JP2005127946A - Ultrasonic flaw detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dispense with cleaning work for a contact medium after ultrasonic flaw detection work. <P>SOLUTION: A sheet forming polymer solution is applied at first on a flaw detection face 2 of a concrete structure 1, and is followed thereafter by drying to form a polymer sheet 6 on a surface of the flaw detection face 2. Then, the liquid contact medium 3 is applied on a surface of the formed polymer sheet 6. Then, an ultrasonic probe 4 is brought into contact with the flaw detection face 2 from an upper side of the contact medium 3 to execute the ultrasonic flaw detection work. The polymer sheet 6 is separated and removed from a surface of the concrete structure 1 after the ultrasonic flaw detection work, and the contact medium adhered onto the surface of the polymer sheet 6 is removed thereby at the same time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an ultrasonic flaw detection method for flaw-detecting a defect portion inside a target structure such as a steel structure or a concrete structure using an ultrasonic echo.

X-ray inspection and ultrasonic flaw inspection are known as typical methods for nondestructively inspecting defects inside a target structure such as a steel structure or a concrete structure. Among these, the ultrasonic flaw detection is to detect the defect part and obtain information thereof by detecting the defect part echo that propagates the ultrasonic wave into the target structure and collides with the defect part and reflects. .

When performing such an ultrasonic inspection, in order to efficiently transmit the ultrasonic waves generated by the ultrasonic probe to the inside of the target structure, the surface of the target structure is supersonic. It is necessary to bring the acoustic probe into close contact. For this reason, it is indispensable to interpose a viscous liquid contact medium such as liquid glycerin or oil that propagates ultrasonic waves between the target structure surface and the ultrasonic probe.

Therefore, conventionally, an ultrasonic flaw detection inspection is performed according to a procedure as schematically shown in FIGS. That is, first, as shown in FIG. 4 (a), when the target structure is, for example, a concrete structure 1, the surface (hereinafter referred to as flaw detection) where the ultrasonic inspection of the concrete structure 1 is to be performed. For example, a liquid glycerin-based contact medium 3 is applied to the surface 2, and then, as shown in FIG. 4 (b), ultrasonic transmission and reception that are connected to a flaw detector not shown. By pressing a pair of ultrasonic probes 4 for use against the flaw detection surface 2 from above the contact medium 3 applied, the contact medium is placed between the flaw detection surface 2 and the ultrasonic probe 4. The ultrasonic flaw detection work is carried out with 3 being interposed without a gap.

After the completion of the ultrasonic flaw detection operation, as shown in FIG. 4 (c), the contact medium 3 remains attached to the flaw detection surface 2, so that the flaw detection surface 2 is set so as not to impair the beauty. The attached contact medium 3 was removed by washing with water or the like.

However, when the glycerin-based contact medium 3 is applied to the concrete structure 1, the glycerin-based contact medium 3 penetrates from the concrete surface, so that the contact medium 3 is removed from the structure surface. There is a problem that a great deal of labor is required for the cleaning operation.

Therefore, as a technique for carrying out the ultrasonic flaw detection work without using the liquid contact medium 3 as described above, a solid gel sheet (film) is formed on the flaw detection surface 2 of the concrete structure 1 as shown in FIG. And the ultrasonic probe 4 is pressed against the concrete structure 1 from the affixed gel sheet 5, so that the flaw detection surface 2 and the ultrasonic probe 4 are placed between the flaw detection surface 2 and the ultrasonic probe 4. Conventionally, it has been proposed to perform ultrasonic flaw detection work on the flaw detection surface 2 with the gel sheet 5 interposed (see, for example, Patent Document 1).

In addition, when cleaning the surface of indoor and outdoor structures, such as concrete structures, the structure surface is cleaned instead of cleaning with a detergent using a brush or the like. The film-forming polymer-containing liquid is applied to the surface of the place to be dried and dried, and the generated film is peeled off from the surface of the structure, so that the dirt adhering to the surface of the structure can be removed together. A so-called pack cleaning method has been developed that peels and removes dirt by adhering to the film side (see, for example, Patent Document 2).

JP 2003-114221 A JP-A-9-141221

However, in the technique in which the solid gel sheet 5 is interposed between the flaw detection surface 2 of the concrete structure 1 and the ultrasonic probe 4 as shown in Patent Document 1, the gel sheet 5 and the concrete structure are disposed. There is a problem that an air layer is easily formed between the flaw detection surface 2 of the object 1 and, as is clear from the experimental results of the examples described later, the ultrasonic attenuation is increased and accurate flaw detection results are often not obtained. There is.

In addition, what was shown by patent document 2 apply | coats a film-forming polymer on the stain | pollution | contamination already adhered to the surface of a structure, is dried, and peels off the produced | generated film | membrane by peeling off the produced | generated film | membrane. This is a technique for removing dirt at the same time. Therefore, the dirt to be removed must adhere to the polymer film to be formed and is applied to remove the liquid contact medium remaining on the surface of the structure after the ultrasonic flaw detection work is completed. It is not possible and no suggestion is made regarding the removal of liquid substances.

Therefore, the present invention provides an ultrasonic flaw detection method that can easily remove the contact medium from the flaw detection surface after the completion of the ultrasonic flaw detection operation and obtain an accurate flaw detection result. It is something to try.

In order to solve the above-mentioned problem, the present invention applies a solution of a polymer having sheet forming ability to a flaw detection surface of a target structure, then forms the polymer into a sheet, and then a polymer formed on the flaw detection surface. An ultrasonic flaw detection method is performed in which a contact medium is applied to the surface of the sheet, and an ultrasonic probe is pressed against the application surface of the contact medium to perform ultrasonic flaw detection on the flaw detection surface of the target structure.

  In the above, the polymer solution is formed into a sheet by drying.

According to the ultrasonic flaw detection method of the present invention, after a polymer solution having sheet forming ability is applied to the flaw detection surface of the target structure, the polymer is formed into a sheet, and then the polymer sheet formed on the flaw detection surface. Since the contact medium is applied to the surface of the contact structure and the ultrasonic probe is pressed against the surface to which the contact medium is applied, the flaw detection surface of the target structure is subjected to ultrasonic flaw detection. Demonstrate the effect.
(1) Since a polymer solution is applied to the surface of the flaw detection surface of the target structure to form a sheet and then a contact medium is applied to the surface of the polymer sheet, the flaw detection operation is performed. Even if there are irregularities, the polymer sheet formed on the surface can smooth the irregularities and reduce the amount of irregularities, so that the ultrasonic probe can be prevented from hitting one piece, and the ultrasonic probe can be attached to the polymer sheet. It is possible to reduce resistance when moving while being in contact with the surface, it is possible to facilitate moving flaw detection, and flaw detection can be performed easily.
(2) Furthermore, in order to form a polymer sheet by applying a polymer solution to the flaw detection surface of the target structure, almost no bubbles that interfere with ultrasonic propagation are mixed into the flaw detection surface. The polymer sheet can be formed.
(3) Therefore, according to the above (1) and (2), it is possible to obtain an accurate ultrasonic flaw detection result.
(4) Moreover, the contact medium applied to the surface of the polymer sheet can be removed together by peeling the polymer sheet from the flaw detection surface after completion of the ultrasonic flaw detection operation. Accordingly, it is possible to eliminate the cleaning work conventionally required for removing the contact medium from the target structure.
(5) In the above, when the polymer solution is formed into a sheet by drying, the polymer sheet applied to the flaw detection surface of the target structure can be dried to easily form the polymer sheet.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

FIGS. 1 (a), (b), (c), and (d) show procedures in an embodiment of the ultrasonic flaw detection method of the present invention. First, as shown in FIG. For example, when the concrete structure 1 is used, a polymer solution having a film-forming property at the time of drying, such as a 15% polyvinyl alcohol aqueous solution, is applied to the flaw detection surface 2 of the concrete structure 1 more than the region to be flaw-detected. The polymer sheet (coating) 6 is formed on the flaw detection surface 2 after being applied so as to be slightly wider and then dried.

Next, as shown in FIG. 1B, for example, a glycerin-based contact medium 3 is applied to the surface of the polymer sheet 6 formed in advance on the flaw detection surface 2 in the same manner as in the prior art. As shown in (c), an ultrasonic probe 4 of an ultrasonic flaw detector is pressed against the coated surface of the applied contact medium 3, and the flaw detection surface 2 of the concrete structure 1 is placed on the contact medium 3. Carry out ultrasonic flaw detection work.

After the ultrasonic flaw detection work is completed, the polymer sheet 6 is peeled off from the surface of the concrete structure 1 as shown in FIG. 1 (d), and is thereby applied and adhered to the surface of the polymer sheet 6. The contact medium 3 is removed from the surface of the concrete structure 1 together with the polymer sheet 6.

The amount of the polymer solution such as the 15% polyvinyl alcohol aqueous solution applied is such that when the polymer sheet 6 formed by drying is peeled off from the surface of the concrete structure 1 as the target structure after flaw detection, The thickness of the sheet 6 is set so as to have a certain strength so that a series of peeling operations can be performed without causing breakage, and the unevenness on the surface of the concrete structure 1 as the target structure is filled to some extent. However, what is necessary is just to adjust suitably according to the characteristic of the polymer to be used.

Thus, according to the ultrasonic flaw detection method of the present invention, after the polymer sheet 6 is formed on the surface of the concrete structure 1 in advance, the contact medium 3 is applied to the surface of the polymer sheet 6,
Since the ultrasonic probe 4 is pressed against the application surface of the contact medium 3 to perform a flaw detection operation, the contact medium 3 can be prevented from directly contacting the concrete surface of the concrete structure 1,
For this reason, the penetration of the contact medium 3 into the concrete surface can be reliably prevented, and the contact medium 3 adhering to the surface of the polymer sheet 6 can also be removed from the surface of the concrete structure 1 at the same time by peeling the polymer sheet 6. Therefore, it is possible to omit the cleaning operation of the contact medium 3 which requires a great amount of labor as conventionally required, and it is possible to reduce the labor required for the entire ultrasonic flaw detection operation.

Further, since the polymer sheet 6 can be formed by applying a polymer solution and then drying it, ultrasonic waves are formed between the polymer sheet 6 to be formed and the surface of the concrete structure 1 or inside the polymer sheet 6. Bubbles that obstruct the propagation are not mixed, and a decrease in ultrasonic flaw detection sensitivity due to the polymer sheet 6 being interposed between the concrete structure 1 and the ultrasonic probe 4 can be suppressed. Furthermore, since the contact medium 3 for propagating ultrasonic waves similar to the conventional one is interposed between the ultrasonic probe 4 and the polymer sheet 6, attenuation of the ultrasonic waves can be suppressed.

Further, even when the surface of the flaw detection surface 2 of the concrete structure 1 is rough and uneven, the polymer sheet 6 is formed on the surface of the concrete structure 1 to smooth the unevenness. Therefore, the ultrasonic probe 4 can be prevented from coming into contact with each other, and the ultrasonic probe 4 can be kept in contact with the surface of the polymer sheet 6. The resistance at the time of movement can be reduced, and moving flaw detection can be facilitated.

Therefore, as is clear from the results of the embodiment as shown in FIG. 3 to be described later, an accurate flaw detection result can be obtained.

In addition, this invention is not limited only to the said embodiment, The polymer to be used is
If the polymer sheet 6 formed without reacting with the surface material of the target structure can be easily peeled off from the surface of the target structure and does not react with the contact medium 3 applied to the surface of the polymer sheet 6, polyvinyl alcohol In addition to drying, the temperature may be changed from a warmed state to cooling to room temperature, reaction with a curing agent mixed in advance before application to the surface of the polymer sheet 6, etc. A polymer that forms a sheet by the chemical reaction of may be used. The target structure can be applied to ultrasonic flaw detection on a target structure other than the concrete structure 1, such as a steel structure, and can be variously modified without departing from the scope of the present invention. .

  Hereinafter, the results of experiments conducted by the present inventors will be described.

As shown in FIG. 2, a 300 mm thick concrete plate 7 is used as a model of the target structure, and a polymer sheet 6 is formed on the flaw detection surface 2 according to the ultrasonic flaw detection method of the present invention, and the surface of the polymer sheet 6 is contacted. After applying the medium 3, the ultrasonic probe 4 is pressed and a frequency of 25
In the case of measuring a back reflected wave (Back-wall echo) due to an ultrasonic wave of 0 kHz and interposing only the contact medium 3 between the flaw detection surface 2 and the ultrasonic probe 4, A comparison was made with the back reflected wave in the case where a gel sheet 5 having a thickness of 5 mm and a thickness of 2 mm was interposed as the proposed gel sheet 5.

As a result, a result as shown in FIG. 3 was obtained. In the case of performing the ultrasonic flaw detection method of the present invention, the attenuation amount of the back reflected wave is, as indicated by a circle in the figure, the contact medium 3 as in the conventional ultrasonic flaw detection method.
It was found that the ultrasonic flaw detection sensitivity was not lowered even in the presence of the polymer sheet 6.

It was also found that the amount of ultrasonic attenuation was small compared to the case of using a 5 mm thick gel sheet (indicated by Δ in the figure) and the case of using a 2 mm thick gel sheet (indicated by □ in the figure).

The procedure in one Embodiment of the ultrasonic flaw detection method of this invention is shown, (A) is the state which apply | coated the polymer polymer solution to the flaw detection surface, and has formed the polymer sheet, (B) is a polymer sheet. (C) shows a state in which an ultrasonic probe is applied to the surface to which the contact medium is applied, and (d) shows a state in which the polymer sheet is peeled off. It is a schematic perspective view. It is a schematic diagram which shows the apparatus structure used for the experiment for comparing the ultrasonic attenuation amount when using the ultrasonic flaw detection method of this invention with the ultrasonic attenuation amount using another method. It is a figure which shows the relationship between what is interposed between an ultrasonic probe and the concrete board used as a test object, and an ultrasonic attenuation amount. The procedure of a conventional ultrasonic flaw detection method is shown. (A) shows a state in which a contact medium is applied to the flaw detection surface, and (B) shows a state in which the ultrasonic probe is applied to the application surface of the contact medium. (C) is a schematic perspective view which respectively shows the state which wash | cleans the contact medium adhering to the flaw detection surface after ultrasonic flaw detection. It is a schematic diagram which shows the ultrasonic flaw detection method using the solid-state gel sheet conventionally proposed.

Explanation of symbols

1 Concrete structure (target structure)
2 Flaw detection surface 3 Contact medium 4 Ultrasonic probe 6 Polymer sheet

Claims (2)

After a polymer solution having sheet-forming ability is applied to the flaw detection surface of the target structure, the polymer is formed into a sheet, and then a contact medium is applied to the surface of the polymer sheet formed on the flaw detection surface. An ultrasonic flaw detection method comprising performing ultrasonic flaw detection on a flaw detection surface of the target structure by pressing an ultrasonic probe against a coated surface of a contact medium. The ultrasonic flaw detection method according to claim 1, wherein the polymer solution is formed into a sheet by drying.

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