Phased array ultrasonic examination system and method
A method and apparatus for phased array ultrasound testing of piping that complies with present-day codes but allows more thorough flaw detection capability. A tapered wedge with a concave face is calibrated by submerging the wedge under sonic coupling fluid, thereby allowing sonic coupling of the concave wedge face to a flat reference plate with minimal error. The flaw detector is configured to display A-scan and S-scan data concurrently and to sweep between 30-70 degrees. A-scan data corresponding with conventional preferred inspection incidence angle is selected, and reject levels are set to 0% to meet current inspection standards. S-scan data allows for detection of flaws that might otherwise be undetectable using only A-scan data. A palette adjustment feature remaps the colors assigned to lower intensity return values so that they are not displayed on the S-scan, thereby de-cluttering sectorial data without filtering A-scan data.
1. A method for inspecting a cylindrical tubular structure ( 240 ) characterized by an inside diameter and an outside diameter, the method comprising the steps of:
providing a phased array ultrasound flaw detection system including a detector electrically connected to a transducer ( 220 ), said transducer mounted to an upper surface of a wedge ( 200 ), said wedge having a lower concave surface ( 202 );
providing a reference plate ( 400 ) having a flat surface;
abutting said concave surface of said wedge against said flat surface of said reference plate thereby defining an interstice between said concave surface and said flat surface;
filling said interstice with a sonic couplant;
calibrating said flaw detection system while said interstice is filled with said sonic couplant;
coating said structure with said sonic couplant;
disposing said concave surface of said wedge against said coated structure at a first point;
introducing an ultrasound wavefront generated at said transducer through said wedge into said coated structure;
sweeping said ultrasound wavefront through a plurality of incidence angles including a preferred incidence angle that is defined by the inverse sine of said inside diameter divided by said outside diameter;
measuring an echo return signal of said ultrasound wavefront received at said transducer at each of said plurality of incidence angles;
displaying all of said measured echo return signal received at said preferred incidence angle in an A-scan format ( 110 ) on said detector while simultaneously displaying at least part of said measured echo return signals received at all of said plurality of incidence angles in an S-scan format ( 120 ) on said detector; then
moving said concave surface of said wedge against said coated structure to a second point; and
repeating said steps of introducing, sweeping, measuring, and displaying at said second point.
2. The method of claim 1 further comprising the step of:
submerging said interstice in said sonic couplant.
3. The method of claim 1 further comprising the step of:
assigning a palette setting of said detector so as to cause any of said measured echo return signals that have low amplitude to not be displayed in said S-scan format ( 120 ′) on said detector.
4. The method of claim 1 further comprising the step of:
moving said concave surface of said wedge circumferentially with respect to said structure from said first point to said second point.
5. The method of claim 1 further comprising the step of:
moving said concave surface of said wedge axially with respect to said structure from said first point to said second point.
6. The method of claim 1 further comprising the step of:
sweeping said ultrasound wavefront through a plurality of incidence angles between 30 and 70 degrees.
7. The method of claim 1 further comprising the step of:
sweeping said ultrasound wavefront through a plurality of incidence angles between 30 and 60 degrees.
8. A method for inspecting a cylindrical tubular structure ( 240 ) characterized by an inside diameter and an outside diameter, the method comprising the steps of:
providing a phased array ultrasound flaw detection system including a detector electrically connected to a transducer ( 220 );
mounting said transducer to an upper surface of a first wedge ( 200 ), said first wedge having a lower concave surface ( 202 ) oriented for circumferential scanning with respect to said structure;
providing a reference plate ( 400 ) having a flat surface;
abutting said concave surface of said first wedge against said flat surface of said reference plate thereby defining a first interstice between said concave surface of said first wedge and said flat surface;
submerging so as to fill said first interstice with a sonic couplant;
calibrating said flaw detection system while said first interstice is filled with said sonic couplant; then
coating said structure with said sonic couplant;
disposing said concave surface of said first wedge against said coated structure; and
while moving said first wedge in a circumferential direction around said structure,
introducing ultrasound wavefronts generated at said transducer through said first wedge into said coated structure,
sweeping said ultrasound wavefronts through a plurality of incidence angles including a preferred incidence angle that is defined by the inverse sine of said inside diameter divided by said outside diameter,
measuring echo return signals of said ultrasound wavefronts received at said transducer at each of said plurality of incidence angles, and
displaying all of said measured echo return signals received at said preferred incidence angle in an A-scan format ( 110 ) on said detector while simultaneously displaying at least part of said measured echo return signals received at all of said plurality of incidence angles in an S-scan format ( 120 ) on said detector.
9. The method of claim 8 further comprising the steps of:
mounting said transducer to an upper surface of a second wedge ( 200 ), said second wedge having a lower concave surface ( 202 ) oriented for axial scanning with respect to said structure;
abutting said concave surface of said second wedge against said flat surface of said reference plate thereby defining a second interstice between said concave surface of said second wedge and said flat surface;
submerging so as to fill said second interstice with said sonic couplant;
calibrating said flaw detection system while said second interstice is filled with said sonic couplant; then
disposing said concave surface of said second wedge against said coated structure; and
while moving said second wedge in a axial direction along said structure,
introducing ultrasound wavefronts generated at said transducer through said second wedge into said coated structure,
sweeping said ultrasound wavefronts through said plurality of incidence angles,
measuring echo return signals of said ultrasound wavefronts received at said transducer at each of said plurality of incidence angles, and
displaying said measured echo return signals on said detector.
10. The method of claim 8 further comprising the step of:
sweeping said ultrasound wavefronts through a plurality of incidence angles between 30 and 70 degrees.
11. The method of claim 8 further comprising the step of:
sweeping said ultrasound wavefronts through a plurality of incidence angles between 30 and 60 degrees.