CA2144597C - Improved emat probe and technique for weld inspection - Google Patents
Improved emat probe and technique for weld inspectionInfo
- Publication number
- CA2144597C CA2144597C CA002144597A CA2144597A CA2144597C CA 2144597 C CA2144597 C CA 2144597C CA 002144597 A CA002144597 A CA 002144597A CA 2144597 A CA2144597 A CA 2144597A CA 2144597 C CA2144597 C CA 2144597C
- Authority
- CA
- Canada
- Prior art keywords
- acoustic
- angle
- specular reflector
- side lobes
- specular
- 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.)
- Expired - Fee Related
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/04—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/24—Probes
- G01N29/2412—Probes using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/24—Probes
- G01N29/2487—Directing probes, e.g. angle probes
-
- 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
- G01N2291/042—Wave modes
- G01N2291/0422—Shear waves, transverse waves, horizontally polarised waves
-
- 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
- G01N2291/042—Wave modes
- G01N2291/0423—Surface waves, e.g. Rayleigh waves, Love waves
-
- 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
- G01N2291/042—Wave modes
- G01N2291/0427—Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
-
- 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
-
- 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
- G01N2291/052—Perpendicular incidence, angular propagation
-
- 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
- G01N2291/10—Number of transducers
- G01N2291/101—Number of transducers one transducer
-
- 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
- G01N2291/26—Scanned objects
- G01N2291/267—Welds
Abstract
A method and apparatus of inspecting for flaws in a specular reflector, where the flaws having an expected length and the reflector is electrically conductive. The method comprises directing a beam of an electromagnetic acoustic transmitting transducer along a beam axis toward the specular reflector for producing a reflected electromagnetic acoustic beam. The transmitted beam has side lobes with zero points therebetween, at least some of the side lobes being major side lobes.
The reflected beam is received using an electro-magnetic acoustic receiving transmitter set at an angle to the beam axis, the angle being selected to be at one of the zero points and passed all of the major lobes of the transmitted beam to eliminate root and crown signals of the weld, in the reflected signal.
The reflected beam is received using an electro-magnetic acoustic receiving transmitter set at an angle to the beam axis, the angle being selected to be at one of the zero points and passed all of the major lobes of the transmitted beam to eliminate root and crown signals of the weld, in the reflected signal.
Description
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates, in general, to EMAT inspections of welds, and in particular, to a new and useful method and apparatus for using crossed or collinear EMATs, to eliminate root and crown signals, while still generating defect or flaw signals for the inspection of a weld or other structure.
DESCRIPTION OF THE RELATED ART
The examination of welds by conventional ultrasonic sensors typically involves a raster type scan in which the time between the resulting crown and root signals is examined for the presence of flaws. This is a slow process that is not well suited for automation because of the requirements for a fluid couplant and a complex mechanical scanner to perform the raster scan.
Electromagnetic Acoustic Transducers (EMATs) are a non-contact method of producing ultrasonic waves in conductors. An EMAT in its simplest form is a coil of wire and a magnet. The RF signals applied to the EMAT coil induce eddy currents at the surface of the conductor. The surface currents interact with the magnetic field, producing the Lorentz force in a manner similar to an electric motor.
The disturbance is transferred to the lattice of the solid, and this is the source of the acoustic wave. The process is reciprocal. If an acoustic wave strikes the surface of a conductor in the presence of a magnetic field, induced currents are generated in the receiving coil much as an electric generator. For the case of ferromagnetic conductors the process is more complicated. In addition to the Lorentz force there are additional stresses produced by magnetostriction. In many cases, the magnetostrictive stresses enhance the signal to much higher levels than could be obtained by the Lorentz interaction alone.
The advantages of EMATs result from the fact that they require no ultrasonic couplant and they are capable of producing more wave modes than conventional piezoelectric ultrasonic techniques. The fact that no couplant is required allows EMATs to scan at very high speeds. Also, the absence of couplant and the use of electromagnets allow EMATs to operate at high temperatures. EMATs are capable of producing all of the modes that are produced by conventional ultrasonics and one mode that is unique to EMATs - the angle beam, horizontally polarized (SH) shear waves. This mode when produced by conventional ultrasonic techniques requires either epoxy or a highly viscous couplant and, thus, it cannot be used for scanning.
The SH shear waves are useful because they undergo no mode conversion upon reflection from an interface. This is particularly useful for inspections of welds and components with complex geometry. SH shear wave EMATs have one more advantage; the beam angle can be changed from 0~ to 90~ by changing the frequency. Surface waves are efficiently produced by EMATs without the wedge noise and damping of the surface waves by couplant that is typical of conventional ultrasonics. Surface waves are very efficiently produced in nonferromagnetic materials such as aluminum using the normal field of a permanent magnet. This is a very compact and useful EMAT sensor for scanning the various aluminum alloys.
EMATs or Electromagnetic Acoustic Transducers, are ideally suited for an automated environment. They do not require a fluid couplant and, therefore, very rapid automated scans can be performed. It is desirable to flood the weld region with sound and thus eliminate the raster scan (motion toward and away from the weld). The presence of the root and crown signals, however, complicate data interpretation. It is desirable to eliminate the root and crown signals, however, there are no known methods in the prior art for achieving this objective. The present disclosure describes unique methods for flaw detection in welds using EMATs that eliminate the root and crown signal.
SUMMARY OF THE INVENTION
Experiments have demonstrated that a crossed beam EMAT can be used to eliminate the root and crown signals and yet allow defect signals to be detected.
The root and crown act as specular reflectors and, therefore, the angle of incidence is equal to the angle of reflection. A small flaw, however, acts as a point source with reflected radiation diffracted over a wide angle. Thus, it was possible to rotate the transmitting and receiving EMATs to detect the defect signal but not the specular reflected signals from the root and crown. Laboratory results have demonstrated the feasibility of detecting both EDM (electrical discharge machining) notches and induced flaws in a 2219 aluminum weld. Three defects were identified using the technique. These three flaws were then examined with real time radiography and, identified as porosity, an "L" shaped crack on the center line of the weld, and a region where there was lack of fusion.
FIELD OF THE INVENTION
The present invention relates, in general, to EMAT inspections of welds, and in particular, to a new and useful method and apparatus for using crossed or collinear EMATs, to eliminate root and crown signals, while still generating defect or flaw signals for the inspection of a weld or other structure.
DESCRIPTION OF THE RELATED ART
The examination of welds by conventional ultrasonic sensors typically involves a raster type scan in which the time between the resulting crown and root signals is examined for the presence of flaws. This is a slow process that is not well suited for automation because of the requirements for a fluid couplant and a complex mechanical scanner to perform the raster scan.
Electromagnetic Acoustic Transducers (EMATs) are a non-contact method of producing ultrasonic waves in conductors. An EMAT in its simplest form is a coil of wire and a magnet. The RF signals applied to the EMAT coil induce eddy currents at the surface of the conductor. The surface currents interact with the magnetic field, producing the Lorentz force in a manner similar to an electric motor.
The disturbance is transferred to the lattice of the solid, and this is the source of the acoustic wave. The process is reciprocal. If an acoustic wave strikes the surface of a conductor in the presence of a magnetic field, induced currents are generated in the receiving coil much as an electric generator. For the case of ferromagnetic conductors the process is more complicated. In addition to the Lorentz force there are additional stresses produced by magnetostriction. In many cases, the magnetostrictive stresses enhance the signal to much higher levels than could be obtained by the Lorentz interaction alone.
The advantages of EMATs result from the fact that they require no ultrasonic couplant and they are capable of producing more wave modes than conventional piezoelectric ultrasonic techniques. The fact that no couplant is required allows EMATs to scan at very high speeds. Also, the absence of couplant and the use of electromagnets allow EMATs to operate at high temperatures. EMATs are capable of producing all of the modes that are produced by conventional ultrasonics and one mode that is unique to EMATs - the angle beam, horizontally polarized (SH) shear waves. This mode when produced by conventional ultrasonic techniques requires either epoxy or a highly viscous couplant and, thus, it cannot be used for scanning.
The SH shear waves are useful because they undergo no mode conversion upon reflection from an interface. This is particularly useful for inspections of welds and components with complex geometry. SH shear wave EMATs have one more advantage; the beam angle can be changed from 0~ to 90~ by changing the frequency. Surface waves are efficiently produced by EMATs without the wedge noise and damping of the surface waves by couplant that is typical of conventional ultrasonics. Surface waves are very efficiently produced in nonferromagnetic materials such as aluminum using the normal field of a permanent magnet. This is a very compact and useful EMAT sensor for scanning the various aluminum alloys.
EMATs or Electromagnetic Acoustic Transducers, are ideally suited for an automated environment. They do not require a fluid couplant and, therefore, very rapid automated scans can be performed. It is desirable to flood the weld region with sound and thus eliminate the raster scan (motion toward and away from the weld). The presence of the root and crown signals, however, complicate data interpretation. It is desirable to eliminate the root and crown signals, however, there are no known methods in the prior art for achieving this objective. The present disclosure describes unique methods for flaw detection in welds using EMATs that eliminate the root and crown signal.
SUMMARY OF THE INVENTION
Experiments have demonstrated that a crossed beam EMAT can be used to eliminate the root and crown signals and yet allow defect signals to be detected.
The root and crown act as specular reflectors and, therefore, the angle of incidence is equal to the angle of reflection. A small flaw, however, acts as a point source with reflected radiation diffracted over a wide angle. Thus, it was possible to rotate the transmitting and receiving EMATs to detect the defect signal but not the specular reflected signals from the root and crown. Laboratory results have demonstrated the feasibility of detecting both EDM (electrical discharge machining) notches and induced flaws in a 2219 aluminum weld. Three defects were identified using the technique. These three flaws were then examined with real time radiography and, identified as porosity, an "L" shaped crack on the center line of the weld, and a region where there was lack of fusion.
It was also confirmed that a pitch-catch attenuation technique could be used to supplement the inspection to detect any flaws that might resemble specular reflectors. The invention includes unique weld sensor and technique.
As a variation of the crossed beam EMAT of the invention, it was observed that two pitch-catch collinear, (focused or nonfocused) sensors could be rotated with respect to the weld center line to achieve the same results as described above for the crossed beam sensor. Although, the probe in this case may not be unique, the technique is unique.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure.
For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
Fig. 1 is a schematic drawing showing the set-up of a crossed beam EMAT
weld sensor in accordance with the present invention;
Fig. 2 is a theoretical plot of a beam profile which agreed with observations made in the laboratory, showing the lobes of the beam;
Fig. 3 is a view similar to Fig. 1 showing a second embodiment of the invention which can be used as an alternative to crossed EMATS; and Fig. 4 is an enlarged view of the transducer which can be used either as a transmitting or receiving transducer, for the present invention.
DESCRIPTION OF THE .PREFERRED EMBODIMENTS
The principle of operating a crossed beam sensor is based on the fact that the root and crown act as a specular reflector (for reasonably smooth welds), and, therefore, the angle of incidence is equal to the angle of reflection. A small flaw, however, acts as a point source and the reflected radiation is scattered over a wide angle. Thus, it is possible to rotate the transmitting and receiving EMATs to detect the defect signal but not the specularly reflected signals from the root and crown.
In practice, the transmitter is positioned perpendicular to the flaw. The receiver is rotated relative to the transmitter at an angle which is past all of the major side lobes and at one of the zero points. This position is then the operating angle for the combination sensor.
As shown in Fig. 1, an EMAT transmitter 10 of conventional construction, is oriented to direct its transmission beam 12 perpendicular to the flat surface of a specular reflector 14, in particular, a surface containing a weld to be inspected according to the present invention. A receiving EMAT 16 is oriented at an angle which is selected according to the present invention and is advantageously 18~
in Fig. 1, to the beam axis of the transmitter 10, for receiving reflected electromagnetic acoustic beams 18 and also reflected beams parallel to the transmission beam 12.
According to the present invention, the angle between the transmitter and receiver is selected so that the receiver is past all major side lobes of the transmission beam and at one of the zero points.
In order to compare the experimental observations with some theoretical results, a computer program based upon Huygen's principle was used to plot a theoretical curve at a metal path of three inches. The results as shown in Fig. 2, agree with the observations made in the laboratory. There were basically two major side lobes that were passed as the receiver was rotated to a "quiet" spot on the base line of the oscilloscope. This corresponds to the arrow 20, marking a zero point on the plot between minor side lobes. The EMATs should be rotated past the side lobes to a zero point and left at that angle as long as the distance from the EMAT to the weld center line is held constant. In the far field, the directivity pattern is simpler and the position of the zeros can be calculated from the usual (sin x) /x relationship.
In practice, the sensors could be SV (vertically polarized shear wave) or SH
(horizontally polarized shear wave) or surface waves. The requirements for the frequency is that the wavelength is no more than two to three times the expected flaw length in order to get a wide diffraction pattern. It is recommended that the technique be supplemented with two pitch-catch sensors through the weld. Any significant loss of signal would indicate the presence of a large flaw acting as a specular reflector.
The alternate technique is illustrated in Fig. 3. Two collinear focused (or nonfocused) EMATs 22, 24 are rotated at a suitable angle with respect to the weld centerline. In practice, the angle can be any convenient value (for example 45~) if the wavelength of the sound is sufficiently close to the flaw dimensions, the flaw acts as a point source 40 and thus exhibits a wide angular diffraction pattern 42.
The results are exactly analogous to those described for the crossed beam sensor.
This technique has the advantage that the angle can be easily changed.
The invention eliminates the presence of the confusing crown and root signals. As a result, the data from the examination of the welds is much more easily examined. The simplicity in data interpretation resulting from the invention together with the elimination of couplant with EMATs greatly improves the automation of weld inspections. The use of this technique allows the position of the sensor to be much closer to the weld than with other techniques because the flaw signals are not obscured by the crown and root signals.
Fig. 4 illustrates a typical EMAT, which can be used with the present invention, including dimensions. The EMAT of Fig. 4 is advantageously an SH, 2 MHz transducer.
The transmitter and receiver EMATs, both illustrated in Fig. 4, are mounted on 2 mil thick sheets of kapton, with the side of the kapton opposite the coils covered with 5 mil thick high molecular weight polyethylene. The side containing the coils was covered with a 1 mil thick sheet of polyethylene to serve as an electrical insulator. When the two coils are placed together in a "sandwich"
configuration, one of the EMATs serves as transmitter and the other as a receiver.
The source of the magnetic field is two neodymium-iron-boron magnets. The two magnets were placed together with a thin copper sheet and thin sheet of cardboard taped to the bottom of the magnets to prevent sound propagating into the magnets themselves. The magnets were placed on the combination EMAT, and the transmitter was rotated at the desired angle with respect to the receiver to achieve the embodiment of Fig. 1.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
As a variation of the crossed beam EMAT of the invention, it was observed that two pitch-catch collinear, (focused or nonfocused) sensors could be rotated with respect to the weld center line to achieve the same results as described above for the crossed beam sensor. Although, the probe in this case may not be unique, the technique is unique.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure.
For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
Fig. 1 is a schematic drawing showing the set-up of a crossed beam EMAT
weld sensor in accordance with the present invention;
Fig. 2 is a theoretical plot of a beam profile which agreed with observations made in the laboratory, showing the lobes of the beam;
Fig. 3 is a view similar to Fig. 1 showing a second embodiment of the invention which can be used as an alternative to crossed EMATS; and Fig. 4 is an enlarged view of the transducer which can be used either as a transmitting or receiving transducer, for the present invention.
DESCRIPTION OF THE .PREFERRED EMBODIMENTS
The principle of operating a crossed beam sensor is based on the fact that the root and crown act as a specular reflector (for reasonably smooth welds), and, therefore, the angle of incidence is equal to the angle of reflection. A small flaw, however, acts as a point source and the reflected radiation is scattered over a wide angle. Thus, it is possible to rotate the transmitting and receiving EMATs to detect the defect signal but not the specularly reflected signals from the root and crown.
In practice, the transmitter is positioned perpendicular to the flaw. The receiver is rotated relative to the transmitter at an angle which is past all of the major side lobes and at one of the zero points. This position is then the operating angle for the combination sensor.
