JP2923510B2 - Inspection method of small diameter pipe inner surface - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for inspecting the inner surface of a small-diameter pipe, and more particularly to a method for inspecting the inner surface of a long small-diameter pipe provided in a state penetrating a lower mirror portion of a container. The present invention relates to an inspection method suitable for performing a metal structure survey or the like.

[Prior Art] Many small-diameter pipes are used in pipes used in nuclear power generation-related facilities, thermal power plants, chemical plants, and the like.

For example, as shown in FIG. 2, a small-diameter pipe 2 for transmitting signals of various sensors for detecting the state of the reactor, etc. are provided in a lower mirror section 1 of a reactor pressure vessel in a boiling water reactor. The small-diameter pipe 2 is attached in a vertically penetrated state by a welded portion 3 and has an inner diameter of, for example, about 38 mm and a length of several meters. In this case, the portion of the welded portion 3 supports the small-diameter tube 2 that penetrates the wall of the lower mirror portion 1 at an angle, and is easily affected by the deformation force due to the expansion and contraction or bending of the small-diameter tube 2. In addition to the requirement for ensuring the weldability, it is desirable to inspect the condition of the wall of the small-diameter pipe 2 at or near the welded portion 3 at the time of periodic inspection or the like.

Conventionally, a method of examining whether a pipe wall attached by welding is subjected to concentrated stress or abnormal by inspecting a metal structure (sampling) by pressing a transfer film against the inner surface of the pipe. Is considered.

"Problem to be Solved by the Invention" However, the above-described inspection method using a transfer film is applicable when the diameter of the pipe is relatively large or when the pipe is short, as in the case of FIG. If the long small-diameter tube 2 is vertically attached to the lower mirror unit 1 and the transfer film must be inserted from below, the pre-processing work until the transfer step is performed. In the vicinity of the lower entrance, it can be applied only to a depth of, for example, about 5 cm, and it is impossible to use a long object that extends over several meters.

The present invention has been made in view of such a problem. In other words, the purpose is to easily investigate the metal structure in the deep part of the small diameter pipe.

"Means for solving the problem" A cleaning liquid ejecting member, an electrode, and a liquid supply nozzle are inserted into a small-diameter pipe in an upright state, in which a sealing member expandable and contractable by air pressure penetrates upward. And at the same time, expand the sealing tool to partition the inside of the small-diameter pipe into upper and lower sections, store oxalic acid solution on the sealing tool, and electrolytically corrode the inner surface of the small-diameter pipe in the oxalic acid atmosphere. An organic solvent is adhered to the inner surface of the small-diameter tube, and the transfer film is pressed against the inner surface of the small-diameter tube to which the organic solvent is adhered to transfer the state of the inner surface.

"Action" By expanding the seal, the inside of the small-diameter pipe is divided into upper and lower sections, and oxalic acid is supplied to the pipe hole above it.
Oxalic acid accumulates on the closure. If the inner surface of the small-diameter tube is electrolytically corroded in the oxalic acid atmosphere, and a defect is formed inside the small-diameter tube, the portion is more significantly electrolytically corroded.

After the electrolytic corrosion, when the transfer film is pressed with the organic solvent adhered to the inner surface of the small-diameter tube, the transfer film in the portion where the contact pressure is large is melted due to the unevenness of the inner surface of the small-diameter tube, and a defect is generated. In this case, dissolution delay or unevenness in the range occurs, and the surface shape is transferred.

The transfer film is taken out of the small-diameter tube and inspected precisely to determine the presence or absence of a defect.

Example An example of the method for inspecting the inner surface of a small-diameter pipe according to the present invention will be described below with reference to FIG.

As shown in FIG. 1 (A), when the small-diameter pipe 2 is attached to the lower mirror section 1 in a standing state (vertical state) by the welding section 3, the small-diameter pipe 2 is surrounded by the welding section 3. Inspection of the inner surface of the small-diameter pipe in the vicinity is performed. That is, an inspection is performed to determine whether the pipe wall of the small-diameter pipe 2 supported by the welded portion 3 is not affected by concentrated stress or the like, and a metallographic examination is performed.

<Polishing Step> The inspection target portion is polished prior to each operation described below. The inside diameter of the small diameter pipe 2 is small (for example, 50
mm or less), for example, the polishing apparatus 4 shown in FIG. 1A is applied.

The polishing apparatus 4 includes a mounting member 4a mounted on the lower flange portion 2a, a support sleeve 4b penetrating through the mounting member 4a and inserted into the inside of the small-diameter tube 2, and freely rotatable into the support sleeve 4b. Torque transmission wire inserted in
4c, a brush-like polishing member 4d attached to the tip of the rotational force transmission wire 4c, a driving source (motor) 4e for rotationally driving the rotational force transmission wire 4c, and a plurality of locations inside the small diameter pipe. And a spacer 4f for preventing the support sleeve 4b from swaying. Reference numeral 4g denotes fasteners such as bolts and nuts.

Then, by operating the drive source 4e, the polishing member
By rotating 4d, a desired portion of the small-diameter tube 2 and a portion to be inspected are polished.

<Oxalic acid supply step> As shown in FIG. 1 (B), the cleaning liquid jetting member connected to the cleaning liquid supply system 5 is provided inside the small-diameter pipe 2 after the polishing operation, with the polishing apparatus removed. 5a, an electrode 7 connected to a DC power supply 6, a liquid supply nozzle 8a connected to an oxalic acid liquid supply system 8, a sealing tool 9a, and the like are inserted. Each of these devices is supported by inserting a support sleeve 4b inside the small-diameter tube 2 according to FIG. 1 (A), but the description is omitted in FIG. 1 (B).

The seal 9a is connected to a seal operating system 9 for expanding the seal 9a by air pressure, and an electric cable 6a, a liquid supply pipe and the like connected to the electrode 7 are supported in a penetrating state. .

Then, pressurized air is sent from the sealing tool operation system 9,
The sealing tool 9a is expanded to partition the inside of the small-diameter pipe 2 into upper and lower sections, and the oxalic acid solution supply system 8 operates to supply the solution supply nozzle 8a.
Supply oxalic acid solution (for example, 10% concentration, normal temperature)
The oxalic acid solution is stored on the sealing tool 9a.

<Electrolytic Corrosion Step> While the oxalic acid solution is stored, that is, while the inspection target portion is maintained in the oxalic acid atmosphere, power is supplied from the DC power supply 6 to perform electrolytic corrosion of the inspection target portion. If a defective portion is formed on the inner surface of the small-diameter pipe 2 due to the electrolytic corrosion, the electrolytic corrosion is performed so that the defective portion is emphasized. In addition, the time for performing electrolytic corrosion is the above-mentioned 10% concentration solution,
In the case of normal temperature, for example, about 5 to 10 minutes.

<Oxalic acid extracting step> After electrolytically corroding the inner surface of the small-diameter pipe in an oxalic acid atmosphere and a portion to be inspected, the air of the sealing tool 9a is evacuated and stored to allow the oxalic acid to flow down.

<Alcohol Cleaning Step and Air Blowing Step> By the operation of the cleaning liquid supply system 5, alcohol as a cleaning liquid is jetted from the cleaning liquid jetting member 5a, and the oxalic acid attached to the inspection target is washed away. Air is blown in to evaporate and remove the alcohol adhering to the inspection target portion.

<Organic Solvent Supplying Step> As shown in FIG. 1 (C), after removing the appliances shown in FIG. 1 (B) which had been inserted into the small-diameter tube 2 after the alcohol washing was completed, A transfer member 10a connected to the transfer tool operation system 10, a spray tool 11a connected to the organic solvent supply system 11, a guide member 12, and the like are inserted. In FIG. 1 (C), a support sleeve for supporting each of these devices is provided.
The description such as 4b is omitted.

An organic solvent such as acetone is supplied from the organic solvent supply system 11, and is spouted from the spray tool 11a, so that an appropriate amount of the organic solvent is attached to the inner surface of the small-diameter tube at a desired inspection target location.

<Transfer Step> In a state where the organic solvent is attached to the inspection target portion, the position of the transfer member 10a is lowered, the diameter is increased, and the transfer film 13 attached to the outer surface is attached to the organic film. Pressing on the inner surface of a small-diameter pipe, the transfer film
The state of the metallographic structure is transferred to the transfer film 13 by maintaining a time (for example, several minutes or more) in which the surface of the metallographic structure 13 is dissolved in accordance with the uneven shape of the metallographic structure.

<Metal Structure Investigation Step> Next, the transfer member 10a is lowered and the transfer film 13 is taken out of the small-diameter tube 2, and a detailed inspection of the metal structure of the inspection target is performed, and the metal structure transferred to the film 13 is performed. From the patterns (1) and (2), it is determined whether the inner surface of the small-diameter tube 2 is normal or a defective portion is present.

In the examples of FIGS. 1 (A) to 1 (C), a description has been given of a case where a plurality of instruments are simultaneously fed into the small-diameter tube 2. It can also be sent.

[Effects of the Invention] As described above, the method for inspecting the inner surface of a small-diameter pipe according to the present invention includes a sealing tool and a liquid supply nozzle that can be expanded and contracted by air pressure with respect to the small-diameter pipe in an upright state. Is inserted to store the oxalic acid solution, and the inner surface of the small-diameter tube is electrolytically corroded. Then, an organic solvent is attached to the inner surface of the small-diameter tube, and the transfer film is pressed onto the inner surface of the small-diameter tube to transfer the inner surface state. Therefore, even if the inspection target is a deep part of the small diameter pipe, it is possible to send each inspection tool and easily investigate the metal structure of the inspection target, and limit the length of the small diameter pipe. Less likely to receive

Even when the small-diameter pipe penetrates obliquely to the wall of the container, such as the lower mirror portion of the container, the present invention can be easily applied.

And so on.

[Brief description of the drawings]

1 (A) to 1 (C) are front sectional views illustrating steps in an embodiment of a method for inspecting the inner surface of a small diameter pipe according to the present invention, and FIG. 2 penetrates a lower mirror portion of a container. It is a front sectional view showing the example of a small diameter pipe. 1 lower mirror part, 2 small-diameter pipe, 2a lower flange part
3 ... welded part, 4 ... polishing device, 4a ... mounting member,
4b …… Support sleeve, 4c …… Turning force transmission wire, 4e ……
Driving source (motor), 4d: polishing member, 4f: spacer,
4g: Fastener, 5: Cleaning liquid supply system, 5a: Cleaning liquid ejection member, 6: DC power supply, 6a: Electric cable, 7: Electrode, 8: Oxalic acid liquid supply system, 8a: Liquid Supply nozzle, 9
... Sealing device operating system, 9a ... Sealing device, 10 ... Transferring device operating system, 10a ... Transferring member, 11 ... Organic solvent supply system, 11a ...
Spraying device, 12 ... Guide member, 13 ... Transfer film.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hiroshi Shimamura 1st Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Ishikawajima-Harima Heavy Industries, Ltd. Yokohama No. 1 Plant (56) References JP-A-1-263532 (JP, A JP-A-57-154038 (JP, A) JP-A-60-56251 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 1/28 G21C 17/00-17 / 14

Claims (1)

(57) [Claims] 1. A cleaning liquid ejecting member (5a) and an electrode (7) in a state in which a sealing member (9a) that can be expanded and contracted by air pressure penetrates upward in a small-diameter pipe (2) in an upright state. ) And the liquid supply nozzle (8a), and the inside of the small-diameter pipe is divided into upper and lower parts by expanding the sealing tool, and the oxalic acid solution is stored on the sealing tool to store the oxalic acid atmosphere. After electrolytically corroding the inner surface of the small-diameter tube, an organic solvent is adhered to the inner surface of the small-diameter tube, and the transfer film (13) is pressed against the inner surface of the small-diameter tube to which the organic solvent is adhered to transfer the inner surface state. A method for inspecting the inner surface of a small-diameter pipe, characterized in that: