JP2000097919A - Ultrasonic flaw detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a method whereby a flaw detection for a fillet weld part can be more easily conducted and the internal defect can be detected, evaluated by carrying out the flaw detection by utilizing a transversal wave generated from a creeping wave probe and a secondary creeping wave generated through a mode transform of the transversal wave at the bottom face. SOLUTION: When an ultrasonic wave is inputted to a fillet weld part 3 by a creeping wave probe (referred to as a probe hereinafter), a part of the wave is turned to a secondary creeping wave 4c through a mode transform from a transversal wave 4b at the bottom face and reflected by an incomplete penetration corner part. The reflected ultrasonic wave is received by the probe 1, amplified and detected by an ultrasonic flaw detector 18 and sent to a data- collecting/processing apparatus 19. The probe 1 is pressed by a driving apparatus 17 to a piping flaw detect face to scan a piping joint in the whole circumferential and axial directions. The collected data are processed by the data-collecting/ processing apparatus 19 after the flaw detection is completed. The data are analyzed on the basis of a detection echo and a position of the probe when detecting the defect. A state of the defect is judged and a fatigue fracture or the like is analyzed for the progress direction.

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 test for a fillet weld, which is suitable for detecting a defect existing in a weld and analyzing and discriminating the nature of the defect. Related to the test method.

[0002]

2. Description of the Related Art There is an ultrasonic flaw detection test method for detecting insufficient penetration and fatigue cracking by using a bevel probe and a vertical probe together for ultrasonic inspection of a fillet weld. Using a transverse probe and a secondary creeping wave that are simultaneously generated using a wave probe, a defect existing in the weld is detected,
There was no ultrasonic testing method that could analyze and determine the nature of the defect.

[0003]

According to the prior art, ultrasonic inspection of a fillet weld is performed by a method in which ultrasonic waves are incident from one direction using an angle probe. In this case, it is difficult to discriminate between cracks at right angles or near horizontal angles to the surface of the inspection object (hereinafter referred to as the flaw detection surface). The source of the sound wave was analyzed.

An object of the present invention is to provide an ultrasonic flaw detection method that can more easily detect a fillet weld and detect and evaluate defects inherent in the weld.

[0005]

Means for Solving the Problems In order to achieve the above-mentioned object, the following configuration is provided.

1) A creeping wave probe 1 (hereinafter referred to as a probe) is connected to a pipe joint socket 2 as shown in FIG.
An ultrasonic flaw detection test of the fillet weld 3 using a transverse wave 4b generated from the probe 1 and a secondary creeping wave 4c generated by the mode conversion of the transverse wave at the bottom surface, which is arranged on the outer surface. I do. The probe 1 has a driving device 17 capable of scanning the pipe joint socket portion 2 in the circumferential direction 22 and the axial direction 23.
Attach to The driving device 17 is provided with a pressing mechanism for pressing the probe 1 on the pipe and position detecting mechanisms 21a and 21b capable of detecting a probe scanning position.

2) The flaw detection data is stored in a data recording processing device 1
9, the beam path position of the recorded detected echo is analyzed, and the following defects inherent in the fillet weld 3 are determined and evaluated.

[0008] Judgment of insufficient penetration and fatigue cracking • Analysis of the direction of fatigue crack propagation In this configuration, fillet welding is performed using transverse waves generated from the probe 1 and secondary creeping waves generated simultaneously from the transverse waves. The ultrasonic inspection of the part 3 is performed.

The ultrasonic flaw detection by the probe 1 of the socket weld, which is a typical fillet weld, will be described below with reference to FIGS. When the probe 1 is placed as shown in FIG. 1, the ultrasonic beam 4 passes through the probe 1 from the ultrasonic flaw detector 18.
Is incident on the welded portion through two routes, a creeping wave 4a and a transverse wave 4b. Of these, a part of the shear wave is converted into a secondary creeping wave 4c by mode conversion on the bottom surface, as shown in FIG.
The light travels along the ultrasonic wave propagation path 5a shown in (a) and (b) and is reflected at the corner portion 6 with insufficient penetration.