As shown in Fig. 1, an EMAT transmitter 10 of conventional construction, is oriented to direct its transmission beam 12 perpendicular to the flat surface of a specular reflector 14, in particular, a surface containing a weld to be inspected according to the present invention. A receiving EMAT 16 is oriented at an angle which is selected according to the present invention and is advantageously 18~
in Fig. 1, to the beam axis of the transmitter 10, for receiving reflected electromagnetic acoustic beams 18 and also reflected beams parallel to the transmission beam 12.
According to the present invention, the angle between the transmitter and receiver is selected so that the receiver is past all major side lobes of the transmission beam and at one of the zero points.
In order to compare the experimental observations with some theoretical results, a computer program based upon Huygen's principle was used to plot a theoretical curve at a metal path of three inches. The results as shown in Fig. 2, agree with the observations made in the laboratory. There were basically two major side lobes that were passed as the receiver was rotated to a "quiet" spot on the base line of the oscilloscope. This corresponds to the arrow 20, marking a zero point on the plot between minor side lobes. The EMATs should be rotated past the side lobes to a zero point and left at that angle as long as the distance from the EMAT to the weld center line is held constant. In the far field, the directivity pattern is simpler and the position of the zeros can be calculated from the usual (sin x) /x relationship.
In practice, the sensors could be SV (vertically polarized shear wave) or SH
(horizontally polarized shear wave) or surface waves. The requirements for the frequency is that the wavelength is no more than two to three times the expected flaw length in order to get a wide diffraction pattern. It is recommended that the technique be supplemented with two pitch-catch sensors through the weld. Any significant loss of signal would indicate the presence of a large flaw acting as a specular reflector.
The alternate technique is illustrated in Fig. 3. Two collinear focused (or nonfocused) EMATs 22, 24 are rotated at a suitable angle with respect to the weld centerline. In practice, the angle can be any convenient value (for example 45~) if the wavelength of the sound is sufficiently close to the flaw dimensions, the flaw acts as a point source 40 and thus exhibits a wide angular diffraction pattern 42.
The results are exactly analogous to those described for the crossed beam sensor.
This technique has the advantage that the angle can be easily changed.
The invention eliminates the presence of the confusing crown and root signals. As a result, the data from the examination of the welds is much more easily examined. The simplicity in data interpretation resulting from the invention together with the elimination of couplant with EMATs greatly improves the automation of weld inspections. The use of this technique allows the position of the sensor to be much closer to the weld than with other techniques because the flaw signals are not obscured by the crown and root signals.
Fig. 4 illustrates a typical EMAT, which can be used with the present invention, including dimensions. The EMAT of Fig. 4 is advantageously an SH, 2 MHz transducer.
The transmitter and receiver EMATs, both illustrated in Fig. 4, are mounted on 2 mil thick sheets of kapton, with the side of the kapton opposite the coils covered with 5 mil thick high molecular weight polyethylene. The side containing the coils was covered with a 1 mil thick sheet of polyethylene to serve as an electrical insulator. When the two coils are placed together in a "sandwich"
configuration, one of the EMATs serves as transmitter and the other as a receiver.
The source of the magnetic field is two neodymium-iron-boron magnets. The two magnets were placed together with a thin copper sheet and thin sheet of cardboard taped to the bottom of the magnets to prevent sound propagating into the magnets themselves. The magnets were placed on the combination EMAT, and the transmitter was rotated at the desired angle with respect to the receiver to achieve the embodiment of Fig. 1.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
Claims (8)
1. A method of inspecting for flaws in a specular reflector, the reflector being electrically conductive, the method comprising the steps of:
transmitting an acoustic beam with an electromagnetic acoustic transmitting transducer along a beam axis toward the specular reflector for producing a reflected acoustic beam, the transmitted acoustic beam having side lobes with zero points therebetween, at leas some of the side lobes being major side lobes of a specular reflection produced by the transmitted beam from the specular reflector;
receiving the reflected beam using an electromagnetic acoustic receiving transducer at an angle to the beam axis, the angle being selected to be at one of the zero points and past all of the major lobes of the specular reflection of the transmitted acoustic beam; and detecting a flaw in the specular reflector based upon changes in the received acoustic beam.
transmitting an acoustic beam with an electromagnetic acoustic transmitting transducer along a beam axis toward the specular reflector for producing a reflected acoustic beam, the transmitted acoustic beam having side lobes with zero points therebetween, at leas some of the side lobes being major side lobes of a specular reflection produced by the transmitted beam from the specular reflector;
receiving the reflected beam using an electromagnetic acoustic receiving transducer at an angle to the beam axis, the angle being selected to be at one of the zero points and past all of the major lobes of the specular reflection of the transmitted acoustic beam; and detecting a flaw in the specular reflector based upon changes in the received acoustic beam.
