JP3487750B2 - Method and apparatus for measuring thickness of deposits on inner wall of pipe - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the thickness of deposits on the inner wall of a pipe for measuring the thickness of deposits such as caulks deposited on the inner wall of various pipes such as heating furnace pipes, and a measuring apparatus therefor. .

[0002]

[Background Art] Like the caulking (carbon, scale, etc.) that adheres to heating furnace pipes in the oil refining process, internal wall deposits that adhere to various pipe inner walls cause fluctuations in the flow velocity and flow rate of the fluid, and heat transfer. Since it also interferes with (heating), it must be removed regularly. In order to efficiently perform this removing work, it is necessary to detect and measure the state of the deposit on the inner wall, particularly the thickness, from the outside.

Conventionally, the thickness of the deposit in the tube is
It was measured by radiography. That is, a radiation isotope is used as a radiation source, the radiation from this radiation source is applied to a measurement tube to be measured, and the radiation transmitted through the measurement tube is projected as an image on a film, and the film adhered to the inner wall is imaged on the film image. The portion was visually judged and its thickness was measured.

In this method, since film shooting is performed,
There is a problem that it takes time to process the film such as developing and drying, and it takes a long time for photographing including the processing time, specifically, about 120 minutes per one place. In addition, since the radiation source intensity of radiation requires a large dose to enable filming, it is complicated to handle and control exposure to radiation, and the procedure is required because notification to the government agency regarding radiation is required. It was troublesome. In particular, since a radiation controlled area that is off limits must be set around the radiation source, there is a problem that work efficiency decreases because it is not possible to work in that controlled area during measurement. .

Further, in the film image, the tube portion, the inner wall adhered portion and the other portions are represented by the black and white density difference, but since the difference in light and shade (contrast) is not so large, the boundary portion It was difficult to make a visual determination, and it could not be detected unless the thickness of the deposit on the inner wall was 3 mm or more. At this time, in the case of a general pipe, the inner peripheral position of the pipe can be registered, so that even if the contrast is small, the pipe portion and the portion of the inner wall deposit can be distinguished, but especially the thick-walled pipe. In the case of a large-diameter tube and a large-diameter tube, it is difficult to determine the difference in concentration, and since the inner peripheral position of the tube cannot be estimated, the distinguishability of the deposits on the inner wall deteriorates, and in some cases it cannot be distinguished at all.

In order to solve such a problem, the applicant of the present invention has proposed a method for measuring the thickness of the deposit on the inner wall from the amount of radiation passing through the measuring tube (Japanese Patent Application No. 9-64372).
issue). That is, a radiation source that emits radiation and a sensor that detects the radiation dose from this radiation source are arranged opposite to each other with a measuring tube in between, and these are moved in the radial direction to scan the measuring tube, and the transmitted radiation detected by the sensor This is a method in which attenuation curve data based on the amount is obtained, and the thickness of the deposit on the inner wall of the measurement pipe is obtained from the inflection point of the attenuation curve data and the minimum value of the attenuation curve data of the contrast pipe measured in advance. According to this, since the thickness of the deposit on the inner wall is measured based on the attenuation curve data calculated from the amount of transmitted radiation, the thickness can be measured easily and accurately in a shorter time than the measurement by film photographing.

[0007]

However, since the tube is scanned and measured in this method, it is necessary to move the source and the sensor in the radial direction while maintaining the mutual position of the source and the sensor. Therefore, there is a problem that the measurement operation becomes complicated and the measurement takes time. In particular, when the radiation source and the sensor are incorporated in the device, a moving means for moving them is required, which causes a problem that the device becomes complicated.

Further, although the radiation source intensity can be made lower than in the case of film photographing, the position at which the thickness at which the radiation is transmitted (transmission thickness) is the maximum is the inner wall position of the tube. A penetrable source intensity was required.
For this reason, the radiation source intensity could not be made sufficiently low, and exposure control and setting of radiation control areas could not be omitted.
In addition, it was not possible to avoid a decrease in work efficiency due to the setting of the radiation control area described above.

It is an object of the present invention to provide a method for measuring the thickness of the deposit on the inner wall of a pipe, which can quickly and easily measure the thickness of the deposit on the inner wall. Another object of the present invention is to provide a device for measuring the thickness of the deposit on the inner wall of a pipe, which can measure the thickness of the deposit on the inner wall quickly and easily with a simple structure.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a method for measuring the thickness of deposits on the inner wall of a pipe for externally measuring the thickness of deposits on the inner wall of the pipe. A reference tube for measurement is prepared, and on a line that intersects with the measurement tube and passes through the center thereof, a radiation source that emits radiation and a sensor for detecting the radiation dose from this radiation source are measured. The tubes are arranged opposite to each other with the tube sandwiched therebetween, the amount of transmitted radiation that has passed through the measuring tube is detected using the sensor, the amount of transmitted radiation is Emx, and the reference transmission dose of the comparative tube measured in advance is E.
s, mass absorption coefficient μ, inner wall deposit density ρc, tube material density ρFe, and wall thickness difference between the comparison tube and the measurement tube obtained by pre-measurement is Δt, and It is characterized in that the thickness Cx of the deposit on the inner wall is obtained from Cx = [In (Es / Emx) / (μ · ρc)] − Δt · (ρFe / ρc). Here, before measuring
The reference transmission dose of the contrast tube is defined in advance in the longitudinal direction of the contrast tube.
It is the average value of the transmitted radiation dose measured at several points.
It

