JP2003066012A - Method and device for inspecting defect by surface wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for inspecting a defect by a surface wave, capable of speedily carrying out inspection with high measurement accuracy. SOLUTION: A transmitting element 3 and a receiving element 4 for a surface wave are disposed so as to straddle an inspection object 101 forming a part of a pipe by being supported by a guiding device G. The inspection object 101 is scanned by these transmitting element 3 and receiving element 4 along the axial direction of the pipe 100 while keeping the distance between them almost constant. The defect D such as reduction of the thickness of the inspection object 101 is inspected by comparing arrival times of the surface wave received by the receiving element 4 at respective scanning positions. Thereby, inspection can be speedily carried out by moving the guide device along the axial direction of the pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for inspecting defects such as thinning due to surface waves. More specifically, for example, the present invention relates to a surface wave defect inspection method and inspection apparatus suitable for inspecting for pipe maintenance such as thinning due to corrosion that occurs in a concealed portion supported by a pedestal of a support portion in piping.

[0002]

2. Description of the Related Art Conventionally, the number of supporting structures (frames, supports, hangers, etc.) for oil plant equipment and piping ranges from tens of thousands to hundreds of thousands depending on the scale of the plant. In addition, most of them are exposed to wind and rain because they are in the outdoor environment, and because they are close to the sea due to the location of the plant, they are affected by salt, so the gap between the pipe and the support structure, that is, the pedestal contact part, is susceptible to external corrosion. In the environment. Therefore, in order to properly maintain and manage the equipment, it is an important issue to improve the reliability of the inspection as a countermeasure against the corrosion of the piping base contact portion.

In order to carry out an accurate inspection, it is necessary to lift the pipe from the pedestal for inspection, which requires a great amount of inspection cost and time, making maintenance of the plant difficult. There is also a problem that it is difficult to apply radiation to large-diameter pipes from the viewpoint of the transmission ability.

Therefore, for example, Japanese Patent Laid-Open No. 2000-5589.
As shown in Japanese Patent No. 0, an inspection method has been proposed in which transverse wave transmission attenuation using a probe by ultrasonic waves is utilized to estimate the degree of corrosion without lifting the pedestal from the pipe.

According to the technique described in the publication, however, the evaluation is only for the attenuation of the transmitted pulse, so the degree of attenuation is greatly affected by the contact condition of the transmitter and the receiver, and the measurement accuracy is also limited. was there. Moreover, because of the influence of the condition of the inner surface of the tube, the overall measurement accuracy was still insufficient in combination with the signal attenuation.

On the other hand, the inventors of the present invention support the transmitter and the receiver on separate carriages, wind the respective carriages around the support so as to be separated from each other in the pipe axial direction, and wind the pipes around each other, to thereby reduce the distance between the carriages. We proposed an inspection method to inspect the support part for corrosion by keeping it and rotating it around the pipe axis. However, according to this method, a trolley needs to be wound around each support,
There is a problem that the inspection process is complicated and time-consuming.

[0007]

SUMMARY OF THE INVENTION In view of the conventional situation as described above, an object of the present invention is to provide a method and apparatus for inspecting defects by surface waves, which has high measurement accuracy and can be implemented quickly. is there.

[0008]

In order to solve the above problems, the feature of the defect inspection method according to the present invention is that a surface wave transmitter and a receiver are provided across a portion to be inspected, which is a part of a pipe. It is arranged to be supported by a guide device, and while the distance between these elements is kept substantially constant by the transmitter and the receiver, the inspection target portion is scanned along the axis of the pipe, and the arrival time of the reception wave by the receiver is determined. The purpose is to inspect defects such as thinning of the inspection target portion by comparing at each scanning position.

In scanning the transmitter and the receiver along the axial direction of the pipe, the guide device includes a carriage for supporting the transmitter and the receiver, and the transmitter and the receiver are provided with the carriage. You may arrange | position on both sides of the said truck so that an orientation line may cross | intersect with respect to the traveling direction of the said truck. According to this feature, since both the transmitter and the receiver are mounted on the carriage, the distance between the transmitter and the receiver is always kept almost constant, and both of them are at the same speed on the pipe surface. Will be scanned.

In addition, the carriage may be made to run over the pipe. Does not require installation work under the pipe,
This is because the installation becomes easy especially in a narrow space.

In scanning the transmitter and the receiver along the axial direction of the pipe, the guide device has a pair of first and second carriages arranged on both sides of the pipe,
The transmitter is supported on the first carriage, the receiver is supported on the second carriage, and both carriages run on rails laid on both sides of the pipe. Good.

