Steam generator nondestructive examination method
First Claim
Patent Images
1. A method of examining a steam generator heat exchanger tube having an elongated axial dimension which is substantially filled with a fluid, comprising the steps of:
- contacting an outer surface of a wall of the tube with an ultrasonic transducer;
establishing a predetermined Lamb wave mode that when transmitted into the wall of the tube is not substantially attenuated by the water in the tube;
transmitting a pseudo helical Lamb wave of the predetermined Lamb wave mode into the wall of the tube from the ultrasonic transducer; and
analyzing reflected or modified waves for wear scar defects in the wall of the tube.
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Abstract
A method of examining a steam generator heat exchange tube from the outside surface employing ultrasonic nondestructive inspection techniques. An ultrasonic transducer contacts the outside surface of the tube and transmits a pseudo helical Lamb wave into the wall of the tube chosen to have a mode that does not significantly interact with water in the tube. The reflected waves are then analyzed for changes in modes to identify defects in the wall of the tube.
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Citations
22 Claims
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1. A method of examining a steam generator heat exchanger tube having an elongated axial dimension which is substantially filled with a fluid, comprising the steps of:
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contacting an outer surface of a wall of the tube with an ultrasonic transducer; establishing a predetermined Lamb wave mode that when transmitted into the wall of the tube is not substantially attenuated by the water in the tube; transmitting a pseudo helical Lamb wave of the predetermined Lamb wave mode into the wall of the tube from the ultrasonic transducer; and analyzing reflected or modified waves for wear scar defects in the wall of the tube. - View Dependent Claims (2, 3, 4, 5, 6, 7, 11, 12, 13, 14, 19)
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8. A method of examining a steam generator heat exchanger tube having an elongated axial dimension which is substantially filled with a fluid, comprising the steps of:
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contacting an outer surface of a wall of the tube with an ultrasonic transducer; establishing a predetermined Lamb wave mode that when transmitted into the wall of the tube is not substantially attenuated by the water in the tube; transmitting a pseudo helical Lamb wave of the predetermined Lamb wave mode into the wall of the tube from the ultrasonic transducer; tuning the frequency of the Lamb wave to sweep across a given band of frequencies, wherein the given band of frequencies extends approximately five percent on either side of a primary frequency; and analyzing reflected or modified waves for wear scar defects in the wall of the tube. - View Dependent Claims (9)
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10. A method of examining a steam generator heat exchanger tube having an elongated axial dimension which is substantially filled with a fluid, comprising the steps of:
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contacting an outer surface of a wall of the tube with an ultrasonic transducer; establishing a predetermined Lamb wave mode that when transmitted into the wall of the tube is not substantially attenuated by the water in the tube; transmitting a pseudo helical Lamb wave of the predetermined Lamb wave mode into the wall of the tube from the ultrasonic transducer; tuning the frequency of the Lamb wave to sweep across a given band of frequencies, wherein the given band of frequencies extends approximately one percent on either side of a primary frequency; and analyzing reflected or modified waves for wear scar defects in the wall of the tube.
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15. A method of examining a steam generator heat exchanger tube having an elongated axial dimension which is substantially filled with a fluid, comprising the steps of:
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contacting an outer surface of a wall of the tube with an ultrasonic transducer; establishing a predetermined Lamb wave mode that when transmitted into the wall of the tube is not substantially attenuated by the water in the tube, wherein the establishing step determines the predetermined Lamb wave mode through experimentation by varying the transducer'"'"'s frequency and angle of introduction of the ultrasonic signal into the tube wall until a mode is identified that results in a response that is least affected by the fluid in the tube and best characterizes a wear scar defect'"'"'s penetration through the tube wall; transmitting a pseudo helical Lamb wave of the predetermined Lamb wave mode into the wall of the tube from the ultrasonic transducer; and analyzing reflected or modified waves for wear scar defects in the wall of the tube. - View Dependent Claims (16, 17, 18)
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20. A method of determining the existence of defects in the walls of an elongated “
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shaped heat exchange tube from the secondary side of a steam generator while a primary side of the steam generator is water solid, comprising the steps of;contacting an outer surface of a wall of the tube with an ultrasonic transducer in an area of a “
U”
-bend of the tube;establishing a predetermined Lamb wave mode that when transmitted into the wall of the tube is not substantially attenuated by the water in the tube; transmitting a pseudo helical Lamb wave into the wall of the tube from the ultrasonic transducer in opposite directions along the elongated dimension of the tube; and analyzing reflected waves for defects in the wall of the tube. - View Dependent Claims (21, 22)
- U”
Specification