JP4262366B2 - Pipe ultrasonic inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic inspection method for inspecting thinning, cracking, and the like generated in a pipe using an ultrasonic water immersion method.
[0002]
As shown in FIG. 5, a plurality of pipes 50 are arranged in parallel in a catalyst packed tube of a reactor, a heat transfer tube of a heat exchanger, and the like, and both ends thereof are fixed by a tube plate 51. Since these pipes 50 may be thinned during use, the pipe thickness is periodically inspected.
[0003]
For pipe wall thickness inspection, an ultrasonic water immersion method that can obtain high inspection accuracy is widely used. In this method, an ultrasonic probe 53 is inserted into a pipe 50 into which water 52 has been injected, and an ultrasonic wave is transmitted directly or from the ultrasonic probe 53 in the axial direction of the pipe 50 as an acoustic mirror. The light is reflected by a light beam (not shown) and vertically incident on the inner surface of the pipe 50. And the method of measuring the difference in propagation distance of the echo S from the normal inner surface without the thinning of the pipe 50 and the echo S ′ from the thinning part as the thinning amount, or the ultrasonic wave in the pipe thickness A method of measuring the propagation time and converting it to a thickness is used.
The lower end of the pipe 50 is previously closed with a water stopper member 54 such as a rubber stopper.
[0004]
[Problems to be solved by the invention]
In order to inspect the pipe 50 by the ultrasonic water immersion method described above, first, water 52 is injected into the pipe 50. In order to perform an inspection over almost the entire length of the pipe 50, the inside of the pipe 50 needs to be almost filled with water 52. For this reason, if the injection amount of the water 52 into the pipe 50 is large, when the thickness measuring jig (hereinafter referred to as a measuring jig) to which an ultrasonic probe is attached is inserted, the water 52 is removed from the pipe 50. There is a risk of overflowing and passing through the tube sheet 51 into another adjacent pipe 50.
[0005]
However, when the pipe 50 is used as a catalyst filling pipe of the reactor, if the water overflowing from the pipe 50 enters the adjacent pipe 50 filled with the catalyst, the packed catalyst is adversely affected.
In addition, when the pipe 50 is used as a heat transfer tube of a heat exchanger, depending on the physical properties of the fluid in the pipe, when the heat exchanger is opened and no measures such as detoxification or cleaning are performed over the entire number of pipes. May hate contact with water.
[0006]
Therefore, when inserting the measuring jig, water must be poured carefully so that the water does not overflow from the pipe 50. However, even if the measuring jig is inserted slightly in the pipe axial direction, the pipe having a small diameter is inserted. At 50, there is a risk that the water surface will rise sharply and the water will overflow. Further, when the measuring jig is pulled out, water does not exist in the upper part of the pipe 50 and inspection by the ultrasonic water immersion method becomes impossible, so it is necessary to add water and inject it. Inspection work this reason had become extremely complicated and difficult.
[0007]
Accordingly, a main object of the present invention is to provide an ultrasonic inspection method for a pipe that facilitates inspection work by suppressing the liquid level from rising greatly even when a liquid such as water is injected into the pipe. It is.
[0008]
[Means for Solving the Problems]
The ultrasonic inspection method of the present invention for solving the above-mentioned problem is to inspect a pipe by inserting an ultrasonic probe into a pipe into which liquid has been injected, and the liquid in the pipe is discharged from the lower end of the pipe. It is characterized by communicating with the liquid in the liquid tank through the extended communication pipe, adjusting the liquid level of the liquid tank, and setting the liquid level in the pipe to a predetermined height.
[0009]
Since the liquid in the pipe and the liquid in the liquid tank are communicated through the communication pipe in this way, when the liquid tank is positioned beside the pipe, the liquid level in the liquid tank and the liquid level in the pipe Is the same height when the pressure loss of the communication pipe is negligibly small. In this state, if the liquid level in the liquid tank is adjusted to set the liquid level in the pipe to a predetermined level, the thickness measurement jig with the probe attached can be inserted into or pulled out of the pipe. Since the liquid in the liquid tank is in communication with the liquid in the pipe, it is possible to prevent the liquid level in the pipe from rising sharply and greatly.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory view showing an ultrasonic inspection method according to this embodiment.
In FIG. 1, reference numeral 1 denotes a pipe to be inspected, and a plurality of pipes 1 are held by a tube plate 2. Among these, the lower end of one pipe 1 is closed by the liquid stopper 3, and one end of the communication pipe 4 is connected to the liquid stopper 3. The other end of the communication pipe 4 is connected to the bottom of the liquid tank 5.
[0015]
Since the communication pipe 4 is a tube made of a flexible material such as plastic or rubber, the height of the liquid tank 5 can be arbitrarily adjusted.
The liquid tank 5 is a container whose upper surface is open. A liquid 6 is placed in the pipe 1 and the liquid tank 5 connected by the communication pipe 4. This liquid 6 is used for the thickness inspection of the pipe 1 by the ultrasonic water immersion method described above, and usually water is used, but instead of water, lower alcohol such as methyl alcohol or other Various liquids may be used.
[0016]
The liquid in the liquid tank 5 and the liquid in the pipe 1 communicate with each other through the communication pipe 4. For this reason, when the liquid tank 5 is positioned beside the pipe 1, the liquid level 8 in the liquid tank 5 and the liquid level 9 in the pipe 1 are positioned in the same horizontal plane. Accordingly, if the liquid level in the liquid tank 5 is set so that the liquid level 9 in the pipe 1 is at a predetermined height, further liquid is injected into the pipe 1 or the ultrasonic probe 7 is used. Even when the liquid level rises by immersing the liquid in the liquid 6 in the pipe 1, the liquid level in the pipe 1 is small, so that the liquid overflows from the upper end of the pipe 1 due to a sudden rise in the liquid level. Inflow into other pipes can be suppressed.
[0017]
The horizontal cross-sectional area of the liquid tank 5 is preferably as large as possible in order to prevent a sudden rise in the liquid level in the pipe 1. In order to suppress the liquid level fluctuation in the pipe 1 within 1 mm, the horizontal cross-sectional area of the liquid tank 5 should be at least m times the horizontal cross-sectional area of the thickness measuring jig inserted into the pipe 1 (however, m is the insertion length (mm) of the thickness measuring jig into the pipe 1). In this case, if the liquid tank 5 having an excessively large horizontal cross-sectional area is used, handling becomes difficult. Therefore, when the liquid level fluctuation allowable amount in the pipe is n (mm), the horizontal cross-sectional area of the wall thickness measuring jig It is appropriate to use the liquid tank 5 having a horizontal sectional area of about m / n times.
[0018]
After the liquid level in the pipe 1 is set at a predetermined position, the probe 7 is immersed in the liquid in the pipe 1 as described above, and ultrasonic inspection is performed. That is, the probe 7 is inserted into the pipe 1 into which the liquid 6 has been injected, and an ultrasonic wave is incident on the inner surface of the pipe 1 directly or via a reflector such as an acoustic mirror (not shown). Then, a method of measuring the difference in propagation distance between the echo S from the normal inner surface without thinning of the pipe 1 and the echo S ′ from the thinned portion as the thinning amount, or the propagation of ultrasonic waves in the pipe thickness A method of measuring time and converting to thickness is used. If this inspection method is used, the presence or absence of the thinned portion can be inspected for each of the inner surface and the outer surface of the pipe 1.
[0019]
As the water stop device 3 shown in FIG. 1, for example, a plug member such as a rubber plug or a cork plug that is inserted through a tube body such as a glass tube or a metal tube can be used. Since it is simply inserted into the lower end of the pipe 1, there is a possibility that the pipe 1 may be accidentally pulled out. Therefore, it is necessary to use a water stop device that can reliably prevent the pipe 1 from coming off and has a high water stop effect.
[0020]
2 and 3 show a water stop device 3 according to a preferred embodiment of the present invention. FIGS. 2A and 2B are a partially broken side view and a cross-sectional view taken along line AA ′ showing the water stopper 3 in a normal state.
[0021]
As shown in FIG. 2 (a), the liquid stopper 3 includes a cylinder 10 that is inserted into the lower end of the pipe, and a sleeve 11 that is externally attached to the outer peripheral surface of the cylinder 10. The cylindrical body 10 has a flange portion 12 formed at the tip, and a male screw portion 13 provided on the outer peripheral surface of the body portion. On the other hand, on the inner peripheral surface of the sleeve 11, a female screw portion 14 that is screwed with the male screw portion 13 of the cylindrical body 10 is provided.
[0022]
A distal end cylindrical portion 18 coaxial with the cylindrical body 10 is integrally attached to the distal end of the cylindrical body 10 by welding or the like, and protrudes from the sleeve 11. Similarly, a rear end cylindrical portion 19 coaxial with the cylindrical body 10 is integrally attached to the rear end of the cylindrical body 10. The communication pipe 4 is fitted to the rear end cylinder part 19.
Further, on the outer peripheral surface of the rear end portion of the tubular body 10, a knob 20 for rotating the tubular body 10 with respect to the sleeve 11 and screwing the male screw portion 13 and the female screw portion 14 is externally fixed. . That is, the knob 20 is provided with a through screw hole 21 for screwing a set screw (not shown) for fixing the knob 20 on the outer peripheral surface of the cylindrical body 10.
[0023]
A large diameter portion 22 is provided at the rear end of the sleeve 11. The large diameter portion 22 is located outside the lower end of the pipe 1 when the water stopper 3 is used, and is used for fixing the sleeve 11 with the other hand when the knob 20 is turned with one hand. .
The back surface of the flange portion 12 and the front end surface of the sleeve 11 are formed in a slope shape so that the gap between them gradually increases outward in the radial direction. Is formed.
[0024]
A plurality of spread pieces 16 are arranged in the groove 15 along the circumferential direction of the cylindrical body 10. Both end surfaces of each spreading piece 16 are formed in inclined surfaces corresponding to the back surface of the flange portion 12 and the front end surface of the sleeve 11, and the surfaces are in contact with each other in the normal state shown in FIG.
The plurality of spread pieces 16 are bound together by an elastic ring 17 mounted in a recess formed on the outer peripheral surface thereof. As the elastic ring 17, for example, a normal O-ring made of a rubber material or the like that is extensible in the radial direction can be used.
[0025]
In the liquid stopper 3 shown in FIG. 2 configured as described above, when the knob 20 is turned to retract the cylinder 10 with respect to the sleeve 11 (in the direction of arrow C), the width of the groove 15 (that is, the cylinder axis) (Directional length) decreases sequentially. Accordingly, each of the expanded pieces 16 is pushed outward in the radial direction of the cylindrical body 10, and as a result, the diameter D shown in FIG. 2 (b) formed by arranging a plurality of expanded pieces 16 is greatly expanded. Become.
[0026]
3 (a) and 3 (b) show an enlarged state in which a plurality of spread pieces 16 are completely extruded from the normal state shown in FIGS. 2 (a) and 2 (b). That is, when the cylindrical body 10 is completely retracted with respect to the sleeve 11, the base portion of the inclined surface is in contact with or close to the distal end surface of the sleeve 11 and the rear surface of the flange portion 12, and the groove 15 is almost a triangle. It becomes a cross-sectional shape. At this time, each of the expanded pieces 16 slides between the end surface of the sleeve 11 and the back surface of the flange portion 12 and is pushed outward in the radial direction of the cylindrical body 10, as shown in FIG. 3 (b). In this way, the diameter D is greatly expanded.
[0027]
Next, a method for closing the lower end of the pipe 1 using the liquid stopper 3 according to the present invention will be described with reference to FIG.
FIG. 4 shows the usage state of the liquid stopper 3. As shown in FIG. 4, a portion of the liquid stopper 3 inserted into the pipe 1 is covered with an elastic cover 23 except for the distal end tubular portion 18. This is because, as shown in FIG. 3 (b), in the expanded state in which the plurality of expanded pieces 16 are pushed outward, a gap is formed between the expanded pieces 16, and there is a risk of liquid leakage from there. This is because the elastic cover 23 prevents liquid leakage.
[0028]
For this reason, the elastic cover 23 may cover at least the outer surface from the pipe-side tip surface of the flange portion 12 to the plurality of spread pieces 16 bound by the elastic ring 17. In this embodiment, the elastic cover 23 has a length with the lower end reaching near the large diameter portion 22, and the lower end is fixed by an elastic ring 24 such as an O-ring. The elastic cover 23 has elasticity and is made of a rubber material such as natural rubber or synthetic rubber.
[0029]
In order to close the lower end of the pipe 1 using the liquid stopper 3, first, the elastic cover 23 is attached to the liquid stopper 3 in a normal state shown in FIG. 2 and then inserted into the pipe 1 from the lower end. Next, the large-diameter portion 22 at the rear end of the sleeve 11 is held and fixed with one hand, and the knob 20 is turned with the other hand to screw the cylinder 10 backward (in the direction of arrow C). Along with this, the width of the groove 15 becomes narrower, and the plurality of spread pieces 16 are gradually pushed outward to increase the diameter D. Then, the elastic cover 23 is brought into contact with the inner surface of the pipe 1, and the knob 20 is further rotated to push the plurality of spread pieces 16 outward, so that the elastic ring 17 is strongly pressed against the inner surface of the pipe 1 through the elastic cover 23. .
[0030]
Thus, as shown in FIG. 4, the liquid stopper 3 is firmly fixed to the lower end of the pipe 1, and there is no risk of falling off easily due to liquid pressure or the like, and also exhibits a high liquid stopper effect to prevent liquid leakage. Therefore, as shown in FIG. 1, it is suitable for use in ultrasonic inspection of a pipe performed by injecting a liquid into a pipe 1 communicated with a liquid tank 5 through a communication pipe 4.
[0031]
In addition, when applied to a pipe having a diameter larger than that of the pipe 1 shown in FIG. 4, the expansion piece 16 is replaced with one having a large thickness, and the outward extrusion length is increased, so that it can be easily handled can do.
[0032]
【The invention's effect】
According to the ultrasonic inspection method of the present invention, the liquid in the pipe is communicated with the liquid in the liquid tank via the communication pipe, the liquid level in the liquid tank is adjusted, and the liquid level in the pipe is set to a predetermined height. Therefore, even if a thickness measuring jig is inserted or pulled out from the pipe, the liquid level in the pipe suddenly rises and the liquid is prevented from overflowing. Therefore, there is an effect that the ultrasonic inspection work becomes easy.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of an ultrasonic inspection method for a pipe according to an embodiment of the present invention.
FIGS. 2A and 2B are a partially broken side view and a cross-sectional view taken along line AA ′ showing a main part of the water stopper in a normal state, respectively.
FIGS. 3A and 3B are a partially broken side view and a sectional view taken along line BB ′ showing a main part of the water stopper in an enlarged state, respectively.
FIG. 4 is a partially broken explanatory view showing a usage state of the water stopper.
FIG. 5 is an explanatory diagram showing a conventional ultrasonic inspection method for pipes.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pipe 2 Tube plate 3 Liquid stop device 4 Communication pipe 5 Liquid tank 6 Liquid 7 Probe 8 Liquid level 9 Liquid level 10 Tube 11 Sleeve 12 Flange part 13 Male thread part 14 Female thread part 15 Groove 16 Expanded piece 17 Elastic ring 23 Elastic cover

Claims (1)

  In an ultrasonic inspection method for inspecting a pipe by inserting an ultrasonic probe into a pipe into which liquid has been injected, the liquid in the pipe is connected to the liquid in the liquid tank via a communication pipe extending from the lower end of the pipe. An ultrasonic inspection method for a pipe, characterized in that the liquid level in the pipe is set to a predetermined height by communicating and adjusting the liquid level in the liquid tank.

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