JP2002005905A - Inspection method of thinning wall or the like by surface wave and inspection device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method of thinning a wall or the like having high measurement accuracy by a surface wave, and an inspection device therefor. SOLUTION: A transmitter 3 of the surface wave and a receiver 4 are arranged across an inspection object part 101 which is a support part of a steel pipe 100 by a flame 102. Scanning of the inspection object part 101 is executed by the transmitter 3 and the receiver 4, keeping the distance between them roughly constant. Thinning or the like D of the inspection object part 101 is inspected by comparing arrival times of received waves by the receiver 4 at each scanning position. Since the arrival times of the received waves are compared at each scanning position and the difference of the arrival times is used, the corrosion state can be inspected more accurately without being influenced by the contact state of the transmitter and the receiver.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method and an inspection apparatus for thinning due to surface waves. For more information,
For example, the present invention relates to an inspection method and an inspection device for wall thinning by a surface wave, which are suitable for inspecting wall thinning due to corrosion generated in a concealing portion supported by a gantry of a support portion in a pipe for maintenance of the pipe.

[0002]

2. Description of the Related Art Conventionally, the number of support structures for a petroleum plant device and pipes (mount, support, hanger, etc.) ranges from tens to hundreds of thousands, depending on the scale of the plant. In addition, most of them are in the outdoor environment and are exposed to the wind and rain, and because of the location of the plant, which is close to the sea, they are affected by salt. In the environment. Therefore, in order to properly maintain and manage the equipment, it is important to improve the reliability of the inspection as a countermeasure against the corrosion of the contact portion of the piping stand.

In order to perform an accurate inspection, the pipe must be lifted from the gantry and inspected, which requires a large amount of inspection cost and time, making maintenance and management of the plant difficult. There is also a problem that it is difficult to apply radiation to large-diameter pipes from the viewpoint of transmission ability.

Therefore, for example, Japanese Patent Application Laid-Open No. 2000-5589
As disclosed in Japanese Patent Publication No. 0, an inspection method for estimating the degree of corrosion using a shear wave transmission attenuation using a contact by ultrasonic waves without lifting a gantry from a pipe has been proposed.

However, according to the technology described in the publication, the evaluation is only for the attenuation of the transmitted pulse, and the degree of attenuation is greatly affected by the contact state of the transmitter and the receiver, and the measurement accuracy is also limited. was there. In addition, since the measurement is affected by the condition of the inner surface of the tube, the overall measurement accuracy is still insufficient in combination with the signal attenuation.

[0006]

SUMMARY OF THE INVENTION In view of such a conventional situation, an object of the present invention is to provide an inspection method and an inspection apparatus for thinning and the like with high measurement accuracy by surface waves.

[0007]

Means for Solving the Problems To solve the above-mentioned problems, a characteristic configuration of the inspection method for wall thinning and the like according to the present invention is to arrange a transmitter and a receiver of a surface wave across an inspection target portion, Scanning of the object to be inspected is performed by these transmitters and receivers while keeping these distances substantially constant, and the arrival time of the received wave by the receiver is compared at each scanning position to inspect the thinning of the object to be inspected. Is to do.

[0008] The inspection target part may be a part of a tube, and a guide device may be provided for scanning the transmitter and the receiver along the circumference of the tube.

On the other hand, the characteristic configuration of the inspection apparatus for thinning and the like according to the present invention is that the transmitter and the receiver of the surface wave arranged over the inspection target part and the inspection part by the transmitter and the receiver are used. A guide device for performing scanning, wherein the guide device includes a pair of first and second guide portions arranged substantially in parallel to support the transmitter and the receiver, respectively, and the first and second guide portions. And a determining means for inspecting a thinned portion of the inspection target portion by comparing the arrival time of the received wave by the receiver at each scanning position. .

Here, the inspection object part may be a part of a tube, and the guide device may scan the transmitter and the receiver along the circumference of the tube.

The first and second guides may be first and second bogies each having a plurality of wheels and being wound along the circumference of the pipe.

The synchronizing means may be a rod connecting the first and second guide portions to each other, so that the structure can be simplified and the synchronization can be ensured. Furthermore, if the similar part is compared by displaying the received wave by shading at each scanning position, visual evaluation becomes possible.

