KR20040001686A - Apparatus for measuring corrosion thickness of insulated pipeline - Google Patents

Abstract

The present invention relates to an apparatus for measuring the corrosion thickness of a pipeline with a thermal insulation material, which is capable of non-destructive and real-time evaluation of the damage caused by corrosion of a pipeline wrapped with a thermal insulation material. With a crawler; A radiation source emitting a gamma ray detachably mounted to an upper center portion of the crawler; A detector disposed on an opposite side of the radiation source with the pipeline interposed therebetween, the detector being fixed to the crawler so as to be movable simultaneously and detecting the intensity of the gamma ray passing through the pipeline; And a data processor electrically connected to the detector and configured to receive, collect, store, analyze, calculate, and output the intensity values of the detected gamma rays.

According to the present invention, the thickness according to the degree of corrosion of the pipeline can be easily measured non-destructively, and because of the ease of movement, the overall flaw detection over the longitudinal direction of the pipeline is very easy, and the accuracy of the measurement is excellent. It is highly reliable and enables real-time collection, processing and analysis of thickness information due to pipeline corrosion.

Description

Corrosion thickness measuring device of pipeline with insulation material {APPARATUS FOR MEASURING CORROSION THICKNESS OF INSULATED PIPELINE}

The present invention relates to an apparatus for measuring the corrosion thickness of a heat insulating material-attached pipeline, which enables non-destructive and real-time evaluation of the damage caused by corrosion of a pipeline wrapped with a heat insulating material.

In order to inspect the degree of corrosion or erosion of the pipeline, it is required to measure the thickness of the pipeline, and the thickness of the pipeline is usually measured using ultrasonic waves.

However, the thickness measurement method requires contacting the transducer with the surface of the pipeline. Therefore, the insulation must be removed first, and the removal and re-installation of such insulation takes a great cost and time, as well as the removal of the insulation and other accessory materials. Since it cannot be produced, it will mass-produce the problem of environmental pollution.

In recent years, in order to measure the thickness of the pipeline without removing the thermal insulation material in consideration of such a problem, for example, it has a high permeability compared to other radiation and its transmittance is directly correlated with the amount of material in the medium. The research on the method of measuring the thickness of the pipeline non-destructively using the gamma ray with the removal of the insulation and other accessory materials.

However, since gamma rays are harmful to humans because they are harmful to the human body, they should have the maximum detection (measurement) efficiency using the smallest amount possible. I'm getting it.

The present invention has been made in view of the above-described problems of the prior art, and has been created to solve this problem, and has a maximum detection efficiency by using a minimum amount of gamma rays, but also has excellent field applicability, thereby causing damage to the pipeline due to corrosion. It is an object of the present invention to provide an apparatus for measuring the thickness of corrosion of pipelines with insulation to enable non-destructive measurement and evaluation of carbon dioxide.

1 is a schematic configuration diagram of an apparatus of the present invention;

2 is a circuit diagram showing an amplifier of the present invention;

Figure 3 is a schematic block diagram showing a detector module of the device of the present invention,

4 is a result graph according to the experiment of the detector of the present invention,

5 is a perspective view and a cross-sectional view showing a collimator of the device of the present invention;

6 is a perspective view showing a crawler of the present invention device;

7 is a longitudinal cross-sectional view and main portion enlarged cross-sectional view of FIG.

8 and 9 is a photograph for reference showing an experimental example of the device of the present invention.

Explanation of symbols on the main parts of the drawings

10: radiation source 20: pipeline

22: thermal insulation material 30: detector

40: data processor 50: collimator

100: base frame 110: vertical post

120: guide groove 130: lower support

140: connecting rod 150: upper support

160: mounting seat 170: fixed plate

180: guide roll 190: drive motor

192: drive gear 194: driven gear

200: crawler

The above object of the present invention is a crawler which is a traveling facility installed to be movable along the pipeline; A radiation source emitting a gamma ray detachably mounted to an upper center portion of the crawler; A detector disposed on an opposite side of the radiation source with the pipeline interposed therebetween, the detector being fixed to the crawler so as to be movable simultaneously and detecting the intensity of the gamma ray passing through the pipeline; It provides an apparatus for measuring the corrosion thickness of the pipeline with insulation, characterized in that it comprises a data processor electrically connected to the detector and configured to receive, collect, store, analyze, calculate, and output the detected intensity value of the gamma ray. Is achieved by.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

First, referring briefly to the measuring principle of the present invention, when the gamma ray generated when the nucleus is released or absorbed by transitioning between energy levels passes through two different media, the transmission coefficient is thinner. It becomes big. Therefore, after measuring the permeability coefficient for each thickness of the pipeline to the table, the thickness information can be known by measuring the permeability of the pipeline coated with the insulation.

At this time, since the heat insulating material is usually composed of light atoms such as hydrogen and carbon, they have a small mass absorption coefficient and a relatively small density compared to the metal of the pipeline material, so that the transmission intensity of gamma rays can not be greatly reduced. It is possible enough.

In addition, by measuring several parts of the same pipeline multiple times and comparing them with each other, it is possible to check in real time the thickness change of the pibrain due to corrosion.

1 is a schematic diagram of a measuring device according to the present invention. The measuring device of the present invention is coated with a radiation source 10 and a heat insulating material 22 as a source to generate gamma rays according to the measuring principle described above. The detector 30 which detects the gamma rays emitted from the radiation source 10 passing through the pipeline 20 and the detector 30 are electrically connected to the detector 30 to collect, store, analyze, calculate, and output the detected information. It comprises a data processor 40).

The radiation source 10 has a half-life of 73.83 days with β decay, and preferably Ir-192 having an energy level at which a photoelectric effect can occur.

Alternatively, it can be Cs-137, which has a half-life of 32 years and an energy of 662keV and emits a single radiation.

The detector 30 is configured by properly arranging the scintillator, the photodiode, the preamplifier and the main amplifier in one circuit board for quick, easy and accurate detection.

The scintillator is preferably a BGO (Bismuth germanate: Bi ₄ Ge ₃ O ₁₂ ) single crystal, which is a scintillator made of Bi ³ -activated activator, and is composed of a material having a high atomic number such as Bi. Because it is physically hard and chemically non-degradable, there is an advantage that, like many other scintillators, the scintillator does not need to be covered.

In particular, the BGO single crystal has a high peak to compton ratio and a full energy to escape peak ratio, thereby improving spatial resolution and data collection efficiency. Its maximum wavelength is 480 nm, its main decay time is about 300 ns, and it does not have long residual light like NaI (Tl) and other scintillators, so it reacts quickly to the intensity of X-rays or gamma rays when used in current mode. It can be used widely in computerized X-ray scanners.

Such BGO single crystals can be grown by the Czochalski method in which a mixture of bismuth oxide and germanium oxide dissolved is pulled by a tensile force to form a crystal.

The photodiode is used to remove spatial constraints in gamma ray detection and to obtain high detection efficiency.

The photodiode refers to a semiconductor optical sensor that can generate a current when light is emitted into a PN junction of a semiconductor. The photodiode has excellent linearity with respect to incident light intensity, has low electrical noise, and can be sensitive to a wide wavelength range. It is mechanically hard and has the advantage of being light and long lasting.

The photodiode is formed by bonding an N-type to a semiconductor P-type, and when a reverse voltage is applied to each semiconductor, a deflection region is formed, and when light generated from the scintillator enters, electrons and holes are formed. In this case, a current is formed by the fields at both ends thereof. At this time, the current flowing is extremely small, and if the proper amplification and current voltage exchanger is used, the amount of input light can be measured.

The preamplifier and the main amplifier are means for amplifying the minute current flowing through the photodiode as described above. As shown in FIG. 2, two amplifiers provided at the front end of the main amplifier 34 are the preamplifier 32 and these preamplifiers. The first and second amplified currents through the amplifier 32 are finally amplified through the main amplifier 34.

In this case, the preamplifier 32 is preferably OP Amp111A, for example, and the current of the photodiode due to the light of the scintillator generated by the gamma ray can be read as a voltage through the circuit configuration of FIG. 2.

The main amplifier 34 is preferably, for example, CA3140 IC, is configured to change the direction of the signal and the direct current through the circuit diagram of Figure 2, and also the voltage difference of the radiation transmission length in each amplification stage of each amplifier By remotely controlling the offset voltage, it is easy to distinguish the thickness change of the pipeline.

The housing is a substantially external shape of the detector 30 in which the circuit board is embedded, and is preferably formed of MC nylon, which is a light shielding and electrical insulator from the outside for easy coupling between the scintillator and the photodiode. The detector 30 is constructed by arranging a diode, a preamplifier and a main amplifier in a proper manner.

That is, the detector 30 is composed of eight BGO scintillator coated with Al ₂ O ₃ and one photodiode array coated with total reflection attenuation resin to form a _{pair of} eight-channel modules.

For example, FIG. 3 shows a detector module 30 'having eight channels in which eight BGO scintillators 36 are combined with one photodiode array 37.

Particularly, the BGO scintillator 36 is preferably coated with Al ₂ O ₃ to prevent light from entering through the other side, but the refractive index of the BGO scintillator 36 is 2.2 and is mainly Si. Since the refractive index of the photodiode array 37 is 1.6, the glare coming in at 37 ° or more with respect to the surface of the photodiode array 37 is scattered and exits so that approximately 1.8 degrees in front of the photodiode array 37 is prevented. It is preferable to coat a resin having a refractive index of.

Figure 4 is a graph showing the measurement results after the artificial defect applied to the stainless plate through the eight-channel detector 30 as described above, a 50mCi Cs-137 radiation source was used for the test.

As a result, it was confirmed that the voltage difference of about 0.6V existed by the stainless plate of 5mm thickness, and the RMS magnitude was 0.1V according to the voltage variation in the specimen without any defect, and it was confirmed that there was a difference of about 0.1V per 1mm. It can be seen that the absolute voltage also has a magnitude of 7.2V at 5V.

Therefore, it was confirmed that the eight-channel detector 30 had sufficient function as a gamma ray detector, and the correction of the length difference of radiation passed to the specimen was performed by appropriately adjusting the offset voltage of the preamplifier 32 or the main amplifier 34. It was found possible by adjusting.

In addition, based on this, since the pipeline is much larger than the specimen in the actual field, it is determined that the width of the detector 30 should exceed at least 20 cm in terms of the ratio, and accordingly, the detector 30 has at least 8 channels. It was judged that it would be suitable for the detection work only if it was 8 pieces long.

5 (a) and (b) is a perspective view showing the collimator of the measuring device according to the present invention and its internal structure, the collimator 50 is such that the gamma rays which are radiation uniformly enters only in the direction of the detector 30. As a means of guiding, the material is made of lead and its thickness is preferably at least 70 mm in consideration of the absorption coefficient of lead.

In the center of the top surface of the collimator 50 is formed a hole for fixing the radiation source 10, the slit-shaped guide hole 54 of the width (d) 3 ~ 5mm in the center downward Perforated.

In addition, since the radiation of about 10 to 20 Ci is emitted when the gamma ray is emitted through the radiation source 10 on the upper surface of the collimator 50, the collimator 50 and A shield 52 of the same shape is integrally connected, and a guide hole communicating with the guide hole 54 is formed at the inner center of the shield 52, and the radiation source 10 can be charged to the collimator 50 side. Insertion hole 56 is formed.

The shield 52 is also preferably made of lead for safety against radiation coating.

On the other hand, using a measuring device of the present invention having the configuration as described above is provided with a crawler (CRAWLER) which is a traveling facility for easy measurement while moving along the pipeline.

6 and 7, the crawler 200, which is a traveling facility, is provided with a base frame 100 having a rectangular plate, and a detector 30 is fixed to a longitudinal center portion of an upper surface of the base frame 100. .

In addition, the vertical post 110 is vertically fixed to the upper upper surface of the base frame 100, respectively.

A pipeline 20 is disposed between the vertical posts 110, and as long as the outer periphery of the pipeline 20 does not come into contact with the detector 30 fixed on the base frame 100. Closely arranged, the base frame 100 is installed to be movable along the longitudinal direction of the pipeline 20.

The front and rear surfaces of each vertical post 10 are formed with a guide groove 120 having a predetermined width in the longitudinal direction, and the guide member 120 has a fixing member for supporting and fixing the lower support 130 under the interposition of the nut 122. 124 is fastened.

The fixing member 124 is a bolt or a hexagon wrench and is inserted therein so as to be movable along the guide groove 120 through the lower support 130 and fastened to the nut 122.

The nut 122 is inserted into the guide groove 120 and is disposed to have a clearance with both sides of the inner wall of the guide groove 120 so as to be movable along the longitudinal direction thereof, and is not rotated when the fixing member 124 is tightened. In order to prevent the shape of the guide groove 120 to correspond to the shape of the square is preferable.

The lower support 130 is fixed to the vertical post 110 by the fixing member 124, and is disposed to be capable of lifting up and down along the guide groove 120, and has a predetermined inclination angle with the vertical post 110. Are arranged upwards.

A connecting rod 132 having a long rod shape in a direction orthogonal thereto, that is, a transverse direction is fixed to the upper end of the lower support 130, and the lower support ( A pair of connecting rods 140 extending upward while having the same inclination angle as 130 are fixed.

The upper support 150 is fixed to each upper end of the connecting rod 140, the upper support 150 is paired with the same upward extension in the opposite direction to each other to form a pair with each top to maintain contact It is connected and fixed by the seating 160.

A pair of fixed bars 162 are disposed at both ends of the seating table 160 disposed parallel to each other at a predetermined distance, while being spaced apart from each other, and fixing plates 170 are respectively disposed on inner surfaces of the fixed bars 162. It is fixed to face each other.

The fixing plate 170 is a member in which the collimator 50 in which the radiation source 10 is detachably embedded is fixed, and a plurality of positions are provided on both sides of the fixing plate 170 so as to adjust the height of the collimator 50. The adjusting hole 172 is formed and the collimator 50 is preferably a structure that can be fastened and fixed to the position adjusting hole 172 by means such as screws or bolts.

For example, the lower support 130, the connecting support 140 and the upper support 150 is inclined upwardly at an angle of about 45 ° and then fixed in contact with the opposite upper support at the upper end of the upper support 150, the interior angle It is preferable to arrange so that it may make 90 degrees.

On the other hand, a pair of support pieces 184 protrude from each other in the connecting cross 132 connecting each connecting rod 140 and the lower support 130 at a distance, and the support piece 184 has a shaft 182 The rotatable arrangement is fixed, and the guide roll 180 is fixed to the shaft 182.

Therefore, by lowering the lower support 130 along the guide groove 120 of the vertical post 110, the guide roll 180 is in a state capable of rolling contact with one point of the outer periphery of the pipeline 20 Can be set.

The guide roll 180 is installed to have the same structure in the opposite side connecting rod, the driven gear 194 is integrally fixed to any one shaft 182 of the guide roll 180, the driven gear 194 Is meshed with the drive gear 192, and the drive gear 192 is integrally fixed to the rotation shaft of the drive motor 190.

The drive motor 190 is disposed in a fixed state so as not to flow to a portion of the support piece 184.

Therefore, the driving gear 192 is driven according to the driving of the driving motor 190, and the driven gear 194 engaged with the driving gear 194 is forced to rotate the guide roll 180 while the upper and lower supporters 130 and the radiation source are driven. The crawler, the assembly 10 is fastened, is movable along the longitudinal direction of the pipeline 20.

Most of the drive motor 190, including a direct current, alternating current motor can be utilized, but it is particularly preferable to use a step motor for ease of control.

The present invention made up of such a configuration has the following operational relationship.

Before the measurement, since the assembly consisting of the base frame 100 of the crawler 200 and the mounting table 160, the upper and lower support 130, 150, the connecting table 140, etc. (hereinafter referred to as the "mounting table assembly"), first, The base frame 100 to which the detector 30 is fixed is disposed while being spaced apart from the lower side of the measurement target pipeline 20.

In this case, the detector 30 is in an electrically connected state with the data processor 40 as shown in FIG. 1.

Subsequently, the guide groove 120 of the vertical post 110 receives an end of the fixing member 124 disposed through one side of the lower support 130 in a state where the seat assembly is positioned above the pipeline 20. At the same time, the nut 122 is prepared to be fastened to the fixing member 124 to have a certain gap, and the guide roll 180 contacts the outer circumferential surface of the pipeline 20 by downwardly moving the seat assembly. Move it as much as possible.

When the guide roll 180 is in contact with the outer circumferential surface of the pipeline 20 to tighten the fixing member 124 at that position to fix the lower support 130, wherein the detector 30 of the base frame 100 is a pipeline ( It should be kept properly spaced so as not to come into contact with the lower side of the outer circumference of 20).

In this state, the collimator 50 in which the radiation source 10 having Ir-192 or Cs-137 as a radiation source is detachably mounted is attached to the fixing plate 170 attached to the fixing cross 162 of the seating table 160. Fit it properly.

The collimator 50 may adjust its fixed position through the positioning hole 172 according to the gamma radiation dose of the radiation source 10 or according to the type of the radiation source 10 and the type of the pipeline 20 or the thickness of the insulation. have.

In this case, a separate shielding means may be provided at the bottom of the collimator 50 to prevent the radiation from being emitted from the radiation source 10 before the measurement starts, and a means for adjusting the radiation emission is added. In this case, it is not necessary to provide the above-described separate shielding means.

In addition, the mounting process of the collimator 50 having the above-described radiation source 10 may be mounted after installing the seating assembly as described above, and before mounting the seating assembly, Of course, the measurement can be performed at the same time.

When emission of radiation from the radiation source 10 starts, gamma rays are transmitted through the pipeline 20 in a non-permeable manner and are detected by the detector 30, and the detected information is sent to the data processor 40 to be collected, stored, and computed. , Compare, judge, display.

If it is necessary to measure the other part of the same pipeline 20, by driving the drive motor 190 to rotate the guide roll 180, the entire crawler is moved along the pipeline 20, and arrives at the measurement location In this case, the measurement at the measurement point is possible by blocking the driving of the driving motor 190.

Hereinafter, the experimental example of this invention is demonstrated.

Experimental Example

First, the radiation source used isotope Ir-192, the built-in scintillator used BGO scintillator, the photodiode array used S5668-01 Si, and the preamplifier and main amplifier capable of amplifying the microcurrent up to 18000 times. An amplifier was used. In addition, in order to have an environment that is close to the measurement in the field, a test piece was manufactured by adding several artificial defects to the pipeline used in the actual field.

The material of the test piece was STPG370 (JIS G 3454), a pipe for pressure piping, and a 5 "sch. 40 pipe with an outer diameter of 139.8 mm and a thickness of 6.6 mm.

Artificial defects in the longitudinal direction of the pipe,

(A) a flat bottom hole having a diameter of 20.0 mm, a depth difference of 0.1 mm between the defects, and a position of 0 °;

(B) a flat bottom hole having a diameter of 20.0 mm, a difference in depth between the defects 0.2 mm, and a position of 90 °;

(C) four flat holes with a depth of 3.0 mm and a diameter of 1.0 to 4.0 mm, the position 0 °;

(D) four flat holes with a depth of 3.0 mm and a diameter of 5.0 mm, in the direction of 180 °;

(E) flat bottom hole distributed in 150 °, 180 °, 210 ° direction, position 180 ° direction;

(F) step defects of 1.0, 1.5, 1.8, 2.0 mm in depth over the entire circumference;

To appear.

Here, the 20.0mm diameter flat holes allow the depth difference of 0.1 ~ 0.2mm between each defect to test the detection capability of the thickness difference of the measuring device, and to evaluate the detection capability of defects such as small fittings. In order to process the flat bottom holes with a diameter of 1.0 ~ 4.0mm arranged in the axial direction. In addition, for the performance evaluation of the defects distributed in the circumferential direction, defects of the same diameter are placed in the 150 °, 180 °, and 210 ° directions. Finally, the step defects for the entire circumference are processed to reduce the overall thickness of the pipeline. The measurement performance was measured.

As a result, as shown in the reference picture of Figure 8, in the case of artificial defects, it could be confirmed that all the defects appear clearly except the defects of diameter 1.0mm and 2.0mm.

However, it was judged that it was difficult to measure smaller than the size of one scintillator used in the detector 30, which did not appear a defect of less than 2.0mm in diameter.

In addition, in addition to the defects, the bolts used to fix the aluminum plate, the gap generated in the portion where the pieces of the heat insulating material abut, it can be confirmed that the part where the aluminum plate overlaps clearly.

Here, in order to test the maximum measurement limit of the measuring device according to the present invention, a measurement test was conducted under several conditions on a pipe on which an artificial defect was processed.

That is, a comparison was made using an Ir-192 radiation source with a strength of 5 Ci (Ci is a radioactive unit) and 17 Ci, and the inside of the pipe specimen for the purpose of testing the measurement limits for the presence of fluid, especially liquid, inside the pipe. Measured by filling with water. In addition, the formula regarding the measurement limit was computed by following formula 1.

(Equation 1)

Here, d is the depth of the defect, sigma is the deviation of the background voltage, V is the measurement voltage, and V _b is the background voltage.

Table 1 below shows the measurement limits when using a 5Ci radiation source, Table 2 shows the results for 17Ci, and Table 3 shows the results for the measurement limits when liquid is filled inside the pipe. Show it.

As shown in Tables 1, 2, and 3, when the 5Ci source was used, the measurement limit was 0.21mm (average), and when using a stronger radiation source, 17Ci, and using a lower amplification degree, the measurement limit was 0.18mm (average). appear.

Here, it can be seen that the measurement limit becomes smaller when measured with a strong radiation source, which is a result that suggests that the difference in thickness can be measured even when a strong radiation source is used.

