JPS6285860A - Ultrasonic flaw detecting method for end part of seam welded tube - Google Patents

Abstract

PURPOSE:To detect the defect of a tube end part, etc., by combining a slanting flaw detecting method in which an ultrasonic wave is made incident at an 8-29 deg. tilt angle with a wide-width flaw detecting method in which an ultrasonic beam is incident at a 12-23 deg. angle of incidence. CONSTITUTION:The ultrasonic beam 5 is slanted in a plane parallel to a tube axis including the incidence direction and made incident at an 8-29 deg. tilt angle (a). Further, the beam 5 is made incident at a 12-23 deg. angle of incidence without slanted in said plane parallel to the tube axis by a single wide-width vibrator. Both methods are used in combination to perform flaw detection. Thus, the defect of the seam welded tube 1 is detected to obtain a reflection echo having a high SN ratio from the defect present at a tube end bevel part 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an ultrasonic flaw detection method for detecting weld defects and base metal defects present at the end of an electric resistance welded tube.

(Prior Art) Conventionally, as shown in FIG. 6, as a method for ultrasonic detection of weld defects in ERW pipes, a probe 3 is attached to a probe shoe 6, and flaws are detected from the upper side of the pipe material 1. The circumferential angle angle flaw detection method is commonly used. In FIG. 8, an ultrasonic beam 5 emitted from a probe 3 enters the tube 1 through water 4 at an incident angle i, is refracted at a refraction angle θ, and is reflected at the inner and outer circumferential surfaces of the tube. If there is a defect, it is reflected there, returns to the same path, and is received by the probe 3.

Conventionally, the probe 3 used in such tube circumferential angle flaw detection method is generally set so that the frequency is 2.25 NIHZ or more and 51 QIHz or less, and the refraction angle θ in Fig. 8 is 37° or more and 90° or less. , the defects in the welded part 2 are detected. Pipe material 1
In the case of steel, if the incident angle i is set to be 16.0° or more and 27.3° or less, the refraction angle θ will be within the above range according to 5nell's law.

In addition, in order to reliably inspect the weld 2, the weld 2 is detected by an electromagnetic induction method, an optical method, a paint mark method, a magnetic mark method, a visual method, etc., and the probe 3 is made to follow the weld 2. Furthermore, a plurality of probes 3 are installed at regular intervals in consideration of the amplitude difference in echo height. In addition, considering the detection and tracing accuracy of the welded part 2, the welded part -
Since flaw detection is carried out by setting gates in a range of about 10 degrees on the left and right in the circumferential direction of the tube, centering on weld defect C, weld defects C as well as hook inclusions A and inclusions, which are less harmful, can be detected. John B is also detected.

(Problems to be Solved by the Invention) In line pipes and the like, the end of the pipe is beveled for intermediate welding. The defects are detected after the tube has been cut to a certain length and beveled, so the beveled portion of the tube end is exposed to the ultrasonic pin 2.
The ultrasonic beam 5 cannot be incident on the tube material 1, and the water 4, which is a couplant, cannot be retained in the probe shoe 6 at the end of the tube even in the non-beveled portion.
Conventional ultrasonic flaw detection methods could not detect defects even if they existed at the end of the tube.

In order to solve these problems, the conventional method is to cut a tube longer than the specified length, perform ultrasonic flaw detection, cut off the undetected area at the end of the tube, and then bevel it. However, it has the disadvantage of reduced yield. However, no literature or patents have been found regarding means for improving these drawbacks.

The present invention was made in order to solve the problems of the conventional method, and it is possible to detect defects in the tube end, which could not be detected by conventional ultrasonic flaw detection, as defects existing in the tube body. Similarly, the purpose is to detect it reliably.

(Means for Solving the Problems) The present invention is directed to an angle ultrasonic flaw detection method using a single probe method for an electric resistance welded tube having a beveled end. It is tilted in a plane parallel to the axis, and the tilt angle a is 8.
An oblique flaw detection method in which the beam is incident at an angle of 12° or more and 29° or less, and a single wide-width transducer is used to make the ultrasonic beam incident at an incident angle of 12° or more and 23° or less without tilting the ultrasonic beam in a plane parallel to the tube axis, including the direction of incidence. This is an ultrasonic flaw detection method for the end of an ERW tube, which is characterized by detecting flaws in combination with a wide-width probe method.

In the present invention, bevel processing refers to cutting a bevel on the pipe end at an angle α (for example, A
The bevel angle α according to the PI standard is 0+5°30. , root face X is 1/16in±1/3
(specified as 2-〇in). The inclination angle a refers to the angle between the tube normal 9 and the ultrasonic beam 5 when viewed from the side when the ultrasonic beam 5 is incident in the tube circumferential direction and in the tube axis direction at the same time. The oblique flaw detection method refers to a flaw detection method in which the ultrasonic beam 5 is incident obliquely in the tube axial direction as well as in the circumferential direction using a probe. The wide-width probe method is, as shown in Fig. 3, in which a probe 3-2 to which a single wide-width transducer is applied is used to beam the ultrasonic beam 5 at an oblique angle only in the circumferential direction. This is a flaw detection method in which the light is incident.