[0013]

According to the above-mentioned feature of the present invention, the arrival time of the received wave is compared at each scanning position and the arrival time difference is used instead of comparing the attenuation of the received wave. The corrosion state can be more accurately inspected without being affected by the contact state of the transmitter and the receiver. Further, since the arrival time of the received wave is compared at each scanning position, even if an error occurs in the distance between the two probes by comparing the sound portions, for example, the error can be easily determined.

In particular, when the arrival times are compared in a state where the received waves are displayed in shades at each scanning position,
Since it is easy to visually recognize the difference in the arrival time of the received wave, it is possible to quickly and easily determine the thickness reduction or the like even without a skilled person.

Other objects, configurations and effects of the present invention will become apparent in the following description of the embodiments of the present invention.

[0016]

Next, embodiments of the present invention will be described in more detail with reference to the drawings. An inspection apparatus 1 according to the present invention is shown in FIGS. The inspection target in this embodiment is a steel pipe 10 used for piping in a plant or the like.
0, the inspection target portion 101 is a portion that is supported and concealed by the gantry 102 and is easily corroded.

The inspection device 1 includes a first carriage 2a, a second carriage 2
b, a transmitter 3 attached to the first carriage 2a, and a receiver 4 attached to the second carriage 2b. The first carriage 2a and the second carriage 2b are connected to the connecting rod 2
The scanning positions by these are read by the encoder 5. Sender 3, Receiver 4
Scans the inspection target portion 101, which is arranged at a position spaced apart in the axial direction of the steel pipe 100 by scissoring the gantry 102 and concealed by the gantry 102.

In the first carriage 2a and the second carriage 2b, a pair of inner plates 21 and
1 and the outer plates 22 are alternately arranged and connected by an axle 23 to form a chain-shaped base. And
By attaching a pair of wheels 25, 25 to each axle 23, a first bogie 2a and a second bogie 2b that can be wound around the outer circumference of the steel pipe 100 and run in the pipe circumferential direction are configured.

A hook 26 is provided at one end of the first truck 2a and the second truck 2b, as shown in FIG.
The first truck 2a and the second truck 2b can be wound around and attached to the outer periphery of the steel pipe 100 by being locked to the tube 3 or the tube 24. The hook 26 has a screw shaft 26a screwed onto the block 26b, and the protrusion amount can be adjusted by relatively rotating the screw shaft 26a and the block 26b.

The steel pipe 10 of the first truck 2a and the second truck 2b
Connecting blocks 27 are attached at two locations in the 0 circumferential direction. The connection block 27 is fixed between the pair of outer plates 22, and penetrates the pair of holes 27 a in a direction along the longitudinal direction of the axle 23. A slit 27b is formed through each of the holes 27a so as to adjust the spread of the holes 27a. Then, while inserting the connecting rod 2c into each of the tightening screws 27c,
By tightening a pair of tightening screws 27c, 27c which are screwed into two places of the connection block 27 by passing through the slits 27b, the connection block 27 is appropriately positioned on the connection rod 2c.
It is possible to fix the first cart 2a and the second cart 2b via the. Connecting rod 2c in one connecting block 27
Are fixed to each other so that the angle between each connecting rod 2c and the first bogie 2a and the second bogie 2b is difficult to expand and contract. Further, by providing two connecting blocks 27, the first bogie 2a and the The second carriage 2b is prevented from being displaced.

FIG. 4 shows a mounting portion of the transmitter 3 and the encoder 5 in the first carriage 2a.
A fixed block 28a is fixed between the base plates 2 and 22, and a channel-shaped pedestal 28b is fixed on the fixed block 28a. Then, the fork-like support arm 29 is extended from one flange of the pedestal 28b to make the transmitter 3
Is supported so as to be elastically pressed against the surface of the steel pipe 100. On the other hand, the encoder 5 is attached to the other flange of the pedestal 28b via a support fitting 30. The encoder 5 includes a wheel 5b that rotates around an axis protruding from the encoder body 5a, and detects a scanning position of the transmitter 3 based on a rotation angle of the wheel 5b. The configuration of the receiver 4 is the same as that of FIG.

FIG. 5 is a block diagram schematically showing the inspection apparatus 1. In this inspection device 1, a transmitter 3, a receiver 4
The scanning position is taken into the personal computer 6 by the encoder 5. In addition, the inspection apparatus 1 includes a pulser 7 that generates an ultrasonic pulse as a surface wave from the transmitter 3 and a receiver 8 that amplifies a reception wave from the receiver 4.
and an A / D converter 8b which converts the amplified wave into digital data and takes it into the personal computer 6.
And The processing results by the personal computer 6 are as shown in FIGS.
a, and output to paper by the printer 9b.

When the inspection target 101 is normal,
The surface wave is transmitted from the transmitter 3 to the receiver 4 along the smooth surface of the inspection target portion 101. However, when the thinned portion D exists in the inspection target portion 101, the surface wave detours along the surface of the thinned portion D, and the arrival time of the received wave with respect to the receiver 4 becomes longer based on the time of transmission, The reception time will be delayed. By examining the time delay at each scanning position, it is possible to determine the presence or absence or the degree of the thinned portion D.

The above-mentioned time delay is determined by comparing similar parts of the wave received by the receiver at each scanning position. FIGS. 6A to 6F show received waveforms at each scanning position. The similar part of the received wave is, for example, the peak P of each waveform in this example.
a to Pf, etc., and the presence or absence of the thinned portion D is determined based on the shift of these time positions based on the transmission time from the transmitter 3. In the figure, (c) to (f) are considered to be corroded portions. Since the time delay between the corroded part and the healthy part is very small, the examination becomes easier if the vicinity of the reception time of the received waveform is enlarged and displayed.

FIG. 7 is a graph showing the B-scan result of the received waveform at each scanning position. Here, the B-scan refers to a process in which the measurement position is moved by a minute distance such as a 1 mm pitch, and a waveform is captured, and the amplitude of the waveform is replaced with the color density. The horizontal axis represents each scanning position, that is, the moving distance of the transmitter 3 and the receiver 4, and the vertical axis represents the time with the transmission time as the reference time. It is possible to determine the portion of the thinned portion D based on a change in the stripe pattern formed by the shading. The example in the figure shows the result of scanning the steel pipe 100 over 120 mm, and the hollow portion of the vertical stripe at the center coincides with the actual thinned portion D. When the stripe pattern is uniformly inclined or when the position in the healthy part is clearly displaced, the entire stripe pattern is corrected by the amount of the inclination or deviation, so that the transmitter 3, A mechanical error generated between the receivers 4 can be canceled.

In the inspection, first, the first carriage 2a and the second carriage 2b are wound around the steel pipe 100 by scissors of the gantry 102. And the first cart 2a and the second cart 2b
After confirming the parallelism, the connecting rod 2c is inserted into each hole 27a and the tightening screw 27c is tightened to synchronize the first carriage 2a and the second carriage 2b. The transmitter 3 and the receiver 4 are coated with a couplant to confirm the contact with the steel pipe 100,
The transmitter 3 and the receiver 4 are positioned on the left and right sides of the sound part which is not hidden by the personal computer 6, and the position by the encoder 5 is reset on the personal computer 6. Next, the ultrasonic pulse is intermittently transmitted from the personal computer 6 and the pulsar 7, and the whole carriage 2 is rotated around the steel pipe 100 by hand or a driving device, and the inspection object 101 is scanned by the transmitter 3 and the receiver 4. Then, the carriage 2 is rotated to the other position not hidden by the gantry 102. Thereafter, the thinned portion D is evaluated based on the position of the stripe pattern of the B scan glove.
By confirming the displacement between the start position and the end position of the B scan graph, the mechanical error between the transmitter 3 and the receiver 4 can be evaluated.

Finally, the possibility of another embodiment of the present invention will be described. In the above embodiment, the inspection target part 101 of the present invention is a concealed part of the steel pipe 100 by the gantry 102. However, according to the present invention, the support portion by the support or the hanger may be used as the inspection target portion 101, and a part of the flat member may be used as the inspection target portion 101.

In the above embodiment, a bogie having wheels is used as a guide device for supporting the transmitter and the receiver. However, the guide device may be constituted by a rail attached to the inspection object portion 101 near the steel pipe 100 or the like, and a slider running in the rail and supporting a transmitter or a receiver. However, there is an advantage that the above-described configuration using wheels is easier to attach to the steel pipe 100 or the like and easier to inspect.

In the above embodiment, the connecting rod 2c is used as a synchronization means for synchronizing the first carriage 2a and the second carriage 2b. However, as the synchronization means, a block-shaped member, a non-contact means for synchronizing the positions of the first carriage 2a and the second carriage 2b by transmitting and receiving ultrasonic waves and infrared rays, and an encoder 5 include One truck 2a and second truck 2b
And means for synchronizing these signals can be used. However, the above configuration using a bar or a block is excellent in that scanning and synchronization of the first truck 2a and the second truck 2b can be simultaneously performed with a simple configuration.

It should be noted that reference numerals written in the claims are merely for convenience of comparison with the drawings, and the present invention is not limited to the configuration of the attached drawings by this writing. .

[Brief description of the drawings]

FIG. 1 is a view in the tube axis direction of an inspection device according to the present invention.

FIG. 2 is a side view of the tube shown in FIG.

FIG. 3 is a plan view of the vicinity of a connecting block in each bogie.

FIG. 4 is a side view near a transmitter and an encoder.

FIG. 5 is a block diagram schematically showing an inspection device of the present invention.

FIG. 6 is a graph showing a received waveform at each scanning position, wherein the horizontal axis represents time, and the vertical axis represents signal intensity.

FIG. 7 is a graph showing a B-scan result of a received waveform at each scanning position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inspection apparatus 2 cart 2a 1st cart 2b 2nd cart 2c Connecting rod 3 Transmitter 4 Receiver 5 Encoder 5a Encoder main body 5b Wheel 6 Personal computer 7 Pulser 8a Receiver 8b A / D converter 9a Monitor 9b Printer 21 Inner plate 22 Outside Plate 23 Axle 24 Tube 25 Wheel 26 Hook 26a Screw shaft 26b Block 27 Connection block 27a Hole 27b Slit 27c Tightening screw 28a Fixing block 28b Base 29 Support arm 30 Support bracket 100 Steel pipe 101 Inspection part 102 Frame D Thinning part.

Continued on the front page (72) Inventor Eiichi Kishi 9138 Goi, Ichihara-shi, Chiba Non-destructive inspection stock company In-house (72) Inventor Takuichi Imanaka 9138 Goi, Ichihara-shi, Chiba non-destructive inspection stock company In-house (72) Inventor Yotsuji Beauty year 37-24, Nittacho, Chuo-ku, Chiba-shi, Chiba F-term (reference) in Idemitsu Engineering Co., Ltd. 2G047 AA07 AB01 BC02 BC11 CB03 GA03 GA19 GJ02 GJ14

Claims (7)

[Claims] 1. A surface wave transmitter (3) and a receiver (4) are arranged across an inspection target part (101), and the distance between them is determined by the transmitter (3) and the receiver (4). Scanning of the inspection target portion (101) is performed while maintaining the constant, and the arrival time of the received wave by the receiver (4) is compared at each scanning position to reduce the thickness (D) of the inspection target portion (101). Inspection method such as wall thinning by surface waves to be inspected. 2. The method according to claim 1, wherein the object to be inspected is a tube.
0) and a guide device (2) for scanning the transmitter (3) and the receiver (4) along the circumference of the tube (100). Item 1. An inspection method for thinning or the like according to item 1. 3. A transmitter (3) and a receiver (4) of a surface wave arranged over the inspection target part (101), and an inspection target part (4) by the transmitter (3) and the receiver (4). 10
A guide device (2) for performing the scanning of 1), wherein the guide device (2) includes a pair of first parallelly arranged first members that respectively support the transmitter (3) and the receiver (4). , A second guide portion (2a, 2b), and a synchronization means (2c) for synchronizing and moving the first and second guide portions (2a, 2b). An inspection apparatus for a thinning by a surface wave, comprising a determination unit for inspecting a thinning or the like (D) of an inspection target portion (101) by comparing arrival times of waves at respective scanning positions. 4. The inspection object part (101) is a tube (10).
0), wherein said guide device (2) is
00) along the circumference of said transmitter (3) and receiver (4)
4. The inspection apparatus for thinning and the like according to claim 3, wherein each of the inspection means is scanned. 5. The first and second guide portions (2a, 2b).
Each comprises a plurality of wheels (25) and said tube (10)
0) wound around the first and second carriages (2)
The inspection apparatus for thinning and the like according to claim 4, wherein the inspection apparatus is any one of (a) and (2b). 6. The thinning method according to claim 1, wherein said synchronization means is a rod connecting said first and second guide portions to each other. Inspection equipment. 7. The method of claim 1 or 2, wherein the comparison of the similar parts is performed by displaying the received wave by shading at each scanning position. 7. The inspection apparatus for thinning or the like according to any one of claims 6 to 6.