A method for detecting a heat dissipation metal tube by using far-field eddy current and a detection device thereof

Abstract

The application discloses a heat dissipation metal pipe far-field eddy current detection method and a detection device thereof, and is used for nondestructive detection of heat conduction metal pipe, such as a metal pipe (1) with heat dissipation fins (11a) or heat dissipation threads (11b) arranged on the pipe wall (11). The heat dissipation metal pipe far-field eddy current detection method comprises a signal-coupled eddy current detection instrument (3) and an inner-wearing far-field eddy current detection probe (2). The inner-wearing far-field eddy current detection probe (2) is characterized in that an excitation coil (21) and a detection coil (22) are slidably arranged on a detection device support (23), the excitation coil (21) and the detection coil (22) are respectively provided with a first permanent magnet ring (24) and a second permanent magnet ring (25), and the relative distance between the excitation coil (21) and the detection coil (22) can be slidably adjusted when the inner-wearing far-field eddy current detection probe is worn in the metal pipe (1) to perform eddy current detection. The application further improves the far-field eddy current detection capability and meets the engineering detection application requirement.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of non-destructive testing, in particular to an eddy current testing evaluation method for metal pipes with heat dissipation fins or heat dissipation threads, and more particularly to a heat dissipation metal pipe far-field eddy current testing method and a testing device thereof. BACKGROUND

[0002] Heat dissipation pipes are used in various industries and widely applied in industries, cultivation, light industry, chemical industry, breeding, daily household appliances, etc. For example, heat dissipation pipes are used in air heaters, air conditioners, etc. Generally, heat dissipation pipes are made of good thermal conductor metals such as steel and copper. In order to increase the contact area with air, heat dissipation fins are usually arranged on the wall of the metal pipe (1), as shown in FIG. 1, or heat dissipation pipes with internal / external threads are arranged on the wall of the metal pipe (1), as shown in FIG. 2. The design of the pipe wall fins and threads can increase the heat conduction capacity. For example, the heat dissipation pipe of an air conditioner is designed with internal / external threads, which can reduce the thickness of the pipe wall by 2.5-3.5 mm, greatly saving the copper material. Therefore, it has become a common practice to arrange fins and threads on the wall of the heat dissipation pipe. Figure 1 Figure 2 However, the application environment of heat dissipation pipes is usually harsh, and the pipes are prone to corrosion or cracks under high pressure. Therefore, regular monitoring and testing are essential, especially for some high-pressure dangerous pipes. In addition, the in-service environment of heat dissipation pipes is usually harsh, and it is preferred to use an eddy current testing method suitable for harsh environments.

[0003] Moreover, the arrangement of heat dissipation fins or heat dissipation threads on the heat dissipation pipe makes the wall of the metal pipe not smooth, which affects the eddy current testing results. As is known, due to the skin effect of electromagnetic eddy current signals, the lift-off value has a great influence on eddy current testing. The unevenness formed by the heat dissipation fins further affects the detection signal and reduces the detection sensitivity.

[0004] In view of the above problems, the present application further improves the technical scheme as follows. SUMMARY

[0005] The purpose of the present application is to provide a heat dissipation metal pipe far-field eddy current testing method and a testing device thereof. The technical scheme disclosed is as follows:

[0006] A heat dissipation metal pipe far-field eddy current testing method is a non-destructive testing method for heat conduction metal pipes with heat dissipation fins or heat dissipation threads arranged on the wall of the metal pipe. An inner-penetrating far-field eddy current testing probe connected to an eddy current testing instrument is used for detection through the indirect coupling signal of the electromagnetic signal of the eddy current sensor coil of the inner-penetrating far-field eddy current testing probe passing through the wall of the metal pipe. The specific detection, evaluation and analysis steps are as follows:

[0007] A heat dissipation metal pipe far-field eddy current testing method is a non-destructive testing method for heat conduction metal pipes with heat dissipation fins or heat dissipation threads arranged on the wall of the metal pipe. An inner-penetrating far-field eddy current testing probe connected to an eddy current testing instrument is used for detection through the indirect coupling signal of the electromagnetic signal of the eddy current sensor coil of the inner-penetrating far-field eddy current testing probe passing through the wall of the metal pipe. The specific detection, evaluation and analysis steps are as follows:

[0008] ​a. Calibration process: detect the standard heat dissipation metal pipe by the inner-wearing far-field eddy current detection probe, and extract the eddy current detection signal calibration value of the detected metal pipe;

[0009] b. Actual detection: put the inner-wearing far-field eddy current detection probe into the metal pipe for scanning detection, and the eddy current detection instrument extracts the detection signal;

[0010] c. Image reconstruction: the eddy current detection instrument performs far-field eddy current data calculation and analysis reconstruction on the extracted detection signal to form a simulation graph;

[0011] d. Defect extraction: the eddy current detection instrument extracts the reconstructed defect value through the signal simulation graph formed in the c step, wherein the defect value extraction in the defect reconstruction also includes the detection signal value of the inherent heat dissipation fins or heat dissipation threads on the pipe wall of the detected metal pipe. In the detection signal defect reconstruction, the uneven detection signal formed by the heat dissipation fins or heat dissipation threads needs to filter the influence of the heat dissipation fin or heat dissipation thread detection signal.

[0012] Further, the excitation coil and the detection coil of the eddy current sensor coil of the inner-wearing far-field eddy current detection probe are respectively provided with a permanent magnet ring. The permanent magnet ring is arranged on the inner-wearing far-field eddy current detection probe, which further improves the far-field eddy current detection capability and meets the engineering detection application requirements. The permanent magnet ring is symmetrically arranged on the inner side or the outer side of the excitation coil and the detection coil, thereby enhancing the indirect coupling magnetic field strength of the excitation coil and the detection coil of the eddy current detection sensor.

[0013] Further, the calibration process in the a step further includes signal calibration between the spacing between the excitation coil and the detection coil in the eddy current sensor coil and the spacing of the inherent heat dissipation fins or heat dissipation threads on the pipe wall. Through the spacing signal value of the heat dissipation fin / heat dissipation thread of the calibrated standard part, the spacing between the excitation coil and the detection coil in the eddy current detection coil is adjusted, so that the coil spacing is equal to the spacing of the heat dissipation fin / heat dissipation thread.

[0014] Further, in the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration, through the process of gradually increasing the adjustment spacing by moving the coil in sequence, the real-time fixed-point detection signal peak value of different coil spacings is extracted, the spacing at which the maximum value appears for the first time or its multiple spacings are compared and extracted as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. Generally, the adjustment spacing is gradually increased in sequence from the minimum value, that is, the spacing between the excitation coil and the detection coil is adjusted from zero, that is, the two coils are gradually separated from the overlapping state, that is, the first appearance of the detection signal peak value is the spacing point at which the two coils first align with the heat dissipation fin / heat dissipation thread protrusion point, which is used as the spacing calibration value.

[0015] Further, the coil spacing is equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration. In the process of gradually reducing the adjustment spacing by moving the coil, a large number of real-time fixed-point detection signal peaks of different coil spacings are extracted, and the spacing at which the last detection signal peak appears or its multiple spacing is extracted as the maximum value, as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. In the calibration process of gradually reducing the adjustment spacing from the large spacing between the excitation coil and the detection coil, multiple detection signal peaks may appear, and the last detection signal peak that appears when the spacing is smallest is used as the spacing calibration value.

[0016] Further, the coil spacing is equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration. In the process of gradually reducing the adjustment spacing by moving the coil, a large number of real-time fixed-point detection signal peaks of different coil spacings are extracted, and the spacing at which the last detection signal peak appears or its multiple spacing is extracted as the maximum value, as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. In the calibration process of gradually reducing the adjustment spacing from the large spacing between the excitation coil and the detection coil, multiple detection signal peaks may appear, and the last detection signal peak that appears when the spacing is smallest is used as the spacing calibration value.

[0017] Further, the coil spacing is equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration. In the process of gradually reducing the adjustment spacing by moving the coil, a large number of real-time fixed-point detection signal peaks of different coil spacings are extracted, and the spacing at which the last detection signal peak appears or its multiple spacing is extracted as the maximum value, as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. In the calibration process of gradually reducing the adjustment spacing from the large spacing between the excitation coil and the detection coil, multiple detection signal peaks may appear, and the last detection signal peak that appears when the spacing is smallest is used as the spacing calibration value.

[0018] Further, the coil spacing is equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration. In the process of gradually reducing the adjustment spacing by moving the coil, a large number of real-time fixed-point detection signal peaks of different coil spacings are extracted, and the spacing at which the last detection signal peak appears or its multiple spacing is extracted as the maximum value, as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. In the calibration process of gradually reducing the adjustment spacing from the large spacing between the excitation coil and the detection coil, multiple detection signal peaks may appear, and the last detection signal peak that appears when the spacing is smallest is used as the spacing calibration value.

[0019] The application also discloses a heat dissipation metal pipe far field eddy current detection device for nondestructive testing of heat conduction metal pipes with heat dissipation fins (11a) or heat dissipation threads (11b) on the pipe wall (11) of the metal pipe (1), which comprises a signal-coupled eddy current detection instrument (3) and an inner-wearing far field eddy current detection probe (2), and is characterized in that the excitation coil (21) and the detection coil (22) of the inner-wearing far field eddy current detection probe (2) are slidably arranged on the detection device support (23), the excitation coil (21) and the detection coil (22) are respectively provided with a first permanent magnet ring (24) and a second permanent magnet ring (25), and the relative distance between the excitation coil (21) and the detection coil (22) can be slidably adjusted when the inner-wearing far field eddy current detection probe is worn in the metal pipe (1) for eddy current detection. The distance between the two coils can be adjusted by rotating the first permanent magnet ring (24) and the second permanent magnet ring (25).

[0020] Further, the distance between the excitation coil (21) and the detection coil (22) is equal to the distance between the heat dissipation fins (11a) or the heat dissipation threads (11b) or a multiple of the distance between the heat dissipation fins (11a) or the heat dissipation threads (11b). During the detection process, the detection signal directly opposite to the heat dissipation fins (11a) or the heat dissipation threads (11b) can be extracted as the analysis detection data.

[0021] According to the above technical solution, the electromagnetic signal of the eddy current sensor coil of the inner-wearing far field eddy current detection probe is indirectly coupled through the metal pipe wall, and the detection signal is constructed by using a pulse alternating current signal for excitation and detection, so that the influence of the uneven detection signal caused by the heat dissipation fins or the heat dissipation threads of the metal heat dissipation pipe is removed, and accurate detection data is obtained. In addition, the distance between the excitation coil and the detection coil is adjusted to equal the distance between the heat dissipation fins or the heat dissipation threads by calibrating the distance between the excitation coil and the detection coil, so that the large detection signal is enhanced, and the difficulty of defect data construction is simplified. Furthermore, the excitation coil and the detection coil are respectively provided with permanent magnet rings with different polarities, which further improves the far field eddy current detection capability and meets the engineering detection application requirements. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The detection device of the best embodiment of the application is used in the state of the schematic diagram;

[0023] Figure 2 The detection device of the best embodiment of the application is used in the state of the schematic diagram;

[0024] Figure 3 The principle of the detection method of the best embodiment of the application is shown in the schematic diagram;

[0025] Figure 4 The structure diagram of the detection device of the best embodiment of the present application;

[0026] Figure 5 The detection diagram of the detection device of the best embodiment of the present application;

[0027] Figure 6 The detection signal diagram of the best embodiment of the present application;

[0028] Figure 7 The detection diagram of the detection device of the best embodiment of the present application;

[0029] Figure 8 The detection amplification diagram of the detection device of the best embodiment of the present application;

[0030] Figure 9 The detection amplification diagram of the detection device of the best embodiment of the present application;

[0031] Figure 10 The structure diagram of the detection device of the best embodiment of the present application;

[0032] Figure 11 The structure diagram of the detection device of the best embodiment of the present application;

[0033] Figure 12 The detection signal diagram of the best embodiment of the present application;

[0034] Figure 13 The coil spacing adjustment diagram of the detection device of the best embodiment of the present application;

[0035] Figure 14 The coil spacing adjustment diagram of the detection device of the best embodiment of the present application. DETAILED DESCRIPTION

[0036] The present application will be further described below in combination with the drawings and specific embodiments.