In any of the above inspection methods, if the received wave is displayed in shades at each scanning position to compare the similar portions, a visual evaluation is possible.

On the other hand, the characteristic structure of the inspection apparatus for defects such as thinning according to the present invention is the inspection apparatus for defects by surface waves used in any of the above-described inspection methods for defects by surface waves according to the present invention. A surface wave transmitter and receiver arranged across the inspection target portion, and a guide device for scanning the inspection target portion while keeping the distance between the transmitter and the receiver substantially constant, It is to compare the arrival time of the received wave by the receiver at each scanning position.

[0014]

As described above, according to the features of the present invention, the arrival time of the received wave is compared at each scanning position and the arrival time difference is utilized instead of comparing the attenuation of the received wave. Corrosion status can be inspected more accurately without being affected by the contact status between the child and the receiver. Further, since the arrival times of the received waves are compared at each scanning position, even if an error in the distance between the two probes occurs, it becomes easier to determine the error by comparing in the sound section. Moreover, since it is sufficient to move the guide device along the tube axis direction, it is possible to quickly perform the inspection.

In particular, when the arrival times are compared in a state in which the received wave is displayed by shading at each scanning position,
Since it is easy to visually recognize the arrival time difference of the received waves, even a person who is not an expert can quickly and easily make a judgment such as thinning. Other objects, configurations and effects of the present invention will be apparent from the description of the embodiments of the present invention given below.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, referring to FIGS.
The first embodiment of the present invention will be described in more detail.
The inspection target in the present embodiment is a steel pipe 100 used for piping in a plant or the like, and the inspection target portion 101 is a portion which is supported by the pedestal 102 and is concealed and easily corroded. In the present embodiment, the thinned portion D generated in the inspection target portion is detected as a defect. In addition, here, the guide device G is run in the axial direction Y of the steel pipe 100 for inspection.

As shown in FIGS. 1 to 3, the guide device G, which is a main part of the inspection device 1, is constructed as a carriage 40 which is placed on the upper portion of the steel pipe 100 and travels in the pipe axis direction Y in this embodiment. is there. This trolley 40 is roughly a trolley body 40a.
And four wheels 40b attached to the sides of the trolley body 40a. Also, as shown in FIG.
Fork-shaped support arm 4 from both sides of the trolley body 40a
The transmitter 1 and the receiver 4 are elastically pressed against the surface of the steel pipe 100 by projecting the protrusions 1 and 41. In this way, both the transmitter 3 and the receiver 4 set these orientation lines L shown in FIG. 1 as the pipe axis direction Y which is the traveling direction of the carriage 40 in the Z-axis direction which is the plane view direction of the carriage 40. Since they are attached to the carriage 40 so as to intersect with each other, the distance between the transmitter 3 and the receiver 4 is always kept substantially constant. It is more desirable that the alignment line L and the tube axis direction Y are orthogonal to each other when viewed in the Z-axis direction,
The same applies to the following embodiments. In addition, this trolley 40
The encoder 5 is attached to the
The main body 5a of the
From the slit 40c provided on the bottom surface to the encoder wheel 5b
Is projected so as to contact the surface of the steel pipe 100, and the scanning positions of the transmitter 3 and the receiver 4 are detected by the rotation angle of the wheel 5b.

FIG. 4 is a block diagram showing the outline of the inspection apparatus 1. In this inspection device 1, the transmitter 3 and the receiver 4
The scanning position of is captured by the personal computer 6 by the encoder 5. In addition, the inspection device 1 includes a pulsar 7 that generates an ultrasonic pulse as a surface wave from the transmitter 3, and a receiver 8 that amplifies the received wave from the receiver 4.
a and an A / D converter 8b that converts this amplified wave into digital data and takes it into the personal computer 6
It has and. The processing result by the personal computer 6 is as shown in FIGS.
It is displayed by a and is output on a sheet by the printer 9b.

When the inspection target part 101 is normal,
The surface wave is transmitted from the transmitter 3 to the receiver 4 along the smooth surface of the inspection target part 101. However, the inspection target unit 101
When there is a thinned portion D in the surface, the surface wave is detoured along the surface of the thinned portion D, and the arrival time of the received wave to the receiver 4 becomes long from the time of transmission and the reception time is delayed. Becomes By examining this time delay at each scanning position, it becomes possible to determine the presence or absence of the thinned portion D or its degree.

