JPS6291806A - Clad thickness measuring method - Google Patents

Abstract

PURPOSE:To measure clad thickness with high accuracy by transmitting ultrasonic waves from an ultrasonic probe provided to the clad surface and using a bottom echo obtained by reflecting on the clad surface at the probe side and a boundary echo obtained by reflecting on a clad boundary part. CONSTITUTION:The ultrasonic probe is provided to a surface part of the clad 11 joined to base material 10 as clad material. Then, when the ultrasonic waves are transmitted from the clad 11 side to the base material 10 side, the boundary echo of the ultrasonic waves reflecting on a path of the base material bottom 15- the clad boundary part 16- the base material bottom 15 like the path 13 of figure (a) is detected. Further, the bottom echo which is obtained by reflecting two times on the surface 17 at the probe side like figure (b) is detected. The thickness of the clad 11 is measured with high accuracy by calculating a difference in detecting time between both echoes.

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 them is a method that is still used as a basic measurement method, and specifically, it measures the cladding thickness by using a caliper to measure the edges of a steel plate used as cladding, for example, at multiple locations. It is a method to measure the

■ Another method is to install an ultrasonic probe 3 on the surface 2 of the base material 1 as shown in FIG. The thickness of the cladding 4 is measured from the difference between the boundary echo obtained by being reflected at the boundary part 5 and the bottom echo obtained by being reflected by the clad bottom part 6.

(Problems to be Solved by the Invention) However, among the above measurement methods, the former method of measuring the cladding thickness using calipers has difficulty in measuring the thickness of the central portion of the cladding 4; Since the thickness cannot be controlled with high precision, there is a risk that, for example, the pressure vessel or the vibrator may be damaged due to corrosion of the cladding 4 after long-term use, resulting in an accident that is difficult to predict.

In addition, in the case where the latter probe 3 is used, as shown in FIG. 4, the level of the reflected wave 7 at the cladding boundary portion 5 is low, and the cladding thickness cannot be measured with high precision using an ultrasonic plate thickness meter.

Therefore, the ultrasonic probe 3 was installed on the 40th surface of the cladding.
It is conceivable to measure the cladding thickness by transmitting ultrasonic waves from the cladding side to the cladding boundary. However, when detecting echoes at the boundary from the cladding side, there is a problem in that the thickness of the cladding 4 cannot be measured because the echoes enter the dead zone of the ultrasonic probe.

The present invention has been made in view of the above points, and it is possible to measure the thickness of any part of the cladding, and to detect boundary echoes at the cladding boundary 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 thickness of a cladding.

[Means for Solving the Problems] In order to achieve the above object, the present invention installs an ultrasonic probe on the surface of the cladding that is joined to the base material as a laminate, and the ultrasonic probe The ultrasonic waves transmitted through the cladding are reflected twice on the cladding surface on the ultrasonic probe side, and the cladding surface is determined from It is used to measure the thickness of

[Effect]

Therefore, by using the above method, the thickness of any part of the cladding can be measured using an ultrasonic probe, and the ultrasonic probe can be installed on the cladding surface to generate ultrasonic waves. Since the measurement is performed using boundary echoes obtained by reflecting from the material side at the cladding boundary, boundary echoes having a sufficient level for measurement can be removed from the dead zone for measurement.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3. In these figures, 10 is a base material that is to become the main body of the pressure vessel Yabaib, etc., and this base material 1
For example, a cladding 1 such as a steel plate is placed on one side of the cladding 1 as a mating material.
1 is joined.

In such a laminated structure, the cladding 1
1, an ultrasonic probe 12 is installed on the surface of the cladding 11, and the thickness of the base material 10 is measured from the cladding 11 side.
When an ultrasonic wave is transmitted to the side, the ultrasonic wave passes through the path shown in 13, that is, the path consisting of the base material bottom surface 15, the cladding boundary part 16 from the base material side, and the base material bottom surface 15, as shown in FIG. 2(a). The boundary echo 81 (see Figure 3) obtained by being reflected by the
), a bottom echo 82 (see FIG. 3) obtained by being reflected twice on the surface 17 on the probe side is detected. In FIG. 3, W represents the propagation path of the ultrasonic wave, and E/H represents the intensity of the reflected sound pressure.

If the boundary echo $1 and the bottom echo 82 are detected as described above, the detection time of the echo 31.82 is x1. By calculating (x2-Xl) from x2,
The thickness of the cladding 11 is determined.

Therefore, according to the configuration of the embodiment as described above, it is possible to measure the thickness of the cladding by installing the ultrasonic probe 12 at any position where the thickness is desired to be measured, and it is possible to measure the thickness of the cladding using the conventional measurement method. Since the thickness of the cladding 11 can be measured over a wider range than when using a single caliper, it is possible to manage the thickness of the cladding and thereby extend the life of the fI1 layer structure. It becomes possible to predict. In addition, since the ultrasonic waves are reflected from the base material 10 side to the cladding boundary 16, the level of the echo 81 is high, and the boundary echo S1 is reflected from the base material bottom surface 15-
Since the reflected echo is detected through a path consisting of the cladding boundary 16 and the base material bottom surface 15 from the base metal surface side, the echo is outside the dead zone, and therefore the ultrasonic probe 1 is placed on the surface of the cladding 11.
2, the boundary echo S1 can be reliably measured 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, although a steel plate is used as the cladding 11, the present invention is not limited to this, and various materials such as stainless steel may be used. However, the present invention can be modified in various ways without departing from the spirit thereof.

[Effects of the Invention] As detailed above, according to the present invention, the thickness of any part of the cladding can be measured, and the cladding thickness can be increased by installing an ultrasonic probe on the surface side of the cladding. A method for measuring cladding that can be accurately measured can be provided.

[Brief explanation of drawings]

1 to 3 are shown to explain an embodiment of the cladding thickness measuring method according to the present invention, and FIG. 1 shows the installation state of the ultrasonic probe, and FIG. (a>, (
b) is an explanatory diagram showing the paths of the boundary echo and the bottom echo, FIG. 3 is a diagram showing the detection timing of the boundary echo and the bottom echo, and FIG. 4 is a diagram illustrating the conventional cladding thickness measuring method. 10... Base material, 11... Clad, Sl... Boundary echo, S2... Bottom echo. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 (a) Figure 2 (b) Figure 3
Figure 4

Claims (1)

[Claims] In a method for measuring the thickness of a cladding that is bonded to a base material as a laminate, an ultrasonic probe is installed on the clad surface, and the ultrasonic waves transmitted from the ultrasonic probe are transmitted to the ultrasonic probe. Cladding thickness measurement characterized in that the thickness of the cladding is measured from a bottom echo obtained by reflection on the cladding surface on the tenter side and a boundary echo obtained by reflection on the cladding boundary seen from the base metal side. Method.