In the present invention as described above, the amount of transmitted radiation that has passed through the reference tube, which serves as a reference without deposits on the inner wall, is determined. That is, the radiation source and the sensor are arranged on a line passing through the center of the contrast tube, and the transmitted radiation dose of the contrast tube is obtained. In addition, the transmitted radiation dose of the measuring tube is measured under the same conditions as the contrast tube. This gives the amount of transmitted radiation that passes through the centers of the contrast tube and the measuring tube.

If deposits adhere to the inner wall of the measuring tube,
The thickness through which the radiation penetrates (permeation thickness) increases by the thickness of the deposit on the inner wall, so the permeation thickness of the measuring tube relative to the permeation thickness of the contrasting tube, that is, each of the contrasting tube and the measuring tube. By determining the difference in the amount of transmitted radiation, the thickness of the deposit on the inner wall can be determined.

In the present invention, the source and the sensor are arranged on a line passing through the center of each of the measuring tube and the contrast tube,
Since the transmitted radiation dose is measured while these are kept stationary, it is not necessary to scan the tube as in the conventional method, and the movement operation of the source and sensor can be omitted, and the measurement can be performed more than the conventional method by scanning. Since the time can be shortened, the measurement can be performed quickly and easily. Further, since the amount of radiation passing through the center of the tube is measured, the thickness of the tube through which the radiation penetrates (the penetration thickness of the tube) can be made smaller than in the case where the inner wall position of the tube is penetrated. Therefore, it is possible to measure with a lower radiation source intensity than the conventional method that requires measurement of the amount of transmitted radiation that passes through the inner wall position, and it is possible to omit exposure control and setting of radiation control areas, which facilitates measurement. it can. In particular, since it is possible to omit the setting of the radiation control area, it is possible to perform other work in the vicinity of the radiation source even during the measurement, so that it is possible to reliably prevent a decrease in work efficiency.

In this case, it is desirable to use, as the comparison tube, a material having substantially the same material and dimensions as the measurement tube.
Here, that the material and the dimension are substantially the same means that the measurement tube and the comparison tube include an error caused by manufacturing conditions, processing accuracy, and the like. By using such a contrast tube, there will be no difference in the amount of transmitted radiation between the measuring tube and the contrast tube due to the difference in material and size, so there is no need to make corrections based on the difference in material, etc. The thickness of the deposit can be easily obtained.

In the above, the radiation source and the sensor are attached to the measuring jig which is detachable from the measuring pipe, and the measuring jig is attached to the measuring pipe to fix the radiation source and the sensor to the measuring pipe. You may make it oppose on the line which passes along the center.

With this arrangement, the radiation source and the sensor can be positioned on the line passing through the center of the pipe and can be held in that state only by mounting the measurement jig on the pipe, so that the measurement operation can be facilitated.

Further, when the thickness of each of the measuring pipe and the contrast pipe is measured and the thickness of the deposit on the inner wall is obtained from the transmitted radiation dose,
It is preferable to make a correction based on the difference in wall thickness between the measuring tube and the contrast tube.

That is, the transmitted radiation dose increases or decreases according to the wall thickness of the tube, that is, the transmitted thickness of the tube. Will include errors due to differences in wall thickness.
Therefore, when the thickness of the deposit on the inner wall is determined, the error due to the difference in the wall thickness can be removed by performing the correction based on the difference in the wall thickness of the pipe, so that the highly accurate measurement can be realized.

On the other hand, the present invention is an apparatus for measuring the thickness of deposits on the inner wall of a pipe for externally measuring the thickness of deposits on the inner wall of the pipe. a sensor for detecting the radiation dose, and these sources and sensors are mounted and detachable measuring jig to said tube, and a personal computer, in a state in which the measurement jig is attached to the tube, the The radiation source and the sensor are arranged so as to be opposed to each other with the tube interposed therebetween on a line that intersects the tube and passes through the center thereof, and the personal computer is
With the radiation source and sensor facing each other with the measuring tube in between.
The obtained radiation dose is Emx, the source and the sensor are paired.
Reference permeation dose obtained with the ratio tube facing each other
, Es, mass absorption coefficient μ, density of inner wall deposit ρc,
The density of the material of the tube is ρFe, said pair obtained by measuring in advance
The difference in wall thickness between the ratio tube and the measuring tube is Δt,
The wall deposits thickness Cx, Cx = [In (Es / Emx) / (μ · ρc)] - Δt ·
It is characterized by being obtained from (ρFe / ρc) .

