JP2862397B2 - Ultrasonic probe for boiler tube flaw detection - 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 probe for flaw detection of a boiler tube which is suitable for detecting a crack in a pipe axis direction generated at a welded portion of a metal fitting of a boiler tube.

[0002]

2. Description of the Related Art A fatigue crack occurs in a pipe axial direction due to a thermal stress caused by starting and stopping at a welded portion of a metal fitting such as a superheater or a reheater of a thermal boiler. However, since the superheater and the reheater have a narrow pipe interval of 50 to 100 mm, the inspector cannot access them. For this reason, fatigue cracks have conventionally been confirmed by collecting a sample tube, so that the number of investigation points is limited, and restoration of the sample collection position requires a great deal of cost.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above circumstances, and a non-destructive crack in a pipe axial direction generated at a location where a boiler tube inspector cannot access is inspected. It is an object of the present invention to provide an ultrasonic probe for boiler tube flaw detection, which is inspected in an optimal condition.

[0004]

Means for Solving the Problems The voice of the present invention to its
An ultrasonic probe for detecting flaws in a tube is a probe that inspects for cracks in the tube axis direction from the inside of the tube by water immersion ultrasonic flaw detection. A probe body that rotates to, a vertical probe for welding bead confirmation mounted on the probe body, and an oblique probe mounted so as to be housed inside the probe body, comprising an eccentric mechanism for eccentrically in the radial direction according to the angle probe to the inner diameter of the tube, the eccentric mechanism, on one end is mounted to the angle probe
The cantilever pivotally attached to the probe body and the cantilever
Energize the bar to rotate the bevel probe to the radius
Eccentric spring and movable to the probe body
Screw the cantilever to restrain the cantilever.
And a cap nut for setting the amount of eccentricity of the angular probe .

[0005]

According to the ultrasonic probe for boiler tube flaw detection of the present invention, a crack generated in a welded metal attachment of a boiler tube is non-destructively subjected to water immersion type ultrasonic flaw detection from inside the pipe.
In addition, because it can be inspected accurately, inspection of adhered metal welds such as superheaters and reheaters of thermal boilers that cannot be accessed by inspectors
Ri as Na performed accurately, Ru unnecessarily name is polished outside the tube surface for inspection. Since is equipped with a vertical probe in order to confirm the position of the weld bead, the identification confirmation and defect inspection position Ru done easily. To detect cracks in the pipe axis direction , rotate the cap nut according to the pipe specifications.
Since the angle probe can any amount but only eccentric in the radial direction, the flaw of the heat exchanger loop is formed by the different diameter pipe 1 by
This is possible with a plurality of ultrasonic probes. In a curved tube portion or the like, an eccentric angled probe is housed in the probe main body, so that insertion into the tube is easy.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the ultrasonic probe for boiler tube flaw detection according to the present invention will be described with reference to the drawings. FIG. 1 is a side view of the probe, FIG. FIG. 4 is an explanatory view of a flaw detection procedure using this probe, FIG. 4 is a diagram showing a relationship between the eccentricity of the oblique probe and a defect echo height, and FIG. 5 is a procedure of detecting a weld bead by a vertical probe. Explanatory drawing, FIG. 6 is a side view showing a mode in which the present probe passes through a curved tube portion, FIG. 7 is a side view showing a mode in which the present probe detects a spacer weld, and FIG. It is explanatory drawing of a jig.

In FIG. 1, an ultrasonic probe 5 has a vertical probe 6 for detecting a weld bead mounted at the center of a probe main body 8 and two ultrasonic probes 5 on the same probe main body 8. The cantilevers 9a and 9b are mounted symmetrically with locking pins 10. The oblique probes 7a and 7b are mounted on the cantilevers 9a and 9b, respectively, so that they can be stored in the main body cutout 8 '. Also, the two cantilevers 9a and 9b are always halfway by a spring 11 and a pin 12 attached to a stop pin 10.
The eccentricity adjusting cap nut 13 is screwed into the probe main body 8 to be eccentric in the radial direction.
Can only be eccentric up to the position where it contacts.

In order to mount a jig for aligning the probe main body 8, spring shafts 14 are mounted before and after the angled probes 7a and 7b. The spring shaft 14 is directly connected to a bearing 32 incorporated in the eccentric amount adjusting cap nut 13 as shown in FIG. The vertical probe 6 and the oblique probes 7a and 7b are composed of a rotor shaft 1 having a double structure with a spring shaft 14.
5 is driven to rotate. That is, the bearing 32 is built in between the probe main body 8 and the spring shaft 14, and the probe main body 8 and the rotor shaft 15 are directly connected by the set screw 33. The main body 8 also rotates.

In detecting a crack in the direction of the tube axis of the boiler tube by such an ultrasonic probe 5, as shown in FIG. 3, the ultrasonic probe 5 inserted into the boiler tube 1 is used. In order to detect cracks 3 in the tube axis direction generated in the welded portion 2 of the metal fitting 1 ′ of the boiler tube 1 by ultrasonic waves through the water 4, an ultrasonic probe 5 is provided in the radial direction of the tube 1. mm eccentricity is required. FIG. 4 shows the relationship between the eccentricity of the probe and the height of the defect echo for several types of tubes commonly used as superheater tubes, and shows the case where the eccentricity of the ultrasonic probe 5 is 6 to 8 mm. It can be seen that the flaw detection sensitivity is the highest.

[0010] When the weld bead is confirmed by the vertical probe 6, the procedure shown in FIG. That is, in FIG. 5, the ultrasonic waves entering the tube when the rotation angle of theta ₁ of the vertical probe 6 is reflected by the extravascular surface multiple reflection echo by the tube wall thickness is obtained. On the other hand, the rotation angle of the vertical probe 6 is θ ₂
In the case of, the ultrasonic wave incident on the tube material propagates into the welded portion 2,
Since the light is irregularly reflected on the surface of the welded portion 2, a reflected echo cannot be obtained. When the weld bead is confirmed by the vertical probe 6 as described above, the fact that the multiple reflection echoes of the pipe wall thickness disappear in the welded portion 2 is used.

Next, the manner in which the ultrasonic probe 5 passes through the curved tube will be described with reference to FIG.
When passing through the curved pipe section, the cantilever 9b and the oblique probe 7b that are in contact with the inner wall of the pipe are housed in the main body cutout 8 'of the probe main body 8, and can smoothly pass through the curved pipe section. When the cantilever 9b and the oblique probe 7b housed in the notch 8 'of the main body are moved to the straight pipe portion through the curved pipe portion, the cantilever 9b and the oblique probe 7b protrude to a position set in advance by the eccentric amount adjusting cap nut 13. It is possible to detect a crack in the axial direction. This point will be described in more detail with reference to FIG. 2. When the nut 13 is screwed in the direction of arrow A, the cantilever 9b moves in the direction of arrow B, and the eccentricity of the oblique probe 7b decreases. When the probe is moved in the direction opposite to the direction of arrow A, the oblique probe 7b
The amount of eccentricity becomes large, and the same applies to the oblique probe 7a. Thus, the flaw detection is performed by setting the amount of eccentricity of the oblique angle probes 7a and 7b in advance by the nut 13.

Further, the ultrasonic probe 5 is used to weld a plate-type spacer of a boiler tube (welded portion in a pipe axial direction).
7 will be described with reference to FIG. 7. The probe main body 8 is held on the center line of the boiler tube 1 by a centering jig 18 attached to the front and rear thereof. Angle beam probe 7
Reference numerals a and 7b always rotate the boiler tube 1 with a constant eccentric amount, and perform flaw detection of the adhered metal welding portion. In the figure, 1
Reference numeral 9 denotes a centering jig holding spring, 20 denotes a holding spring adjusting nut, 21 denotes a guide, 22 denotes a welded portion, and 23 denotes a plate spacer.

Here, the alignment mechanism of the alignment jig 18 and the structure of the guide 21 will be described. The alignment jig 18 uses nylon 34 as a material. The length of the material is managed, and as shown in FIG. 8, when the diameter of the alignment jig 18 is larger than the inner diameter of the pipe,
The nylon 34 is uniformly crushed, and the probe main body 8 can be aligned. In this case, if the alignment of the probe main body 8 is bad, the eccentric amounts of the oblique probes 7a and 7b are not constant during rotation, so that flaw detection becomes impossible. The guide 21 is a spring shaft 14.
A ball made of Teflon is attached to the tip of the shaft to prevent the tip of the spring shaft 14 from sticking to a projection such as the inner surface of the welded portion.

Thus, according to such an ultrasonic probe 5, the crack 3 in the pipe axis direction of the attached metal weld 2 can be detected from the inner surface side of the boiler tube 1 of the pipe by the water immersion method. No polishing for collection is required. Further, since the vertical probe 6 for confirming the weld bead is mounted at the center of the probe main body 8, it is easy to confirm the flaw detection position and identify the defect. Furthermore, since it has a function to decenter the angled probes 7a and 7b by an arbitrary amount in the radial direction according to the specification of the pipe, the crack 3 in the pipe axis direction can always be detected in an optimal state. Further, when passing through the curved tube portion, the eccentric angled probes 7a and 7b are stored in the main body cutout 8 ', so that the passage through the curved tube portion is smooth.

[0015]

As described in detail above, the boiler of the present invention
According to the ultrasonic probe for tube inspection, the following effects can be obtained.
can get. (1) If there is any adhesion at the welded metal parts of the boiler tube
The fissure was non-destructively and immersed in the pipe by water immersion ultrasonic testing.
Can be inspected accurately, so thermal
Inspection of deposited metal welds such as superheaters and reheaters
Polished outer surface for inspection
Also becomes unnecessary. (2) Use a vertical probe to check the position of the weld bead.
Easily check flaw detection position and identify defects
Done in (3) In order to detect cracks in the pipe axis direction, conform to the pipe specifications.
Then, rotate the angled probe radially by rotating the cap nut.
Can be eccentric by any amount in the direction, so loops are formed with different diameter pipes.
Inspection of the heat exchanger to be performed is possible with one ultrasonic probe
There is an eccentric beveled probe inside the probe body
Since it is stored in the pipe, it is easy to insert it into the pipe.

[Brief description of the drawings]

FIG. 1 is a side view of one embodiment of an ultrasonic probe for boiler tube flaw detection of the present invention.

FIG. 2 is a longitudinal sectional view of the rotation mechanism of the same.

FIG. 3 is an explanatory diagram of a flaw detection procedure using the present probe.

FIG. 4 is a diagram showing the relationship between the amount of eccentricity of the oblique probe and the height of a defect echo.

FIG. 5 is an explanatory diagram of a procedure for detecting a weld bead with a vertical probe.

FIG. 6 is a side view showing a mode in which the present probe passes through a curved tube portion.

FIG. 7 is a side view showing a mode in which the probe detects a flaw in a spacer weld.

FIG. 8 is an explanatory diagram of a centering jig in the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler tube 1 'Deposited metal 2 Welded part 3 Crack 4 Water 5 Ultrasonic probe 6 Vertical probe 7a, 7b Angle probe 8 Probe body 8' Main body cutout 9a, 9b Cantilever 10 Stop pin 11 Spring 12 Pin 13 Cap nut for adjusting eccentricity 14 Spring shaft 15 Rotor shaft

Claims (1)

(57) [Claims] 1. A probe for inspecting a crack in a pipe axial direction from the inside of a pipe by water immersion ultrasonic testing, wherein the probe is inserted into the pipe so as to be movable in the pipe axial direction and rotates around the axis. Body and
A vertical probe for welding bead confirmation mounted on the probe main body, an oblique probe mounted so as to be housed inside the probe main body, and the oblique probe connected to a tube. comprising an eccentric mechanism for eccentrically in the radial direction in response to an inner diameter, the eccentric mechanism, the upper
The bevel probe is attached and one end is pivotally attached to the probe body.
To rotate the cantilever and the cantilever
To bias the angle probe in the radial direction by urging the probe
And movably screwed onto the probe body and
The eccentricity of the angle probe is set by restraining the bar.
Characterized in that it consists of a constant to the cap nut, the ultrasonic probe for boiler tube flaw.