JPH03148006A - Thickness measuring method of duplex pipe of different materials - Google Patents

Abstract

PURPOSE:To conduct measurement at the installing spot by irradiating the surface of a duplex pipe which is made of different materials with radioactive rays and the thickness of which is to be measured to detect a measuring part, and then irradiating the wall of the measuring part of the pipe with radioactive rays to detect the thickness. CONSTITUTION:Radioactive rays 8 are projected to the face of an inner tube 5 of a duplex pipe 6 from a focus 7 obtained by the near focusing method. A film 9 photographed by X rays passing through the surface of the tube has dark and bright parts in density, reflecting the thickness of the inner tube 5. Since the thickness of the inner tube 5 where the X rays pass is different from the thickness (distance L) from the center of the pipe 6, the density distribution is operated with a suitable correction through mathematic treatments, whereby a part where the tube is worn down is detected. Then, after the worn part is shifted sideways in parallel to the film 9 from the center of the pipe 6, radioactive rays 8 are irradiated to the wall of the tube from the focus 7 according to the far focusing method. Accordingly, an image of the worn part is received on the film 9. The density change of the image during the photography is measured to detect the degree of the wear, thereby presum ing the time while the function of the pipe 6 can be maintained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The disclosed technology is a double-layer structure in which an outer tube is made of different materials such as a steel tube and an inner tube is made of a ceramic tube, and an inner tube is made of different materials. It belongs to the technical field of measuring wall thickness change phenomena due to wear and tear over time due to operation of at least one of the outer tube and the inner tube.

<Summary of the gist> As mentioned above, the invention of this application provides a double-walled pipe in which the outer pipe is made of carbon steel, the inner pipe is made of ceramics, etc., and the outer pipe and the inner pipe are made of different materials. A reproduction made of different materials in which the change in wall thickness due to wear and tear over time due to operation of at least one of the outer tube and the inner tube is measured by irradiation with radiation such as X-rays to determine the continuous operation time, etc. This invention relates to a method for measuring the wall thickness of a double pipe, and in particular, first, radiation such as X-rays is irradiated onto the surface of the target double pipe using a near-focus method, etc., and the back side is brought into line contact, etc. The wall thickness measurement area is detected by measuring the density distribution of the density of the photographed film, and then X-rays, gamma rays, etc. The wall thickness of the tube wall is measured by irradiating the tube wall, and by measuring the density distribution of the image, by visual inspection, or by electrical analysis measurement of the image, or even at the initial stage of manufacturing, etc., which serves as a standard. This invention relates to a method for measuring the wall thickness of a duplex tube made of different materials, which determines the continuous operating time, etc. by comparing it with the standard concentration distribution of a duplex tube in a perfectly circular state.

<Prior Art> As is well known, piping plays an extremely important role, as it has come to be used not only for fluid transportation, but also for information transmission, strength members for building structures, etc.
Among these, in the original use such as for fluid transportation, for example, oil country tubular goods and atomic couplant piping, etc., which have multiple functions at the same time such as heat resistance, pressure resistance, corrosion resistance, and wear resistance. In many cases, it is not possible to create piping for these applications that can meet all the requirements using one type of material. Therefore, for example, the outer tube is made of carbon steel and the inner tube is made of stainless steel, which are tied together. Double pipes made of different materials are increasingly being used.

Therefore, in general, the conventional double pipe made of different materials has an outer pipe,
Many of the inner tubes were made of metal for various reasons, but
Recently, in addition to the above-mentioned heat resistance, pressure resistance, and corrosion resistance, functions such as wear resistance have become required, and for example, double-walled pipes in which the inner pipe is made of ceramic have been devised and put into practical use. Due to various problems such as the material of the double pipes, the manufacturing process, the high cost of transportation to the installation site, and the complicated manufacturing management, once the pipes are installed, they have to be replaced for many years. Therefore, it has become necessary to monitor the state of wear and tear of the outer tube and inner tube over time during operation, and to control the point at which their function can no longer withstand the conditions of use.

<Problems to be Solved by the Invention> However, the above-mentioned conventional system for monitoring the wear and tear of metal or other double pipes over time has been improved by the development of technologies such as ultrasonic flaw detection. Techniques have been developed in which a probe is set on the outside of the outer tube and the degree of wear and tear is measured using ultrasonic waves to measure the aging life of the operating function. Due to the nature of the measuring means, it is impossible to use this method in double-walled tubes made of different materials, such as the inner tube made of ceramics, etc., and there is at least a problem in that the effectiveness is limited.

In measurement using ultrasonic waves, the ultrasonic waves cannot pass through the inner tube made of ceramics or the like when the ultrasonic waves are applied from the outside of the outer tube. , due to changes in refraction and reflection of the intermediate layer such as mortar, cement, or adhesive, or changes in transmittance, the input ultrasonic waves may not be able to pass through to the inner tube, making measurement physically impossible, or If an attempt is made to measure or measure from the inside of the inner tube, there is a drawback that practical use is impossible if the inner tube has a small diameter or is curved.

For example, as shown in Fig. 3, the front and rear flanges 1 and 2 (
The outer pipe 3 having a and b) at both ends is an outer pipe made of carbon steel, and the pipe 6 is provided with an inner pipe 5 made of ceramic as an inner pipe via an intermediate layer 4 such as cement. On the other hand, the results of measuring the wall thickness using the ultrasonic flaw detection method are shown in Table 1 below, and as can be seen, the measurement was only for the outer tube 3 as the outer tube. Therefore, it was not possible to measure the wall thickness of not only the intermediate layer 4 but also the ceramic tube 5 as the inner tube.

Table 1: Therefore, due to eutectoid materials and material revolutions in the future, it will not be possible to measure the wall thickness using ultrasonic waves for duplex pipes such as double pipes where the outer and inner pipes are made of different materials. There was a problem.

To deal with this, flaw detection is performed by measuring the wall thickness of the outer and inner tubes made of different materials by irradiating them with radiation such as X-rays, which can reliably pass through the tubes, although there may be differences in their transmittance. For example, Japanese Patent Application Laid-open No. 57-96208
The invention disclosed in No. 2003 and the invention disclosed in Japanese Patent Application Laid-open No. 62-277542 have been developed, but in the former, the intensity of transmitted X-rays is converted into an electrical signal by an image processing system via an image intensifier, etc., and processed. Since this method measures the inner diameter of the piping, the system has extremely complex mechanisms and circuits, requires skill to operate, and has the drawbacks that the processing operations are extremely complicated.

In addition, in the latter case, a monitor tube with a known wall thickness is used as a test tube to circumscribe the target piping, and the circumscribed part is X-ray transmitted to compare the photographic density of the film. Not only the tube, but also the wall thickness of the test tube must be measured with extremely high precision, and there are defects that make it unsuitable for on-site testing, etc. Also, it requires skill, and the preparation and post-processing are complicated. There was the inconvenience of having to go through a procedure.

<Object of the Invention> The object of the invention of this application is to provide at least one of the outer pipe and the inner pipe of a double pipe such as a double pipe in which the outer pipe and the inner pipe are made of different materials based on the above-mentioned prior art. If the wall thickness is subject to wear and tear due to operation over time, a technical issue to be solved is to measure the wall thickness to predict and estimate the possibility of functional maintenance over time. By using radiation such as X-rays to measure the wall thickness and measuring the density of the pattern on the film, it is possible to measure the degree of wear over time and the life of the piping function. make it possible,
However, we would like to provide an excellent method for measuring the wall thickness of double pipes made of different materials, which can sufficiently maintain the material function as pipes and be useful in the field of piping technology used in various industries. It is something to do.

In order to solve the above-mentioned problems, the structure of the invention of this application, which is based on the above-mentioned claims, is to solve the above-mentioned problems. Measure the change in wall thickness at the desired timing of opening a double-walled pipe made of a different material, such as a double-walled pipe where the inner tube is made of ceramics and the outer tube is made of metal, etc., so that it cannot be easily removed or replaced over time. X
A damaged part of the wall thickness is detected by irradiating the tube surface of the duplex pipe with radiation such as a line using a near-focus method, etc., and then the radiation is irradiated onto the wall surface of the damaged part using a far-focus method, etc. At this time, the tube surface and tube wall are measured by capturing the irradiated radiation on a film, etc., and measuring the density of the image visually or electrically. This technology uses technical means to detect flaws by comparing the concentration distribution with the standard concentration distribution state of a true circular double pipe, and to estimate the degree of functional maintenance of the double pipe over time. be.

<Example> Next, an example of the invention of this application is shown in FIG. 1 with reference to FIG.
The explanation will be as follows with reference to FIGS. 6 to 6.

The embodiment shown in Fig. 1.2 is a basic aspect of the invention of this application, and the double pipe 6 as a double pipe shown in Fig. 3.4 is a straight unit pipe of a predetermined length. The outer tube 3 as an outer tube is made of carbon steel, and an inner tube 5 as an inner tube made of ceramics is installed inside the inner tube 3 through an intermediate layer 4 of cement and is integrated with the inner tube 3, for example, an atomic couplant. The outer tube 3 is used for piping, etc., and controls heat resistance and pressure resistance, while the inner tube 5 controls wear resistance and corrosion resistance, and the front and rear flanges 1.2
It is installed as a pipe of a predetermined length through (a, b), and the wear and tear due to operation over time of the inner pipe 5 made of ceramics at the fork part C is measured using X-rays as radiation. The purpose of this is to estimate the length of maintenance of function over time at the time of the measurement, so that predetermined measures can be taken.

Thus, the focal point 1 of an appropriate radiation generation irradiation device (not shown)
The radiation 8 is irradiated using a near focus method, and the film 9 is
The measurement is performed by installing the X-ray in line contact with the double tube 6 (outer tube 3), receiving the irradiated X-rays, and measuring the density distribution of the image. As a first step, as shown in FIG. 1, radiation 8 is irradiated from a focal point 7 using a near-focus method onto the tube surface of the inner tube 5 through a predetermined aperture, and the X-rays that pass through the tube surface are In the photographing 2 in the film 9, gradations of density are formed depending on the thickness of the inner tube 5, and the thickness of the inner tube 5 through which X-rays pass through the area is different from the center of the double tube 6. Since the wall thickness (distance L) is different from the wall thickness (distance L), this can be done by appropriate mathematical processing (using basic mathematical means).

) Measure the concentration distribution with appropriate correction, measure wear and thinning over time due to pipe operation, detect the wear area, and then detect the wear detection area as shown in Figure 2. The double tube 6 is positioned in the horizontal part parallel to the film 9 from the center and its posture is changed, and the radiation 8 is irradiated from the focal point 1 by the far focus method through the thick part, that is, the tube wall, to prevent wear and tear. The developed wall thickness is imaged on the film 9 and the change in density of the image is measured to determine the degree of wear and tear, and from the accumulated data etc., the time required to maintain the function as a double tube after the measurement timing is estimated. do.

The above embodiment is for the case where the double pipe 6 is a straight pipe, but as shown in FIG. 5, in the case of a curved pipe 6', the film 9'
Measurement is performed by bending the planar posture to a curved pipe state and making line contact.

The data obtained in this way becomes a feature of a characteristic graph as shown in FIG. 6, and this is used to measure the wall thickness of the inner tube 5 as the inner tube.

Accordingly, in accordance with the aspect of the basic embodiment described above, 7 shown in FIG.
7 langes 1.2 (a,
b) and - The thickness of the measurement position of the crotch C was measured by irradiating X-rays using the near-focus method, and the results are shown in Table 2 below.

Below is a margin Table 2 Table 3 Wall thickness measurement results using X-rays 3 - As shown in the data in Table 2, the wall thickness measurement by irradiating X-ray radiation according to the invention of this application is as follows: Of course, the wall thickness is measured not only for the outer tube 3, but also for the intermediate material 4 of the intermediate layer, and of course for the ceramic inner tube 5 as the inner tube. The measurement effect is different from the data of the prior art shown in Table 1 above, in which the measurement was not performed, and the accuracy of the data for the outer tube 3 is almost the same as that obtained by applying ultrasonic waves. Therefore, from this point, it can be seen that the reliability of measuring the measurement data for the outer tube, the intermediate layer, and the inner tube is high.

Then, the concentration distribution of these data is calculated, for example, by
The service life of the double layered pipe 6 is measured as a state of function maintenance after measurement using the function maintenance data accumulated by comparing the concentration distribution with the measurement data obtained by measuring the wall thickness through the wire. It is possible to estimate the timing of pipe replacement, maintenance, inspection, etc., prevent unexpected situations, and maintain pipes based on comfort and economic benefits.

It should be noted that the embodiments of the invention of this application are, of course, not limited to the above-mentioned embodiments. For example, measurement by measuring the density distribution state of a received image on a film of radiation irradiated by a near-focus method is as follows. In addition to visual inspection, the density distribution state of the photographed film can be electrically analyzed and analyzed using an image sensor, etc., and displayed digitally, displayed on a CRT, or displayed according to predetermined criteria on a display. Various aspects can be adopted, such as.

Furthermore, it goes without saying that the radiation is not limited to X-rays, but may also be radiation such as gamma rays.

Furthermore, wall thickness measurements of double-walled pipes can be performed not only on the inner pipe, but also on the outer pipe and the intermediate layer, and of course, can be performed on all of them. .

It goes without saying that the different materials for double-walled pipes can be applied not only to ceramics but also to plastics and other new materials.

<Effects of the Invention> As described above, according to the invention of this application, the outer tube is basically a steel tube that controls heat resistance, pressure resistance, etc., and the inner tube is made of ceramics and controls wear resistance and corrosion resistance. The outer and inner tubes of a double-walled pipe, etc., are made of different materials.6 Changes in wall thickness due to wear and tear due to operation over time of a double-walled pipe, etc., cause aging while maintaining its function as a double-walled pipe. When you want to measure the health of a hemorrhoid, you can measure its wall thickness using a near-focus method using radiation such as X-rays, and estimate the subsequent functional maintenance time, allowing you to prepare for unexpected situations. Not only does it have the effect of First, it is possible to carry out on-site measurements while the piping is installed on-site, and has the advantage of being extremely easy to operate and being cost-effective.

Therefore, in the invention of this application, radiation such as X-rays is first irradiated to the tube surface of the double tube using a near-focus method to detect a worn portion of the inner tube, etc. It is possible to accurately measure the wall thickness of the inner tube, etc. by irradiating radiation to the tube wall portion of the site by measuring the density distribution of the decoy light of the image received on the film. Spot-like conditions such as dents and hollows,
The excellent effect is that the linear state can be reliably grasped qualitatively and quantitatively, and the life span, such as the number of years the double pipe can maintain its function under the relevant state, can be reliably measured.

Detection of the qualitative position and quantitative measurement of the worn state of the inner tube of a double pipe as described above has the effect of reliably adding to the function measurement of the double pipe.

In addition, the wall thickness measuring method of the invention of this application does not require any special measuring equipment, and can be carried out by human experience, making it easy to perform on-site measurements even for complex plant piping. It's also effective.

[Brief explanation of the drawing]

The drawings are detailed explanatory diagrams of the invention of this application, and are shown in Section 1.2.
The drawings are examples of the principle mode. Fig. 1 is a longitudinal cross-sectional view of the tube surface using a near-focus method of X irradiation, Fig. 2 is a partially cutaway perspective view of a double tube, and Fig. 3 is the same tube. A cross-sectional view of the X-ray irradiation for wall thickness measurement, Figure 4 is a side view of the double pipe in a straight state, Figure 5 is a side view of the front of the curved 8 tube, and Figure 6 is a graph of the measurement. be. 3...Outer tube 5...Inner tube 6...Double tube 8...Radiation 9...Film 9

Claims (6)

[Claims] (1) In a method of measuring the wall thickness of at least one of the outer tube and the inner tube of a double-walled tube in which the outer tube and the inner tube are made of different materials, first, the wall thickness is measured. 2. A method of manufacturing different materials characterized by irradiating a tube surface portion with radiation to detect a wall thickness measurement site, and then irradiating a tube wall at the detection site with radiation to measure the wall thickness. How to measure the wall thickness of heavy pipes. (2) The method for measuring the wall thickness of a double pipe made of different materials according to claim 1, characterized in that the radiation irradiation is performed by a near-focus method. (3) A method for measuring the wall thickness of a double pipe made of different materials as set forth in claim 1, characterized in that the measurement is carried out by film image reception. (4) A method for measuring the wall thickness of a double pipe made of different materials as set forth in claim 1, characterized in that the radiation is performed as an X-ray. (5) Claim 1, characterized in that the above measurement is performed by measuring the density distribution of a plane image of the film.
Method for measuring the wall thickness of double pipes made of different materials as described in . (6) The method for measuring the wall thickness of a double-walled pipe made of different materials as set forth in claim 1, characterized in that the measurement is carried out by comparison with a standard concentration distribution of a reference perfect circular double-walled pipe.