of the pipeline; 8 represents the stress internal detection probe disclosed in the embodiment of the utility model, and multiple groups of stress internal detection probes 8 are arranged along the circumference (circumferential direction) of the pipeline 6, preferably to fully cover the pipeline 6. In this embodiment, the magnetic sensor 4 can be a three-axis Hall sensor, which is not limited here. The magnetic sensors 4 are closely arranged in parallel along the radial direction of the pipeline 6, and the number is not limited, preferably to cover the width of the L-shaped magnetic core 3.

[0021] Combination Figure 3 In this embodiment, the excitation coil 2 is set to a square wave pulse excitation mode, and VIN is a square wave excitation signal. A common-phase proportional operational amplifier circuit composed of an operational amplifier U1, resistors R1 and R2 is set on the circuit board 5. The value of the output voltage VO1 can be adjusted by adjusting the values ​​of the resistors R1 and R2, thereby increasing the magnetization intensity of the steel plate, as shown in the following formula:

[0022]

[0023] U2 is set as a single-pole double-throw analog switch. The control terminal S of U2 is connected to the Select signal. The Select signal can be issued by a single-chip microcomputer or other embedded processors, and there is no restriction here. When the Select signal is high, the 4-pin A and 1-pin B2 of the single-pole double-throw analog switch U2 are connected, and the output voltage VO1 charges the energy storage fuse C1. When the single-chip microcomputer controls the Select signal to become low, the 4-pin A and 3-pin B1 of the single-pole double-throw analog switch U2 are connected, and the energy storage capacitor C1 charges the excitation coil L1 (i.e. Figure 1 The excitation coil 2 in the circuit is discharged to generate the required oscillating magnetic field. At this time, the energy storage capacitor C1 and the excitation coil L1 form a series resonant circuit. If the excitation coil L1 is made of superconductor material and the impedance in the circuit is ignored, the Serlkct signal becomes a low level period, and the law of the change of magnetic induction intensity over time can be regarded as a sine wave.

[0024] Figure 4 The signal waveform sampling timing diagram is shown in Figure 2. The Serlkct signal is a control signal with a period of 60us (the frequency of the signal can be changed with the speed of the stress detector disclosed in this embodiment, and is not limited here). The signal sampling timing is divided into two parts:

[0025] Part 1: Pulse excitation cycle, starting from the 0us to the 30us of this cycle, the Serlkct signal becomes a low level number, and the energy storage electric fuse C1 discharges to the excitation coil L1. At this time, the excitation coil L1 experiences 4 states, namely:

[0026] (1) The forward discharge of the energy storage electric fuse C1 ends, and the forward current of the inductance of the excitation coil L1 is the maximum;

[0027] (2) The energy storage electric fusion C1 is filled in reverse phase;

[0028] (3) The reverse phase discharge of the energy storage electric fuse C1 ends, and the reverse phase current of the inductance of the excitation coil L1 is the maximum;

[0029] (4) The energy storage electric fuse C1 is fully charged in the positive phase.

[0030] The second part: the magnetic signal sampling period, which starts from 30us and lasts to 60us. At this time, the Select signal is at a high level, and the output voltage VO1 charges the energy storage electric melting C1. In the first part of the sampling period, the pipeline 6 is magnetized by the excitation coil L1; in the second part, the magnetic field of the excitation coil L1 disappears. At this time, the wall of the pipeline 6 still has residual magnetism. Since stress will change the residual magnetization intensity of ferromagnetic materials, the magnetic sensor 4 is used to sample the weak magnetic signal in the second part, so that the stress can be characterized and the purpose of stress detection can be achieved.

[0031] The above-mentioned embodiments are merely examples and do not limit the scope of the present invention. These embodiments can also be implemented in various other ways, and can be omitted, replaced, and changed in various ways without departing from the scope of the present invention. In addition, it should be noted that the innovation of the present invention does not involve software, and the software part involved in the above description can be derived by those skilled in the art based on common sense after knowing the hardware structure proposed by the present invention.

Claims

1. A pipeline stress internal detection probe, characterized in that: It includes a pair of L-shaped magnetic cores, two excitation coils are respectively wound on the pair of L-shaped magnetic cores in the same direction, the excitation coils are connected to the driving circuit, when the driving circuit passes the current i in the same direction through the excitation coils, a uniform magnetic field area is formed between the two excitation coils near the spacing l, and a plurality of magnetic sensors are arranged in the uniform magnetic field area.

2. A pipeline stress internal detection probe as claimed in claim 1, characterized in that: The two excitation coils are made of the same material and have the same number of turns, and are parallel and coaxial to each other.

3. A pipeline stress internal detection probe as claimed in claim 1, characterized in that: The distance l between the two excitation coils is equal to the radius R of any one of the excitation coils.

4. A pipeline stress internal detection probe as claimed in claim 1, characterized in that: All the magnetic sensors are arranged in parallel along the radial direction of the pipeline, covering the width of the L-shaped magnetic core.

5. The pipeline stress internal detection probe according to claim 1, characterized in that: A plurality of groups of pipeline stress internal detection probes are arranged along the circumference of the pipeline, and all of the pipeline stress internal detection probes cover a circumference of the pipeline.

6. A pipeline stress internal detection probe as claimed in claim 1, characterized in that: The driving circuit includes a common-phase proportional operational amplifier circuit, the input end of the common-phase proportional operational amplifier circuit is connected to the square wave excitation signal VIN, the output end of the common-phase proportional operational amplifier circuit is connected to the input end 1 of the single-pole double-throw analog switch, the input end 2 of the single-pole double-throw analog switch is connected to the excitation coil and then grounded, the output end of the single-pole double-throw analog switch is grounded via the energy storage capacitor C1, and the control end S of the single-pole double-throw analog switch is connected to the Select signal.

7. A pipeline stress internal detection probe as claimed in claim 6, characterized in that: The in-phase proportional operational amplifier circuit includes an operational amplifier U1, the inverting input terminal of the operational amplifier U1 is grounded via a resistor R2, the in-phase input terminal of the operational amplifier U1 is connected to the square wave excitation signal VIN, a resistor R1 is bridged between the inverting input terminal and the output terminal of the operational amplifier U1, and the output terminal of the operational amplifier U1 is connected to the input terminal 1 of the single-pole double-throw analog switch.

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