On the other hand, when the inside of the pipe was filled with water was slightly higher value of 0.26mm, while the precision was found to be somewhat lower.

Therefore, it was confirmed that the thickness measurement according to the corrosion of the pipeline was very accurate and easy, and the reliability was very excellent.

Based on this, as a result of the measurement, as shown in the reference picture of FIG. 9, the thickness distribution according to the corrosion was displayed differently depending on the corrosion degree from 6.25 to 4.3, and it was confirmed that it was almost in agreement with the prediction in the test of the specimen. It was confirmed that the measuring device of the present invention can be easily utilized in actual field.

As described in detail above, according to the present invention provides the following effects.

First, the thickness according to the degree of corrosion of the pipeline can be easily measured nondestructively.

Secondly, the ease of movement makes the overall flaw detection easier over the length of the pipeline.

Third, the accuracy of the measurement is excellent and the reliability is high.

Fourth, it is possible to collect, process and analyze the thickness information according to the corrosion of the pipeline in real time.

Claims (10)

A crawler 200 which is a traveling facility installed to be movable along the pipeline 20; A radiation source 10 emitting a gamma ray detachably mounted at a central portion of the upper end of the crawler 200; Disposed on the opposite side of the radiation source 10 with the pipeline 20 interposed therebetween and fixed to the crawler 200 so as to be movable simultaneously and detecting the intensity of the gamma ray passing through the pipeline 20. A detector 30; The thermal insulation material attached pipeline, characterized in that it comprises a data processor 40 electrically connected to the detector 30 and provided to receive, collect, store, analyze, calculate, and output the intensity value of the detected gamma ray. Corrosion thickness measuring device. According to claim 1, The crawler 200 is spaced apart below the outer periphery of the pipeline 20 and the center of the upper surface of the detector 30 is fixed to the base frame (100); Vertical posts 110 which are placed on both ends of the upper surface of the base frame 100 and the guide groove 120 is formed along the longitudinal direction; A lower support 130 detachably inserted into the guide groove 120 of the vertical post 110 and movably disposed along the longitudinal direction thereof; An upper support 150 connected by a connecting rod 140 extending obliquely upward from the lower support 130 and converged at one point of the upper support and disposed to be in contact with each other; A seating plate 160 fixed flat to an upper end of the upper support 150; A fixing plate 170 fixed to a transverse center portion of the seating table 160 to detachably support the radiation source 10; It is characterized in that it comprises a guide roll 180 is supported on the connecting rod 132 coupled with the connecting rod 140 and disposed in contact with the outer circumferential surface of the pipeline 20 having a diameter of various sizes so as to be in contact with the cloud. Corrosion thickness measuring apparatus of pipeline with insulation. According to claim 2, wherein the guide roll 180 is provided with a drive motor 190 on the adjacent side, a drive gear 192 on the rotation axis of the drive motor 190, the guide roll 180 And a driven gear (194) engaged with the driving gear (192) on the shaft (182) of the corrosion thickness measuring apparatus of the pipeline with insulation, characterized in that the crawler 200 is installed to be movable. The apparatus of claim 2, wherein the fixing plate (170) is formed with a plurality of position adjusting holes (172) that can adjust the height of the radiation source (10) in the vertical direction. The apparatus of claim 1, wherein the radiation source (10) is Ir-192 or Cs-137. The method of claim 1, wherein the radiation source 10 is formed of a lead material so that the emitted radiation is not leaked to the outside only to the detector 30 side and detachably fixed on the fixing plate 170 of the crawler 200 And a rectangular collimator (50) having a V-shaped guide hole (54) is placed in the corrosion thickness measuring apparatus of the pipeline with insulation. According to claim 6, The collimator 50 is formed in the same shape and material as the upper surface and the shielding body 52 having a hole communicating with the V-shaped guide hole 54 of the collimator 50 therein. Corrosion thickness measuring apparatus of the pipeline with insulation. According to claim 1, The detector 30 is composed of eight BGO scintillator coated with Al ₂ O ₃ and one photodiode array coated with a total reflection attenuation resin to form a group of eight channels. Corrosion thickness measuring apparatus of pipeline with insulation. The method of claim 8, wherein the module is variable, continuously installed in accordance with the diameter change of the pipeline 20 has a structure that can change the length of the detector 30, the corrosion thickness measurement of the pipeline with insulation insulation Device. The corrosion detector of claim 8, wherein the detector 30 is provided with a preamplifier 32 and a main amplifier 34 for converting the collected current into a voltage and amplifying a signal. Thickness measuring device.