JP2001074712A - Apparatus and method for ultrasonic flaw detection inspection to small diameter piping weld part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspecting apparatus and an inspecting method whereby a welding defect of particularly a small diameter piping can be quantitatively and surely inspected through ultrasonic flaw detection. SOLUTION: The ultrasonic flaw detection inspection apparatus comprises a measuring part 1 including an ultrasonic probe 2 set to a piping P to be measured, a scanning mechanism part 4 for rotating the probe 2 along a circumferential wall P0 of the piping P and a fixing means 3 for arranging and fixing the ultrasonic probe 2 into touch with the circumferential wall of the piping P, and a data-collecting/recording/processing part 21 for controlling driving the scanning mechanism part 4, controlling driving the probe 2 and, executing a process of collecting, recording and operating data received by the probe 2, etc. The apparatus has an ultrasonic wave-transmitting part 2a for bringing longitudinal waves or plate waves to the ultrasonic probe 2 with an angle to an axis direction of the piping P, and a receiving part 2b for receiving the emitted ultrasonic waves. A weld part of the piping is inspected by the inspecting apparatus according to the inspecting method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting a welded portion of a small-diameter pipe made of stainless steel or the like by a non-destructive method using ultrasonic waves and an inspection method using the apparatus.

[0002]

2. Description of the Related Art Conventionally, when performing single-sided butt welding,
The shape of the groove is processed into I type, V type, D type, J type and U type, and welding is performed. When performing welding with these groove shapes, if the inner surface of the weld surface of the groove portion is not welded and remains, insufficient strength or cause of crevice corrosion, and even the extremely minute In a piping system in which metal particles are a problem, there has been a problem that they are a source of particles. For example, the misalignment of the aim of the arc during welding causes a deviation in the welding line, and the penetration bead does not reach the inner side of the butt, leaving a groove, or complete penetration due to incorrect setting of welding conditions. However, the groove on the inner surface side of the welded portion of the pipe may remain.

[0003] Further, when welding dissimilar metals, even if welding is performed exactly along the welding line, the amount of penetration differs due to the difference in the melting points of the metals to be welded, and the one-sided penetration of the weld metal into one metal occurs. The groove on the inner surface side of the welded portion of the pipe may remain, resulting in poor welding. Furthermore, even if the same metals are welded together, the surface tension of the molten metal differs due to the difference in the impurity content of the metals to be welded. Therefore, there has been a problem that it will occur.

For this reason, after welding, usually, the inside of the welded portion of the pipe is visually checked using a borescope to check for these defects. However, in the case of a pipe having a long path or a small diameter pipe, , It is difficult to confirm this situation,
By inspecting the state of the outer surface of the welded portion, the only way to estimate the back surface of the welded portion is to judge the quality of the welded portion, which requires a high level of skill. Moreover, this judgment was only non-quantitative.

[0005] For this reason, as a method for non-destructively and quantitatively inspecting the inner surface condition of a welded portion of a butt pipe, a radiation transmission test and an ultrasonic inspection test are generally adopted. However, when inspecting the inner surface of a small-diameter pipe in a radiation transmission test, it is difficult to reliably find a defect due to the small size of the welded portion, but the cost for performing the test is high, It was not practical as a quantitative inspection of the butt portion of small-diameter pipes because of the necessity of ensuring safety for using the wire.

In addition, when an ordinary transverse wave is used in the ultrasonic flaw detection, the transverse wave has a very high directivity. Therefore, in order to inspect the thickness (depth) direction of the welded portion, an ultrasonic vibrator must be connected to a pipe. In the direction of the length of the pipe, and it was necessary to pass a shear wave through the entire thickness of the pipe. In addition, it is necessary to move the pipe in the longitudinal direction of each pipe along the welding line of the pipe welded part, and it takes much time to inspect one welded part. Moreover, especially small-diameter pipes are often installed in extremely narrow areas,
It was almost impossible to inspect each part of the weld line while manually moving it along the length of the pipe after welding.

[0007] In addition, when an ultrasonic flaw detection test is carried out particularly on austenitic stainless steel, coarse columnar crystals at the weld produce a small noise, a forest-like echo, which overlaps with a pseudo echo having a large amplitude. In a small butt weld, it was extremely difficult to recognize a defect echo by a difference in amplitude normally performed. In this case,
It is necessary to make a delicate movement to judge whether the echo is a pseudo echo, and to improve the inspection accuracy, experienced skill and time based on experience are required, and automation is also difficult.

[0008]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention is a non-destructive inspection for welding defects remaining on the inner surface of a pipe weld due to poor penetration, displacement of a welding line, dissimilar metals and impurities. An object of the present invention is to make it possible to reliably determine the defect using an ultrasonic inspection test.
In particular, it is an object of the present invention to provide an inspection method and an apparatus which is simple and does not require moving a probe (ultrasonic oscillator) in the length direction of a pipe and which quantitatively indicates a defect. .

[0009]

Means for Solving the Problems The above-mentioned conventional disadvantages,
Claim 1 for solving the problem and solving the problem.
The present invention relates to an ultrasonic probe arranged in contact with a pipe to be measured, a scanning mechanism for rotating the ultrasonic probe around a central axis of the pipe to be measured, and the ultrasonic probe. A measuring unit comprising fixing means arranged and fixed so as to be in contact with the peripheral wall of the pipe to be measured, control of driving of a scanning mechanism unit of the measuring unit, operation control of an ultrasonic probe, and an ultrasonic probe Along with being a data recording processing unit that performs a recording calculation process on the received data, the ultrasonic probe transmits an ultrasonic wave composed of a longitudinal wave or a plate wave, and has an angle along the axial direction of the pipe to be measured. An ultrasonic flaw detection apparatus for a small-diameter pipe weld, comprising: an ultrasonic transmitting unit arranged so as to be incident thereon; and a receiving unit for receiving the transmitted ultrasonic wave. The invention according to claim 2 is to perform a numerical integration operation on a half-wave rectified waveform or a full-wave rectified waveform of the ultrasonic waveform received by the ultrasonic probe in the data recording processing unit with respect to an inspection range in a fixed distance section. 2. An ultrasonic flaw inspection apparatus for welding small-diameter pipes according to claim 1, further comprising a waveform digitizing circuit and a computer having an arithmetic processing circuit. The invention according to claim 3 is characterized in that the ultrasonic probe is provided with a biasing member for bringing the ultrasonic probe into contact with the pipe to be measured. An ultrasonic flaw inspection apparatus for a small-diameter pipe weld described in the above. The invention according to claim 4 is:
4. The ultrasonic probe according to claim 1, wherein a surface of the ultrasonic probe facing the pipe to be measured is substantially equal to a curvature of the pipe.
It is an ultrasonic inspection device for small diameter pipe welds described in the item. The invention according to claim 5 is characterized in that the shape of the piezoelectric element forming the ultrasonic wave transmitting section in the ultrasonic probe has a curved surface concentric with the pipe to be measured to be inspected. An ultrasonic flaw detection apparatus for welding small-diameter pipes according to any one of the preceding claims.

According to a sixth aspect of the present invention, an ultrasonic probe is installed near a welded portion of a pipe, and a longitudinal or plate wave ultrasonic wave is transmitted from an ultrasonic wave transmitting section provided in the ultrasonic probe. After transmitting the transmitted ultrasonic wave at an angle in the axial direction of the pipe to be measured, the ultrasonic probe is rotated at a fixed interval around the center axis of the pipe to be measured after receiving the transmitted ultrasonic wave, and the ultrasonic Transmitting and receiving, and then repeatedly rotating a predetermined angle repeatedly, transmitting and receiving ultrasonic waves at each angular position of the entire circumference, and numerically integrating the received wave amount of the welded part predetermined inspection target range at each rotational angle position An ultrasonic flaw detection method for a small-diameter pipe weld is characterized in that the quality of the weld is evaluated by calculation.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a flaw detection inspection apparatus for a small-diameter pipe weld according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic system diagram illustrating an ultrasonic inspection equipment for a small-diameter pipe welded part according to the present invention. FIG. 2 is a schematic system diagram illustrating an example of a data recording processing unit used in the apparatus of the present invention. As shown in FIG. 1, the ultrasonic inspection apparatus for small-diameter pipe welds according to the present invention includes a measuring section 1 for inspecting and measuring a defective portion of a welded section, and a measurement data from the measuring section 1 connected to the measuring section 1. It comprises a data recording processing unit 21 including a computer unit for recording and calculating and a drive control unit for controlling the driving of the measuring unit.

