JP3017346B2 - Inspection method for nozzle inner surface flaw - 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 inspection method ,
In particular, the present invention relates to an ultrasonic flaw detection method suitable for flaw detection of a defect on an inner surface of a nozzle hole.

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional ultrasonic flaw detector comprises a fixed angle probe 1 'and a flaw detector 2'. When detecting flaws inside a structure, a thickness t of 2
About twice as much probe scanning space was required. For this reason, as shown in FIG. 8, it is impossible to use the ultrasonic flaw detector for the purpose of detecting an inner surface defect in a nozzle portion where the nozzle pitch is narrow and the space scanned by the probe cannot be secured. Was. An example of the prior art is described in Japanese Patent Publication No. 15821/1990.

[0003]

The prior art described above is
No consideration has been given to the detection of inner surface defects in the nozzle,
There is a problem that ultrasonic flaw detection cannot be applied to the detection of an inner surface defect of a nozzle.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. An electron sector scan single-point incidence probe is determined by the hole pitch of the nozzle from the center of the hole of the nozzle and the thickness of the nozzle. a predetermined distance, and the shape is set at a predetermined angle with respect to the tangential direction of the hole edge of the nozzle stub Eco - defect Eco - identification and to facilitate, probe position detecting means and the ultrasonic bi - beam Circuit for calculating the refraction angle of the beam and the beam path
It has a means to output only the eco-signal within the range and a beam path / amplitude automatic correction circuit. The application of ultrasonic flaw detection.

[0005]

According to the present invention, a longitudinal wave / shear wave combined flaw detection method using an electron sector scan single-point incidence type probe is used to move the probe from the center of the hole of the nozzle to the nozzle. A predetermined distance determined by the hole pitch and the thickness near the pipe, and 20 ± 10 degrees with respect to the tangential direction of the hole edge of the nozzle .
A method for inspecting an inner surface of a nozzle is provided, wherein the ultrasonic beam is set to an angle within the range and an electronic beam is scanned by an electronic sector.

In this case, a circuit for calculating an incident angle, a refraction angle, and a beam path of the ultrasonic beam transmitted to the inner surface of the nozzle, a beam incident point position measuring means of the probe, and Means for outputting only the eco signal within the gate range, and beam path /
Estimation of defect position and defect using automatic amplitude correction circuit
The echo signal level is compensated.

[0007]

The single point incident electron sector scan ultrasonic inspection method can transmit an ultrasonic beam over a wide range. Therefore, the probe is placed at a predetermined distance determined by the hole pitch of the nozzle and the thickness near the nozzle from the center of the hole of the nozzle, and an angle within a range of 20 ± 10 degrees with respect to the tangential direction of the hole edge of the nozzle. it is possible to set, it is not necessary to scan the ultrasonic probe in narrow nozzle stub portion.

Further, according to the present invention, the probe is connected to the hole of the nozzle.
Angle within 20 ± 10 degrees to tangent direction of edge
By setting to, the shape echo on the inner surface of the nozzle will not be detected, so that it is easy to distinguish between the shape eco and the defect eco.

Further, according to the present invention, a function for calculating the beam incident position, incident angle, refraction angle, and beam path of the probe and a function for outputting only an echo signal within the gate range, Since the beam path / amplitude automatic correction circuit function increases the defect position estimation accuracy and the defect quantification accuracy, the ultrasonic flaw detection method can be applied to the detection of defects on the inner surface of the nozzle.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIG. 1. In the ultrasonic inspection of the inner surface of the nozzle, a one-point incident electron sector scan probe 1, an electronic scan ultrasonic inspection device 2, a power supply device The probe 1 is moved from the center O of the nozzle hole using the ultrasonic flaw detector constituted by the

The incident point 6 of the ultrasonic beam 5 is set to the distance AL obtained by the equation (1) .

[ Equation 1] AL = [{((B2 + GAP + B3) sin70 °｝ ² + {(B2 + GAP + B3) cos70 ° + R1} ² ] ^1/2

[Number 2] B2 = {(R2cos70 ° + R2sin70 ° × tan70 °) -R1} cos70 ° , where, R1 is the inner radius of the nozzle, R2 is the radius of the weld line, G
AP indicates the distance between the probe and the welding line, and B3 indicates the distance from the front surface of the probe to the beam incident point 6.

When detecting a defect at the point A on the inner surface of the nozzle, the beam incident point 6 of the probe 1 is set on the circumference at a distance AL from the center O of the nozzle hole. The ultrasonic beam 5 is projected at an angle of 20 degrees with respect to the tangential direction of the point.

The principle of flaw detection will be described with reference to FIG. The single-point incident electron sector scan probe 1 has 64 elements 10 arranged in an arc shape, and the 16 elements are simultaneously excited by the electronic scanning ultrasonic flaw detector 2 as shown by a in FIG. 5 is generated. Next, by simultaneously exciting the 16 elements while shifting them by one element as in b and c, the incident angle at one point on the tube 20 from above the arc is changed, so that a wide range of different refraction angles are obtained. The ultrasonic beam 5 can be projected onto the inner surface of the nozzle, so that the probe 1 can be detected without scanning.

The flaw detection on the inner surface of the nozzle and the nozzle will be described with reference to FIG. A crack of the nozzle of the inner surface is what occurs in the radiation shape starting from the edge portion A point is at most, 45 not with respect to cracking direction and 90-degree angle with ultrasound bi -
A flaw is detected by projecting an ultrasonic beam at an angle of 20 degrees with respect to the edge tangent direction at which the corner-eco is no longer detected due to the relationship between the angle and the defect / corner-eco shown in FIG. By projecting a beam, a sufficiently large defect echo can be detected, and no corner echo is detected.

FIG. 5 shows an example of a change in the refraction angle in the direction of the incident point 6 of the ultrasonic beam on the inner surface of the nozzle near the nozzle. Understood.

As described above, even if the probe is set, the angle of refraction and the path of the ultrasonic beam differ depending on the position of the inner surface of the nozzle to be flawed. Therefore, as shown in FIG. , There is a risk of underestimating defects. However, the provision of the circuit for calculating the angle of refraction of the ultrasonic beam with respect to the flaw detection position and the beam path and the circuit for automatically correcting the beam path / amplitude make the defect size the same even if the detection position is different. It is possible to improve the quantitative evaluation accuracy.

[0016]

According to the present invention, the single point incident electron sector scan probe for projecting a wide range ultrasonic beam can be set at a flaw detection position where the shape of the inner surface of the nozzle is not visible. There is an effect that ultrasonic flaw detection can be applied to defect detection on the inner surface of the table.

Further, the incident position, the incident angle of the ultrasonic beam ,
Calculation of refraction angle and beam path, output of only the echo signal within the gate range, and automatic correction of beam path / amplitude, improving defect position estimation accuracy and defect quantification accuracy Has the effect.

In particular, when compared with the prior art, there is a remarkable effect that an inspection of a narrow portion such as a nozzle and an inner surface of a pipe, which could not be inspected by the conventional technology, can be inspected nondestructively, with high accuracy and in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic view of a method and an apparatus for ultrasonic inspection of an inner surface of a nozzle according to the present invention.

FIG. 2 is an explanatory diagram of the principle of one-point incident electron sector scan ultrasonic flaw detection.

FIG. 3 is a cross-sectional view showing an example of flaw detection on the inner surface of the nozzle.

FIG. 4 is a view showing a defect echo and a shape echo on the inner surface of the nozzle with respect to the flaw detection angle.

FIG. 5 is a diagram showing a change in a refraction angle when a probe is located at an optimum position for detecting a nozzle inner surface defect.

FIG. 6 is a diagram showing a relationship between a change in a refraction angle (beam path) and an eco-signal level.

FIG. 7 is a scanning spectrum of a probe in conventional ultrasonic testing.
FIG.

FIG. 8 is a plan view of a boiler nozzle and a nozzle to which ultrasonic testing is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Single point incident electron sector scan probe 2 ... Electronic scan ultrasonic flaw detector 3 ... Power supply device 4 ... Monitor television 5 ... Ultrasonic beam 6 ... Input point 10 ... Element 20 ... Yoke 21 ... Stub 1 ' … Fixed angle probe 2 '… Ultrasonic flaw detector

Continuation of the front page (56) References JP-A-57-194349 (JP, A) JP-A-53-26186 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 29 / 00-29/28

Claims (2)

(57) [Claims] 1. A longitudinal wave / shear wave combined flaw detection method using an electron sector scan one-point incidence type probe, wherein said probe is determined by the hole pitch of the nozzle and the thickness of the nozzle near the center of the hole of the nozzle. Electronic sector scanning of an ultrasonic beam by setting an angle within a range of 20 ± 10 degrees with respect to a tangential direction of a hole edge of the nozzle at a predetermined distance to be determined, and performing an electronic sector scan of the nozzle. Flaw inspection method. 2. A method according to claim 1, wherein the inner surface of the nozzle is inspected.
Te, ultrasonic bi are transmitted to the pipe base inner surface - the angle of incidence of the beam,
A circuit for calculating a refraction angle and a beam path, a means for measuring a beam incident point position of a probe, a means for outputting only an echo signal within a gate range, and a beam path / amplitude automatic correction Circuit and using the defect location estimation and defect echo signal level
A method for inspecting an inner surface flaw of a nozzle, comprising: