JPH0433368B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a cladding thickness measuring method for measuring the thickness of a cladding that is bonded to a base material that becomes the main body of, for example, a pressure vessel or a pipe.

[Conventional technology]

There are several methods for measuring this type of cladding thickness, and these methods will be explained below.

One of these methods is still used as a basic measurement method, and specifically measures the edges of a steel plate used as a cladding at multiple locations using a caliper. This is a method of measuring thickness.

The other one is the base material 1 as shown in Figure 4.
An ultrasonic probe 3 is installed on the surface 2 of the cladding 4, and an ultrasonic wave is transmitted from the ultrasonic probe 3, and a boundary echo obtained by being reflected at the boundary 5 of the cladding 4 and a reflection at the bottom 6 of the cladding 4 are obtained. The thickness of the cladding 4 is measured from the difference between the bottom echo and the obtained bottom echo.

[Problem that the invention seeks to solve]

However, among the above measurement methods, the former method, which uses calipers to measure the cladding thickness,
It is difficult to measure the thickness of the central part of the cladding 4, and the thickness cannot be controlled with high precision, so there is a risk that the cladding 4 will corrode during long-term use, resulting in damage to the pipes of the pressure vessel, resulting in unpredictable accidents. There is.

In addition, in the latter method of measuring cladding thickness using ultrasonic waves from the base metal side, if you want to specify a measurement point from the cladding side (for example, if a decrease in cladding thickness is observed from the cladding side and you want to measure the location) ), it is necessary to find the measurement point on the base material side for that point, making it difficult to identify the location.

Therefore, it is conceivable to install the ultrasonic probe 3 on the surface of the cladding 4 and transmit ultrasonic waves from the cladding side to the cladding boundary to measure the cladding thickness. However, in this case, the thickness of the cladding 4 may not be measured because boundary echoes enter the dead zone of the ultrasonic probe.

The present invention has been made in view of the above points, and is capable of measuring the thickness of any part of the cladding, and detecting boundary echoes at the cladding boundary area outside the dead zone of the ultrasonic probe. An object of the present invention is to provide a cladding thickness measuring method that can reliably measure the cladding thickness.

[Means for solving problems]

In order to achieve the above object, the cladding thickness measuring method of the present invention involves installing an ultrasonic probe on the surface of the cladding that is joined to the base material as a laminate, and injecting ultrasonic waves from the surface of the cladding. The ultrasonic waves transmitted through the cladding are reflected on the bottom of the base material, transmitted through the cladding, reflected on the surface of the cladding, reflected again on the bottom of the base material, transmitted through the cladding, and detected by an ultrasonic probe. The bottom echo and the incident ultrasonic waves pass through the cladding, are reflected at the bottom surface of the base material, are reflected at the interface between the base material and the cladding, are reflected again at the bottom surface of the base material, and are transmitted through the cladding to generate ultraviolet waves. The boundary echoes detected by the sonic probe are determined, and the thickness of the cladding is calculated from the detection time difference between the determined echoes.

[Effect]

That is, in the present invention, the bottom echo and the boundary echo are both echoes of ultrasonic waves that are reflected twice at the bottom surface of the base material, but in the bottom echo, the ultrasonic wave reaches the cladding surface in the middle and is reflected from this cladding surface. On the other hand, a boundary echo is an echo in which the ultrasonic wave does not reach the cladding surface but is reflected at the interface between the base material and the cladding. Therefore, there is a time difference between the two echoes required to travel back and forth across the cladding. Then,
The cladding thickness is calculated from this time difference.

Furthermore, with the above configuration, the thickness of any part of the cladding can be measured, and furthermore,
Boundary echoes can be measured by removing the dead zone of the ultrasound probe.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In these figures, reference numeral 10 denotes a base material that is likely to be the main body of a pressure vessel, a pipe, etc., and a cladding 11, such as a steel plate, is bonded to one side of the base material 10 as a mating material. When measuring the thickness of the cladding 11 in such a laminated structure, an ultrasonic probe 12 is installed on the surface of the cladding 11 and ultrasonic waves are transmitted from the cladding 11 side to the base material 10 side. ,
The ultrasonic waves are reflected along the path shown in 13, that is, the path consisting of the base material bottom surface 15 - cladding boundary 16 - base material bottom surface 15 as shown in FIG. 2a, resulting in a boundary echo S1 (see FIG. 3). Detection is performed, and further the base material bottom surface 1 is detected along the path shown in 14, that is, as shown in FIG.
Bottom echo S2 (third
(see figure). In FIG. 3, W represents the ultrasonic beam path, and E/H represents the echo height. In addition, FIG. 3 shows each echo displayed on the display screen of a CRT display device, for example.
The echo indicated by SO is an ultrasonic wave transmitted from the ultrasonic probe 12 that passes through the cladding 11, is reflected by the bottom surface 15 of the base material, and is transmitted through the cladding 11 in the opposite direction. This is an echo incident on the

If the boundary echo S1 and the bottom echo S2 are detected as described above, the detection time (beam path) x1, x of these echoes S1, S2
The thickness of the cladding 11 is determined by calculating (x2-x1) from 2.

Therefore, according to the configuration of the embodiment as described above,
Place the ultrasonic probe 12 at any position where you want to measure the thickness.
The thickness of the cladding 11 can be measured by setting up a cladding 11, and the thickness of the cladding 11 can be measured over a wider range compared to the conventional measuring method using calipers. This makes it possible to manage the damage and thereby extend the life of the laminated structure, and to predict the life of the cladding 11 sufficiently. In addition, since the boundary echo S1 is detected as a reflected echo through a path consisting of the base metal bottom surface 15 - the cladding boundary 16 from the base metal surface side - the base metal bottom surface 15, it deviates from the dead zone and is therefore reflected on the surface of the cladding 11. Even if the ultrasonic probe 12 is installed, the boundary echo S1 can be reliably detected, and the thickness of the cladding 11 can be measured with high precision.

Note that the present invention is not limited to the above embodiments. For example, a steel plate is used as the cladding 11, but the cladding 11 is not limited to this, and various materials such as stainless steel may be used. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

〔Effect of the invention〕

As detailed above, according to the present invention, the thickness of any part of the cladding can be measured, and by detecting the boundary echo at the cladding boundary part outside the dead zone of the ultrasonic probe, It is possible to provide a cladding measuring method that can measure reliably and with high precision.

[Brief explanation of drawings]

Figures 1 to 3 are shown to explain an embodiment of the cladding thickness measuring method according to the present invention, and Figure 1 shows the installation state of the ultrasonic probe, and Figure 2 a and b are explanatory diagrams showing the paths of boundary echoes and bottom echoes, Fig. 3 is a diagram showing the detection timing of boundary echoes and bottom echoes, and Fig. 4 is a diagram explaining the conventional method of measuring cladding thickness using ultrasonic waves. It is. 10...Base metal, 11...Clad, S1...Boundary echo, S2...Bottom echo.

Claims (1)

[Claims] 1. A method for measuring the thickness of a cladding joined to a base material as a cladding material, which includes: installing an ultrasonic probe on the cladding surface, injecting ultrasonic waves from the cladding surface; The ultrasonic wave passes through the cladding and is reflected at the bottom of the base metal, passes through the cladding, is reflected on the cladding surface, is reflected again at the bottom of the base metal, and then passes through the cladding again to detect the bottom surface of the cladding with the ultrasonic probe. The echo and the incident ultrasonic wave pass through the cladding, are reflected at the bottom surface of the base material, are reflected at the interface between the base material and the cladding, are reflected again at the bottom surface of the base material, and are transmitted through the cladding to produce ultrasonic waves. A method for measuring cladding thickness, characterized in that the thickness of the cladding is calculated from the detection time difference between the determined echoes by determining boundary echoes detected by a probe.