In the present invention, the measuring jig is attached to the tube, the amount of transmitted radiation emitted from the radiation source and transmitted through the tube is detected by the sensor, and the thickness of the adhered material on the inner wall is determined from the amount of transmitted radiation as described above. Ask for.

In the present invention, since the radiation source and the sensor are attached to the measuring jig, it is possible to position the radiation source and the sensor on a line passing through the center of the pipe by simply mounting the measuring jig on the pipe and in that state. The measurement work can be performed quickly and easily. Further, since the transmitted radiation dose is measured while fixing the radiation source and the sensor on a line passing through the center of the tube, it is possible to omit the moving means for moving the radiation source and the sensor, thereby simplifying the device.
Measurement can be performed easily in a shorter time than the conventional method using scanning.

Since the radiation source and the sensor are arranged so as to face each other on the line passing through the center of the tube, the amount of radiation passing through the center of the tube can be measured. (Thickness) can be made smaller than in the case of transmitting through the inner wall position of the tube. Therefore, it is possible to measure with a lower radiation source intensity than the conventional method that requires measurement of the amount of radiation passing through the inner wall position, and it is possible to omit exposure control and setting of radiation control areas, which facilitates measurement. it can. In particular,
Since the setting of the radiation control area can be omitted, it is possible to perform other work around the radiation source even during the measurement, so that it is possible to avoid a decrease in work efficiency.

Further, it is preferable that the measuring jig has a pair of holding pieces for holding the tube, and one end of these holding pieces is rotatably connected.

As described above, when the pipe is sandwiched by the pair of sandwiching pieces, regardless of the direction of the pipe, that is, the pipe extends in any of the vertical direction, the horizontal direction and the like. Since it can be securely mounted, versatility can be enhanced. Further, by rotatably connecting one end of the sandwiching piece, the pair of sandwiching pieces can be integrated, so that good handleability can be obtained, the number of parts can be reduced, and the sandwiching piece can be easily mounted on the pipe.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a measuring device 1 of this embodiment. The measuring device 1 is a device for externally measuring the thickness of the deposit 3 on the inner wall of the pipe 2A using γ-rays, which is, for example, caulk attached to the inner wall of a heating furnace pipe used for petroleum refining. Is a measuring device for measuring the thickness of the.

The measuring apparatus 1 of the present embodiment has a measuring tube 2A as a measuring object and a comparing tube 2B as a reference for measurement (see FIG. 4).
And FIG. 5), the thickness of the adhered substance on the inner wall of the measuring tube 2A is determined by measuring the respective transmitted γ doses. Specifically, the measuring apparatus 1 includes a radiation source 10 that emits γ rays.
A sensor 20 for detecting the .gamma. Dose from the radiation source 10 as an electric pulse, and a measuring jig 30 for mounting the radiation source 10 and the sensor 20 on the tubes 2A and 2B.
And a measuring device 40 for obtaining the γ-dose from the electrical pulse detected by the sensor 20, and a personal computer 50 for processing the γ-dose data obtained by the measuring device 40 and obtaining the thickness of the inner wall deposit 3. Is configured.

The radiation source 10 is, for example, a γ-ray source constructed by using cesium 137 having a radioactivity of 3.7 MBq, and is attached to the above-mentioned measuring jig 30. As shown in FIG. 2, the measuring jig 30 has a pair of clamping pieces 31 and 32 for clamping the tubes 2A and 2B, and the tubes 2A and 2B.
Is formed in a ring shape along the outer peripheral surface of the tube and is configured to be attached to and detached from the tubes 2A and 2B by opening and closing in the radial direction. Specifically, the sandwiching pieces 31 and 32 are formed in a semicircular arc shape that divides the ring into two and have substantially the same shape. One end of each of the sandwiching pieces 31 and 32 has a hinge 3
3 (only part of which is shown) is rotatably connected and can be opened and closed in the radial direction by rotating the holding pieces 31 and 32 around the hinge 33 as a shaft.

The other end of each of the sandwiching pieces 31, 32 is provided with a stopper member 3.
A buckle 34 composed of 41 and a locking member 342 can be connected and fixed to each other. That is, the stopper member 341 having the hook portion 341A is fixed to the other end of the one sandwiching piece 31, and the other end of the other sandwiching piece 32 is provided with the hanging portion 342A that can be engaged with the hook portion 341A. Locking member 342 is fixed, and these stop members 34
1 and the locking member 342 are mounted side by side on the outer peripheral surfaces of the sandwiching pieces 31, 32. The locking member 342 includes a tightening portion 342B that slides and holds the hanging portion 342A in a direction away from the hook portion 341A.

Such a buckle 34 has a hook 342.
A is hooked on the hook portion 341A and locked, and the tightening portion 34
By sliding the hook portion 342A with 2B, the hook portion 341A and the hook portion 342A are tightened and firmly engaged with each other, whereby the other ends of the sandwiching pieces 31 and 32 are connected and fixed to each other. Also, the sandwiching piece 31,
When separating the other ends of 32, the fastening portion 342B is loosened and the hook portion 342A is removed from the hook portion 341A.

