JP3033438B2 - Ultrasonic flaw detection method for piping - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detection method for continuously detecting a corrosion defect or a welding defect in a pipe using a pig.

[0002]

2. Description of the Related Art As an example of a conventional pig for detecting a defect in a welded portion of a pipe, there is a device disclosed in Japanese Utility Model Laid-Open No. 62-91254. This invention is based on an ultrasonic surface wave probe for detecting the position of the weld in the circumferential direction of the pipe and an oblique angle probe for detecting defects on the pipe inner surface. The tentacles are arranged at a predetermined interval in the pipe axis direction so as to continuously and accurately inspect the welded portion.

Also, as shown in, for example, Japanese Patent Application Laid-Open No. H5-119025, an ultrasonic probe is symmetrically arranged on the surface of a tube around a welded portion, and the tube is moved to remove defects in the welded portion. The two-probe method for detection has also been put to practical use.

[0004]

Problems to be Solved by the Invention
The pig described in Japanese Patent Publication No. 4 transmits ultrasonic waves in a direction orthogonal to the circumferential weld, so that when detecting a defect in the circumferential weld or a pit-like corrosion defect in the base material, the pig is detected. Since the rate is proportional to the flaw coverage, it is necessary to equip the pig with as many probes as possible.

For example, when flaw detection is performed on a circumferential weld of a 600 A steel pipe, if the flaw detection effective width of the probe is 20 mm,
For all-line flaw detection, it is necessary to equip the pig with about 95 probes. Therefore, depending on the size of the pig, the probe may be equipped with two, three or staggered probes. In practice, it has been difficult to satisfy the 100% covering rate requirement. Note that flaw detection of a vertical seam weld was not possible in principle with such pigs.

Further, in the pig as described above, since the echo from the extra bank of the welded portion becomes noise and lowers the detection accuracy, it is necessary to provide a special means for removing noise from the extra bank echo. There was a problem.

Further, according to the two-probe method disclosed in Japanese Patent Application Laid-Open No. H5-119025, the above problem can be solved.
It cannot be applied to a pig running in a pipe due to the complicated arrangement of the ultrasonic probe.

The present invention has been made in order to solve the above-mentioned problems, and has a pig equipped with a small number of ultrasonic probes.
It is an object of the present invention to obtain an ultrasonic flaw detection method capable of detecting defects of a vertical seam weld, a circumferential weld, and a base material of a pipe with high accuracy. Another object of the present invention is to provide an ultrasonic flaw detection method which is not affected by an echo from a weld pile.

[0009]

SUMMARY OF THE INVENTION An ultrasonic flaw detection method for a pipe according to the present invention includes a tire-type ultrasonic probe, and a pig running in the pipe. In the ultrasonic flaw detection method for detecting defects in
A single tire-type ultrasonic probe is disposed in the pipe, and the tire-type ultrasonic probe is moved leftward by 35 ° to 55 ° or 125 ° to 145 with respect to the traveling direction of the pig.
°, or 35 ° to 55 ° or 125 ° to 1 to the right
The ultrasonic wave is transmitted in the direction of 45 °, and the reflected wave from the defect in the flaw detection area is received by the single tire-type ultrasonic probe, so that the defect on the entire surface of the base material of the pipe and the entire area of the welded portion is obtained. Is to be detected.

Further, in the ultrasonic inspection method for a pipe according to the present invention, a defect is detected on an entire surface of the base material of the pipe and an entire area of a welded portion by a pig equipped with a tire-type ultrasonic probe and traveling in the pipe. In the ultrasonic flaw detection method, a plurality of the tire-type ultrasonic probes are arranged in a circumferential direction in the pipe, and each of the plurality of tire-type ultrasonic probes is arranged in a traveling direction of the pig. Transmit ultrasonic waves sequentially in the direction of 35 ° to 55 ° or 125 ° to 145 ° to the left, or 35 ° to 55 ° or 125 ° to 145 ° to the right,
By detecting a reflected wave from a defect in each flaw detection area for each of the plurality of tire-type ultrasonic probes, a defect is detected in the entire base material of the pipe and in the entire welded area.

In the above-described ultrasonic inspection method for piping, the ultrasonic wave transmission direction is set to 45 ° or 135 ° to the left or 45 ° or 1 ° to the right with respect to the traveling direction of the pig.
35 °. Further, as a tire type ultrasonic probe, a probe capable of simultaneously transmitting a transverse wave and a surface wave having a large angle of refraction, a bevel probe, a surface wave probe, or a bevel probe and a surface wave probe Any one of the child combination is used.

[0012]

According to the present invention, the ultrasonic wave transmitted from the tire type ultrasonic probe basically propagates inside or on the pipe wall of the pipe or helically propagates inside or on the pipe wall. ,
With the progress of the pig, it is possible to substantially perform full-surface inspection of the base material, full-line inspection of the vertical seam weld, and full-line inspection of the circumferential weld. In extreme cases, that is, when the output of the probe is large, the receiving sensitivity is high, and the flaw detection distance can be sufficiently long, while the diameter of the pipe is relatively small, one probe can cover the entire surface. And all-line flaw detection. In general, when an ultrasonic wave is obliquely incident on a plane with respect to a welding line, the echo does not change in the incident direction even if there is reflection from an extra bank. Therefore, it is usually unnecessary to consider noise removal for extra echoes, which is a problem associated with ultrasonic flaw detection, and it is possible to eliminate hardware and software complexity.

In the flaw detection method according to the present invention, the intersection where the vertical seam weld and the circumferential weld intersect in a T-shape may become a source of ultrasonic wave reflection. Since the extra inner and outer surfaces near the pipe end of the vertical seam weld have been removed, consideration of this point is unnecessary.

[0014]

FIG. 2 is a side view of an example of a pig used in the present invention, and FIG. 3 is an enlarged sectional view of the pig along AA. In both figures, reference numeral 1 denotes a pig, and a measuring device pig 2 and 3 of the first and second vehicles are equipped with a storage device 7 and an ultrasonic measuring device 8.
A plurality of tire-type ultrasonic probes 1 are mounted on the sensor pig 4 of the vehicle.
0a to 10h are mounted. These are connected by connectors 5a and 5b. 6a and 6b are measuring rollers provided at the rear end of the sensor pig 4.

A plurality of (eight are shown in the figure) tire-type ultrasonic probes (hereinafter referred to as "probes") 10a to 10h (hereinafter referred to as "probes") are arranged at equal intervals on the sensor pig 4 via a leaf spring 9. (Sometimes simply denoted by reference numeral 10). As shown in FIGS. 4 and 5, an example of the probe 10 is shown in FIGS.
A water chamber 12 containing water as an inner ultrasonic signal propagation body and an outer rubber tire 13 around an axis 11.
And an ultrasonic sensor 14 attached to the shaft 11 in the water chamber 12. In addition, 15 is a holder and P is a pipe.

By the way, the inventors have studied the echo heights of the tube axis direction defect and the circumferential direction defect, the echo heights of the vertical seam weld margin and the circumferential weld margin, and the transmission / reception direction (angle) of ultrasonic waves. As a result of repeating a long-term study and many experiments on the relationship, the following conclusions were obtained as shown in FIG.

As is apparent from FIG. 6, the transmitting / receiving direction of the ultrasonic wave by the probe, that is, the transmitting / receiving angle α is 35 ° to 55 ° about 45 ° to the left or right with respect to the traveling direction of the pig. (Or 125 ° centered around 135 °
In the range of 145 °), the echo height of the echo from the tube axial defect and the echo from the circumferential defect both exceed the defect detection level. Defects can be detected. For this reason, the number of probes can be reduced. Also, in the above range, the echo from the vertical seam weld margin and the echo from the circumferential weld margin are both affected by noise when detecting a defect because the echo height is lower than the noise level. Never.

On the other hand, in the range A of α <35 °, the echo of the tube axial defect is lower than the defect detection level, and α> 55.
In the range B of °, since the echo of the circumferential defect is lower than the defect detection level, in these ranges, it is impossible to detect a defect in all directions with one type of probe, and a defect in all directions is detected. For this purpose, two or more types of probes are required, so that the number of probes cannot be reduced. In addition, the above α <35
In the range of ° and α> 55 °, since the height of the echo from the circumferential weld margin and the vertical seam weld margin is high, it is easy to erroneously detect the echo from the weld margin as a defect,
Accurate flaw detection may not be possible.

Each probe 1 mounted on the pig 1 according to the present invention
0 is 35 ° to 55 ° or 125 ° to 145 ° leftward from the ultrasonic sensor 14 with respect to the traveling direction a of the pig 1 as shown in FIG.
Or 35 ° to 55 ° or 125 ° to 145 to the right
° direction, preferably 45 ° or 135 ° to the left
Alternatively, it is configured to transmit ultrasonic waves in the direction of 45 ° or 135 ° to the right.

FIG. 8 is a block diagram of an example of the measuring device. The pulser 22 sequentially transmits a transmission pulse to the probes 10a to 10h based on a signal from the delay circuit 21. Signals received from the probes 10a to 10h are amplified by the preamplifier 23 and the defect detection main amplifier 24a. The main amplifier 24a for defect detection is an amplifier 24b for automatic sensitivity adjustment.
The sensitivity is automatically adjusted by the reference echo detection circuit 25b.

The echo from the defect is detected by a defect echo detection circuit 2
5a, the echo height is measured by the echo height measuring circuit 27.
Is measured by The time from transmission of the ultrasonic wave to reception of the echo due to the defect is measured by the time measurement circuit 26.
The height and time measurement data of the defect echo are collected by the data collection circuit 28 at predetermined intervals according to signals from the measuring roller 6 and the odometer 30, and the collected data is stored in the storage device 29. . Measuring device 8
Is controlled by the control signal circuit 20.

Next, an example of an ultrasonic flaw detection method for detecting a defect in a pipe using the pig 1 as described above will be described with reference to FIG. FIG. 1 is a schematic view showing an embodiment in which a defect in a pipe is detected by an ultrasonic flaw detection method according to the present invention in a pipeline, and P indicates a state where a pipe to be inspected is developed in a plane. In the figure, 10a, 10b, 10c,...
The probe mounted on the pig 1 at the interval L shown in FIG. 3 moves in the pipe P in the direction of the arrow a. Each of the probes 10a, 10b, 10c,... Is 35 ° to the right with respect to the traveling direction a of the pig 1 as described with reference to FIG.
In the direction of 55 ° (the direction of 45 ° to the right in this embodiment),
A transverse wave and a surface wave having a large refraction angle are simultaneously transmitted and propagated.

Reference numeral 34 denotes an extra bank of the vertical seam weld, 35 denotes an extra bank of the circumferential weld, 36 denotes a base metal defect of the pipe P, 37 denotes a defect of the vertical seam weld, and 38 denotes a defect of the circumferential weld. It is.

In the above configuration, the relative position between the pig 1 and the inner surface of the pipe P, that is, the probes 10a, 10b,
When the positional relationship between the probe 10c and the inner surface of the pipe P is in the state I, the ultrasonic waves 31a, 31b, 31c transmitted from the probes 10a, 10b, 10c have defects 36, 37, 38.
Has not been encountered. In addition, the extra 34 of the vertical seam welded portion
Reflects an ultrasonic wave in some cases, but the extra echo 32a does not return to the probe 10a. Therefore,
Does not become a noise source.

As the pig 1 advances, the probes 10a, 10a
The b and 10c change from the state II to the state III. During the change from the state I to the state II, the base material defect 36 is detected by the probe 10b, and in the state II, the defect 37 in the vertical seam weld is detected.
Is detected by the probe 10a. In the state III, the ultrasonic wave 31a from the probe 10a passes through the intersection 39 between the extra weld 34 of the vertical seam weld and the extra weld 35 of the circumferential weld, and performs flaw detection of the circumferential weld. I have. This intersection 39 may normally be a source of ultrasound reflection,
Since the extra seam 34 of the vertical seam weld at the end of the pipe is removed so that the inner and outer surfaces are flush with the base material, it does not become a reflection source, and therefore does not become a noise source in this case.

The reflection and transmission of the ultrasonic wave at the extra bank 35 of the circumferential weld are the same as those described in the vertical seam weld. In short, extra echo from a healthy weld can be ignored. In addition, the defect 3 of a circumference weld part
8 indicates that the probe 10 is further moved by the pig 1
a.

Thus, the probes 10a, 10b,
The ultrasonic waves transmitted from 10c,... Propagate in the pipe wall or surface of the pipe, or propagate helically in the pipe wall or surface, and substantially the base material and the vertical seam as the pig 1 advances. The entire surface of the weld and the circumferential weld is inspected, and the detected defect is measured by the measuring device 8 described with reference to FIG. 8, and the defect state and position are stored in the storage device 7.

Also, even if there are reflections from the extra welds 37 and 38 of the vertical seam weld and the circumferential weld, the extra echo is not returned to the ultrasonic wave incident direction, and therefore to the probe. Therefore, it is not affected by extra echo and therefore noise.

As described above, according to the present invention, by transmitting the ultrasonic wave obliquely to the traveling direction of the pig 1, that is, in the present embodiment, in a direction of 45 ° to the right, a small number and one type of Inspection of pipe base material and vertical seam weld
The whole line flaw detection of the circumferential weld can be performed, and these defects 36, 37, and 38 can be detected easily and with high accuracy.

In the above description, a case has been described in which a probe capable of simultaneously transmitting a transverse wave and a surface wave having a large refraction angle transmits an ultrasonic wave in a direction 45 ° to the right with respect to the traveling direction of the pig. The invention is not limited to this, and an oblique probe, a surface wave probe, or both may be used. Also, the transmission direction of the ultrasonic wave is 35 ° to 55 ° or 125 ° to 145 ° to the left with respect to the pig's traveling direction.
Or 35 ° to 55 ° or 125 ° to 145 to the right
° direction.

Further, the pig used in the present invention is not limited to the configuration shown in FIGS. 2 to 5 and the measuring device shown in FIG. 8, but may be used for pigs having other configurations and measuring devices. it can.

