JPS61231404A - Method and apparatus for inspecting of film on inner surface of heat exchange pipe provided with inner surface coating film - Google Patents

Abstract

PURPOSE:To enhance inspection efficiency and to improve inspection accuracy, by reflecting light from a light emitting element by a rotary mirror to irradiate the film on the inner surface of a pipe to be inspected to perform rotary scanning and receiving the change in the quantity of reflected light by a photoelectric converter element. CONSTITUTION:The laser beam generated from a semiconductive laser element is condensed by a lens to be projected to a pipe to be inspected in the center axis direction thereof and reflected by a rotary mirror to irradiate the inner wall of the pipe to be inspected as a spot with a diameter of 1mm or less. The photoelectric converter element of a light receiver receives weak reflected beam from the surface of the film on the inner surface of said pipe to photoelectrically convert of reflected beam. This electric signal is amplified by an amplifier 20 through a connection cable 16 to be inputted to a cathode ray tube oscilloscope 22 of a cathode the through a differentiator 21 and receives the observation of a wave form to be automatically recorded on a pen writing oscillograph 24 through a peak hold circuit 23. When there was a voltage signal exceeding the threshold value preset by a comparator 25, that is, the increase in the quantity of reflected beam, an alarm is emitted by an automatic alarm 26 to discriminate the pressure of a coating inferior part.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method and apparatus for inspecting the inner surface coating of heat exchanger tubes with an inner surface coated coating used as cooling tubes for condensers in thermal power and nuclear power plants. @do.

The cooling capillary of the condenser has an outer diameter of 1 to 11/4 inches (25,4
~51.75 @l), small diameter long tubes with a length of about 10 to 25 m, and around 910,000 tubes are used per device.

(Prior Art) The corrosion resistance of various heat exchanger tubes, including the cooling capillary tubes of the condenser mentioned above, is maintained! iIt largely depends on the properties of the film.

The corrosion resistance of a copper-aluminum alloy called aluminum glass, which is often used as condenser cooling tubes, mainly depends on the iron oxide film formed on the inner surface of the tubes.

Y'11961 Boatwi as a protective film generation technology
ck is the first sulfuric acid injection method tI! Since its introduction, fL has been adopted at various power plants, and excellent corrosion protection has been required.

However, if the seawater that passes through the pipes as cooling water is contaminated, this method also has the problem of forming a protective film, and in recent years, from the perspective of environmental conservation, chemical injection methods that pose a risk of chemicals leaking into the seawater have been discouraged. Due to this situation, for the purpose of corrosion prevention on the inner surface of heat exchanger tubes,
(1) At the pipe manufacturing factory, a paint containing iron is applied to the inner surface of the pipe to artificially preserve the skin. Form lIt. (
1) It has become possible to artificially form a protective film on the inner surface of pipes in use, that is, old pipes, by applying the coating treatment described above.

In this way, when forming an artificial protective film on the inner surface of a heat exchanger tube made of #1 alloy to improve corrosion resistance, 1. If even a partial film remains, pores will be concentrated in that part. Erosion or ulceration occurs. Therefore, the pipe that was filled with the paint spoon mentioned above.

It is desirable to carry out the inspection over the entire circumference and entire length of the inner surface of the tube.

However, as mentioned above, condenser cooling thin tubes, etc. are subject to dimensional restrictions and quantitative restrictions on the number of tubes, so in the conventional inspection method, the following sampling inspection is carried out at 1i! It was just being done.

+1) Extraction FIL destructive inspection of representative sample tube Total 1 of 0
．． 148i&C is removed after 3M of painting and its inner surface condition is observed. (1) Observation with an endoscope The inner surface of the tube is observed using a private device such as a borescope T7ttt fiberscope. Due to structural and functional constraints, the applicable range of borescopes is limited to 1 to 5 m from the end of the tube.1m fiberscopes are manufactured in long lengths with an applicable range of 10 to 20 m. Although it is possible to observe the entire length inside the condenser cooling tube, the inspection speed is slow at approximately 1 m/min.
Due to a fundamental problem with the Eye Pass 1, the resolution is insufficient, and since visual judgment must be made, skill is required, which poses problems in terms of inspection efficiency and accuracy. In any case, it is considered impossible to conduct a complete inspection on a large number of samples, and only 4C samples of 1 to 2% of the total quantity are actually inspected.

(Problems to be Solved by the Invention) The present invention solves the problems of the conventional inspection techniques described above, and makes it possible to inspect the entire length and circumference of small diameter long tubes such as condenser cooling tubes. I can do it.

Another object of the present invention is to provide an inspection method and apparatus which have a fast inspection speed, high inspection efficiency, can perform a full inspection of a large number of items, have good inspection accuracy, and are highly reliable.

(Next Means for Solving the Problems 1 Effects, Examples) The purpose is 1 to detect a probe type that can be moved in the tube axis direction inside a heat exchanger tube with an inner surface coating film, which is a tube to be inspected, by the method of the present invention. A light-emitting element, a rotating mirror, and a set of photoelectric conversion elements are mounted inside the transparent cylindrical envelope of the vessel, and the light from the light-emitting element is reflected by the rotating mirror to irradiate and rotate the inner skin of the tube to be inspected. Reflected light 111o quality is light I! The light is received by the conversion element and converted into a change in electrical iI, which becomes the P3 surface BcWX.

This is achieved by performing FC to detect defective parts.

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

First, we will sequentially explain the configuration of the detection section, the control section, and the entire device, starting from the basic configuration of the optical system that enables ambiguity detection with high detection accuracy based on a change in received light without relying on visual observation.

Generally, it is used as a test method for surface flaws on steel plates, etc.
An optical inspection method using visible light or Helium neon gas LED light is known. This method targets a so-called sheet material and irradiates the target object with light from one light emitter.
When the target object is opaque, its reflected light is converted into soy 1-. When the material is transparent, such as a transparent material, the 0-reflection light method detects the loR of the transmitted light with a light receiver and detects the defect tI/g1.There are two types: the defect entry method and the defect continuous light method. The defective joining ceremony is as shown in Figure 1 (a), where the light receiver (alt is placed in a position where it does not receive the normal reflected light from the surface of the target object (b), as shown in Figure 1 IP). When the target object has a defect (c) such as a scratch, the reflected light is scattered, so the scattered light is received and photoelectrically converted. In the case of the defect beaming method, the receiver (a) is set to receive regular reflected light as shown in Fig. 1(c)k, and the scattering due to the defect (C) is set as shown in Fig. 1(c). Ninthly, the change in the attenuation of the regular reflected light l is photoelectrically converted.

The present invention adopts a new reflected light amount method that utilizes a first-order phenomenon, which is different from any of the above-mentioned reflected light amount methods. In other words, if the surface of an object is discolored or dirty, light will not be scattered and the amount of reflected light will be due to absorption. The present invention makes it possible to inspect coatings by making reverse use of this phenomenon. Where the experiment was conducted.

The ratio of the amount of normal reflected light from the metal surface (d) to the normal reflected light from the south of the painted film (s) in the object of the present invention is approximately 4.
Since the amount of light reflected from the coating surface is extremely weak (90:0:1), in the present invention, the light receiver (a) is arranged as shown in FIG. As shown in (f), when the metal surface (d) of the incompletely painted part passes through, the normal reflected light l increases by about 40 times, and passing through the metal surface is detected.Unlike the defect double-beam method, the scattered reflected light This method does not utilize the decrease in received light 1 due to

In the present invention, since the position to be inspected is the inner surface of the tube, the ninth step of utilizing the above phenomenon is to position the light emitting device on the central axis of the tube so that it emits light in the direction of the central axis force. It is received by a one-rotation mirror, radiated toward the inner wall of the tube, and a light receiving element is placed at a position where it can receive the regular reflected light weight. Figure 2 shows the probe type detection 1 of the optical system used in the present invention! An example of (1) is shown below. This detector (1) is small! ! A long tube to be inspected (2) A guide (3) with a small diameter for the IC transfer gap so that the inner surface can be moved in the tube axis direction (3) (a
) is combined with an intermediate transparent cylinder (4) to form a mantle (5). Light emitting with a light emitting element (6) inside the outer transparent cylindrical body (4)! (7) h rotating mirror (8), photoelectric conversion element (9)
Securely stores the receiver (to) with a

As the light emitting element (6), a semiconductor laser is used for optical communication etc. due to the limitation of the size that can be inserted into the tube, and the CD beam is used from the point of view of directivity.

For example, one with an output of 4 mw, a wavelength of 0.8 μm, and near-infrared light is used. The radar beam generated by the semiconductor radar element [6] is focused by the lens (2) in the light emitter holder (b) and emitted in the direction of the center axis of the tube, reflected by the rotating mirror (8), and reflected by the transparent cylindrical body. (4) and is irradiated onto the inner wall of the tube to be inspected (2) as a spot with a diameter of 1a or less. The photoelectric conversion element (9) of the light receiver αQ is placed at the intersection of the regular reflection line from the tube inner wall and the center line of the transparent inner cylinder, and constantly receives and reflects the weak reflected light from the tube inner wall coating surface. The zero-rotation mirror (8) that photoelectrically converts the light 1 is given high-speed rotation of about 12.00 Orpm by a small DC motor (2), and the radar spot beam is irradiated onto the inner wall of the tube at this rotation speed and is rotated in the circumferential direction. Perform scanning.

A cable connector α◆ is provided at the end of the probe-type detector on the receiver side, and is connected to an external control device a (g), which will be described later, as shown in Figs. 3 and 4 via a connecting cable (to). Connected. Connecting iron piece (b) to the Glow 1 detector Fi reflection end
have.

Figure 3 shows one of the configurations of a control device connected to a probe-type detector (1) that moves in the pipe by a connecting cape tv o#.
To give an example: This device consists of a ninth radar ik# (to) circuit of a probe type detector (1), four motor power supply circuits, a light reception signal processing control circuit, a display/distribution device, etc. As mentioned above, the reflected light from the inner wall of the tube is received by the photoelectric conversion element (9) and photoelectrically converted, and this electrical signal is amplified by the amplifier 4 through the connection cable (to) and then sent to the differentiator (2). ), the waveform is observed by inputting it to the Grain tube oscilloscope (2), and the threshold set in advance by the 01st order comparator (to the peak hold circuit), which automatically records it to the pen oscilloscope (2). If there is a voltage signal that exceeds the value, that is, an increase in the amount of reflected light, an automatic alarm will issue an alarm to determine the presence of unpainted areas. Figure 4 shows the tube of the probe-type detector (1). The overall configuration of the inspection device including the axial moving means is shown.

Prepare a permanent magnet at the tip of a rod-shaped body such as Bakelite, and prepare a late connection device, and connect a tension cable to the
control device (to) and reflector I in the tube to be inspected using
It is sent from l (g) and allowed to pass through, and the probe type detector (1) is connected to the other side (4) by the attraction of a permanent magnet @, tkM rabbit. In this way, the automatic winding machine (51) is driven to move the probe type detection m(1) from the mu side to B1# with a constant motion in the direction of the tube axis through the cable @ and the connection Am, while the rotating mirror (8) A rotary scan of the inner surface of the tube is performed using a horsefly. This transition speed is 12 m when the spot diameter of the irradiated radar light is 1-1 and the rotation speed of the rotating mirror (8) is 12*000 rpm.
/min. When the detector (υ) reaches the B side, the automatic winder (si) is stopped and the detection 4m1 (1
)T Remove with a series of knots @, pull back, and move on to inspecting the next pipe.

FIG. 5 shows an example of a detected waveform. In the JIES diagram) is a normal pipe section with no coating defects, and Figure 5 (b) is the middle 3-2 length of 15 m.
An example of detecting a defective part of the film, FIG. 5 - An example of detecting a defective part of the film having a large area, FIG. 5) is an example of detecting a collection of point-like film defects.

(Effect of the invention) According to the present invention, the following OH effect can be obtained.

(1) High efficiency is achieved.

It has become possible to carry out automatic inspections that do not rely on human visual judgment using a medium such as a fiberscope, and the efficiency has been improved by about 10 times compared to conventional technology. Therefore, it becomes possible to inspect all the condenser cooling tubes (Otori) Improved detection accuracy (-Since it does not depend on visual regeneration, it is possible to identify undisappeared parts by kW
& Natsuri does not require any training and there is no oversight of the unpainted part.

(b)1! With American technology, the limit of identification of unidentified parts based on the resolution limit of the 7-eye scope is 1- or more, and if t is 1, according to the present invention, irregularities of 0.5- or more can be detected with sufficient accuracy, and the inspection accuracy is significantly improved. improved by 90

[Brief explanation of drawings]

Figure 1 (a) is a diagram showing the arrangement of the optical system of the defective light incident type of reflected light 1 method, Figure 1 (b) is a diagram showing the state at the time of defect 1! ) is a diagram showing the layout of the optical system of the defective edge light type of the reflected light 1 method, Figure 1) is a diagram showing the state when the defect occurs, and Figure 1 (e) is the diagram of the optical system of the present invention. A diagram showing the arrangement and light reception state. Fig. 1(f) is a diagram showing an increase in the amount of light received when gold 1I4rN arrives at the incompletely painted part, and Fig. 2 is a longitudinal side view showing an example of the detector of the optical system used in the present invention. , 5th
The cause is a Glock wiring diagram showing the configuration of the in-tube detector and the extra-tube control device, and the fourth reason is the overall partial longitudinal layout of an example of the inspection device used in the present invention, including the means for moving the detector in the tube axis direction aA Figure 5 (Figure 5 is a detection waveform diagram of the oscilloscope hoop oscillograph for a normal tube section, Figure 5 (b) is a waveform diagram for detecting the amount of a linear coating defect, and Figure 5 G-→ is a detection waveform diagram for the area under the planar membrane. s, m
Figure 5) shows the detection waveform of ILs under the membrane in the form of aggregated points. (1) @ Probe-type detector, (2) Self-inspection tube. (3)・O guide* (4) Fist・Transparent Enzaki body, (5)
··mantle. (6)...Light emitting element, (7)...Light emission! , (8)...Rotating mirror, (9)...Light w1 conversion element, Ql)...Light receiving l, (B)...-Emitting m holder, (2)...Lens &-...
・Motor, (141...cable connector, (to)
·Control device. −・Working connection cable, (B)・Connecting iron piece, (To)・
・Laser power supply, (to) ・・Light power supply, GIJ・・Intensifier, @・・Differentiator, @・・1 quan tube oscilloscope, @・・Peak hold circuit, (Foundation)・・・Benn book oscilloscope Graph, @... Comparator, (2) - Life alert! i1. @・
・Permanent magnet, @...Connector, @-Tension case-7"/I
/, working - air gun, (si)... automatic winding a machine, (
4) CB)...tube end symbol, (a)...light receiver. (b)...Target object, (C)...Defect, (Yu...Surious face. (・)Fist/film surface.

Claims (3)

[Claims] (1) A set of light-emitting elements, rotating mirrors, and photoelectric conversion elements are mounted inside the transparent cylindrical jacket of a probe-type detector that can be moved in the tube axis direction inside a heat exchanger tube with an inner surface coating, which is the tube to be inspected. Then, the light from the light emitting element is reflected by a rotating mirror to irradiate the inner surface coating of the tube to be inspected and then rotated and scanned, and the change in the amount of reflected light is received by a photoelectric conversion element and converted into a change in the amount of electricity, which detects the inner surface coating. A method for inspecting the inner surface coating of a heat exchanger tube with an inner surface coating film, which is characterized by detecting defective parts. (2) The method according to claim 1, wherein the regularly reflected light from the inner surface film is received by a photoelectric conversion element. (3) A probe-type detector whose jacket is made of a transparent cylindrical body and a set of light-emitting elements, rotating mirrors, and photoelectric conversion elements are mounted inside it; A heat exchanger tube with an inner surface coating, consisting of a traction transfer device that scans the inside of the exchanger tube in the tube axis direction, and a drive, control, and measurement device connected from a probe-type detector through the tube in the traction and reflection directions. Inspection device for inner surface coating.