The one holding piece 31 to which the stopper member 341 is attached has, at one end and the other end thereof, a radiation source holding portion 35 for holding the radiation source 10 and a sensor holding portion for holding the sensor 20. 36 are provided. The radiation source holding portion 35 and the sensor holding portion 36 are attached so as to project toward the other sandwiching piece 32 side, so that the pipes 2A and 2B are attached with the measuring jig 30 attached to the pipes 2A and 2B.
The tubes 2A and 2B are arranged so as to face each other on a line passing through the center of the tube.

The radiation source holding portion 35 is attached to one axial end surface (arc-shaped end surface) of the one holding piece 31, and the radiation source 10 is provided.
Is configured to be inserted and held. From the radiation source 10 held by the radiation source holding portion 35, γ rays are emitted through the centers of the tubes 2A, 2B in a direction orthogonal to the tubes 2A, 2B. The sensor holding portion 36 is attached to the other end surface (arc-shaped end surface) of the sandwiching piece 31 in the axial direction, that is, at a position deviated from the γ ray passing through the tubes 2A and 2B. The sensor holding portion 36 is formed in a cylindrical shape and holds the sensor 20 in the inserted state. A plurality of types of measuring jigs 30 having different inner diameters may be prepared and appropriately selected and used according to the outer diameters of the tubes 2A and 2B.

The sensor 20, as shown in FIG. 3, has a cylindrical scintillator 21, a photomultiplier tube 22 and an amplifier 2.
The combination of 3 and the like is stored in a cylindrical stainless case 24, and can be configured using an existing scintillation counter. As the scintillator 21, for example, an outer dimension having a diameter of 50 mm and a length of 30 mm can be adopted. By mounting the sensor 20 on the sensor holding portion 36 of the measurement jig 30 described above, the scintillator 21 is connected to the radiation source 10 of the radiation source holding portion 35 on a line orthogonal to the tubes 2A and 2B and passing through the center thereof. Tube 2
They are arranged to face each other with A and 2B in between.

Scintillator 21 and photomultiplier tube 22
In order to shield the radiation, a portion opposite to the side facing the radiation source 10 and a portion opposite to the side are covered with a half-cylindrical body 25 made of lead and having a shape obtained by dividing the cylinder in half. In addition, the photomultiplier tube 22
A magnetic shield 26 is provided around the. In such a sensor 20, when γ-rays are emitted from the radiation source 10, the transmitted γ-rays that have passed through the tubes 2A and 2B are scintillator 21.
To generate photons and strike out photoelectrons from the photocathode (not shown) of the photomultiplier tube 22. The photoelectrons are multiplied by the photomultiplier tube 22, and the multiplied electron flow is amplified by the amplifier 23 connected to the photomultiplier tube 22 through the socket 27 and measured as an electric pulse by the measuring device 40.
To be sent to.

Returning to FIG. 1, the measuring instrument 40 includes the sensor 20.
Device (scaler) for counting the output pulses of
And has a discriminator, a pulse shaping circuit, a counting circuit, and the like. In such a measuring device 40, the output pulse from the sensor 20 is adjusted by a discriminator and a pulse shaping circuit and then counted by a counting circuit, whereby the number of γ rays, that is, γ dose, is counted,
The signal of the count value is sent to the personal computer 50 which is a processing device.

The personal computer 50 is constructed so as to obtain the thickness of the deposit on the inner wall of the measuring tube 2A by carrying out a calculation based on the output signal from the measuring instrument 40. That is, the measurement tube 2A to be measured and the comparison tube 2B serving as a reference for measurement are irradiated with γ-rays from the radiation source 10 to measure the transmitted γ-ray dose, thereby the personal computer 5
The signals of the transmitted γ doses of the measurement tube 2A and the comparison tube 2B are input to 0. In this personal computer 50, data that has been input in advance from an input means (not shown) such as a keyboard, specifically, a mass absorption coefficient μ, a density ρc of the inner wall deposit 3, and tubes 2A and 2B are configured. The material density ρFe and the wall thickness difference Δt between the measurement tube 2A and the comparison tube 2B are stored. The personal computer 50 of the present embodiment is configured to calculate the thickness of the deposit on the inner wall of the measuring tube 2A using these data and the count values of the measuring tube 2A and the comparison tube 2B input from the measuring instrument 40. ing.

In the present embodiment thus constructed, the thickness of the deposit on the inner wall of the measuring tube 2A, specifically the caulking thickness, is measured by the following procedure. First, a measurement tube 2A to be measured and a comparison tube 2B to be a reference for measurement are prepared. The comparison tube 2B has substantially the same material and dimensions as those of the measurement tube 2A, and has no deposit such as caulk attached to its inner peripheral surface. The measurement tube 2A and the comparison tube 2B may be made of the same material and of the same standard. Further, the radiation source 10 and the sensor 20 are held by the radiation source holding portion 35 and the sensor holding portion 36 of the measurement jig 30.

Next, the transmission γ dose is measured by using the measuring device 1 with respect to the measuring tube 2A and the comparison tube 2B. That is, to explain the comparison tube 2B, the buckle 34 of the measurement jig 30 is removed, the sandwiching pieces 31, 32 are opened in the radial direction, and the comparison tube 2B is covered. After this, the clamping pieces 31,
32 are rotated in a direction in which they approach each other to be in a closed state, and the hooking portion 342A is locked to the hook portion 341A.
Tighten with 2B. When the measuring jig 30 is attached to the measuring tube 2A in this way, as shown in FIG.
A line connecting the sensor 20 (scintillator 21) and the sensor 20 (scintillator 21) passes through the center of the comparison tube 2B and is orthogonal to the comparison tube 2B.

Then, γ rays are emitted from the radiation source 10,
A transmission γ dose passing through the center of the contrast tube 2B is measured for a predetermined time. At this time, the γ rays transmitted through the comparison tube 2B are detected by the sensor 2
At 0, it is detected as an electric pulse, and is counted by the measuring device 40 to obtain the transmitted γ dose (count value). The signal of this count value is sent to the personal computer 50 and stored. Contrast tube 2B
Since no adhered matter adheres to the inner peripheral surface of the, the thickness at which γ rays penetrate (transmission thickness) corresponds to the wall thicknesses T3 and T4 at the γ ray transmitting points P3 and P4 of the comparison tube 2B. It becomes thick. The above-described measurement of the comparison tube 2B is performed at a plurality of locations, for example, two locations, by changing the mounting position of the measurement jig 30 along the longitudinal direction of the comparison tube 2B.

In the same manner as the measurement of the comparison tube 2B, the transmission γ dose is also measured for the measurement tube 2A. The measurement of the measuring tube 2A is performed at a plurality of points in the longitudinal direction of the measuring tube 2A, for example, at four points. At this time, as shown in FIG. 5, the caulking 3 is attached to the inner peripheral surface of the measuring tube 2A, so that the transmission thickness thereof is the wall thickness T1 at the γ-ray transmitting points P1 and P2 of the measuring tube 2A. , T2, the thickness of the caulking 3 is increased by t1, t2. As shown in FIG. 6, the amount of attenuation of transmitted γ-rays is proportional to the thicknesses t1 and t2 of caulking (internal wall deposits). Therefore, the transmitted γ-ray dose of the measuring tube 2A is greater than the transmitted γ-ray dose of the comparison tube 2B. Less.

The same measuring device 1 is used to measure the transmitted γ-dose in this order for the measuring tube 2A and the comparison tube 2B. At this time, the measurement of the comparison tube 2B is performed before and after the measurement of the measurement tube 2A. For example, when the contrast tube 2B is measured at two points, first, the contrast tube 2B is measured at one point, then each point of the measurement tube 2A is measured, and then the contrast tube 2B remains. Measure at one location.

Further, the wall thicknesses T1 and T2 of the measuring tube 2A and the wall thicknesses T3 and T4 of the comparing tube 2B are strictly measured by using an existing ultrasonic wall thickness measuring device or the like, for example, with an accuracy of ± 0.1 mm. taking measurement. This wall thickness is measured by γ in each tube 2A, 2B.
This is performed for the line transmission points P1, P2, P3 and P4. Then, the wall thicknesses T1, T2, T3 of the obtained tubes 2A, 2B,
From T4, the wall thickness difference Δt between the measuring tube 2A and the comparison tube 2B is determined by the following equation (1). In this embodiment,
Although the measurement tube 2A and the comparison tube 2B have the same dimensions, if there is an error due to manufacturing conditions, processing accuracy, etc., the thickness difference Δt is calculated here.

[0042]

[Equation 1]

On the other hand, in the personal computer 50, the mass absorption coefficient μ, the density ρc of the deposits on the inner wall, and the density ρ of the material forming the tubes 2A and 2B are input by an input means (not shown) such as a keyboard.
Fe and the thickness difference Δt between the measurement tube 2A and the comparison tube 2B are input and stored. The difference in wall thickness Δt is
From A, 2B thickness T1, T2, T3, T4 to PC 5
It may be calculated at 0. Then, after the measurement of the measurement tube 2A and the comparison tube 2B is completed, the stored count value data (transmission γ dose) of each measurement point of the comparison tube 2B is averaged to calculate the reference transmission γ dose Es. Next, this reference transmission γ dose Es and the stored measuring tube 2A
Using the count value data (permeation γ dose) at each measurement point and the data such as the mass absorption coefficient μ previously input with a keyboard or the like, the thickness of the deposit on the inner wall of the measuring tube 2A is calculated as follows. It is calculated by the equation (2).

[0044]

[Equation 2]

This equation (2) can be derived by the following method. That is, the absorption of γ-rays and X-rays by a substance follows Lambert's law, which represents the relationship between the incident light intensity and the transmitted light intensity in an absorptive medium, as in the case of light. From this law, in the case of the contrast tube 2B, the contrast tube 2B
The relationship between the incident γ-dose I ₀ that is incident on and the transmitted γ-dose Ir that passes through the contrast tube 2B is represented by the following equation (3).