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As shown in Fig. 11V11/r, as shown in Fig. 1, probe 3-
By detecting flaws in the ERW tube 1 by tilting the ultrasonic beam 5 from the ERW tube 1 in a plane parallel to the tube axis including the incident direction, reflected echoes with a high S/N ratio can be obtained from defects existing in the beveled portion 7 of the tube end. I found out that it can be done.

Figure 1 shows an example of the arrangement of the probe and tube material.
) is a cross-sectional view, and (b) is a side view. The electric resistance welded tube 1 is made of carbon steel, and has an outer diameter of 8% and a wall thickness of 0.322mm.
The bevel angle α is between 32° and root face or 1.6°. Using a water immersion probe 3' with a frequency of 5 MHz and a transducer diameter of 10 mm, the incident angle i is 17 degrees and the inclination angle a is 0 degrees ~
Inject the ultrasonic beam 5 into the electric resistance welded tube 1 within a range of 30°,
Depth 0.82g and length 4g machined inside the pipe end bevel part 7
The reflected echo height and the noise echo height from a notch with a width of 1.0 fi and a width of 1.0 fi were measured, and the SN ratio (ratio of the reflected echo height to the noise echo height) was determined. The results were as shown in FIG.

If the S/N ratio is 10 dB or more, stable automatic flaw detection is possible in the same way as the circumferential angle flaw detection method using a conventional water immersion probe. In other words, the S/N ratio is 10 dB or more.
is 8° or more and 29° or less, and this range is optimal. Note that when the incident angle i is changed, in the range of 12° or more and 23° or less, the tilt angle a- is 8°, and in the upper 29° or less range, S
The N ratio becomes 10 dB or more.

Furthermore, as shown in Fig. 8, in order to detect the tube end with high accuracy and efficiency, ultrasonic waves are applied to the circumferential angle angle flaw detection method using a single wide transducer probe using the one-probe method. It was discovered that the detection characteristics similar to those of a normal water immersion probe were improved by injecting a beam into the probe.

Figure 3 shows an example of the arrangement of the probe and tube material.
) is a cross-sectional view, and (b) is a side view. ERW pipe 1 is the first
The same one as in the figure was used. Using a wide probe 3'' with a frequency of 5 MHz, a transducer width of 50.8 fl, and a transducer length of (3.35 m), the incident angle i is 11° to 24° (the tilt angle a is set to Oo). ) The ultrasonic beam 5 was incident on the tube end 8 of the tube material 1 to a depth of 0.8:2 m, a length of 4,
The height of the reflected echo and the height of the noise echo from an artificial defect of a notch with a width of 1.01 and a width of 1.1011 were measured.

The results are as shown in FIG. 4, and in the SN ratio curve in the figure, O indicates an external defect and ■ indicates an internal defect. In other words, the S/N ratio for both external and internal defects is 10 dB.
The above incident angle i is between 12° and 23°, and this range is optimal.

In addition, using the probe 3-1.3-2, there is an oblique flaw detection method in which the incident angle i is set to 17° and the forward angle a is set to 17°; Using the wide probe method set to 0.00, N10 notches of various lengths (10% depth of the wall thickness (notch) was processed to determine the S/N ratio. The measurement results using the oblique probe method and the wide probe method are shown in FIGS. 5 and 6, respectively.

That is, both the oblique flaw detection method and the wide probe method can reliably detect an NIO notch with a length of 1 mm or more at an S/N ratio of 10 dB or more. Further, in the oblique flaw detection method, although the bevel angle α is 32°, detection is possible with the above-mentioned notch S/N ratio of 10 dB or more in the range of 30° or more and 60° or less. In the wide probe method, as shown in FIG. 3(b), in order to reliably test the tube end 8, the probe end face 1
It is preferable that the gap 12 in the tube axis direction between the tube end surface 11 and the tube end surface 11 be equal to the tracing accuracy.

(Example) Examples of the present invention will be shown below. As shown in Table 1, the test pieces were carbon steel electric resistance welded tubes of various outer diameters and wall thicknesses, which were beveled so that various defects were present at the tube ends and the beveled tube ends. Bevel angle α is 32°, root face
was set at 1.6 m.

FIG. 7 shows an example of an apparatus configuration for implementing the present invention.

The oblique flaw detection method uses a frequency of 5 MHz and a transducer diameter of 10 mm.
Using the chain water immersion probe 3-1, the incident angle i was set to 17° and the inclination angle a was set to 17°. Three were placed at regular intervals.

The wide-width probe method uses a probe 3-2 with a frequency of 5) VlHz, a transducer width of 50.8 mm, and a transducer length of 6.35 mm.
The incident angle i was set to 17° and the tilt angle a was set to 00.