2. A method according to claim 1, wherein the specular reflector comprises a conducting material containing a weld having a root and a crown which normally produce root and crown signals in the reflected beam, the method including transmitting the acoustic beam toward the weld and receiving the reflected acoustic beam which is substantially free of root and crown signal, however, contains signals corresponding to a flaw in the weld.
3. A method according to claim 1, wherein the flaws include natural flaws.
4. A method according to claim 1, wherein each of the transmitting and receiving transducers have a transducer axis, the method including maintaining the transmitting transducer axis perpendicular to a surface of the specular reflector and maintaining the receiving transducer axis at the angle.
5. A method for inspecting flaws in a specular reflector, comprising the steps of:
transmitting an acoustic beam with an electromagnetic acoustic transmitter at an angle toward the specular reflector for producing a reflected acoustic beam, the transmitted acoustic beam having side lobes with zero points therebetween, at least some of the side lobes being major side lobes of a specular reflection produced by the transmitted acoustic beam from the specular reflector;
positioning an electromagnetic acoustic receiver in a collinear relationship with respect to the electromagnetic acoustic transmitter;
receiving the reflected beam using the electromagnetic acoustic receiver;
rotating the electromagnetic acoustic transmitter and receiver at the angle to the specular reflector, the angle being selected to be at one of the zero points and past all of the major side lobes of the specular reflection of the transmitted acoustic beam; and detecting a flaw in the specular reflector based upon changes in the received acoustic beam.
transmitting an acoustic beam with an electromagnetic acoustic transmitter at an angle toward the specular reflector for producing a reflected acoustic beam, the transmitted acoustic beam having side lobes with zero points therebetween, at least some of the side lobes being major side lobes of a specular reflection produced by the transmitted acoustic beam from the specular reflector;
positioning an electromagnetic acoustic receiver in a collinear relationship with respect to the electromagnetic acoustic transmitter;
receiving the reflected beam using the electromagnetic acoustic receiver;
rotating the electromagnetic acoustic transmitter and receiver at the angle to the specular reflector, the angle being selected to be at one of the zero points and past all of the major side lobes of the specular reflection of the transmitted acoustic beam; and detecting a flaw in the specular reflector based upon changes in the received acoustic beam.
6. An apparatus for detecting flaws in a specular reflector, the reflector being electrically conductive, the apparatus comprising:
an acoustic transmitting transducer for directing a transmitted acoustic beam along a beam axis toward the specular reflector for producing a reflected acoustic beam, the transmitted beam having side lobes with zero points therebetween, at least some of the side lobes being major side lobes of a specular reflection produced by the transmitted acoustic beam from the specular reflector; and, an electromagnetic acoustic receiving transducer for receiving the reflected beam, at an angle to the beam axis, the angle being selected to be at one of the zero points and past all of the major lobes of the specular reflection of the transmitted beam, wherein a flaw in the specular reflector is detected based upon changes in the received reflected beam.
an acoustic transmitting transducer for directing a transmitted acoustic beam along a beam axis toward the specular reflector for producing a reflected acoustic beam, the transmitted beam having side lobes with zero points therebetween, at least some of the side lobes being major side lobes of a specular reflection produced by the transmitted acoustic beam from the specular reflector; and, an electromagnetic acoustic receiving transducer for receiving the reflected beam, at an angle to the beam axis, the angle being selected to be at one of the zero points and past all of the major lobes of the specular reflection of the transmitted beam, wherein a flaw in the specular reflector is detected based upon changes in the received reflected beam.
7. An apparatus according to claim 6, wherein the transmitting and receiving transducers each have respective transducer axes which are at the angle with respect to each other.
8. An apparatus according to claim 6, wherein the flaws include natural flaws.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US21084894A | 1994-03-18 | 1994-03-18 | |
| US08/210,848 | 1994-03-18 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2144597A1 CA2144597A1 (en) | 1995-09-19 |
| CA2144597C true CA2144597C (en) | 1999-08-10 |
Family
ID=22784514
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002144597A Expired - Fee Related CA2144597C (en) | 1994-03-18 | 1995-03-14 | Improved emat probe and technique for weld inspection |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5760307A (en) |
| CA (1) | CA2144597C (en) |
Families Citing this family (40)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3377395B2 (en) * | 1997-03-21 | 2003-02-17 | 株式会社荏原製作所 | Focused electromagnetic ultrasonic transducer and electromagnetic ultrasonic inspection method |
| US6158285A (en) * | 1997-08-26 | 2000-12-12 | Mcdermott Technology, Inc. | EMAT inspection of welds in thin steel plates of dissimilar thicknesses |
| US6715354B2 (en) | 1998-02-24 | 2004-04-06 | Massachusetts Institute Of Technology | Flaw detection system using acoustic doppler effect |
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| FR2806801B1 (en) * | 2000-03-23 | 2002-05-03 | Snecma | RESILIENCE EVALUATION METHOD OF A WELDED ASSEMBLY AND CORRESPONDING ANALYSIS APPARATUS MEASURING SURFACE ULTRASONIC WAVE SPEEDS |
| NZ522139A (en) | 2000-04-24 | 2004-12-24 | Shell Int Research | In situ recovery from a hydrocarbon containing formation |
| US6833554B2 (en) * | 2000-11-21 | 2004-12-21 | Massachusetts Institute Of Technology | Laser-induced defect detection system and method |
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| CA2463110C (en) * | 2001-10-24 | 2010-11-30 | Shell Canada Limited | In situ recovery from a hydrocarbon containing formation using barriers |
| MY128610A (en) * | 2001-12-31 | 2007-02-28 | Shell Int Research | Method for interconnecting tubulars by forge welding |
| CN100377828C (en) * | 2002-07-17 | 2008-04-02 | 国际壳牌研究有限公司 | Joining expandable tubulars |
| CN100385236C (en) * | 2002-07-17 | 2008-04-30 | 国际壳牌研究有限公司 | EMAT weld inspection |
| US7282663B2 (en) * | 2002-07-29 | 2007-10-16 | Shell Oil Company | Forge welding process |
| AU2003285008B2 (en) | 2002-10-24 | 2007-12-13 | Shell Internationale Research Maatschappij B.V. | Inhibiting wellbore deformation during in situ thermal processing of a hydrocarbon containing formation |
| US20040091076A1 (en) * | 2002-11-08 | 2004-05-13 | Pacific Gas & Electric Company | Method and system for nondestructive inspection of components |
| AU2004235350B8 (en) | 2003-04-24 | 2013-03-07 | Shell Internationale Research Maatschappij B.V. | Thermal processes for subsurface formations |
| US7774917B2 (en) * | 2003-07-17 | 2010-08-17 | Tubefuse Applications B.V. | Forge welding tubulars |
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| WO2008051822A2 (en) | 2006-10-20 | 2008-05-02 | Shell Oil Company | Heating tar sands formations to visbreaking temperatures |
| AU2008242797B2 (en) | 2007-04-20 | 2011-07-14 | Shell Internationale Research Maatschappij B.V. | In situ recovery from residually heated sections in a hydrocarbon containing formation |
| RU2496067C2 (en) | 2007-10-19 | 2013-10-20 | Шелл Интернэшнл Рисерч Маатсхаппий Б.В. | Cryogenic treatment of gas |
| DE102008002394A1 (en) * | 2008-04-01 | 2009-10-22 | Ge Sensing & Inspection Technologies Gmbh | Universal test head for non-destructive ultrasound examination and associated method |
| US8177305B2 (en) | 2008-04-18 | 2012-05-15 | Shell Oil Company | Heater connections in mines and tunnels for use in treating subsurface hydrocarbon containing formations |
| AU2009303610A1 (en) | 2008-10-13 | 2010-04-22 | Shell Internationale Research Maatschappij B.V. | Systems and methods for treating a subsurface formation with electrical conductors |
| US8327932B2 (en) | 2009-04-10 | 2012-12-11 | Shell Oil Company | Recovering energy from a subsurface formation |
| US9033042B2 (en) | 2010-04-09 | 2015-05-19 | Shell Oil Company | Forming bitumen barriers in subsurface hydrocarbon formations |
| US8701769B2 (en) | 2010-04-09 | 2014-04-22 | Shell Oil Company | Methods for treating hydrocarbon formations based on geology |
| US8820406B2 (en) | 2010-04-09 | 2014-09-02 | Shell Oil Company | Electrodes for electrical current flow heating of subsurface formations with conductive material in wellbore |
| US8631866B2 (en) | 2010-04-09 | 2014-01-21 | Shell Oil Company | Leak detection in circulated fluid systems for heating subsurface formations |
| US20110296922A1 (en) * | 2010-06-07 | 2011-12-08 | Syed Mohamed Ali | Emat for inspecting thick-section welds and weld overlays during the welding process |
| US9016370B2 (en) | 2011-04-08 | 2015-04-28 | Shell Oil Company | Partial solution mining of hydrocarbon containing layers prior to in situ heat treatment |
| CA2850741A1 (en) | 2011-10-07 | 2013-04-11 | Manuel Alberto GONZALEZ | Thermal expansion accommodation for circulated fluid systems used to heat subsurface formations |
| CA2862463A1 (en) | 2012-01-23 | 2013-08-01 | Genie Ip B.V. | Heater pattern for in situ thermal processing of a subsurface hydrocarbon containing formation |
| AU2012367826A1 (en) | 2012-01-23 | 2014-08-28 | Genie Ip B.V. | Heater pattern for in situ thermal processing of a subsurface hydrocarbon containing formation |
| US9689845B2 (en) | 2012-05-18 | 2017-06-27 | Areva Inc. | Angle beam ultrasonic probe for internal hex socket bolts |
| NL2023174B1 (en) * | 2019-05-21 | 2020-12-01 | Beugen J Van Beheer Bv | Apparatus and method for pipeline inspection |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2227259A1 (en) * | 1972-06-05 | 1973-12-20 | Joachim Dipl Phys Dr Herbertz | METHOD AND DEVICE FOR CONTACTLESS MATERIAL TESTING USING ULTRASOUND |
| US4289030A (en) * | 1979-08-01 | 1981-09-15 | Rockwell International Corporation | Nondestructive testing utilizing horizontally polarized shear waves |
| JPS5841347A (en) * | 1981-09-04 | 1983-03-10 | Hitachi Ltd | Detecting device of welded section |
| GB8402098D0 (en) * | 1984-01-26 | 1984-02-29 | Atomic Energy Authority Uk | Ultrasonic inspection of tube |
| EP0382844A4 (en) * | 1988-05-20 | 1991-03-20 | Moskovskoe Vysshee Tekhnicheskoe Uchilische Imeni N.E.Baumana | Method for ultrasonically checking weld seams of articles |
| US5154081A (en) * | 1989-07-21 | 1992-10-13 | Iowa State University Research Foundation, Inc. | Means and method for ultrasonic measurement of material properties |
| US5085082A (en) * | 1990-10-24 | 1992-02-04 | The Babcock & Wilcox Company | Apparatus and method of discriminating flaw depths in the inspection of tubular products |
| US5359898A (en) * | 1991-06-04 | 1994-11-01 | The Babcock & Wilcox Company | Hydrogen damage confirmation with EMATs |
| US5237874A (en) * | 1991-10-07 | 1993-08-24 | The Babcock & Wilcox Company | Rotating electromagnetic acoustic transducer for metal inspection |
| US5497662A (en) * | 1993-09-07 | 1996-03-12 | General Electric Company | Method and apparatus for measuring and controlling refracted angle of ultrasonic waves |
| US5537876A (en) * | 1994-08-02 | 1996-07-23 | Davidson; Paul K. | Apparatus and method for nondestructive evaluation of butt welds |
-
1995
- 1995-03-14 CA CA002144597A patent/CA2144597C/en not_active Expired - Fee Related
- 1995-09-07 US US08/531,573 patent/US5760307A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| US5760307A (en) | 1998-06-02 |
| CA2144597A1 (en) | 1995-09-19 |
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