[0046]

[Equation 3]

Similarly, in the case of the measuring tube 2A, the incident γ
The relationship between the dose I ₀ and the transmitted γ-dose Emx that passes through the measuring tube 2A is expressed by the following formula (4), where the thickness of the inner wall deposits at the γ-ray transmission points P1 and P2 is t1 and t2. .

[0048]

[Equation 4]

Here, when the equation (4) is divided by the equation (3), the following equation (5) is obtained.

[0050]

[Equation 5]

Taking the logarithm of both sides of the equation (5), the equation (5) is transformed into the following equation (6).

[0052]

[Equation 6]

Therefore, from this equation (6), the sum of the thicknesses t1 and t2 of the inner wall deposits at the γ ray transmitting points P1 and P2 is expressed by the following equation (7).

[0054]

[Equation 7]

Substituting the equation (1) into the equation (7), the sum (t1 + t2) of the thicknesses t1 and t2 of the deposits on the inner wall is defined as Cx, and the transmission γ-dose I ₀ of the contrast tube 2B is averaged. The formula (2) is obtained by setting a certain reference transmission γ dose Es.

The thickness Cx of the deposit on the inner wall obtained from the equation (2) is sent to and displayed on a display means (not shown) connected to the personal computer 50, for example, a display such as a CRT or a printer.

According to this embodiment, the following effects can be obtained. That is, the radiation source 10 and the sensor 20 are arranged on a line passing through the centers of the tubes 2A and 2B, and the transmission γ dose passing through the centers of the tubes 2A and 2B is measured in a stationary state. Does not have to be scanned, and the moving operation of the radiation source 10 and the sensor 20 can be omitted, so that measurement can be easily performed. Further, the measuring time can be shortened as compared with the conventional method of scanning the tube. Specifically, since the measuring time at one place is about 3 to 5 minutes, the thickness of the deposit on the inner wall can be measured quickly and easily. .

Further, since the transmission γ dose passing through the centers of the tubes 2A and 2B is measured, the thickness of the tubes 2A and 2B through which the γ rays penetrate (transmission thickness of the tubes 2A and 2B) is It can be made smaller than when the inner wall position is transmitted. Therefore, as compared with the conventional method that requires measurement of the amount of transmitted radiation passing through the inner wall position, the source 10 having a source intensity of about 14/10000 can be used. 10
Since the radiation source intensity of 0000 is sufficient, it is possible to omit the exposure control and the setting of the radiation control area, and it is possible to further easily measure the thickness of the deposit on the inner wall. In particular, since the setting of the radiation control area can be omitted, other work can be performed around the radiation source 10 even during the measurement, so that the deterioration of the work efficiency can be reliably prevented.

Further, since the thickness of the inner wall deposit 3 is calculated from the respective transmitted γ doses of the measuring tube 2A and the comparison tube 2B, if the thickness of the inner wall deposit is about 1 mm or more, it can be reliably detected. Superior detection accuracy can be obtained as compared with the conventional method by photographing.

Since the material and dimensions of the comparison tube 2B are substantially the same as those of the measurement tube 2A, there is no need to make a correction due to the difference in material and dimensions, and therefore the thickness of the deposit on the inner wall can be easily obtained. You can Moreover, for example, even if the material of the measuring tube 2A is unknown, the measuring tube 2A
Since it is possible to perform the measurement by using the contrast tube 2B made of the same material as the above, various tubes can be easily and surely measured.

Further, the radiation source 10 and the sensor 20 are attached to the measurement jig 30, and the measurement jig 30 is attached to the tubes 2A and 2B, so that the radiation source 10 and the sensor 20 are attached to the tube 2.
Since they are arranged so as to face each other on the line passing through the centers of A and 2B, simply by mounting the measuring jig 30 on the pipes 2A and 2B,
Since the radiation source 10 and the sensor 20 can be positioned and held in that state, the measurement work can be facilitated.

Further, the respective wall thicknesses T1, T2, T3, T4 of the measuring pipe 2A and the comparing pipe 2B are measured, and in the formula (2), the thickness Cx of the adhered substance on the inner wall is calculated by the measuring pipe 2A and the comparing pipe 2B.
Since it is calculated as a value corrected based on the thickness difference Δt of B, the measurement tube 2A having the same size as each other is assumed.
Even if there is an error in each wall thickness of the comparison tube 2B, the error in the transmission γ dose caused by this error can be reliably removed in the formula (2), so that highly accurate measurement can be realized.

Furthermore, since the measurement is carried out at a plurality of points in the longitudinal direction of the measuring tube 2A, it is possible to accurately grasp the state of adhesion of the inner wall deposit 3 on the measuring tube 2A. In particular, in the case of a heating furnace tube, since the adhered state of caulking can be accurately measured, the caulking removal work can be performed efficiently.