[0032]

As is apparent from the above description, the present invention detects a defect on the entire surface of the base material of the pipe and the entire area of the welded portion by using a pig running in the pipe equipped with a tire type ultrasonic probe. In the ultrasonic flaw detection method described above, the single tire-type ultrasonic probe is disposed in the pipe, and the tire-type ultrasonic probe is moved leftward with respect to the traveling direction of the pig from the tire-type ultrasonic probe.
The ultrasonic wave is transmitted in the direction of 5 ° to 55 ° or 125 ° to 145 °, or 35 ° to 55 ° or 125 ° to 145 ° to the right, and the reflected wave from the defect in the flaw detection area is transmitted to the single tire. A defect is detected on the entire surface of the base material of the pipe and the entire area of the welded portion by receiving with the ultrasonic probe, or a plurality of the tire-type ultrasonic probes are arranged in the circumferential direction in the pipe. 35 ° to 55 ° or 125 ° to 145 to the left with respect to the traveling direction of the pig from each of the plurality of tire-type ultrasonic probes.
°, or 35 ° to 55 ° or 125 ° to 1 to the right
The ultrasonic waves are sequentially transmitted in the direction of 45 °, and the reflected waves from the defects in the respective flaw detection areas are received for each of the plurality of tire-type ultrasonic probes, whereby the entire base material of the pipe and the entire welded portion are received. Since the defect in the area is detected, the following remarkable effects can be obtained.

(1) The coverage of flaw detection can be increased with a small number of probes, so that the detection rate and the detection accuracy can be improved. (2) Since there is no influence of the extra peak echo from the extra peak of the welded portion, it is not necessary to consider noise for the extra peak echo, and both hardware and software can be simplified.

(3) Since the number of probes can be greatly reduced and the number of pigs can be reduced, the equipment cost and the running cost can be reduced. (4) The running stability is improved because the pigs can be formed with a small number of vehicles,
The risk of stacking is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a flaw detection method according to the present invention.

FIG. 2 is a side view showing an example of a pig used in the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view of the probe of FIG. 2;

FIG. 5 is a sectional view taken along line BB of FIG. 4;

FIG. 6 is a diagram illustrating a relationship between a transmission / reception direction of an ultrasonic wave and an echo height.

FIG. 7 is a schematic diagram showing a propagation direction of ultrasonic waves of the probe of FIG. 2;

FIG. 8 is a block diagram illustrating an example of a defect measuring apparatus using a pig.

[Explanation of symbols]

 1 pig 7 storage device 8 measuring device 10a to 10h probe P piping

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-293153 (JP, A) JP-A-2-157652 (JP, A) JP-A-62-108152 (JP, A) (58) Investigation Field (Int. Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (4)

(57) [Claims] 1. An ultrasonic flaw detection method for detecting defects in the entire base material and the entire welded area of a pipe by using a pig equipped with a tire-type ultrasonic probe and traveling in the pipe, wherein: One tire-type ultrasonic probe is disposed, and 35 to 55 degrees or 125 to 145 to the left from the tire-type ultrasonic probe with respect to the traveling direction of the pig.
°, or 35 ° to 55 ° or 125 ° to 1 to the right
The ultrasonic wave is transmitted in the direction of 45 °, and the reflected wave from the defect in the flaw detection area is received by the single tire-type ultrasonic probe, so that the defect on the entire surface of the base material of the pipe and the entire area of the welded portion is obtained. An ultrasonic flaw detection method for piping, comprising: 2. An ultrasonic flaw detection method for detecting defects in the entire base material of a pipe and the entire area of a welded portion by a pig equipped with a tire-type ultrasonic probe and running in the pipe, wherein: A plurality of the tire-type ultrasonic probes are disposed in a circumferential direction, and each of the plurality of tire-type ultrasonic probes is 35 ° to 55 ° to the left with respect to the traveling direction of the pig from each of the plurality of tire-type ultrasonic probes.
Or 125 ° to 145 °, or 35 ° to 5 to the right
Ultrasonic waves are sequentially transmitted in directions of 5 ° or 125 ° to 145 °, and reflected waves from defects in the respective flaw detection areas are received for each of the plurality of tire-type ultrasonic probes, whereby the motherboard of the pipe is formed. An ultrasonic flaw detection method for piping, comprising detecting defects on the entire surface of a material and the entire region of a weld. 3. The transmission direction of the ultrasonic wave is 45 ° to the left or 135 ° to the traveling direction of the pig or 45 ° to the right.
The ultrasonic flaw detection method for piping according to claim 1 or 2, wherein the angle is 135 °. 4. A probe, a bevel probe, a surface wave probe, or a bevel probe and a surface wave capable of simultaneously transmitting a transverse wave and a surface wave having a large refraction angle. 3. The ultrasonic flaw detection method for piping according to claim 1, wherein the method is one of combined use of probes.