In addition, some ultrasonic waves are left as shear waves,
The light travels along the ultrasonic wave propagation path 7a shown in FIGS. The reflected ultrasonic wave is received by the probe 1 and sent to the ultrasonic flaw detector 18 as an electric signal.

At this time, as shown on the right of FIGS. 2A and 2B, the flaw detection waveform of the ultrasonic flaw detector includes a reflection echo 5b at the corner with insufficient penetration and a reflection echo 7b at the end with insufficient penetration.
Will be displayed as When the welded portion where the fatigue crack 9 has occurred in the vertical direction is inspected, the reflected wave from the fatigue crack is detected along the ultrasonic wave propagation path 10a as shown in FIGS. When the weld displayed at the position of the upper part 10b and the fatigue crack 11 has occurred in the horizontal direction is inspected, the reflected wave from the fatigue crack is transmitted through the ultrasonic wave propagation path as shown in FIGS. 4 (a) and 4 (b). 12a is detected and displayed at the position of 12b on the flaw detection waveform.

When the welded portion where the fatigue crack 13 has occurred is detected in a diagonal direction, the reflected wave from the fatigue crack follows the ultrasonic wave propagation path 14a as shown in FIGS. 5 (a) and 5 (b). Is displayed at the position 14b on the flaw detection waveform.
In addition, the circumferential direction 22 of the welded pipe joint is controlled by the driving device 17.
By performing scanning in the axial direction 23, an ultrasonic inspection of the welded portion can be performed, and the probe position is detected by the circumferential position detecting mechanism 21a and the axial position detecting mechanism 21b provided in the driving device 17. Thus, the position of the defect existing in the welded portion can be obtained from the probe position and the beam path 15 of the detected defect echo.

As described above, the ultrasonic inspection using the transverse wave and the secondary creeping wave generated from the creeping wave probe detects the defect existing in the socket weld and detects the defect. The operation of determining and evaluating the properties can be performed by one flaw detection. Further, by analyzing the time difference relationship between the reflected echoes by the data recording processing device, it is possible to determine the defect existing in the welded portion and to analyze the direction of the fatigue crack propagation.

[0014]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to (a) and (b). FIG. 1 (a), (b)
1 shows a configuration example of a fillet weld ultrasonic testing device. When ultrasonic waves enter the fillet weld with the probe 1, some of the ultrasonic waves become secondary creeping waves 4 c by mode conversion from the transverse waves 4 b on the bottom surface, and are reflected at the corner portions 6 with insufficient penetration. . Some of the ultrasonic waves are incident as shear waves, and the insufficient penetration edge 8 and fatigue cracks 9, 11, 1
It is reflected at 3. The reflected ultrasonic wave is received by the probe 1, amplified and detected by a receiving amplifier in the ultrasonic flaw detector 18, and sent to the data recording / processing device 19.

The ultrasonic flaw detection signal is A / D converted by the data recording / processing device 19 and recorded together with the probe position signal sent from the driving device 17. The probe 1 includes a driving device 1
7 presses against the flaw detection surface of the pipe and scans the entire circumference of the pipe joint and in the axial direction. The recorded data is processed by the data recording / processing device 19 after the end of the flaw detection, and is analyzed based on the beam path of the detected echo, the echo height, and the probe position when the defect is detected, and the nature of the defect For the determination and fatigue cracking, the direction of development is analyzed. Defects mainly observed in the fillet weld include insufficient penetration and fatigue cracks caused by the insufficient penetration. The data processing for discriminating the defect in the present invention utilizes the fact that the corner portion with insufficient penetration can be simultaneously detected by the secondary creeping wave and the end portion by the transverse wave in the welded portion where the fatigue crack has occurred.

If there is no insufficient penetration into the fillet weld, no defect waveform is detected, but if there is insufficient penetration, the waveforms shown in FIGS. 2A and 2B are displayed. When there is a fatigue crack that has developed in the vertical direction as shown in FIGS. 3 (a) and 3 (b), the defect echo appears on the right side of the poor penetration edge echo on the flaw detection waveform, and there is a fatigue crack that has developed in the horizontal direction. In this case, it appears on the left side of the echo of the corner with insufficient penetration. In addition, when there is a fatigue crack that has developed in an oblique direction, it appears between the insufficient penetration edge echo and the poor penetration corner echo.

[0017]

As described above, according to the configuration of the present invention, defect detection and analysis such as insufficient penetration of fillet welds and fatigue cracking can be performed only once by attaching the flaw detection device to the inspection object. Maintenance inspections can be streamlined.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a configuration diagram for explaining a configuration of an ultrasonic flaw detection test apparatus showing an embodiment of the present invention and an ultrasonic incident state of a creeping wave probe, and FIGS. 2 is an enlarged side sectional view of a portion A of FIG.

FIGS. 2 (a) and (b) are an ultrasonic wave propagation path diagram and a defect waveform diagram thereof when detecting insufficient penetration according to an embodiment of the present invention.

FIGS. 3A and 3B are an ultrasonic wave propagation path diagram and a defect waveform diagram thereof when detecting a fatigue crack that has developed in a direction perpendicular to a flaw detection surface according to the embodiment of the present invention.

FIGS. 4 (a) and (b) are an ultrasonic wave propagation path diagram and a defect waveform diagram when detecting fatigue cracks that have developed in a horizontal direction with respect to a flaw detection surface according to the embodiment of the present invention.

5 (a) and 5 (b) are an ultrasonic wave propagation path diagram and a defect waveform diagram when detecting fatigue cracks which have developed in an oblique direction to a flaw detection surface according to the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Creeping wave probe, 2 ... Pipe joint socket part, 3 ... Fillet welded part, 4a ... Creeping wave, 4b ... Lateral wave, 4c ... Secondary creeping wave, 5a ... Penetration by secondary creeping wave Ultrasonic wave propagation path at the time of detection of an insufficient corner portion, 5b ... Echo of a corner with insufficient penetration due to secondary creeping wave, 6 ... Corner portion with insufficient penetration, 7a ...
Ultrasonic propagation path at the time of detection of insufficient penetration edge by transverse wave,
7b: echo of insufficient penetration edge due to shear wave, 8: edge of insufficient penetration, 9: fatigue crack propagated in vertical direction, 10a
... Ultrasonic propagation path of fatigue cracks that have developed in the vertical direction
b: Fatigue crack echo propagated in the vertical direction, 11: Fatigue crack propagated in the horizontal direction, 12a: Ultrasonic propagation path of the fatigue crack propagated in the horizontal direction, 12b: Fatigue crack echo propagated in the horizontal direction, 13: Oblique Fatigue cracks,
14a: Ultrasonic propagation path of fatigue cracks extending in an oblique direction, 14b: Echo of fatigue cracks extending in an oblique direction, 15
... Defect echo beam path, 16 ... Defect echo peak value,
17 ... Drive device, 18 ... Ultrasonic flaw detector, 19 ... Data recording / processing device, 20 ... Control device, 21a ... Circumferential probe position detector, 21b ... Axial probe position detector, 22 ... Circle Circumferential scanning direction, 23: axial scanning direction, 24: transmitting oscillator, 2
5 ... Reception vibrator.

Continued on the front page (72) Inventor Saburo Yamazaki 3-2-1 Sachimachi, Hitachi City, Ibaraki Prefecture Inside Hitachi Engineering Co., Ltd. (72) Inventor Tsutomu Masumoto 3-2-1 Sachimachi, Hitachi City, Ibaraki Hitachi Within Engineering Co., Ltd. (72) Inventor Yasuhiro Mabuchi 3-1-1, Sachimachi, Hitachi-shi, Ibaraki F-term in Hitachi, Ltd. Hitachi Plant F-term (reference) 2G047 AB07 BA03 BC02 BC07 CB00 CB02 CB06 GA05 GA19 GG09 GG19 GG27

Claims (2)

[Claims] In an ultrasonic flaw detection method using a creeping wave probe, the arrival time difference between a reflected wave of a transverse wave and a reflected wave of a secondary creeping wave, which are generated simultaneously with the creeping wave, is measured and evaluated. An ultrasonic flaw detection method characterized in that: 2. The ultrasonic flaw detection method according to claim 1, wherein the property of the reflection source is evaluated from the time difference between the shear wave reflected wave and the secondary creeping reflected wave.