In addition, flaw detection was performed by rotating the tube material in the Z direction at a speed of 45 rpm using both the oblique flaw detection method and the wide probe method by applying an ultrasonic beam. In the wide probe method, the probe end face and the tube end face were manually traced, and the gap between the probe end face and the tube end face in the tube axis direction was adjusted to 10 rm.

In addition, in FIG. 7, the ultrasonic flaw detector and recorder are omitted. Furthermore, in order to confirm the detection characteristics of the method of the present invention, flaw detection was also performed using the conventional method. In the conventional method, 1 frequency is 5
Using a water immersion probe with a frequency of MHz and a transducer diameter of J orms, the incident angle i was set to 17°, the inclination angle a was set to 00, and the probe was spaced at regular intervals to ensure flaw detection of the weld. Three pieces were installed, and ultrasonic beams were incident on both sides of the weld, and the inspection speed V was 45 m/min.

As a result, as shown in Table 1, defects at the tube ends and tube end bevel portions could not be detected using the conventional method, but with the method of the present invention, all defects could be detected with an S/N ratio of 10 dB or more.

Here are the flaw detection results for a pipe material whose end has been beveled (bevel end material).
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), it is possible to detect flaws to the very end of the tube using only the wide probe method.

In this case, a probe with a single wide transducer was used to perform high-accuracy and high-efficiency flaw detection at the tube end, but instead of the wide probe, multiple water immersion probes were installed. Flaw detection is also possible, although the adjustment is complicated.

Although the above embodiments are about carbon steel ERW pipes, similar defect detection is possible by the method of the present invention for welded parts of other low alloy steels, stainless steels, and even non-ferrous metals. It can also be applied to seamless pipes and other welded pipes. Further, the shape is not limited to circular pipes, and the same applies to welded parts of square pipes with beveled ends.

Table 1 (Effects of the Invention) As detailed above, according to the ultrasonic flaw detection method of the end of an ERW tube according to the present invention, the end of the tube, which was considered undetectable by the conventional ultrasonic flaw detection method, can be detected. 2. It is possible to reliably detect defects in the pipe end bevel, which contributes to lateral distortion of pipe materials used in particularly harsh environments such as cold environments, and greatly improves the quality assurance of ERW pipes. can be improved. Therefore, it has become possible to use ERW pipes in fields where only seamless pipes have conventionally been used.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an example of the arrangement of the probe and pipe material when detecting defects existing in the beveled part of the pipe end using the method of the present invention (in the case of oblique flaw detection method), and Fig. 2 is an explanatory diagram of an example of the arrangement of the probe and the pipe material when detecting defects existing in the beveled part of the pipe end using the method of the present invention. A diagram of defect detection characteristics when changing the inclination angle of the probe (in the case of oblique flaw detection method). Figure 3 shows the arrangement of the probe and tube material when detecting defects at the end of a tube using the method of the present invention. An explanatory diagram of an example (
Fig. 4 is a diagram of the defect detection characteristics when detecting defects existing at the end of a tube using the method of the present invention (in the case of the wide probe method).
Figure 5 is a graph of the artificial defect detection characteristics processed into the beveled part of the tube end using the method of the present invention (in the case of the oblique flaw detection method). A diagram of the processed artificial defect detection characteristics (in the case of the wide probe method), Figure 7 is one of the practical aspects of the present invention. FIG. 8 is an explanatory diagram of conventional tube circumference angle flaw detection, and FIG. 9 is an explanatory diagram of defects occurring in an electric resistance welded tube. 1; Tube material 2; Welded portion 3; Probe 4: Water 5; Ultrasonic beam 6; Probe shoe 7; Tube end bevel portion 8; Tube end 9: Tube normal 10; Probe end face 11; Tube end surface 12; Gap i in the tube axis direction between the probe end surface and the tube end surface; Incident angle θ: Refraction angle A: Hook inclusion B; Inclusion C; Venetrator 2: Rotation direction α of the tube material; Bevel angle X; Root Face 0; Signal-to-noise ratio curve for external defects I; Signal-to-noise ratio curve for internal defects Agent Patent attorney Tatsuo Chanoki Figure 2 ip*° (1 [de9] Figure 3 n (0) (b) Figure 4 Incident angle i rdegJ Fig. 5 Hatch length L (mm) Fig. 6 Nona length L, (rnm) Fig. 7 Fig. 8 Fig. 9

Claims (1)

[Claims] In the tube circumferential angle ultrasonic flaw detection method using the one-probe method for an ERW tube with a beveled tube end, the ultrasonic beam is tilted in a plane parallel to the tube axis including the incident direction, and the tilt angle a is set to 8°. Above 29
An oblique flaw detection method in which the ultrasonic beam is incident at an angle of 12° or more and less than 23°, and a wide detection method in which the ultrasonic beam is made incident at an incident angle of 12° or more and 23° or less without tilting the ultrasonic beam in a plane parallel to the tube axis including the incident direction using a single wide-width transducer. An ultrasonic flaw detection method for the end of an ERW tube, characterized by flaw detection in combination with a probe method.