The above-mentioned time delay is judged by comparing the similar portions of the received wave by the receiver at each scanning position. 5A to 5F show received waveforms at each scanning position. The similar portion of the received wave is, for example, the peak P of each waveform in this example.
a to Pf and the like, and the presence or absence or the degree of the thinned portion D is determined based on the deviation of these time positions based on the transmission time from the transmitter 3. In the figure, (c) to (f) are considered to be corroded parts. Since the time delay between the corroded portion and the sound portion is small, the examination becomes easier by enlarging and displaying the vicinity of the reception time of the reception waveform.

FIG. 6 is a graph showing the B-scan result of the received waveform at each scanning position. Here, the B scan is a scan in which the measurement position is moved by a minute distance such as a pitch of 1 mm to capture a waveform and the amplitude of the waveform is replaced with the density of color. 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 by the change of the striped pattern formed by the light and shade.

The example of the figure shows the result of scanning the steel pipe 100 over 150 mm, and the recessed portion of the vertical stripes at the central portion coincided with the actual thinned portion D. If the striped pattern is uniformly inclined or if the position in the sound portion is clearly misaligned, the entire striped pattern is corrected by the amount of the inclination or displacement, so that the transmitter 3, It is possible to cancel the mechanical error that occurs between the receivers 4.

In the inspection, first, mount the truck 40 on the steel pipe 1.
00 Place on top. Then, a contact medium is applied to the transmitter 3 and the receiver 4 to confirm contact with the steel pipe 100, and the transmitter 3 and the receiver 4 are positioned on the left and right of the sound part not hidden by the gantry 102, and the position by the encoder 5 is set. 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 carriage 40 is caused to travel in the tube axis direction Y by at least the length of the concealed portion by the gantry 102 by means of a hand or a driving device to perform scanning in the tube axis direction Y. To do. afterwards,
The thinned portion D is evaluated based on the position of the striped pattern on the B scan graph. By this scanning, continuous data in the pipe axis direction Y can be collected, and the location of the thinned portion D can be estimated. In addition, by checking the positional deviation between the start position and the end position of the B scan graph, the transmitter 3,
The mechanical error between the receivers 4 can be evaluated.

Next, a second embodiment according to the present invention will be described with reference to FIGS. In each of the following embodiments, a part different from the previous embodiment will be mainly described, and the same members as those in the above embodiment are denoted by the same reference numerals. In the present embodiment, the guide device G, which is a main part of the inspection device 1, is configured as a carriage 50 that can be wound around the outer circumference of the steel pipe 100 and travel in the axial direction Y thereof.

The carriage 50 has end carriages 51, 51 for respectively supporting the transmitter 3 or the receiver 4, and a plurality of intermediate carriages 52 arranged at appropriate intervals in the pipe circumferential direction X. There is. Then, these adjacent end carriages 51 and intermediate carriages 52 are connected by connecting rods 53, respectively. Specifically, these connections prevent the positional displacement between the end carriage 51 and the intermediate carriage 52 adjacent to each other in the pipe axis direction Y. Further, since the transmitter 3 and the receiver 4 are fixed to the end carriages 51 and 51, respectively, the distance between the transmitter 3 and the receiver 4 is always kept substantially constant.
An encoder (not shown) is attached to the end cart 51 to detect the scanning positions of the transmitter 3 and the receiver 4.

The end carriage 51 and the middle carriage 52 have carriage bodies 51a and 52a, respectively. Further, four wheels 51 are provided on both sides of the carriage main bodies 51a and 52a in the pipe circumferential direction X.
b and 52b are attached respectively. Then, the end carriage 51 and the intermediate carriage 52 travel in the pipe axis direction Y by the rolling of the wheels 51b and 52b. Inside the end carriage main bodies 51a, 51a respectively located at the end portions of the whole, the transmitter 3 and the receiver 4 are attached so as to contact the surface of the steel pipe 100. Then, the support carriages 51, 51 and the support carriages 51 and the intermediate carriage 52 are connected by a connecting rod 53 so as to be bendable around an axis 54 along the pipe axis direction Y. With such a configuration, the diameter of the loop formed by the carriage 50 as a whole can be adjusted, and it becomes possible to apply the steel pipes 100 of various diameters.

For the inspection, the carriage 50 is attached to the steel pipe 100.
Wrap around and install. After that, the carriage 50 is moved in the pipe axis direction Y and an inspection is carried out by a procedure similar to that of the first embodiment. In addition, in the present embodiment having the plurality of carriages 51 and 52, an error may occur due to the influence of the unevenness existing on the outer surface of the steel pipe 100, and in that respect, the above embodiment is superior.

Next, a third embodiment according to the present invention will be described with reference to FIGS. In the present embodiment, the guide device G, which is a main part of the inspection device 1,
A pedestal 10 is provided along the tube axis direction Y with the inspection target portion 101 interposed therebetween.
It is provided with a pair of rails 61 laid on the rail 2 and a carriage 62 traveling on the rails 61. Further, the trolley 62 has a first trolley 62a that supports the transmitter 3 and a second trolley 62b that supports the receiver 4.

The second carriage 62b, as shown in FIG.
Lower trolley 63 traveling on rail 61 and lower trolley 6
3 and an upper trolley 64 arranged on the upper side. The lower carriage 63 has four wheels 63b traveling on the rail 61.
Is provided. Further, the receiver 4 is attached inside the upper carriage main body 64a so as to come into contact with the steel pipe 100. Then, the rolling of these wheels 63b causes the lower carriage 63 to travel in the pipe axis direction Y. Also, the upper trolley body 6
4a is attached to the lower carriage main body 63a so as to be tiltable around an axis 65 along the pipe axis direction Y, so that the steel pipe 10
The inclination of the upper bogie main body 64a can be adjusted so as to match the diameter of 0, and it is possible to apply it to pipes of various diameters. The first truck 62a, which is the guide device G on the transmitter 3 side, has the same configuration as the second truck 62b described above, and is configured symmetrically with respect to the steel pipe 100.

The first carriage 62a and the second carriage 62b include
An encoder (not shown) is attached to detect the scanning position of the transmitter 3 or the receiver 4. Then, according to a command from the above-mentioned computer, the first bogie 62a and the second bogie 6
The traveling speed of 2b is controlled to be the same speed. Thus, the relative positional relationship between the first carriage 62a and the second carriage 62b is always kept substantially constant, so that the first carriage 62a and the second carriage 62b are synchronized.

In the inspection, rails 61 are laid along the pipe axis direction Y on the left and right sides of the pedestal 102 on the side of the pipe 100 to be inspected, and the carriages 62 are arranged on the rails 61. Thereafter, the first carriage 62 is driven by a driving device (not shown).
a, the second bogie 62b is caused to travel in the tube axis direction Y at the same speed. After that, the inspection is performed by a procedure substantially similar to that of the first embodiment.

Finally, the possibility of another embodiment of the present invention will be described. In each of the above-described embodiments, the inspection target portion 101 of the present invention is the concealed portion of the steel pipe 100 by the pedestal 102. However, in the present invention, the support portion by the support or the hanger may be the inspection target portion 101, or a part of the flat plate-shaped member may be the inspection target portion 101.

In each of the above-mentioned embodiments, since the arrival time of the received wave at the receiver 4 becomes longer from the time of transmission as the surface wave detours along the surface of the thinned portion D, the delay of this reception time is caused. Was measured. However, defects other than the thinned part,
For example, in the case of carburizing or the like, it is conceivable that the reception time of the surface wave passing through the defective portion may be earlier than the arrival time of the surface wave passing through the sound portion. Therefore, the difference in arrival time of surface waves for evaluating defects can be determined as both positive and negative.

In the third embodiment described above, the lower carriage 63 is run on the rail 61 by the wheels 63b. Instead, the lower carriage 63 may be run on the rail 61 using a gear. Since the gear has no positional deviation due to slippage as compared with the wheel, the scanning positions of the transmitter 3 and the receiver 4 can be detected more accurately by the number of teeth meshed with the gear during movement.

Although it is not actually necessary to inspect the oil pipe, it is also possible to scan the pipe 100 in the pipe circumferential direction X and use it in combination with any of the first to third embodiments. In this case, the two-dimensional spread (shape) of the inspection target portion 101 in curved surface coordinates having the tube axis direction Y and the tube circumferential direction X as coordinate axes is more accurately determined from the scan data in both the tube axis direction Y and the tube circumferential direction X. Can be estimated.

The reference numerals in the claims are merely for convenience of comparison with the drawings, and the present invention is not limited to the configuration of the accompanying drawings by the reference. .

[Brief description of drawings]

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

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

FIG. 3 is a partially cutaway cross-sectional view in the vicinity of a truck according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing an outline of an inspection device.

