JPH0438282B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of measuring wall thickness, etc. of pipes such as underground pipes, heat exchangers, and underwater pipes using ultrasonic waves.

[Conventional technology]

For example, when a steel pipe is buried underground for a long period of time, it is subject to corrosion due to moisture in the soil and changes in electric potential. If this corrosion is left untreated, it will lead to a leakage accident of the transport fluid. Therefore, it is required to understand the situation of thinning due to corrosion at an appropriate time.

On the other hand, it is known to use ultrasonic waves to measure the wall thickness of a pipe, and methods for inserting a sensor into a pipe are described in Japanese Patent Application Laid-Open No. 59-79146 and Japanese Patent Publication No. 59-29815. Things such as these are known.

[Problem that the invention seeks to solve]

Regarding underground pipes, when measuring the wall thickness of underground pipes using ultrasonic waves, it is possible to dig up the soil one by one and measure the wall thickness from the outside surface, but this method is difficult to work with. Not only that, but if the outer surface is corroded, good contact between the ultrasonic probe and the tube cannot be obtained. Therefore, measurements from the outside are virtually impossible.

On the other hand, since the inner surface of a pipe is generally smooth and free from corrosion, it is effective to measure the wall thickness from the inner surface. On the other hand, when measuring wall thickness from the inner surface side, as long as ultrasonic measurement is performed, it is necessary to interpose a propagation medium such as water or oil between the ultrasonic probe and the tube. However, in order to introduce the propagation medium liquid, the piping must be dug up and partially cut.
It is necessary to install a valve or a blind plate and dam it up, and also to remove the used propagation medium liquid after measurement, so this type of method cannot be adopted in terms of man-hours and costs.

Therefore, a method is desired in which an ultrasonic probe is inserted through the opening at one end of the tube while the tube remains buried, but the methods described in the above-mentioned publications are not effective for ultrasonic wall thickness measurement. In particular, both publications do not disclose how the propagation medium liquid is interposed between the probe and the buried pipe.

Therefore, an object of the present invention is to allow an ultrasonic propagation medium liquid to be easily interposed between a probe and a tube, and to enable measurement with the tube buried in the soil without digging up the soil. The object of the present invention is to provide a measurement method using ultrasonic waves that is extremely easy to work with.

[Means for solving problems]

To solve the above-mentioned problems, the present invention has a bottomed tube filled with ultrasonic propagation medium liquid from one end opening of the piping, and inserted into the pipe by the liquid pressure, and the piping is inserted into the bottomed tube. An ultrasonic probe is inserted from one end of the tube to measure the wall thickness of the tube.

It should be noted that the present invention is applicable not only to the wall thickness of a pipe but also to flaw detection and the like using an ultrasonic contactor.

[Effect]

In the present invention, the wall thickness of a pipe is measured, for example, while the pipe is buried underground. For this purpose, a bottomed tube is inserted into the tube from its bottom. During this insertion, the bottomed tube is filled with an ultrasonic propagation medium liquid, and the water head pressure of the liquid or external pressure applied to the liquid is applied. As a result, the bottomed tube is advanced forward within the tube, and insertion is attempted. Thereafter, when an ultrasonic probe is inserted into the bottomed tube, the liquid becomes an ultrasonic propagation medium liquid between the probe and the tube, making it possible to directly measure meat pressure, etc.

[Specific examples of the invention]

The present invention will be explained in more detail below with reference to the drawings.

In FIGS. 1 to 3, reference numeral 1 indicates an underground pipe (hereinafter simply referred to as a pipe) made of a steel pipe or the like, and a part of the pipe extends above ground. After burying, the above-ground piping section is cut off at an appropriate point to form an opening. In contrast, preferably, a flexible long bottomed tube 2 is prepared in advance. For example, this tube 2
The inner side is made of synthetic resin such as polyester,
It can have a two-layer structure with the outer surface made of the same fiber. Further, a liquid reservoir mouthpiece 3 is disposed at the mouth of the tube 2 .

Thus, the folded tube 2 is placed at the open end of the tube 1 together with the base 3, and the opening of the tube 2 is folded back to the outside of the opening of the tube 1 to be locked to the tube 1. Thereafter, an ultrasonic propagation medium liquid such as water 4 is continuously introduced into the mouthpiece 3. As a result, the head pressure of the water 4 acts on the bottom of the tube 2, and the tube 2 is successively inserted into the tube 1. Prior to inserting the tube 2, the contact surface of the two-layered tube with the tube 1 should be such that the fiber layer is on the contact surface, and the fiber layer 2 is immersed in water or the like before insertion, and an external couplant such as water is applied. tube 2 and tube 1 at the opening after insertion.
The couplant 5 is interposed between the outer surface of the tube 2 and the inner surface of the tube 1 by being press-fitted from between the tube 2 and the inner surface.

Simultaneously with or after the insertion of this tube 2,
The cart 7 carrying the probe 6 is inserted into the tube 2 while being pushed through a flexible insertion rod such as a spring wire 8. Wheels 9 are provided at the front and rear of the trolley 7 to facilitate the insertion work.
The probe 6 and external equipment are connected via a signal coupling 10 and a signal line 11. Also,
A motor 12 for rotating the probe 6 in the circumferential direction is provided at the base end of the spring wire 8. 13 is earth.

On the other hand, as shown in FIG.
5, recorder 16, etc.

When measuring thickness, tube 2 and trolley 7
is inserted into the tube 1, an ultrasonic wave is transmitted from the vertical probe 6 (T in FIG. 4 is the transmitted wave), and the distance between the inner surface echo S and the outer surface echo B of the tube 1 (ultrasonic propagation time) and convert it into a thickness value.

The thickness can be measured while moving the probe 6 intermittently or continuously in the tube length direction. In the case of continuous measurement, by synchronizing the feeding of the recording paper of the recorder 16 and the feeding of the probe 6 in the tube length direction, the specific position of partial thinning, etc. can be found.

In the above example, prior to inserting the tube 2, the cloth layer on the outer surface is soaked in water to form a stable ultrasonic medium layer in the gap between the tube 2 and the tube 1. desirable. tube 2
The material is not limited as long as it is flexible and liquid-tight. The ultrasonic propagation medium liquid (coupleant) may be oil or the like in addition to water. Furthermore, in the above example, the probe 6 is rotated in the circumferential direction by a motor 12 outside the tube, but in the case of a large diameter tube, a rotation drive device may be incorporated into the cart 7. Further, the analog output signal of the ultrasonic thickness gauge 14 is digitized via an AD converter, and the thickness signal can be automatically processed in a computing unit (not shown). On the other hand, when inserting the tube 2, if the water head pressure alone is not enough, either seal the opening of the cap 3 and press water in.
Air may be introduced to force water.

FIG. 5 is a waveform diagram on the oscilloscope 15, and it can be seen that echoes appear without being influenced by the tube 2. FIG. 6 shows the correspondence between the measured values and the actual values measured at the same measurement point using a micrometer, and shows sufficient correspondence. 7th
The figure shows the output result of the pen recorder 16, and the wall thickness can be measured by the amplitude of the pen. Although this embodiment has been described above to measure the wall thickness of underground pipes, it can also be applied to wall thickness measurements of heat exchangers, underwater pipes, etc., and flaw detection for defects.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to perform measurements while the pipe is buried, and the workability is extremely high.
Further, since the liquid used for inserting the tube becomes the ultrasonic propagation medium liquid as it is, there is an advantage in this respect as well, such as fewer man-hours.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the implementation state of the method of the present invention, Fig. 2 is a cross-sectional view thereof, Fig. 3 is a longitudinal sectional view of the tube inserted into the tube, and Fig. 4 shows the arrangement of the thickness measuring device together with waveforms. FIG. 5 is an example of one waveform on an oscilloscope, FIG. 6 is a correlation diagram between ultrasonic measurement values and actual measurement values, and FIG. 7 is an example of output from a pen recorder. 1... Underground pipe, 2... Bottomed tube, 3... Base, 4... Water (ultrasonic propagation medium), 6... Probe.

Claims (1)

[Claims] 1 Fill a bottomed tube with an ultrasonic propagation medium liquid and insert it into the tube using the liquid pressure from the opening at one end of the piping, insert an ultrasonic probe into the bottomed tube from one end of the piping, An ultrasonic measuring method for piping characterized by measuring the wall thickness of the pipe.