[0037] As shown in the drawings, Figures 1 to 14 A heat dissipation metal pipe far field eddy current detection method for nondestructive testing of heat conduction metal pipes with heat dissipation fins 11a or heat dissipation threads 11b on the pipe wall 11 of the metal pipe 1, which adopts an inner-penetrating far field eddy current detection probe 2 connected to an eddy current detection instrument 3, detects through the indirect coupling signal of the electromagnetic signal of the excitation coil and the detection coil of the eddy current sensor of the inner-penetrating far field eddy current detection probe 2 passing through the metal pipe wall 11, and the specific detection evaluation and analysis steps are as follows:

[0038] a. Calibration process: detect standard heat dissipation metal pipes through the inner-penetrating far field eddy current detection probe, and extract the eddy current detection signal calibration value of the detected metal pipe;

[0039] b. Actual detection: The inner-wearing far-field eddy current detection probe is put into the metal pipeline for scanning detection, and the eddy current detection instrument extracts the detection signal;

[0040] c. Image reconstruction: The eddy current detection instrument performs far-field eddy current data calculation and analysis reconstruction on the extracted detection signal to form a simulation graph;

[0041] d. Defect extraction: The eddy current detection instrument extracts the reconstructed defect value from the signal simulation graph formed in the c step, wherein the defect value extraction in the defect reconstruction also includes the detection signal value of the inherent heat dissipation fins or heat dissipation threads on the pipe wall of the detected metal pipeline. In the detection signal defect reconstruction, the uneven detection signal formed by the heat dissipation fins or heat dissipation threads needs to filter the influence of the heat dissipation fin or heat dissipation thread detection signal. As shown in Figure 6 , three defect values H1, H2, and H3 shown in the reconstructed defect value.

[0042] As shown in Figure 4 and Figure 10 , 11 , the detection sensor excitation coil 21 and the detection coil 22 of the inner-wearing far-field eddy current detection probe 2 are respectively provided with permanent magnet rings. As shown in Figure 10 , 11 , the permanent magnet rings are additionally provided on the inner-wearing far-field eddy current detection probe to further improve the far-field eddy current detection capability and meet the engineering detection application requirements. The permanent magnet rings are respectively a first permanent magnet ring 24 and a second permanent magnet ring 25 symmetrically arranged on the inner side or the outer side of the excitation coil 21 and the detection coil 22, which enhances the indirect coupling magnetic field strength of the excitation coil and the detection coil of the eddy current detection sensor. As shown in Figure 10 , the symmetric first permanent magnet ring 24 and the second permanent magnet ring 25 are symmetrically arranged on the inner side of the excitation coil 21 and the detection coil 22, and are oppositely arranged in different genders; as shown in Figure 11 , the symmetric first permanent magnet ring 24 and the second permanent magnet ring 25 are symmetrically arranged on the outer side of the excitation coil 21 and the detection coil 22, and are oppositely arranged in different genders.

[0043] As shown in Figure 5 and Figures 7 to 9 , the calibration process in the a step also includes signal calibration of the distance between the excitation coil and the detection coil in the eddy current detection coil and the distance between the inherent heat dissipation fins or heat dissipation threads on the pipe wall. By adjusting the distance or multiple values between the excitation coil and the detection coil in the eddy current detection coil to equal the distance between the heat dissipation fins or heat dissipation threads through the distance signal value of the heat dissipation fins / heat dissipation threads of the calibrated standard piece, the coil distance is equal to the distance between the heat dissipation fins / heat dissipation threads.

