JPH0257973A - Angle beam flaw detecting head for pipe and angle beam flaw detecting apparatus using said head - Google Patents

Abstract

PURPOSE:To detect flaws by mounting a plurality of vertical probes and slant angle probes on an arc shaped side plates having a concentric circle with a pipe under test in an array pattern, and setting slant angle probe heads at specified positions regardless of the outer diameter and the thickness of the pipe under test. CONSTITUTION:A slant angle probe 12 comprises a vertical probe 14 having a rectangular contact surface and a sound wedge 15 having a radial angle width. The width of the probe 12 in the circumferential direction of the pipe is several mm or less. A plurality of the slant angle probes 12 are arranged in a pipe circumference shape in an array pattern. Therefore, the width of the wedge in the pipe circumference direction is machined in a radial angle shape. The probes are attached to side plates 16a and 16b in an arc shape that is concentric with a pipe under test 10. Abrasion resisting shoes 17a and 17b are attached before and after the probe group in order to hold the gap between the wedges 15 and the surface of the pipe 10 and to prevent the abrasion of the wedges 15. Therefore, flaw detection of pipe material can be performed readily, and the following to welded parts is not required, while the adjustment in changing the thickness of the pipes is not required, too.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an angle angle flaw detection head for pipes and an angle angle flaw detection device for pipes using the same, and is particularly suitable for detecting defects in the pipe axial direction at welded parts of ERW steel pipes, and has a weld tracking method. The present invention relates to an oblique flaw detection head for pipes and an oblique flaw detection device for pipes using the same, which eliminates the need for adjustment when changing pipe thickness.

[Conventional technology]

In general, an angle angle flaw detection method is used to detect defects in the pipe axis direction in a welded portion of an electric resistance welded steel pipe. In this method, ultrasonic waves are applied obliquely to the inspection surface of the material to be inspected (hereinafter referred to as the "test tube"), and the reflected waves reflected by defects in the test tube are used to detect defects on the inner and outer surfaces of the horizontal tube. It detects defects. In addition, in order to detect defects over the entire length of the welded portion of the ERW steel pipe, an ultrasonic probe is scanned parallel to the welded portion of the ERW steel pipe, and the ultrasonic beam is propagated at right angles to the welded portion. A method is used to However, in the above-mentioned angle angle flaw detection method, variations in the distance from the point where the ultrasonic beam is incident to the defective part, that is, the probe
It is known that the echo height from the defect changes greatly as shown in FIG. 8 as the defect distance changes. This can be seen, for example, in JP-A-55-140148 No. 2.
This is disclosed in Figure 1 of Japanese Patent Publication No. 57-8420. For this reason, it is difficult to determine the reference echo height, and accurate flaw detection becomes difficult when the probe-defect distance changes.To alleviate this problem, the following methods have been adopted. Ta. That is, FIG. 9 is an explanatory diagram of the configuration of the conventional example, and FIG.
A), (B), and (C) are respectively the AA' sectional view, the BB' sectional view, and the CC' sectional view of FIG.
As shown in these figures, a test tube 10 such as an electric resistance welded steel pipe is
For example, three oblique probes 18a to 18C118d to 18f are arranged on one side of the welded part 11, and the ultrasonic beams incident on the test tube 10 from these probes are directed at the center of the welded part 11. The outer surface (see Fig. 10 (A)), the center (see Fig. 10 (B)), and the inner surface (see Fig. 10 (C)
(see). Furthermore, as disclosed in Japanese Patent Publication No. 57-8420, for example, the amount of twist of the welded part and the length of the tube to be tested are preset, and then the length of the current position is sequentially detected.
The amount of deviation of the probe from the welded part can be calculated to track the welded part, or, as disclosed in JP-A No. 59-43354, the probe can be moved in the circumferential direction of the tube to be tested. Install multiple transmitter/receiver coils along the line, judge the reception signal levels of these transmitter/receiver coils sequentially over time, maintain the relative position of the weld and the probe in a constant relationship, and track the weld. I was trying to do it. However, in the above conventional example, firstly, as the distance between the probe and the defect changes, the echo height changes greatly as described above, so there is a problem that the welded part must be followed. Second, there is a problem that the appearance position of the beak echo differs depending on the outer diameter and thickness of the tube to be examined. That is, the appearance position of the beak echo is expressed by the following equation (1), and varies depending on the outer diameter of the tube to be examined and the value of the tube thickness t. Therefore, the distance between the probe and the welded portion had to be adjusted depending on the tube thickness t. L,=N-to-t-tanθr...(1)
Here, N is a coefficient depending on the number of skips S (N=S10.
5), K is a correction coefficient determined by the refraction angle θr and t/D. Thirdly, there is a problem in that sensitivity adjustment work must be performed in order to set the sensitivity of the main body of the flaw detection apparatus using the beak echo.

[Problem to be achieved by the invention]

The present invention has been made in view of the above-mentioned problems, and solves all of the above-mentioned problems 1 to 3. In particular, the present invention solves the problem of An object of the present invention is to provide an oblique flaw detection head for pipes suitable for detecting defects and an angle flaw detection device for pipes using the same.

[Means to achieve the task]

The present invention provides an angle angle flaw detection head for pipes in which an angle probe consisting of a vertical probe with a rectangular contact surface and an acoustic wedge with a radial angular width is placed in a concentric circle with the tube to be inspected. The above problem is solved by mounting a plurality of probes in an array on an arc-shaped side plate and providing wear-resistant shoes before and after each of the bevel probe groups. Further, the present invention solves the above problem by using the above-mentioned angle angle flaw detection head for pipes in an angle angle flaw detection apparatus for pipes, and simultaneously exciting the angle probes in the head to test the test tube. This is what I did. Furthermore, the present invention provides an angle angle flaw detection device for pipes, which uses the angle angle flaw detection head for pipes, holds all the angle probes in the head in a receivable state, and detects each angle probe. This problem has been solved by testing the test tubes while sequentially exciting them one by one.

[Effect]

As shown in FIGS. 1 and 2 (A) or (B), the angle pipe inspection head of the present invention includes a vertical probe 14 having a rectangular contact surface and a radial angular width. acoustic wedge 1
A plurality of bevel probes 12 having a circumferential width of, for example, several square meters or less are arranged in an array around the tube. Here, the number n of the angle probes 12 (n=6 in the figure) is:
It can be determined to cover the maximum one-skip distance S or more in the test tube 10. In order to arrange the probes in an array along the circumference of the tube, the width of the acoustic wedge 15 in the tube circumferential direction is processed to have a radial angle of, for example, β°, and the probes are arranged in the same direction as the tube 10 to be tested. It is attached to the arc-shaped side plates 16a and 16b of the core circle. Furthermore, wear-resistant shoes 17a and 17b are attached to the front and rear of the probe group in order to maintain a gap between the acoustic wedge 15 and the surface of the test tube 10 and to prevent wear of the acoustic wedge 15. Therefore, flaw detection can be easily performed on tubular materials.
As will be described later, there is no need to follow the weld, and there is no need to make adjustments when changing the pipe thickness.

[Embodiment 1] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. An embodiment of the oblique flaw detection head for steel pipes according to the present invention has a structure as shown in FIGS. 1 and 2 (A) and (B). That is, the bevel probe 12 is composed of a vertical probe 14 having a rectangular contact surface and an acoustic wedge 15 having a radial angular width (for example, several tens of meters or less). It is attached to the wedge 15 with machine screws or the like (not shown). Furthermore, there is a thin film (not shown) of oil or the like between the contact surface of the vertical probe 14 and the mounting surface of the acoustic wedge 15.
The vertical probe 14 and the acoustic wedge 15 are acoustically coupled. On the other hand, the space between each of the oblique probes 12 is divided by an acoustic dividing plate (not shown). The acoustic wedge 15 has a radial angular width as described above, and specifically, the acoustic wedge 15 has a radial angular width of β° in the circumferential direction of the tube to be inspected (ERW steel pipe) 10 . Also, the sound velocity of the incident wave entering the acoustic wedge 15 and the test tube 1
When the sound speeds of refracted waves refracted at zero are Ci and Cr, respectively, the relationship between the incident angle θi of the incident wave and the refraction angle θr of the refracted wave follows the so-called Snell's law, and the following formula (2) holds true. Cr/sin θr=Ci/sin θi −(2) Therefore, in order to obtain the desired refraction angle θr, the shape of the acoustic wedge 15 is formed so that the incident angle is the above incident angle θ. Incidentally, the acoustic wedge 15 has a radial width as described above, and the radiation angle β' of the width is determined by the outer diameter of the test tube 10 and the width of the vertical probe 14. acoustic wedge 15
By processing the circumferential width of the acoustic wedge 15 into the radiation angle β' as described above, the acoustic wedge 15 is placed on the circumference of the tube 10 to be tested.
It is easy to arrange them in an array as shown in the figure. Furthermore, as shown better in FIGS. 2(A) and 2(B), the above-mentioned oblique probe 12 consisting of a vertical probe 14 and an acoustic wedge 15 is arranged in a concentric circle with the test tube 10. It is held by side plates 16a and 16b having arcuate shapes via machine screws or the like (not shown). The side plates 16a and 16b are used to easily hold the bevel probes 12 in an array on the circumference of the test tube 10. In addition, wear-resistant shoes 17a and 17b are attached to the front and rear of the bevel probe group via machine screws or the like (not shown). The shoes 17a, 17b prevent the acoustic wedge 15 from being worn out, and also prevent the acoustic wedge 15 from being worn out.
It is used to maintain a gap between the test tube 10 and the surface of the test tube 10. In addition, in FIGS. 1 and 2, the above-mentioned angle probe 12
Although the number is six, the present invention is not limited to this number, and this number is determined by the dimensional range (maximum skip distance) of the test tube 10, as already explained in section 7. be done. On the other hand, the angle flaw detection apparatus for steel pipes of the present invention using the above-described angle flaw detection head for steel pipes has the following configuration. That is, as shown in FIG. 1, the angle flaw detection heads for steel pipes described in detail with reference to FIGS. The device is configured. Depending on the method of excitation of the angle probe 12 in the above-mentioned angle inspection head for steel pipes, angle angle flaw detection apparatuses for steel pipes are roughly divided into those that use simultaneous excitation of all channels and those that use sequential excitation of individual channels. An angle flaw detection device for steel pipes with simultaneous excitation of all channels simultaneously excites all channels 1 to n of each angle probe 12 in an angle flaw detection head for steel pipes, and excite alternately left and right for each angle flaw detection head. The welded portion 11 of the tube to be inspected 10 is inspected for flaws. For this reason, each angle flaw detection head is configured to have one set of a pulser receiver and a gate unit, and the scale of the angle flaw detection apparatus for steel pipes can be reduced (downsized, etc.). In addition, the angle flaw detection device for steel pipes using the individual channel sequential excitation method has all the angle probes 1 in the angle flaw detection head for steel pipes.
2 in a receivable state, sequentially excite each of the angle probes one by one, for example from N011 to No.
The welded portion 11 of the test tube 10 is tested for flaws. Therefore, one set of pulsar receiver and gate unit is required for each angle probe, and the scale of the equipment becomes larger (larger, etc.) than in the case of the simultaneous excitation method for all channels. This method has the advantage that the position of a defect in a welded portion of a tube to be inspected can be determined geometrically from the beam path of the defect echo. FIG. 3 is a diagram showing the timing of sequential excitation in the steel pipe angle flaw detection apparatus using the individual channel sequential excitation method. In this figure, the transmission of the bevel probes is performed one by one by each bevel probe (No. 1 to No. n bevel probe), and the reflected echo from the defect in the test tube is transmitted. is received by all angle probes. As shown in Fig. 4, using the oblique flaw detection head for steel pipes of the present invention, an N5 notch (notch depth 0°48 mm) on the outer surface machined to an outer diameter of 406.4 mw+ and a pipe thickness of 9.52 μm was detected. When the test tube was inspected for flaws, the results shown in FIGS. 5 to 7 were obtained. FIG. 5 is a diagram showing the distance-amplitude characteristics of each probe investigated using the oblique flaw detection head for steel pipes of the present invention.
(A) to (C) are each angle probe (specifically, NO12
-N014) shows the distance amplitude characteristics for each of the oblique angle probes). In Figures 5 (A) to (C), which are similar to the conventional example, the peak echo height is shown at the skip point, and it can be seen that the echo height changes greatly as the distance between the bevel probe and the defect changes. . On the other hand, Figure 6 shows the distance amplitude characteristics when all channels of the angle probes in the steel pipe angle flaw detection head of the present invention are simultaneously excited. It can be seen that the height change is extremely small. Furthermore, Fig. 7 shows the concept of the distance amplitude characteristic when each angle probe in the angle probe head for steel pipes of the present invention is individually and sequentially excited. It can be seen that even if the distance between the angle probe and the defect changes, the change in echo height is extremely small, as in the case of the all-channel simultaneous excitation method. In the above embodiments, the present invention was applied to flaw detection of steel pipes, but it is clear that the present invention is not limited to this and can be similarly applied to flaw detection of tubular materials in general. [Effects of the Invention] According to the present invention as described in detail above, the echo height remains constant even if the distance between the probe and the defect changes. ! There is only a slight change, and there is no need to follow the weld as in the conventional example. In addition, since there is no peak in echo height, the bevel probe head can always be set at a fixed position regardless of the outer diameter or thickness of the tube to be inspected. This has excellent effects such as eliminating the need to adjust the sensitivity of the device itself.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an angle pipe flaw detection head and an angle pipe flaw detection apparatus using the same according to the present invention, and FIG. 2(A) is a view taken from the direction of arrow A in FIG. 2(B) is a plan view as seen from the direction of arrow B in FIG. 1. FIG. 3 is a diagram showing the timing of sequential excitation in an angle flaw detection device for steel pipes using an individual channel sequential excitation method. , FIG. 4 is a cross-sectional view for explaining the operation of the embodiment of the present invention, and FIG. Figure 6 is a diagram showing an example of the distance amplitude characteristic for each probe. Figure 8 is a diagram showing the concept of distance-amplitude characteristics when the angle probe uses the individual sequential excitation method. Figure 8 is a diagram showing an example of distance-amplitude characteristics in the conventional angle-angle flaw detection method. FIG. 9 is a plan view showing the configuration of an example of a conventional angle flaw detection device for steel pipes, and FIGS. 10 (A), (B), and (C) are lines A-A' and B- It is a sectional view taken along line B'' and line c-c'. 0... Test tube, 2... Oblique probe, 4... Vertical probe, 5a, 16b... Side plate. , 7a, 17b... Shoe 11... Welding part, 13... Ultrasonic beam, 15... Acoustic wedge,

Claims (3)

[Claims] (1) Multiple oblique probes consisting of a vertical probe with a rectangular contact surface and an acoustic wedge with a radial width are arrayed on an arc-shaped side plate concentric with the test tube. 1. An oblique flaw detection head for pipes, characterized in that the bevel probe group is mounted in the same shape as the bevel probe group, and wear-resistant shoes are provided at the front and rear of the bevel probe group. (2) comprising the angle tube flaw detection head according to claim 1;
An angle angle flaw detection device for a tube, characterized in that a tube to be inspected is tested for flaws by simultaneously exciting each angle probe in the head. (3) comprising the angle pipe flaw detection head according to claim 1;
An angle angle flaw detection for pipes characterized by holding all the angle angle probes in the head in a receivable state and testing the test tube while sequentially exciting each angle probe one by one. Device.