Further, since the measuring device 1 measures the transmitted radiation dose while fixing the radiation source 10 and the sensor 20 on the line passing through the centers of the tubes 2A and 2B, the radiation source 10 and the sensor 20 are moved. Since the moving means can be omitted, the device configuration can be simplified and the measurement can be performed easily in a shorter time than the conventional method using scanning.

Further, the measuring jig 30 includes a pair of clamping pieces 3.
Since the pipes 2A and 2B are sandwiched between the pipes 1 and 32, regardless of the direction of the pipes 2A and 2B, that is, the pipe 2
Even if A and 2B extend in any direction such as the vertical direction and the horizontal direction, they can be surely mounted, so that excellent versatility can be secured.

Further, since one ends of the sandwiching pieces 31 and 32 are rotatably connected to each other, the pair of sandwiching pieces 31 and 32 can be integrated so that good handling can be obtained and the number of parts can be reduced. Moreover, it can be easily attached to the tubes 2A and 2B. The other ends of the sandwiching pieces 31, 32 are configured so that they can be connected and fixed by the buckle 34, so that they can be easily attached to and detached from the tubes 2A, 2B.

The present invention is not limited to the above-described embodiment, but includes other configurations and the like that can achieve the object of the present invention, and the following modifications and the like are also included in the present invention.

That is, although the sandwiching pieces 31 and 32 of the measuring jig 30 of the above-described embodiment are rotatably connected to each other at one end through the hinge 33, they may be separated from each other and may be separated at the time of mounting. Both ends may be connected to each other.
Further, although the other ends of the sandwiching pieces 31 and 32 are connectable by the buckle 34, they are not limited to the buckle 34,
For example, a fastener such as a screw may be used for connection. Further, in the above-described embodiment, the radiation source 10 and the sensor 20 are mounted on the tubes 2A and 2B via the measurement jig 30, but the measurement jig 30 may be omitted. In this case, the radiation source and the sensor are not used. Each may be individually attached to the tube.

In the above embodiment, the measurement of the measuring tube 2A is
Although the measurement was performed at a plurality of locations in the longitudinal direction, the measurement of the plurality of locations in the radial direction also enables more accurate measurement of the adhered state of the inner wall deposit 3 on the measurement pipe 2A.

In the above embodiment, the signal of the transmitted γ dose from the measuring instrument 40 is processed by the personal computer 50 to obtain the thickness of the deposit on the inner wall. However, the personal computer may be omitted. For example, by connecting a CRT, a printer, or the like to the measuring device 40, the transmitted γ dose of each tube 2A, 2B is displayed, and the value of the transmitted γ dose is used to calculate the thickness of the inner wall deposit by the formula (2). May be.

[0071] In the above embodiment, the radiation source 10 and γ-ray source, were subjected to measurement by γ-ray, the type of radiation is not limited to γ-rays, for example, but it may also be an X-ray.

The radiation source 10 of the above-mentioned embodiment is a cesium 137.
However, the present invention is not limited to this, and other radioactive isotopes such as cobalt-60 may be used.

[0073]

EXAMPLES Next, the usefulness of the present invention will be described based on specific examples. [Example] This example is an experiment for measuring the coking thickness of the heating furnace tube based on the above-described embodiment, and the following specific conditions were adopted.・ Outer diameter of heating furnace tube (measurement tube and comparison tube): 6B ・ Heating furnace tube (measurement tube and comparison tube) wall thickness: 11.1 mm ・ Measurement tube measurement points: 4 points ・ Comparison tube measurement point: 2 places

-Type of radiation source: Cesium-137-Intensity of radioactivity: 3.7 MBq (100 μCi) -Irradiation time: 1 minute 40 seconds-Irradiation dose: 4 × 10 ^-9 C / kg (14 μR) The measurement results are shown in Table 1 together with the actually measured values of the caulking thickness.

Comparative Example This comparative example is an experiment for measuring the coking thickness of a heating furnace tube by a conventional radiographic method, and the same heating furnace tube as in Example 1 was measured. That is, the radiation from the radiation source is applied to the heating furnace tube (measurement tube), and the radiation that has passed through this measurement tube is projected as an image on the film, and each part of the measurement tube and the inner wall deposit is visually observed on the film image. Then, the thickness of the deposit on the inner wall was measured. The specific conditions are as follows.・ Type of radiation source: Iridium 192 ・ Intensity of radioactivity: 259 GBq (7 Ci) ・ Irradiation time: 10 minutes ・ Irradiation dose: 2.06 × 10 ^-4 C / kg (0.8R) It shows in Table 1.

[0076]

[Table 1]

From Table 1, it can be seen that in the example, the measurement result of the caulking thickness almost agrees with the actual measurement value, and the high-precision measurement result can be obtained even when the source intensity is very small.
The usefulness of the present invention was confirmed. On the other hand, in the comparative example, it can be seen that the difference between the measurement result of the caulking thickness and the actual measurement value is large, and the measurement accuracy is inferior to that of the present invention.

[0078]

As described above, according to the present invention,
For each of the measuring tube and the contrast tube, the radiation source and sensor are placed on the line passing through the center, and the transmitted radiation dose is measured while keeping them stationary, so there is no need to scan the tube as in the past. Therefore, the movement operation of the radiation source and the sensor can be omitted, and the measurement time can be shortened as compared with the conventional method by scanning, so that the measurement can be performed quickly and easily. Further, since the amount of radiation passing through the center of the tube is measured, the thickness of the tube through which the radiation penetrates (the penetration thickness of the tube) can be made smaller than in the case where the inner wall position of the tube is penetrated. Therefore, it is possible to measure with a lower radiation source intensity than the conventional method that requires measurement of the amount of transmitted radiation that passes through the inner wall position, and it is possible to omit exposure control and setting of radiation control areas, which facilitates measurement. it can. In particular, since it is possible to omit the setting of the radiation control area, it is possible to perform other work in the vicinity of the radiation source even during the measurement, so that it is possible to reliably prevent a decrease in work efficiency.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a measuring jig of the embodiment.

FIG. 3 is a partially cutaway view showing the sensor of the embodiment.

FIG. 4 is a schematic diagram showing a measurement state of the contrast tube of the embodiment.

FIG. 5 is a schematic diagram showing a measuring state of the measuring tube of the embodiment.

FIG. 6 is a graph showing the relationship between the caulking thickness and the amount of attenuation of transmitted γ rays in the above embodiment.

[Explanation of symbols]

1 Measuring device 3 Inner wall deposits 2A measuring tube 2B contrast tube 10 radiation sources 20 sensors 30 measuring jig 31,32 sandwiching piece

Continuation of front page (56) Reference JP-A-61-274210 (JP, A) JP-A-6-235627 (JP, A) JP-A-5-18729 (JP, A) JP-A-4-95706 (JP , A) Japanese Unexamined Patent Publication No. 4-151505 (JP, A) Actual Development Sho 63-99209 (JP, U) Actual Public Sho 36-27860 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G01B 15/00-15/08 G01N 23/00-23/227

Claims (5)

(57) [Claims] 1. A method for measuring the thickness of deposits on the inner wall of a pipe for externally measuring the thickness of deposits on the inner wall of the pipe, comprising: a measuring pipe to be measured; and a comparison pipe serving as a reference for measurement. Prepare, on a line that intersects with the measurement tube and passes through the center thereof, a radiation source that emits radiation and a sensor for detecting the radiation dose from this radiation source are arranged facing each other across the measurement tube, The amount of transmitted radiation that has passed through this measuring tube is detected using the sensor, and the amount of transmitted radiation is Emx, which is the previously measured value of the comparison tube.
Reference transmission dose is Es, mass absorption coefficient is μ,
The density is ρc and the density of the material of the tube is ρFe.
Assuming that the difference in wall thickness between the contrast pipe and the measuring pipe is Δt,
The thickness Cx of the deposit on the inner wall of the measuring tube is Cx = [In (Es / Emx) / (μ · ρc)] − Δt ·
A method for measuring the thickness of deposits on the inner wall of a pipe, which is obtained from (ρFe / ρc) . 2. The method for measuring the thickness of deposits on the inner wall of a pipe according to claim 1, wherein the reference pipe is made of a material and dimensions substantially the same as those of the measuring pipe. Method of measuring deposit thickness. 3. The method for measuring the thickness of deposits on the inner wall of a pipe according to claim 1, wherein the radiation source and the sensor are attached to a measuring jig that is detachable from the pipe, A method for measuring the thickness of deposits on an inner wall of a pipe, wherein the radiation source and the sensor are arranged to face each other on a line passing through the center of the pipe by mounting a measuring jig on the pipe. 4. An apparatus for measuring the thickness of deposits on the inner wall of a pipe for externally measuring the thickness of deposits on the inner wall of the pipe, comprising: a radiation source that emits radiation; and a radiation dose from the radiation source. a sensor for, with these sources and sensors are mounted and detachable measuring jig to said tube, and a personal computer, in a state in which the measurement jig is attached to the tube, the radiation source and sensor but the tube and intersect and when being configured to be disposed facing each other across the tube on the line passing through the center
In both cases, the personal computer sandwiches the measuring tube between the radiation source and the sensor.
The radiation dose obtained in the state of being opposed to is Emx,
With the radiation source and sensor facing each other with the contrast tube in between
Obtained reference transmission dose is Es, mass absorption coefficient is μ, inner wall
Measure the density of the deposits ρc and the density of the material of the pipe ρFe in advance.
The thickness difference between the contrast tube and the measuring tube obtained by
Then, the thickness Cx of the deposit on the inner wall of the measuring tube is Cx = [In (Es / Emx) / (μ · ρc)] − Δt ·
An apparatus for measuring the thickness of deposits on the inner wall of a pipe, which is obtained from (ρFe / ρc) . 5. The apparatus for measuring the thickness of deposits on the inner wall of a pipe according to claim 4 , wherein the measuring jig has a pair of holding pieces for holding the tube, and these holding pieces have one end An apparatus for measuring the thickness of deposits on an inner wall of a pipe, which is rotatably connected.