[0044] As shown in Figures 12 to 14As shown in the figure, the coil spacing is equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration. In the process of gradually increasing the adjustment spacing by moving the coil, the real-time fixed-point detection signal peak U of different coil spacings is extracted, the maximum value U1 is compared, the spacing point where the first detection signal peak U1 appears is extracted as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. As shown in the figure, Figure 14 As shown in the figure, the coil spacing is equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration. In the process of gradually increasing the adjustment spacing by moving the coil, the real-time fixed-point detection signal peak U of different coil spacings is extracted, the maximum value U1 is compared, the spacing point where the first detection signal peak U1 appears is extracted as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. As shown in the figure,

[0045] As shown in the figure, Figures 12 to 14 As shown in the figure, the coil spacing is equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration. In the process of gradually increasing the adjustment spacing by moving the coil, the real-time fixed-point detection signal peak U of different coil spacings is extracted, the maximum value U1 is compared, the spacing point where the first detection signal peak U1 appears is extracted as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. As shown in the figure, Figure 13 As shown in the figure, the coil spacing is equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration. In the process of gradually increasing the adjustment spacing by moving the coil, the real-time fixed-point detection signal peak U of different coil spacings is extracted, the maximum value U1 is compared, the spacing point where the first detection signal peak U1 appears is extracted as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. As shown in the figure,

[0046] As shown in the figure, Figure 9 As shown in the figure, the coil spacing is equal to the heat dissipation fin / heat dissipation thread spacing adjustment signal calibration. In the process of gradually increasing the adjustment spacing by moving the coil, the real-time fixed-point detection signal peak U of different coil spacings is extracted, the maximum value U1 is compared, the spacing point where the first detection signal peak U1 appears is extracted as the coil spacing equal to the heat dissipation fin / heat dissipation thread spacing calibration value. As shown in the figure,

[0047] The vortex sensor excitation coil applies a pulsed alternating signal. The pulsed alternating electric signal has regular time intervals, and the regularity is suitable for the detection of the protruding heat dissipation fins / heat dissipation threads on the metal pipe wall through the adjustment of the detection instrument. The inner-penetrating far-field vortex detection probe includes multiple groups of vortex sensor excitation coils and detection coils. The multiple groups of vortex sensor excitation coils and detection coils with the same interval constitute the inner-penetrating vortex detection probe, and the multiple groups of vortex sensors are connected to the multi-channel detection instrument, so that the detection area can be increased, the long-distance scanning time can be reduced, and the work efficiency can be improved.

[0048] As shown in Figure 4 The present application also discloses a heat dissipation metal pipe far-field vortex detection device for non-destructive testing of heat conduction metal pipes such as the pipe wall 11 of the metal pipe 1 provided with heat dissipation fins 11a or heat dissipation threads 11b, which comprises a vortex detection instrument 3 and an inner-penetrating far-field vortex detection probe 2 connected in signal. The excitation coil 21 and the detection coil 22 of the inner-penetrating far-field vortex detection probe 2 are slidably arranged on a detection device support 23, and the excitation coil 21 and the detection coil 22 are respectively provided with a first permanent magnet ring 24 and a second permanent magnet ring 25. When the inner-penetrating far-field vortex detection probe penetrates into the metal pipe 1 for vortex detection, the relative distance between the excitation coil 21 and the detection coil 22 can be adjusted.

[0049] As shown in Figure 5 and Figure 6 The distance between the excitation coil (21) and the detection coil (22) is equal to the distance between the heat dissipation fins (11a) or the heat dissipation threads (11b), or is equal to a multiple of the distance between the heat dissipation fins (11a) or the heat dissipation threads (11b). During the detection, the detection signal directly opposite to the heat dissipation fins (11a) or the heat dissipation threads (11b) can be extracted as the analysis detection data.

[0050] The above is one of the embodiments of the present application. In addition, it should be noted that any equivalent or simple changes made according to the structure, features and principles of the present patent concept are included in the protection scope of the present patent.

Claims

1. A method of eddy current testing of heat dissipating metallic pipes in the far field, for non-destructive testing of heat conducting metallic pipes provided with heat dissipating fins or heat dissipating threads for the wall of the metallic pipe, characterized in that The inner penetrating far field eddy current detection probe is connected with the eddy current detection instrument, and the detection is performed through the indirect coupling signal of the electromagnetic signal of the eddy current sensor coil of the inner penetrating far field eddy current detection probe passing through the metal pipe wall, the eddy current sensor coil of the inner penetrating far field eddy current detection probe includes an excitation coil and a detection coil, and the excitation coil and the detection coil are respectively provided with permanent magnet rings; The specific detection, evaluation and analysis steps are as follows: a. Calibration process: the inner penetrating far field eddy current detection probe detects the standard piece of the heat dissipation metal pipe, and extracts the eddy current detection signal calibration value of the detected metal pipe; the calibration process further includes signal calibration of the distance between the excitation coil and the detection coil of the eddy current sensor coil of the inner penetrating far field eddy current detection probe and the distance of the inherent heat dissipation fins or heat dissipation threads on the pipe wall, the distance between the excitation coil and the detection coil of the eddy current sensor coil is adjusted through the distance signal value of the calibrated standard piece of the heat dissipation fins / heat dissipation threads, so that the coil distance is equal to the distance of the heat dissipation fins / heat dissipation threads; b. Actual detection: the inner penetrating far field eddy current detection probe is placed in the metal pipe for scanning detection, and the eddy current detection instrument extracts the detection signal; c. Image reconstruction: the eddy current detection instrument performs far field eddy current data calculation and analysis reconstruction on the extracted detection signal to form a simulation graph; d. Defect extraction: the eddy current detection instrument extracts the reconstructed defect value through the signal simulation graph formed in the c step, wherein the defect value extraction in the defect reconstruction further includes the detection signal value of the inherent heat dissipation fins or heat dissipation threads on the pipe wall of the detected metal pipe.

2. The method of claim 1, wherein In the coil distance equal to the heat dissipation fin / heat dissipation thread distance adjustment signal calibration, in the process of gradually increasing the adjustment distance by moving the coil in sequence, the real-time fixed-point detection signal peak value of different coil distances is extracted, the distance at which the first detection signal peak value appears or its multiple distance is extracted by comparing the maximum value, and the distance is taken as the distance calibration value of the coil distance equal to the distance of the heat dissipation fins / heat dissipation threads.

3. The method of claim 1, wherein In the coil distance equal to the heat dissipation fin / heat dissipation thread distance adjustment signal calibration, in the process of gradually decreasing the adjustment distance by moving the coil in sequence, the real-time fixed-point detection signal peak value of different coil distances is extracted, the distance at which the last detection signal peak value appears or its multiple distance is extracted by comparing the maximum value, and the distance is taken as the distance calibration value of the coil distance equal to the distance of the heat dissipation fins / heat dissipation threads.

4. A method of remote field eddy current testing of a heat dissipation metal tube according to claim 2 or 3, characterized in that Further including adjusting the distance between the excitation coil and the detection coil of the eddy current sensor coil of the inner penetrating far field eddy current detection probe to be the same as the distance of the heat dissipation fins / heat dissipation threads through the distance calibration value, and extracting the signal value when the detection coil is directly opposite the heat dissipation fins / heat dissipation threads as the detection result value during the actual eddy current scanning detection.

5. The method of claim 4, wherein The excitation coil in the eddy current sensor coil applies a pulse alternating signal.

6. The method of claim 4, wherein The inner penetrating far field eddy current detection probe includes multiple groups of excitation coils and detection coils.

7. A heat dissipation metal pipe far field eddy current testing device for nondestructive testing of heat conduction metal pipe with heat dissipation fins (11a) or heat dissipation threads (lib) arranged on the pipe wall (11) of the metal pipe (1), which utilizes the heat dissipation metal pipe far field eddy current testing method according to any one of claims 1-6, comprising a signal-coupled eddy current testing instrument (3) and an inner-wearing far field eddy current testing probe (2), characterized in that The excitation coil (21) and the detection coil (22) of the inner-wearing far-field eddy current detection probe (2) are slidably arranged on the detection device support (23), the excitation coil (21) and the detection coil (22) are respectively provided with a first permanent magnet ring (24) and a second permanent magnet ring (25), when the inner-wearing far-field eddy current detection probe is worn in the metal pipe (1) to perform eddy current detection, the relative distance between the excitation coil (21) and the detection coil (22) can be slidably adjusted.

8. A heat dissipation metal tube far-field eddy current inspection apparatus according to claim 7, characterized in that The adjusted distance of the excitation coil (21) and the detection coil (22) is equal to the distance of the heat dissipation fins (11a) or the heat dissipation threads (11b), or is equal to the multiple of the distance of the heat dissipation fins (11a) or the heat dissipation threads (11b).

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