JPH057528Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a pipe thickness measuring device that measures the thickness of a pipe from inside the pipe.

BACKGROUND ART When gamma rays emitted from a radiation source pass through an object, a portion of the gamma rays collide with atoms of the object and are scattered back. For example, if a steel plate is irradiated with gamma rays and the energy and number of backscattered gamma rays are measured with a scintillation detector, the peak value of the resulting multiple scattering spectrum or the total number of counts in a certain range and the plate thickness can be calculated. The plate thickness can be estimated from the measured number of counts, since it is proportional to the number of counts.
Taking advantage of this fact, for example, the thickness of a cast iron pipe under construction that has a corroded layer has been measured non-destructively from inside the pipe.

As shown in FIG. 3, in the conventional tube thickness measuring device using the above gamma ray irradiation method, a scintillator 1, a photomultiplier tube 2, and an amplifier 3 are connected in sequence in the longitudinal direction, and a radiation source 4 and a scintillator 1 are connected in sequence. The receiving section 1 a is arranged at the most distal end surface of the scintillator 1 and faces in the same direction as the longitudinal direction of the photomultiplier tube 2 .

Problems to be Solved by the Invention The mode of use of the conventional tube thickness measuring device shown in FIG. 3 above is as shown in FIG. In order to face each other, it is placed inside the tube 5 so that its longitudinal direction is perpendicular to the tube wall. Therefore, the pipe thickness that can be measured by the above-mentioned pipe thickness measuring device is limited to the pipe 5 whose inner diameter is larger than the length l in the longitudinal direction of the pipe thickness measuring device, and cannot be measured for pipes smaller than l. There was a problem.

The present invention is intended to solve the above-mentioned problems, and aims to provide a pipe thickness measuring device that can measure the thickness of a pipe from inside the pipe even if the inner diameter is relatively small.

Means for Solving the Problems In order to solve the above problems, the tube thickness measuring device of the present invention connects a radiation source, a scintillator, a photomultiplier tube, and an amplifier in order, and measures the thickness of the tube toward the tube wall inside the tube. In the apparatus for measuring tube thickness by emitting radiation from the radiation source and measuring the intensity of backscattered radiation, the radiation direction of the radiation source disposed outside the tip of the scintillator and the radiation direction disposed at the tip of the scintillator are provided. The scintillator is connected to the photomultiplier tube via a light pipe so that the receiving direction of the receiving section crosses the longitudinal direction of the photomultiplier tube.

Effect With the above configuration, the scintillator with the radiation source disposed on the outside of the tip is connected to the light pipe so that the radiation direction of the radiation source and the reception direction of the reception section at the tip intersect with the longitudinal direction of the photomultiplier tube. Since the radiation source and the receiving part of the scintillator are connected to the photomultiplier tube through the tube, when inserting it into the tube to measure the tube thickness, insert the tube with its longitudinal direction along the tube wall. It can be placed opposite the wall of the pipe to be measured, and the thickness of pipes with relatively small inner diameters can also be measured.

Embodiment An embodiment of the present invention will be described based on the drawings.
FIG. 1 is a plan view of a pipe thickness measuring device according to an embodiment of the present invention, and FIG. 2 is a front view of the same pipe thickness measuring device. In the pipe thickness measuring device 11 shown in FIGS. 1 and 2,
A receiving section 13 is provided at the tip of the scintillator 12, and when a radiation source 14 is directed near the receiving section 13 in the same direction (arrow M) as the receiving direction (arrow L) of the receiving section 13, the outer side of the scintillator 12 The scintillator 12 is disposed half-embedded in a lead plate 15 attached to the photomultiplier tube 16 in the longitudinal direction (arrow N) at the opposite end of the receiving section 13.
The direction of the light is changed without loss so that the receiving direction and radiation direction (arrows L, M) of the receiving section 13 and the radiation source 14 are perpendicular to the longitudinal direction (arrow N) of the photomultiplier tube 16. A photomultiplier tube 16 is connected to the photomultiplier tube 16.
The other end is connected to an amplifier 18. Reference numeral 19 denotes a protective frame for the connection portion by the light pipe 17.

With the above configuration, when the pipe thickness measuring device 11 is inserted into a pipe to measure the pipe thickness, if the pipe thickness measuring device 11 is inserted with its longitudinal direction (arrow N) along the pipe wall,
The receiving section 13 of the scintillator 12 remains as it is.
With the radiation source 14 facing the tube wall and its receiving direction and radiation direction (arrows L, M) perpendicular to the tube wall, the tube thickness can be measured. This pipe thickness measurement assumption 11 indicates that the length h between the receiving section 13 of the scintillator 12, the upper surface of the radiation source 14, and the lower end of the protective frame 19 is much larger than the length l in the longitudinal direction of the conventional device. Small (about 1/2.
5) The thickness of tubes with small inner diameters can be easily measured.

Note that the angle of intersection between the reception direction and radiation direction (arrows L, M) of the reception section 13 of the scintillator 12 and the radiation source 14 (arrows L, M) and the longitudinal direction (arrow N) of the photomultiplier tube 16 is 90° in the above embodiment. You can also set it to any other angle as needed.

In measuring the tube thickness using the tube thickness measuring device 11, if the radiation source 14 irradiates gamma rays toward the tube wall (not shown), when the gamma rays pass through the tube wall, the rate increases in proportion to the tube thickness. Some of them collide with atoms forming the tube and are scattered backwards, and the scintillator 12 receives the backscattered gamma rays at the receiving section 13, emits light in proportion to the intensity of the gamma rays, and converts the light into photoelectrons. Multiplier tube 1
6 converts it into a current, amplifies it with an amplifier 18, analyzes it with a multiple wave height analyzer (not shown), and measures the pipe thickness from the number of integrated counts in a certain energy width of the obtained multiple scattering spectrum. be able to.

Effects of the invention According to the tube thickness measuring device of the invention, since the radiation direction of the radiation source and the reception direction of the reception section of the scintillator intersect with the longitudinal direction of the photomultiplier tube, the radiation direction of the radiation source and the reception direction of the reception section of the scintillator intersect, The thickness of a tube with a small inner diameter and a small length between the top surface and the bottom end of the device can be easily measured.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a pipe thickness measuring device according to an embodiment of the present invention, FIG. 2 is a front view of the same pipe thickness measuring device, and FIG. 3 is a schematic front view of a conventional device. 12...scintillator, 13...receiving section, 14
...Radiation source, 16...Photomultiplier tube, 17...
Light pipe, 18...amplifier.

Claims (1)

[Scope of utility model registration request] A radiation source, a scintillator, a photomultiplier tube, and an amplifier are connected in sequence, and radiation is emitted from the radiation source toward the tube wall within the tube, and the tube thickness is measured by measuring the intensity of the backscattered radiation. In the apparatus, the scintillator is connected to a light pipe such that the radiation direction of the radiation source disposed outside the scintillator tip and the reception direction of the receiver disposed at the scintillator tip intersect with the longitudinal direction of the photomultiplier tube. A tube thickness measuring device, characterized in that it is connected to the photomultiplier tube via a tube thickness measuring device.