The measuring section 1 includes an ultrasonic transmitting section 2a for transmitting an ultrasonic wave and an ultrasonic receiving section 2b for receiving a reflected wave of the ultrasonic wave emitted from the transmitting section 2a. The probe 2, a scanning mechanism 4 for rotating the ultrasonic probe 2 at a constant interval, and a fixing such as a clamp for fixing the ultrasonic probe 2 to the outer peripheral wall P _O of the pipe P to be measured. Means 3
It is composed of The scanning mechanism 4 is disposed in a housing H fixedly connected to the fixing means 3 and is for rotating and moving the ultrasonic probe 2 along the outer peripheral direction of the pipe P to be measured. A rotary drive motor 5,
It comprises a rotation detection encoder 6 for controlling the movement of the rotation angle to a predetermined angle. The rotation of the rotation drive motor 5 is transmitted to a circumferential rotation gear 9 via a power gear 7 and an intermediate gear 8. The circumferential rotating gear 9 is provided with an insertion portion 9c for inserting and placing the pipe P to be measured at a center portion thereof, and a rotation guide groove 9b formed in an inner circumferential portion thereof is provided on the clamp 3 with a rotation guide groove 9b. It is rotatably supported by support shafts 10 and 10 provided on a pedestal H _O connected to a housing H which is fixedly connected. The ultrasonic probe 2 is fixed to a side surface 9 a of the circumferential direction rotating gear 9 via a substrate 11.

The rotation of the circumferential rotating gear 9 of the measuring unit 1 is transmitted to the circumferential rotating gear 9 via the power gear 7 and the intermediate gear 8 by the driving of the rotating drive motor 5. by the rotation, fixedly connected ultrasound probe 2 in the side wall is rotated around the outer peripheral wall P _O of the measurement pipe P.

The ultrasonic probe 2 in the measuring unit 1 configured as above records and processes data for digitizing ultrasonic waves received by the ultrasonic probe 2 and controls the driving of the ultrasonic probe 2. Therefore, a data recording processing unit 21 is provided in connection with the ultrasonic probe 2, the rotation drive motor 5, and the rotation detection encoder 6. An example of the data recording processing unit 21 will be described with reference to the schematic system diagram of FIG. The data recording processing section 21 of the apparatus of the present invention is provided in the drive control section 22 which is connected to the rotation drive motor 5 and the scanning mechanism section 4 of the rotation detection encoder 6 to control the rotation scanning, and in the ultrasonic probe 2. Ultrasound transmitting / receiving unit 2 connected to transmitting unit 2a and receiving unit 2b
3. A waveform digitizing circuit 24 connected to the ultrasonic transmitting / receiving unit 23 for digitizing the waveform of the received reflected wave, and the drive control unit 22 and the ultrasonic transmitting / receiving unit 2
3. It is composed of a computer 25 connected to the waveform digitizing circuit 24 for recording and calculating data and storing and instructing measurement operations.

Next, the relationship between the measuring section 1 and the data recording processing section 21 will be described along with the actual operation. When the computer 25 receives an input to start the inspection, the drive control unit 22 is started, and a current flows through the rotation drive motor 5 of the measurement unit 1 to rotate it. Then, the rotation rotates the circumferential rotation gear 9 via the power gear 7 and the intermediate gear 8, and the rotation of the ultrasonic probe 2 starts. At the same time, the drive control unit 22 obtains a signal from the rotation detection encoder 6 and performs position conversion for outputting the rotation position to the computer 25.

The computer 25 instructs the drive control unit 22 to stop the rotation when the rotational position reaches a predetermined pitch which is set and stored in advance, and issues an instruction to start transmission and reception of ultrasonic waves. Send to section 23. Then, a transmission pulse is output from the ultrasonic transmission / reception unit 23, and the piezoelectric element of the transmission unit 2a in the ultrasonic probe 2 vibrates. The ultrasonic wave used in the present invention uses a longitudinal wave (T). The ultrasonic wave of the longitudinal wave (T) is directed to the welded portion W, and an angle (α) with respect to the axial direction (length direction) of the pipe P to be measured. It is characterized in that it is incident with.

Since the longitudinal wave (T) has a characteristic of being converted into a transverse wave (Y), the longitudinal wave (T) travels through the pipe P while being reflected on the inner and outer surfaces of the pipe P to be measured. Are instantaneously and successively converted into transverse waves (Y). Since the transverse wave (Y) is a wave having high directivity, the transverse wave (Y) propagates over the entire thickness of the pipe P. Therefore, there is no need to move the ultrasonic probe 2 in the axial direction (length direction) of the pipe P to be measured, which is necessary when a transverse wave (Y) having a straight traveling property is incident as ultrasonic waves. Inspection of the welded portion W can be performed.

The above-described measuring operation method can be similarly performed by using a plate wave (I) as an ultrasonic wave.
The plate wave (I) can be generated by changing the mounting angle of the piezoelectric element that generates the ultrasonic wave. However, since the transverse wave (Y) is a wave generated for the entire plate,
In the case of a tube, the sound wave travels through the entire thickness. Accordingly, the entire weld W can be inspected while the ultrasonic probe 2 is fixed.

The longitudinal wave (T) and the transverse wave (Y) converted from the longitudinal wave (T) travel while reflecting only on the inner surface and the outer surface of the pipe P to be measured when there is no defect in the welded portion W. Does not return to the ultrasonic probe 2 instantaneously. However, when there is a defect due to insufficient penetration at the welded portion W and an unwelded portion exists from the inner surface to the outer surface of the pipe P to be measured, the transverse wave (Y) can proceed from the unmelted portion. Without
The light is reflected by the unmelted portion and returns to the ultrasonic probe 2. Then, the returned transverse wave (Y) is received by the receiving unit 2b in the ultrasonic probe 2. When the length of the unmelted portion at the welded portion W of the pipe P to be measured is long, many transverse waves (Y) are reflected and return to the ultrasonic probe 2, depending on the depth of the defect. The amount of reception varies.

Thus, the receiving section 2 of the ultrasonic probe 2
The transverse wave (Y) received at b is transmitted to the ultrasonic transmission / reception unit 23 and amplified by the transmission / reception unit 23. Then, the signal is sent to the waveform digitizing circuit 24, where it is continuously A / D-converted at a sampling frequency twice or more the frequency of the ultrasonic signal, and is input to the computer 25. Computer 25
Then, this waveform data is stored in the memory.

When the measurement at one position is completed by such a measurement operation, the rotation drive motor 5 and the rotation detection encoder 6 of the scanning mechanism unit 4 are operated by the instruction from the computer 25 via the drive control unit 22. The ultrasonic probe 2 rotates by a fixed angle around the center of the pipe P to be measured and moves to the next measurement position. After the rotation, the transmitting unit 2a of the ultrasonic probe 2 is also transmitted through the ultrasonic transmitting / receiving unit 23 in accordance with an instruction from the computer 25 of the data recording processing unit 21 in the same manner as described above.
A longitudinal wave (T) is transmitted from and the state of the welded portion W at the moving position is measured. In this way, the computer 25
Is repeatedly rotated at a predetermined pitch that has been stored and set, and a longitudinal wave (T) is incident at each moving position at an angle α along the axial direction of the pipe P to be measured, whereby the pipe P to be measured is moved. It is possible to obtain data of measurement of the entire welded portion W over one round.

[0022] In this manner, in the inspection target range W _Z of the weld at a specific measurement position, it is received in the receiving portion 2a of the ultrasonic probe 2 via the ultrasonic wave transmitting and receiving section 23 and the waveform digitizing circuit 24 When the waveform data recorded in the computer 25 is represented by, for example, full-wave rectification, a graph of the relative amount of the reflected wave with respect to the distance from the ultrasonic wave transmitter 2a is obtained as shown in FIG. In the graph of FIG. 3, the abscissa axis indicates the traveling distance of the ultrasonic wave (ultrasonic beam path) (mm) from the transmitting unit 2a (mm), and the ordinate axis indicates the relative amount of the reflected wave. That is, the ultrasonic wave obliquely incident from the piezoelectric element, which is the transmitting portion 2a inside the ultrasonic probe 2, travels in the thickness of the pipe P to be measured. First, a reflected wave (A) is obtained from the vicinity of the welded portion W together with the grain boundary noise, and thereafter, the welded portion W is delayed.
Has a defect, a reflected wave (a) is obtained from the defect. Subsequently, the reflected wave (c) received later than this is a wave reflected at a point further ahead of the welded portion W or a wave reflected at a slower propagation speed.

Among these, the object to be detected is the wave reflected first from the vicinity of the welded portion W (A), and the wave reflected first, and the inspection target range _WZ is set to clarify this portion. . Configuring the inspection target range W _Z is preferably placed in advance the range positioned to keep the computer 25 stores in preliminary tests. 5m when setting up the inspection target range W _Z, usually by using the edge portion or the like of the measurement pipe P, the range where the reflected wave is obtained by the ultrasonic transmission and reception at the ends
It is set to a range obtained by adding about m. At this time, the positional relationship between the probe 2 and the end of the pipe P to be measured only needs to be approximately the same as the positional relationship between the probe 2 and the welded portion W when actually performing the probe.
Such waveform data included in the reflected wave of the test target range W _Z obtained by the adding and numerical integration on a computer 25, the evaluation value of the measurement point. In the case of austenitic stainless steel welds, there is reflection noise at the crystal grain boundaries formed during welding, so that the presence or absence of a reflection signal alone cannot be used to evaluate the welds. Therefore, an evaluation value of a sound weld portion calculated in advance is set as a reference value, collated and compared with this reference value, and a comprehensive evaluation is performed based on the difference. Thus, an evaluation reference value line is provided for each pitch, and the soundness of the welded portion can be confirmed by checking whether the measured value line exceeds this reference value.

The scanning mechanism 4 is attached so that the ultrasonic probe 2 is in contact with the pipe P to be measured, and the computer 25
, A longitudinal wave (T) or a plate wave (I) ultrasonic wave is sequentially generated at each measurement point, and data of the welded portion W can be obtained. Therefore, it is not necessary to move the ultrasonic probe 2 in the axial direction (length direction) of the pipe P to be measured. Further, after inspecting one measurement point of the welded portion W, the ultrasonic probe 2 can be automatically rotated and arranged at the next measurement point, so that the entire circumference of the welded portion can be inspected in a short time. , Which can provide an excellent inspection method that can be quantitatively evaluated.

[0025]

EXAMPLES To confirm the performance of the ultrasonic flaw detection apparatus of the small-diameter piping welds of the present invention, as in Example 1 to prepare the measurement pipe P _G where the sound butt welding, the present invention apparatus of this weld It was examined using, to produce a butt welded measured pipe P _B lack penetration in example 2 was tested the weld using the present invention apparatus.

Example 1 3/8 inch in diameter, 1 m thick
Using SUS316 of m, sound butt welding was performed. And this in the measurement pipe P _G where the sound butt weld obtained was examined by ultrasonic flaw detector of the small-diameter piping welds of the present invention. The rotation pitch of the measurement position to be inspected was set to 6 degrees, and the inspection was performed so that 360 degrees of one round of the pipe, which is one welded portion W, was inspected over 60 locations. The ultrasonic probe 2 was mounted at a position 1 mm away from the weld metal.
In this case, the arrangement position was 1 mm from the weld metal, but this arrangement position only needs to be in the vicinity of the welded part, and there is no need to strictly restrict it. A longitudinal wave having a frequency of 5 MHz of the used ultrasonic wave was transmitted.

[0027] The test data for the pipe P _G that this sound welding, shown in FIGS. FIG. 4 shows data of the welded portion W at a position rotated 12 degrees in the clockwise direction from the top of the pipe. The X axis represents the distance (m) from the transmitting unit 2a converted from the arrival time of the ultrasonic wave and the velocity of the ultrasonic wave.
m), and the Y-axis indicates the relative reception amount of the reflected wave of the received ultrasonic wave. After inspection start, ultrasonic traveling stroke distance (ultrasonic beam path length) was inspected range W _Z the distance between 37mm about 22 mm. This is the distance at which the ultrasonic wave returns to the probe 2 when the ultrasonic probe 2 is arranged at a position several millimeters from the welded portion W, and the ultrasonic wave is reflected on a portion where the penetration is insufficient. The ultrasonic wave during this period is integrated, and the welded portion W at that portion is evaluated.

[0028] In this way, at each rotation angle position over the entire circumference of the welded portion W of the pipe P _G, on the basis of the data obtained in threshold measured in FIG 4, in the inspection target range W _Z at each measurement position FIG. 5 shows the integrated value of the amount of reception of the reflected wave as an evaluation value at that position corresponding to the measurement position. Concentric circles (A), (I), and (U) in FIG. 5 indicate the standard values of the integrated values (evaluation values), and the concentric circles (I) indicate the reference values, and evaluation values larger than the reference values are shown. The value, that is, the value that goes out of the concentric circle and approaches the concentric circle is evaluated and judged that a defective weld exists.
On the other hand, when the evaluation value is smaller than the reference value, that is, the value is within the concentric circle (i) and approaches the concentric circle (i), it is determined that there is no defective weld.

[0029] In the pipe P _G in the first embodiment, the reference value of the concentric circles (ii) in FIG. 5 is set as 4500, evaluation values at each measurement point was in the concentric circles (ii) of this reference value Thus, the value indicates a value close to the concentric circle (a), indicating that a sound butt weld having no defective weld is formed. Strictly speaking, the inner surface of the welded portion W changes depending on the installation state of the pipe at the time of welding because the molten portion of the metal to be welded is affected by gravity. For example, when the pipe is welded horizontally, the upper weld metal is slightly convex toward the pipe inner surface due to gravity, and the lower part is slightly convex toward the pipe outer direction, completely equivalent to the inner pipe pipe inner surface. Is not in a circle. However, all the values were within the reference values, and no welded spots were found as defects. This data was set as the reflection noise at the crystal grain boundaries.

[0030] [Embodiment 2] Next, as Example 2, were fabricated to be measured welding pipe P _B having a lack penetration as a sample. The pipe used for this welding was made of SUS316 having a diameter of 3/8 inch and a wall thickness of 1 mm as in the first embodiment.
Butt welding with insufficient penetration was performed. And
This obtained in the pipe P _B, it was examined by ultrasonic flaw detector of the small-diameter piping welds of the present invention. The measurement conditions for the inspection were the same as in Example 1. In other words, the rotation pitch of the measurement position to be inspected is set to 6 degrees, and one round of the pipe W which is one welded portion 360
The degree was set to perform the test over 60 locations. The ultrasonic probe 2 was mounted at a position 1 mm away from the weld metal. In this case, the arrangement position was 1 mm from the weld metal, but this arrangement position only needs to be in the vicinity of the welded part, and there is no need to strictly restrict it. The ultrasonic wave used transmitted a longitudinal wave having a frequency of 5 MHz.

[0031] The test data for the pipe P _B having insufficient penetration, shown in FIGS. FIG. 6 shows data of a weld at an angle of 0 degree. It can be seen that the relative amount of received ultrasonic wave received by the inspection target range W _Z is very large. Such inspection is performed at each angular position, an inspection target range W by integrating the reflected reception of ultrasonic waves in the _Z, 7 that was shown to correspond to the integrated value at each angular position of each angular position is there. This FIG. 7 shows three concentric circles (A), (I), and FIG.
In (iii), are shown a guide value for evaluating a value obtained by integrating the received amount of the reflected wave in the test object target range W _Z (evaluation value). A concentric circle (i) indicates the reference value, which is 4500 as in FIG.

[0032] In the pipe P _B having a weld insufficient penetration in this Example 2, evaluation value of the measurement points of each angular position In the outside of concentric circles (ii) of the reference value, a concentric (U)
, Indicating that a defective weld exists. More compared against the Figure 5 shows the test data of the pipe P _G a is healthy butt welding of Example 1 which is formed, at each angular position, that is welding defects such as insufficient penetration present, more You can make a clear decision.

In the above-described inspection in the first and second embodiments, the time required for setting the ultrasonic probe 2 in the pipe and completing the inspection over the entire circumference of the welded portion is about 60 hours.
In seconds, the inspection was completed in a very short time.

In each of the above embodiments, a pipe having an outer diameter of 3/8 inch and a thickness of 1 mm is inspected at a rotation angle of 6 ° pitch, and the welding line along the outer circumference is calculated to have a width of 0.4 mm. While transmitting and receiving ultrasonic waves while shifting, the piezoelectric element which is the transmitting unit 2a in the ultrasonic probe 2 has 3 piezoelectric elements.
Since it has a width of mm, the same point is actually transmitted and received ultrasonic waves 7 to 9 times.
Therefore, more accurate results can be obtained by averaging a plurality of points near the measurement point. In addition, the pseudo echo which makes it difficult to determine the defect is the ultrasonic probe 2
Are often lost when the position is slightly shifted, and by averaging, the influence of the pseudo echo can be reduced. The graphs of FIGS. 5 and 7 in each of the first and second embodiments are obtained by averaging the data at nine positions in the vicinity of the measurement point at each angular position as a center.

In each of the above embodiments, a 3/8 inch stainless steel pipe was used.
Its curvature increases. If the surface of the ultrasonic probe that is in contact with the pipe is flat, the ultrasonic probe and the pipe will be in line contact,
In this case, slight displacement between the ultrasonic probe and the piping
This affects the amount of ultrasonic waves received. Therefore,
It is desirable that the surface of the ultrasonic probe that comes into contact with the pipe has substantially the same curvature as that of the pipe. However, the curvature of the surface of the ultrasonic probe 3 that comes into contact with the pipe is not limited thereto, and may be any smaller than the curvature of the pipe.

Further, since the curvature of the piezoelectric element constituting the transmitting portion 2a in the ultrasonic probe 2 is set to be a concentric circle of the curvature of the pipe to be inspected, the ultrasonic wave generated from this piezoelectric element has a high efficiency. Can be well communicated to the plumbing. Also, since the pipes to be installed are not necessarily straight pipes, even in such a case, the ultrasonic probe 2 which needs to be arranged so as to be in contact with the pipe to be measured which is not a straight pipe is formed by using an elastic member or the like. It is desirable that the ultrasonic probe 2 is biased so as to be pushed into the pipe. With such a biasing structure, at any position of the piping,
The ultrasonic probe 2 can be brought into close contact with the pipe.

In each of the above-described embodiments, the ultrasonic probe 2 has both the transmitting part 2a and the receiving part 2b, and recognizes the ultrasonic wave reflected by the defect of the welding part as the defect of the welding part. However, for example, it is necessary to reduce the size of the ultrasonic probe 2 because the straight pipe portion of the pipe to be measured is short, and when the ultrasonic probe 2 cannot have both the transmitting unit 2a and the receiving unit 2b. The transmitter 2a and the receiver 2 sandwich the weld.
b, without receiving the reflected wave, receiving the ultrasonic wave coming straight and if there is a lot of ultrasonic wave, it can also be judged that it has a healthy weld, It may be selected and used at any time depending on the length of the straight pipe portion, the presence or absence of an inspection space, and the like.

[0038]

The present invention is implemented in the above-described embodiment, and has the following effects. A longitudinal wave or a plate wave is used as the ultrasonic wave to be transmitted for inspection, and the ultrasonic wave is incident at an angle along the axial direction (length direction) of the pipe to be measured. It is not necessary to move the pipe in the length direction, and it is possible to reliably inspect whether or not the groove is left in the welded portion of the pipe. Therefore, even if an unmelted portion is generated at the end of the inner wall surface of the pipe due to insufficient penetration due to insufficient heat input, displacement of the welding line, and partial penetration caused by dissimilar materials in welding, ultrasonic welding of the small-diameter pipe welded portion of the present invention. By using the test device, it can be detected immediately.

In addition, the provision of the drive control section enables a quantitative test to be automatically performed in a short time over the entire circumference of the welding line. Furthermore, by attaching an elastic member to the ultrasonic probe and biasing it in the pipe direction, the test can be performed with high accuracy even when the vicinity of the welded portion does not go straight. By making the surface of the ultrasonic probe in contact with the pipe a surface having substantially the same curvature as that of the pipe, the test can be performed with higher accuracy. Furthermore, in the ultrasonic transmission test, even in austenitic stainless steel where it is difficult to judge the quality, the S / N
The ratio is obtained with sufficiently clear values.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram illustrating an ultrasonic inspection apparatus for a small-diameter pipe welded portion according to the present invention.

FIG. 2 is a schematic system diagram illustrating an example of a data recording processing unit used in the apparatus of the present invention.

[3] In the inspection target range W _Z welds, the graph to explain the relative amount of received reflected reflected waves.

[4] The welds in pipes with healthy butt welds of Example 1, the ultrasonic relative reception amount of a graph of reflected in the inspection target range W _Z specific measurement position.

[5] The welds in pipes with healthy butt welds of Example 1, a graph of the integrated value of the amount of reflection shown in correspondence to each measurement position in the inspection target range W _Z measured across the pipe.

[6] The welds in the pipe having a weld with a weld defect of Example 2, the inspection target range W _Z Oite reflected ultrasound relative reception amount of graphs were specific measurement position.

FIG. 7 is a graph showing the integrated value of the amount of reflection in the inspection target range measured over the entire pipe for a welded part having a welded part having a weld defect in Example 2 corresponding to each measurement position.

[Explanation of symbols]

1 ... measurement unit, 2 ... ultrasonic probe, 2a ... transmission unit,
2b receiving section 3 fixing means 4 scanning mechanism section 5 rotation drive motor 6 rotation detection encoder 7 power gear 8
Intermediate gear, 9: circumferential rotation gear, 9b: rotation guide groove, 9c: insertion portion, 10: support shaft, 11: substrate,
21: data recording processing unit, 22: drive control unit, 23:
Ultrasonic transmission / reception unit, 24 ... waveform digitizing circuit, 25 ...
Computer, H: Housing, H _O : Pedestal, P
… Measured pipe, W… weld, W _Z … inspection range

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Nakamura, Inventor Koji Nakamura, 1-16-1 Nishi-Shimbashi, Minato-ku, Tokyo Inside (72) Mikio Kushita, 6-2 Higashi-Kasai, Edogawa-ku, Tokyo No. 3 F-term in Aspect Co., Ltd. (reference) 2G047 AB01 AB07 BB02 BC02 CA01 CB01 CB04 EA09 EA10 GA19 GB04 GG09 GG14 GG19

Claims (6)

[Claims] An ultrasonic probe arranged in contact with a pipe to be measured, a scanning mechanism for rotating the ultrasonic probe about a central axis of the pipe to be measured, and the ultrasonic probe. A measuring unit comprising fixing means arranged and fixed so as to be in contact with the peripheral wall of the pipe to be measured, control of driving of a scanning mechanism unit of the measuring unit, operation control of an ultrasonic probe, and an ultrasonic probe Along with being a data recording processing unit that performs a recording calculation process on the received data, the ultrasonic probe transmits an ultrasonic wave composed of a longitudinal wave or a plate wave, and has an angle along the axial direction of the pipe to be measured. An ultrasonic inspection apparatus for a small-diameter pipe weld, comprising: an ultrasonic transmitter that is arranged to be incident; and a receiver that receives the transmitted ultrasonic wave. 2. A waveform digital for performing a numerical integration operation of a half-wave rectified waveform or a full-wave rectified waveform of an ultrasonic waveform received by an ultrasonic probe in the data recording processing unit in a test range of a fixed distance section. And a computer provided with an arithmetic circuit and an arithmetic processing circuit.
Ultrasonic inspection equipment for small diameter pipe welds as described. 3. The small diameter probe according to claim 1, wherein said ultrasonic probe is provided with an urging member for bringing said ultrasonic probe into contact with a pipe to be measured. Ultrasonic flaw inspection equipment for pipe welds. 4. The ultrasonic flaw detection of a small-diameter pipe weld according to claim 1, wherein a surface of the ultrasonic probe facing the pipe to be measured is substantially equal to a curvature of the pipe. Inspection equipment. 5. The ultrasonic probe according to claim 1, wherein a shape of the piezoelectric element forming an ultrasonic wave transmitting section has a curved surface concentric with a pipe to be inspected.
Ultrasonic flaw inspection equipment for small-diameter pipe welds according to the above item. 6. An ultrasonic probe is installed in the vicinity of a welded portion of a pipe, and ultrasonic waves of a longitudinal wave or a plate wave are transmitted from an ultrasonic wave transmitting portion provided in the ultrasonic probe in an axial direction of a pipe to be measured. After transmitting at an angle and receiving the transmitted ultrasonic wave at the receiving unit, the ultrasonic probe is rotated at a constant interval around the center axis of the pipe to be measured, and the ultrasonic wave is transmitted and received again in the same manner, and thereafter. Repeatedly rotate a predetermined angle repeatedly and transmit ultrasonic waves at each angular position around the entire circumference.
An ultrasonic flaw inspection method for a small-diameter pipe weld, comprising: receiving, receiving, and numerically integrating a received wave amount in a predetermined inspection target range of a weld at each rotation angle position to evaluate the quality of the weld.