CA2007420A1 - Ultrasonic flaw detecting method - Google Patents
Ultrasonic flaw detecting methodInfo
- Publication number
- CA2007420A1 CA2007420A1 CA 2007420 CA2007420A CA2007420A1 CA 2007420 A1 CA2007420 A1 CA 2007420A1 CA 2007420 CA2007420 CA 2007420 CA 2007420 A CA2007420 A CA 2007420A CA 2007420 A1 CA2007420 A1 CA 2007420A1
- Authority
- CA
- Canada
- Prior art keywords
- flaw
- inspecting object
- ultrasonic
- echo
- shielding member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/044—Internal reflections (echoes), e.g. on walls or defects
Landscapes
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An ultrasonic flaw detecting method of this invention includes the steps of detecting a surface flaw of an inspecting object having a uniform thickness by causing a probe to scan while emitting ultrasonic waves at a predetermined oblique angle onto the surface of the inspecting object and quantitatively measuring the depth of the surface flaw by a tip echo method. The method of this invention is characterized by abutting an ultrasonic wave shielding member against the surface of the inspecting object in an area between the point of incidence of the ultrasonic waves and the surface flaw, thereby eliminating surface wave which causes parasitic echo on a screen of oscilloscope.
An ultrasonic flaw detecting method of this invention includes the steps of detecting a surface flaw of an inspecting object having a uniform thickness by causing a probe to scan while emitting ultrasonic waves at a predetermined oblique angle onto the surface of the inspecting object and quantitatively measuring the depth of the surface flaw by a tip echo method. The method of this invention is characterized by abutting an ultrasonic wave shielding member against the surface of the inspecting object in an area between the point of incidence of the ultrasonic waves and the surface flaw, thereby eliminating surface wave which causes parasitic echo on a screen of oscilloscope.
Description
200'74~
"ULTRASONIC FLAW DETECTING METHOD"
BACKGROUND_OF~ _INVENTION
The present invention in general relates to maintenance technology of equipment such as steam drums, heat transfer tubes of a steam generator, pressure tubes used in a pressure tube type nuclear reactor, and equipment and piping such as pressure vessels and pipes for use in a nuclear reactor and an ordinary plant. More particularly, it relates to an ultrasonic flaw detecting method for detecting a surface flaw of the above-mentioned equipment and piping and for quantitatively measuring the depth of the surface flaw.
Ultrasonic flaw inspection has conventionally been carried out for maintenance management of the above-mentioned plant equipment and piping as an object to be inspected. Specifically, surface flaws of the inspecting object are inspected by a ultrasonic angle beam method in which, as shown in Fig. 5, a probe ~ scans the surface of the inspecting object 1 while emitting ultrasonic waves onto the surface of the inspecting object 1 at a predetermined oblique angle. The ultrasonic waves enter into the inspecting object 1 at a predetermined angle of refraction, . When no surface flaw exists in the inspecting object 1, the ultrasonic angle beame is repeatedly reflected at the surface and the bottom of the inspecting object I to be propagated forward within the inspecting object l. When a surface flaw 3 exists, however, the ultrasonic angle beam which is reflected on the bottom of the inspecting object meets a corner of the surface flaw, i.e. an intersection of the side wall of the flaw 3 and the surface of the inspecting object l. As a result, an echo appears at the corner and runs back to the point of incidence by following the same path. The echo is detected and converted into an electrical signal, and is observed as "flaw corner echo"
having the maxinum amplitude at a position W1 of the distance axis (axis of abscissas) on the screen of an oscilloscope 4 which is electrically connected to the probe 2. By observing the flaw corner echo, the surface flaw 3 of the inspecting object l is detected according to the ultrasonic angle beam method.
In order to quantitatively measure the flaw depth of the surface flaw 3 ("H" in Fig. 5), there maY be employed a tip echo method. When the probe 2 moves to the position 2' in Fig. 5 during the scanning, "flaw tip echo" which appears at the pointed end of the flaw 3 is observed at a position W2 on the screen of the oscilloscope 4. The position W1 of the flaw corner echo and the position W2 of the flaw tip echo observed on the same osilloscope screen correspond to the propagation distance of the ultrasonic waves from the point of the emission of the ultrasonic angle beam and the point of the reception of the echo by the probe 2 and by the probe 2', respectively. According to the tip echo method, the flaw depth H of the surface flaw 3 is obtained by first reading the positions of the flaw corner echo W1 and the flaw tip echo W2 observed on the distance axis of the oscilloscope screen, calculating the difference in distance (Wt - W2), and then substituting the obtained difference and the angle of refraction ~ into the following equation (1):
H = ~W~ - W2) X COS ~ ............. (1) However, in the case where a quantitative measurement of the surface flaw depth of the inspecting cbject is actually made by the tip echo method, a parasitic echo appears on the oscilloscope screen in addition to the above-mentioned flaw corner echo and flaw tip echo. This parasitic echo is produced by ultrasonic waves which are emitted from the probe 2 or 2' onto the inspecting object 1 and run as "surface waves" on the surface of the inspecting object, without entering into the inspecting object (see Fig. ~).
This parasitic echo is almost indistinguishable from the flaw tip echo and often causes troubles in the measurement.
For example, in the case of a flaw whose flaw depth is 2 to 3mm present in a pressure tube of 4.3mm in thickness used in a pressure tube type nuclear reactor, a parasitic echo appears near the flaw tip echo. Such a parasitic echo is so indistinguishable from the flaw tip echo that it causes even a skilled operator to mistake one for the other. As a result, the measurement error is as great as about l.5mm, ~0074X(~
thereby impairing the accuracy of measurement. In the case of a flaw depth of 3 to 4mm, a parasitic echo which overlaps and succeeds the flaw tip echo appears. In this case, it is impossible to quantitatively measure the surface flaw depth of the inspecting object. Thus, the tip echo method is not always practically applicable to the quantitative measurement of the surface flaw with respect to a thin material whose thicknss is about 5 to 6mm or below.
SUMMARY OF THE IN~ENTION
The present invention has been made in view of the foregoing, and has an object to provide an ultrasonic flaw detecting method in which the depth of surface flaws of a thin material whose thickness is about 5 to 6mm or below can quantitatively be measured by the tip echo method easily and accurately.
The ultrasonic flaw detecting method according to the present invention includes the steps of detecting a surface flaw of an inspecting object which has a uniform thickness by causing a probe to scan while emitting ultrasonic waves at a predetermined oblique angle onto the surface of the inspecting object and quantitatively measuring the depth of the surface flaw by a tip echo method. The above object can be achieved by abutting an ultrasonic wave shielding member against the surface of the inspecting object in an area between the point of incidence of the ultrasonic waves and the surface flaw.
Any material which can absorb and thereby shield surface waves of the ultrasonic waves may generally be used as the above-mentioned ultrasonic wave shielding member. A rubber material is preferably used as the ultrasonic wave shielding member for the reason that it is possible to ensure a stable contact with the inspecting object even in the case where the inspecting object is a pipe having a bent portion. For the same reason, it is preferable that the material be abutted against the surface of the inspecting object by pressing.
According to the present invention, the surface flaw of the inspecting object can be detected by the ultasonic angle beam method, and the flaw depth of the surface flaw can be quantitatively measured by the tip echo method in the same manner as the conventional measuring system.
Particularly in the present invention, the surface waves which cause the parasitic disturbing echo can be absorbed and shielded by abutting the ultrasonic wave shielding member against the surface of the inspecting object in the area between the point of incidence of the ultrasonic waves and the surface flaw. In Fig. 5, the flaw depth of the surface flaw does not exceed the thickness of the inspecting object, and the inspecting object is presumed to be a flat plate having a uniform thickness of T. In such a case, the ultrasonic wave sielding member may be positioned and 200742~) abutted againsl the surface of the In.spectlng object, in prlnciple from the flbove-mentioned equation (1), withln a range extending from the point of incidence of the ultrasonic waves to a point which is away as much as T x tan 8 from the point of incidence of the ultrasonic waves in the direction of scanning with the probe 2. The position of the ultrasonic wave shielding member within the above-decsribed range will cause no problem in measuring the flaw tip echo unless the surface flaw is much extensive.
Further, in order to ensure the measurement of the flaw tip echo, it is preferable to position the ultrasonic wave shielding member as close to the point of incidence of the ultrasonic waves as possible.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. 1 and 2 are explanatorY views showing an embodiment of a measuring system according to the present invention;
Fig. 3 shows an oscilloscopic waveform indicating the surface flaw of the inspecting object recorded by the measuring system shown in Figs. 1 and 2;
Fig. 4 shows an oscilloscopic waveform with the ultrasonic wave shielding member eliminated from the measuring system shown in Figs. 1 and 2; and Fig. 5 is an explanatory view showing an example of a 2007~20 conventional measuring system.
PR~EERR~P_EMBODIMENTS OF ~HE IN~ENTION
The present invention will be described hereinbelow with reference to the drawings and embodiments of the invention.
Figs. 1 and 2 show an example of a measuring system to be used when a method according to the present invention is employed to measure a surface flaw 3 casued along the axis of an inspecting object 1 which is a pressure tube for use in a pressure tube type nuclear reactor and which is 118mm in bore and 4.3mm in thickness. The measuring system comprises a horizontal flat support plate 5 which is disposed within the inspecting object 1 so as to be coaxially rotatable therewith. A proe ~ is fixed by a probe fixing means 6 at a predetermined eccentric position on the support plate 5 so as to emit the ultrasonic waves on to the inner surface of the inspecting object 1 at a predetermined oblique angle. Thus, the emission of the ultrasonic waves and the detection of the ultrasonic echoes can be carried out while the support plate 5 is rotated, and the scanning with the probe 2 can be conducted. An ultrasonic wave shielding member 7 made of a plate-shaped rubber such as a rubber wiper is also fixed by a fixing means 8 on the support plate 5. The tip portion of the ultrasonic wave shielding member 7 is abutted against the inner surface of the inspecting object 1 at a position slightly moved in the 200~42~3 direction of scann~ng relatlve to the point of Incidence of the ultrasonic waves. Further, water serving as a couplant is filled inside the pressure tube of the inspecting object l, i.e., between the inspecting object l and the probe 2.
The probe 2 is electrically connected to an oscilloscope 4 which is externally provided to record on the screen thereof echo signals detected by the probe 2.
Using the measuring system thus constructed, the surface flaw 3 which has been caused along the axis of the inspecting object l is detected by the above-described ultrasonic angle beam method and the surface flaw depth is quantitatively measured by the tip echo method, under the condition that the support plate 5 is rotated counterclockwise while the probe 2 and the oscilloscope 4 are operated.
The echo images recorded on the screen of the oscilloscope 4 are shown in Fig. 3, and the echo images measured without using the ultrasonic wave shielding member 7 are shown in Fig. 4. These echo images have been obtained as the results of the above detection and measurement.
It is apparent from the comparison between the data shown in Figs. 3 and 4 that, according to the ultrasonic flaw detecting method of the present invention, the parasitic echoes have efficiently been eliminated.
When a high-resolution ultrasonic flaw detector is used togehter with a high-frequency wave (about lO MHz), high-200~420 resolutlon and focused type probe, lt is posslble to confinethe measurement error withln about ~0.5mm for the inspection of a pressure tube used in a pressure tube type nuclear reactor whose thickness is 4.3mm.
During the rotation of the support plate S in the above measurement, the ultrasonic wave shielding member 7 may possibly be detached from the surface of the inspecting object 1 due to the rising of the ultrasonic wave shielding member 7, or unsmooth rotation of the support plate 5 may possibly occur. In order to prevent such inconveniences, it is preferable to interpose a spring or the like member (not shown) between the ultrasonic wave shielding member 7 and its fixing means 8 to thereby properly press the ultrasonic wave shielding member 7 against the surface of the inspecting object 1.
From the foregoing description, it is understood that, according to the present invention, the surface wave which forms a parasitic echo is effectively absorbed and thereby shielded by the ultrasonic wave shielding member abutted against the surface of the inspecting object in the area between the point of incidence of the ultrasonic waves and the surface flaw. Accordingly, in the inspection of, for example, a pressure tube of 4.3mm in thickness which is for use in a pressure tube type nuclear reactor, it is possible to confine the measurement error within about l0.5mm in contrast to the conventional measurement error of about I1.5mm, when the flaw depth of the surface flaw whose depth is 2 to 3mm is measured. On the other hand, when the flaw depth of 3 to 4mm Is measured in the above-mentloned inspection, even the skllled operator has not been able to distinguish the flaw tip echo from the parasitic echo.
According to the method of the present invention, however, the measurement of such flaw depth of the surface flaw can be easily performed by an operator having an ordinary skill in the ultrasonic flaw detection technology, and the measurement error can be confined within about +0.5mm.
Further, the quantitative measurement of the surface flaw depth can easily and accurately be conducted even with respect to an inspecting object made of a thin material of about 5 to 6mm in thickness or an inspecting object which is not flat but tubular.
Therefore, by the method of the present invention, a quantitative inspection can be accomplished with respect to the extent of progress of abnormality such as a leak due to the breakage of plant equipment or piping before such abnormality becomes apparent. This provides an advantage in that a better maintenance management of the plant equipment, piping and the like can be performed. Accordingly, the present invention can greatly contribue to the improvement of safety especially in a nuclear reactor plant which demands extremely higher safety than an ordinary plant does.
"ULTRASONIC FLAW DETECTING METHOD"
BACKGROUND_OF~ _INVENTION
The present invention in general relates to maintenance technology of equipment such as steam drums, heat transfer tubes of a steam generator, pressure tubes used in a pressure tube type nuclear reactor, and equipment and piping such as pressure vessels and pipes for use in a nuclear reactor and an ordinary plant. More particularly, it relates to an ultrasonic flaw detecting method for detecting a surface flaw of the above-mentioned equipment and piping and for quantitatively measuring the depth of the surface flaw.
Ultrasonic flaw inspection has conventionally been carried out for maintenance management of the above-mentioned plant equipment and piping as an object to be inspected. Specifically, surface flaws of the inspecting object are inspected by a ultrasonic angle beam method in which, as shown in Fig. 5, a probe ~ scans the surface of the inspecting object 1 while emitting ultrasonic waves onto the surface of the inspecting object 1 at a predetermined oblique angle. The ultrasonic waves enter into the inspecting object 1 at a predetermined angle of refraction, . When no surface flaw exists in the inspecting object 1, the ultrasonic angle beame is repeatedly reflected at the surface and the bottom of the inspecting object I to be propagated forward within the inspecting object l. When a surface flaw 3 exists, however, the ultrasonic angle beam which is reflected on the bottom of the inspecting object meets a corner of the surface flaw, i.e. an intersection of the side wall of the flaw 3 and the surface of the inspecting object l. As a result, an echo appears at the corner and runs back to the point of incidence by following the same path. The echo is detected and converted into an electrical signal, and is observed as "flaw corner echo"
having the maxinum amplitude at a position W1 of the distance axis (axis of abscissas) on the screen of an oscilloscope 4 which is electrically connected to the probe 2. By observing the flaw corner echo, the surface flaw 3 of the inspecting object l is detected according to the ultrasonic angle beam method.
In order to quantitatively measure the flaw depth of the surface flaw 3 ("H" in Fig. 5), there maY be employed a tip echo method. When the probe 2 moves to the position 2' in Fig. 5 during the scanning, "flaw tip echo" which appears at the pointed end of the flaw 3 is observed at a position W2 on the screen of the oscilloscope 4. The position W1 of the flaw corner echo and the position W2 of the flaw tip echo observed on the same osilloscope screen correspond to the propagation distance of the ultrasonic waves from the point of the emission of the ultrasonic angle beam and the point of the reception of the echo by the probe 2 and by the probe 2', respectively. According to the tip echo method, the flaw depth H of the surface flaw 3 is obtained by first reading the positions of the flaw corner echo W1 and the flaw tip echo W2 observed on the distance axis of the oscilloscope screen, calculating the difference in distance (Wt - W2), and then substituting the obtained difference and the angle of refraction ~ into the following equation (1):
H = ~W~ - W2) X COS ~ ............. (1) However, in the case where a quantitative measurement of the surface flaw depth of the inspecting cbject is actually made by the tip echo method, a parasitic echo appears on the oscilloscope screen in addition to the above-mentioned flaw corner echo and flaw tip echo. This parasitic echo is produced by ultrasonic waves which are emitted from the probe 2 or 2' onto the inspecting object 1 and run as "surface waves" on the surface of the inspecting object, without entering into the inspecting object (see Fig. ~).
This parasitic echo is almost indistinguishable from the flaw tip echo and often causes troubles in the measurement.
For example, in the case of a flaw whose flaw depth is 2 to 3mm present in a pressure tube of 4.3mm in thickness used in a pressure tube type nuclear reactor, a parasitic echo appears near the flaw tip echo. Such a parasitic echo is so indistinguishable from the flaw tip echo that it causes even a skilled operator to mistake one for the other. As a result, the measurement error is as great as about l.5mm, ~0074X(~
thereby impairing the accuracy of measurement. In the case of a flaw depth of 3 to 4mm, a parasitic echo which overlaps and succeeds the flaw tip echo appears. In this case, it is impossible to quantitatively measure the surface flaw depth of the inspecting object. Thus, the tip echo method is not always practically applicable to the quantitative measurement of the surface flaw with respect to a thin material whose thicknss is about 5 to 6mm or below.
SUMMARY OF THE IN~ENTION
The present invention has been made in view of the foregoing, and has an object to provide an ultrasonic flaw detecting method in which the depth of surface flaws of a thin material whose thickness is about 5 to 6mm or below can quantitatively be measured by the tip echo method easily and accurately.
The ultrasonic flaw detecting method according to the present invention includes the steps of detecting a surface flaw of an inspecting object which has a uniform thickness by causing a probe to scan while emitting ultrasonic waves at a predetermined oblique angle onto the surface of the inspecting object and quantitatively measuring the depth of the surface flaw by a tip echo method. The above object can be achieved by abutting an ultrasonic wave shielding member against the surface of the inspecting object in an area between the point of incidence of the ultrasonic waves and the surface flaw.
Any material which can absorb and thereby shield surface waves of the ultrasonic waves may generally be used as the above-mentioned ultrasonic wave shielding member. A rubber material is preferably used as the ultrasonic wave shielding member for the reason that it is possible to ensure a stable contact with the inspecting object even in the case where the inspecting object is a pipe having a bent portion. For the same reason, it is preferable that the material be abutted against the surface of the inspecting object by pressing.
According to the present invention, the surface flaw of the inspecting object can be detected by the ultasonic angle beam method, and the flaw depth of the surface flaw can be quantitatively measured by the tip echo method in the same manner as the conventional measuring system.
Particularly in the present invention, the surface waves which cause the parasitic disturbing echo can be absorbed and shielded by abutting the ultrasonic wave shielding member against the surface of the inspecting object in the area between the point of incidence of the ultrasonic waves and the surface flaw. In Fig. 5, the flaw depth of the surface flaw does not exceed the thickness of the inspecting object, and the inspecting object is presumed to be a flat plate having a uniform thickness of T. In such a case, the ultrasonic wave sielding member may be positioned and 200742~) abutted againsl the surface of the In.spectlng object, in prlnciple from the flbove-mentioned equation (1), withln a range extending from the point of incidence of the ultrasonic waves to a point which is away as much as T x tan 8 from the point of incidence of the ultrasonic waves in the direction of scanning with the probe 2. The position of the ultrasonic wave shielding member within the above-decsribed range will cause no problem in measuring the flaw tip echo unless the surface flaw is much extensive.
Further, in order to ensure the measurement of the flaw tip echo, it is preferable to position the ultrasonic wave shielding member as close to the point of incidence of the ultrasonic waves as possible.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. 1 and 2 are explanatorY views showing an embodiment of a measuring system according to the present invention;
Fig. 3 shows an oscilloscopic waveform indicating the surface flaw of the inspecting object recorded by the measuring system shown in Figs. 1 and 2;
Fig. 4 shows an oscilloscopic waveform with the ultrasonic wave shielding member eliminated from the measuring system shown in Figs. 1 and 2; and Fig. 5 is an explanatory view showing an example of a 2007~20 conventional measuring system.
PR~EERR~P_EMBODIMENTS OF ~HE IN~ENTION
The present invention will be described hereinbelow with reference to the drawings and embodiments of the invention.
Figs. 1 and 2 show an example of a measuring system to be used when a method according to the present invention is employed to measure a surface flaw 3 casued along the axis of an inspecting object 1 which is a pressure tube for use in a pressure tube type nuclear reactor and which is 118mm in bore and 4.3mm in thickness. The measuring system comprises a horizontal flat support plate 5 which is disposed within the inspecting object 1 so as to be coaxially rotatable therewith. A proe ~ is fixed by a probe fixing means 6 at a predetermined eccentric position on the support plate 5 so as to emit the ultrasonic waves on to the inner surface of the inspecting object 1 at a predetermined oblique angle. Thus, the emission of the ultrasonic waves and the detection of the ultrasonic echoes can be carried out while the support plate 5 is rotated, and the scanning with the probe 2 can be conducted. An ultrasonic wave shielding member 7 made of a plate-shaped rubber such as a rubber wiper is also fixed by a fixing means 8 on the support plate 5. The tip portion of the ultrasonic wave shielding member 7 is abutted against the inner surface of the inspecting object 1 at a position slightly moved in the 200~42~3 direction of scann~ng relatlve to the point of Incidence of the ultrasonic waves. Further, water serving as a couplant is filled inside the pressure tube of the inspecting object l, i.e., between the inspecting object l and the probe 2.
The probe 2 is electrically connected to an oscilloscope 4 which is externally provided to record on the screen thereof echo signals detected by the probe 2.
Using the measuring system thus constructed, the surface flaw 3 which has been caused along the axis of the inspecting object l is detected by the above-described ultrasonic angle beam method and the surface flaw depth is quantitatively measured by the tip echo method, under the condition that the support plate 5 is rotated counterclockwise while the probe 2 and the oscilloscope 4 are operated.
The echo images recorded on the screen of the oscilloscope 4 are shown in Fig. 3, and the echo images measured without using the ultrasonic wave shielding member 7 are shown in Fig. 4. These echo images have been obtained as the results of the above detection and measurement.
It is apparent from the comparison between the data shown in Figs. 3 and 4 that, according to the ultrasonic flaw detecting method of the present invention, the parasitic echoes have efficiently been eliminated.
When a high-resolution ultrasonic flaw detector is used togehter with a high-frequency wave (about lO MHz), high-200~420 resolutlon and focused type probe, lt is posslble to confinethe measurement error withln about ~0.5mm for the inspection of a pressure tube used in a pressure tube type nuclear reactor whose thickness is 4.3mm.
During the rotation of the support plate S in the above measurement, the ultrasonic wave shielding member 7 may possibly be detached from the surface of the inspecting object 1 due to the rising of the ultrasonic wave shielding member 7, or unsmooth rotation of the support plate 5 may possibly occur. In order to prevent such inconveniences, it is preferable to interpose a spring or the like member (not shown) between the ultrasonic wave shielding member 7 and its fixing means 8 to thereby properly press the ultrasonic wave shielding member 7 against the surface of the inspecting object 1.
From the foregoing description, it is understood that, according to the present invention, the surface wave which forms a parasitic echo is effectively absorbed and thereby shielded by the ultrasonic wave shielding member abutted against the surface of the inspecting object in the area between the point of incidence of the ultrasonic waves and the surface flaw. Accordingly, in the inspection of, for example, a pressure tube of 4.3mm in thickness which is for use in a pressure tube type nuclear reactor, it is possible to confine the measurement error within about l0.5mm in contrast to the conventional measurement error of about I1.5mm, when the flaw depth of the surface flaw whose depth is 2 to 3mm is measured. On the other hand, when the flaw depth of 3 to 4mm Is measured in the above-mentloned inspection, even the skllled operator has not been able to distinguish the flaw tip echo from the parasitic echo.
According to the method of the present invention, however, the measurement of such flaw depth of the surface flaw can be easily performed by an operator having an ordinary skill in the ultrasonic flaw detection technology, and the measurement error can be confined within about +0.5mm.
Further, the quantitative measurement of the surface flaw depth can easily and accurately be conducted even with respect to an inspecting object made of a thin material of about 5 to 6mm in thickness or an inspecting object which is not flat but tubular.
Therefore, by the method of the present invention, a quantitative inspection can be accomplished with respect to the extent of progress of abnormality such as a leak due to the breakage of plant equipment or piping before such abnormality becomes apparent. This provides an advantage in that a better maintenance management of the plant equipment, piping and the like can be performed. Accordingly, the present invention can greatly contribue to the improvement of safety especially in a nuclear reactor plant which demands extremely higher safety than an ordinary plant does.
Claims (3)
1. In an ultrasonic flaw detecting method including the steps of detecting a surface flaw of an inspecting object having a uniform thickness by causing a probe to scan while emitting ultrasonic waves at a predetermined oblique angle onto the surface of said inspecting object and quantitatively measuring the depth of the surface flaw by a tip echo method, the improvement comprising abutting an ultrasonic wave shielding member against the surface of said inspecting object in an area between the point of incidence of the ultrasonic waves and said surface flaw.
2. The method according to claim 1, wherein said ultrasonic wave shielding member is made of a rubber material.
3. The method according to claim 1 or 2, wherein said ultrasonic wave shielding member is abutted against said surface of said inspecting object by pressing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1-6996 | 1989-01-13 | ||
| JP1006996A JPH02187658A (en) | 1989-01-13 | 1989-01-13 | Ultrasonic flaw detecting method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2007420A1 true CA2007420A1 (en) | 1990-07-13 |
Family
ID=11653732
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2007420 Abandoned CA2007420A1 (en) | 1989-01-13 | 1990-01-09 | Ultrasonic flaw detecting method |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH02187658A (en) |
| CA (1) | CA2007420A1 (en) |
-
1989
- 1989-01-13 JP JP1006996A patent/JPH02187658A/en active Pending
-
1990
- 1990-01-09 CA CA 2007420 patent/CA2007420A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02187658A (en) | 1990-07-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |