ULTRASONIC-PULSE-ECHO FLAW INSPECTION AT A HIGH TESTING SPEED ON THIN-WALLED PIPES IN PARTICULAR

• US 20170016860A1
• Filed: 03/10/2015
• Published: 01/19/2017
• Est. Priority Date: 03/10/2014
• Status: Active Grant

• Current Assignee: GE Sensing & Inspection Technologies GmbH (General Electric Company)
• Original Assignee: GE Sensing & Inspection Technologies GmbH (General Electric Company)
• Inventors: PRAUSE, Reinhard, DICK, Wolfgang
• Granted Patent: US 10,241,084 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects
• CPC Class Codes: G01N 2291/056 Angular incidence, angular propagation
• CPC Class Codes: G01N 29/043 in the interior, e.g. by shear waves
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/221 Arrangements for directing or focusing the acoustical waves electronic orientation or focusing G01N29/262; sound directing or focusing G10K11/26; mechanical steering of sound transducers or their beams G10K11/35
• CPC Class Codes: G01N 29/2487 Directing probes, e.g. angle probes directing arrangements G01N29/221
• CPC Class Codes: G01N 29/36 Detecting the response signal , e.g. electronic circuits specially adapted therefor
• CPC Class Codes: G01N 29/38 by time filtering, e.g. using time gates
• CPC Class Codes: G01N 29/40 by amplitude filtering, e.g. by applying a threshold or by gain control
• CPC Class Codes: G01N 29/4463 Signal correction, e.g. distance amplitude correction [DAC], distance gain size [DGS], noise filtering

Abstract

Embodiments relate to a method for ultrasonic testing according to the pulse-echo method as well as an arrangement for performing such a method. By means of an ultrasonic transducer, an ultrasonic pulse is obliquely incident into a sound incidence surface of a test object. Next, an echo signal is received from the test object. This takes place either by means of the ultrasonic transducer, which has emitted the ultrasonic pulse or with another ultrasonic transducer. The time amplitude characteristic of the echo signal is evaluated in a predefined defect expectation interval of time. The evaluation step includes, in at least one section of the amplitude characteristic, an amplification of the amplitude and/or a reduction in the threshold value. For example, the amplitude of the received echo signal is then compared with the predefined threshold value.

Claims

1. A method for ultrasonic testing, comprising:

using an ultrasonic transducer to cause oblique sound incidence of an ultrasonic pulse via an input surface into a test object;

receiving the echo signal from the test object with the ultrasonic transducer or another ultrasonic transducer; and

evaluating the amplitude characteristic of the echo signal over time in a predefined defect expectation interval of time,

wherein the step of evaluation includes amplification of the amplitude with a gain factor and/or a reduction in a threshold value in at least one section of the amplitude characteristic of the echo signal in the defect expectation interval of time.

2. The method according to claim 1, wherein the gain factor varies within the at least one section.

3. The method according to claim 1, wherein the amplification of the amplitude or the reduction in the threshold value in the at least one section is designed so that a drop in amplitude, which is brought about by damping, is due to the damping and/or a power loss and is compensated partially or preferably entirely.

4. The method according to claim 1, wherein the at least one section is situated on the back end chronologically of the defect expectation interval of time.

5. The method according to claim 1, wherein the gain factor in the at least one section of the amplitude characteristic of the echo signal in the defect expectation interval of time increases steadily with time or decreases steadily with time.

6. The method according to claim 1, having a plurality of sections in the defect expectation interval of time, wherein the sections differ in the characteristic of the gain factor over time and/or in the threshold value variation.

7. The method according to claim 6, wherein the gain factor increases steadily over the entire amplitude characteristic of the echo signal in the defect expectation interval of time.

8. The method according to claim 1, wherein the test object is a body having walls parallel to one another, and one of the walls comprises the sound incidence surface.

9. The method according to claim 8, wherein the test object has a wall thickness in the range of 0.5 mm to 10.0 mm.

10. The method according to claim 1, wherein the duration of the defection expectation interval of time is selected, so that multiple reflections in the test object are covered by the time characteristic of the echo signal in the defect expectation interval of time.

11. The method according to claim 1, having a plurality of sound incidence steps following one another in time and a plurality of intermediate or simultaneous steps of relative movement.

12. The method according to claim 1, wherein the sound incidence angle set in the step of oblique sound incidence is selected so that the main direction of propagation of the ultrasonic pulse forms an angle with the sound incidence surface immediately after the ultrasonic pulse passes through the sound incidence surface, this angle being in the range of 40°

to 50°

.

13. The method according to claim 1, wherein the ultrasonic transducer has a maximum outside dimension of its sound-emitting surface in the range of greater than 10.0 mm.

16. The method according to claim 1, wherein the amplification of the amplitude or the reduction in the threshold value in the at least one section is designed so that a drop in amplitude, which is brought about by damping, is due to the damping and/or a power loss and is compensated entirely.

17. The method according to claim 3, wherein the damping is attributed to the material and the geometry of the test object and/or by a power loss at the side of the sound emission cone of the ultrasonic transducer.

18. The method according to claim 8, wherein the body is comprised of a pipe or a sheet metal.

19. The method according to claim 10, wherein the multiple reflections of the walls of the test object are covered by the time characteristic of the echo signal in the defect expectation interval of time.

20. The method according to claim 11, wherein the relative movement comprises relative rotational and/or translational movement, between the ultrasonic transducer emitting the sound and the test object, to achieve a complete sound bombardment of the test object.

14. An arrangement for ultrasonic testing, the arrangement comprising:

an ultrasonic transducer for oblique sound incidence of an ultrasonic pulse over a sound incidence surface into a test object and for receiving the echo signal from the test object; and

an evaluation unit for evaluating the amplitude characteristic of the echo signal over time in a predefined defect expectation interval of time and for comparison of the amplitude with a predefined threshold value,

wherein the evaluation unit is also designed to amplify the amplitude characteristic of the echo signal in at least one section of the defect expectation interval of time and/or to lower the threshold value.

15. The arrangement according to claim 14, further comprising a test object, wherein the test object is a body having parallel walls, and one of the walls comprises the sound incidence surface.