FIG. 5 is a graph showing a received waveform at each scanning position, in which the horizontal axis represents time and the vertical axis represents signal intensity.

FIG. 6 is a graph showing a B scan result of a received waveform at each scanning position.

FIG. 7 is a view corresponding to FIG. 1 in the second embodiment of the present invention.

FIG. 8 is a view in the tube axis direction in the vicinity of the connecting portion between the intermediate carriage and the connecting rod in the second embodiment of the present invention.

FIG. 9 is a side view of the pipe of FIG.

FIG. 10 is a view corresponding to FIG. 1 in the third embodiment of the present invention.

FIG. 11 is a pipe axis direction view in the vicinity of a receiver and a carriage in the third embodiment of the present invention.

[Explanation of symbols]

1: Inspection device, 3: Transmitter, 4: Receiver, 5: Encoder, 5a: Encoder main body, 5b: Wheel, 6: Personal computer, 7: Pulsar, 8a: Receiver, 8b: A / D converter, 9a: Monitor, 9
b: printer, 40: dolly, 40a: dolly body, 40
b: wheel, 40c: slit, 41: support arm, 5
0: dolly, 51: end dolly, 51a: end dolly body,
51b: wheels, 52: intermediate trolley, 52a: intermediate trolley body, 52b: wheels, 53: connecting rod, 54: shaft, 61: rail, 62: trolley, 62a: first trolley, 62b: second trolley, 63: Lower trolley, 63a: Lower trolley body, 63b:
Wheels, 64: upper carriage, 64a: upper carriage body, 64
b: wheel, 65: shaft, 100: steel pipe, 101: inspection target part, 102: frame, D: thickness reduction part, G: guide device, X:
Pipe circumferential direction, Y: Pipe axial direction

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Eiichi Kishi             9138 Goi, Ichihara-shi, Chiba Non-destructive inspection stock association             In-house (72) Inventor, Yasukazu Yokono             9138 Goi, Ichihara-shi, Chiba Non-destructive inspection stock association             In-house (72) Inventor Takuichi Konaka             9138 Goi, Ichihara-shi, Chiba Non-destructive inspection stock association             In-house (72) Inventor Yoshitoshi Tsuji             37-24 Nitta-cho, Chuo-ku, Chiba-shi, Chiba Idemitsu             Engineering Co., Ltd. F term (reference) 2G047 AA07 AB01 BA02 BC02 CB03                       EA09 EA14 GA13

Claims (6)

[Claims] 1. A transmitter (3) and a receiver (4) for surface wave are arranged so as to be supported by a guide device (G) across an inspection object (101) which is a part of a tube (100). , The axial direction (Y) of the pipe (100) while keeping these distances substantially constant by the transmitter (3) and the receiver (4).
The inspection target portion (101) is scanned along the line, and the arrival time of the received wave by the receiver (4) is compared at each scanning position to detect defects (D) such as thinning of the inspection target portion (101). Inspection method for defects by surface waves. 2. A dolly (40, 50) in which the guide device (G) supports the transmitter (3) and the receiver (4).
The trolley (40, 5) so that the transmitter (3) and the receiver (4) intersect these orientation lines (L) with the traveling direction (Y) of the trolley (40, 50).
0) arranged on both sides of 0).
The method for inspecting defects by surface waves according to. 3. The method for inspecting defects by surface waves according to claim 2, wherein the carriage (40) travels above the pipe (100). 4. The guide device (G) comprises the pipe (10).
0) a pair of first and second bogies (6
2a, 62b), the transmitter (3) is supported on the first carriage (62a), and the second carriage (62a).
The receiver (4) is supported by b), and the carriages (62a, 62b) both run on rails (61, 61) laid on both sides of the pipe (100). The method for inspecting defects by surface waves according to claim 1. 5. The method for inspecting a defect by surface wave according to claim 1, wherein the similar portions are compared by displaying the received wave by shading at each scanning position. 6. An apparatus for inspecting defects by surface waves used in the method for inspecting defects by surface waves according to claim 1, wherein the surface waves are arranged across an inspection target portion (101). The transmitter (3) and the receiver (4) and the guide device (G) for scanning the inspection target portion (101) while keeping the distance between the transmitter (3) and the receiver (4) substantially constant. ) And inspecting for defects (D) such as thinning of the inspection target portion (101) by comparing the arrival time of the reception wave by the receiver (4) at each scanning position. apparatus.