Pipe quality monitoring mechanism

• US 4,160,385 A
• Filed: 06/30/1977
• Issued: 07/10/1979
• Est. Priority Date: 06/30/1977
• Status: Expired due to Term

• Current Assignee: Uponor B.V.
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.), Sonic Instruments Incorporated
• Inventors: Gromlich, Roy J., Cist, John D., Brech, deceased, Kilian H.
• Primary Examiner(s): Ruehl, Charles A.
• Application Number:
  US05/811,975
• Time in Patent Office: 740 Days
• Field of Search: 73/615, 73/618-628
• US Class Current: 73/622
• CPC Class Codes: G01B 17/02 for measuring thickness
• CPC Class Codes: G01N 2291/02854 Length, thickness
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects
• CPC Class Codes: G01N 2291/2634 cylindrical from outside
• CPC Class Codes: G01N 29/0618 synchronised with scanning, e.g. in real-time
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/22 Details , e.g. general constructional or apparatus details
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency
• CPC Class Codes: G01N 29/4454 Signal recognition, e.g. specific values or portions, signal events, signatures

Abstract

As an ultrasonic transducer is continuously rotated about a pipe which is fed axially through a water-filled cavity, it sends sufficient periodic pulses to the pipe to cover essentially the entire pipe surface. The transducer also receives reflections from the outside and inside walls of the pipe from which information about pipe qualities is derived. A thickness processor module employs precision peak detectors in various circuits, including one in which flaw conditions are compared on successive rotation of the transducer in order to verify the presence of a flaw before an alarm is indicated. The thickness processor module may also provide display information about maximum and minimum values, average values, and eccentricity. In addition to the precision peak detector, there is also provided a rate of change filter which monitors rate of change of wall information and detects flaws by any major rate of change. If tolerances are exceeded in any respect or rate of change indicates a cavity or other discontinuity in the surface, alarms may be sounded, but before an alarm is sounded, verification is preferably accomplished by alarm verification, memory and logic means.

Claims

1. A system for inspecting the wall of tubular material in which the tubular material passes through an inspection apparatus including a chamber supplied with fluid to fill the path between the tubular material and ultrasonic transducer means providing means to transmit ultrasonic pulses inwardly to the tubular material and receive pulses reflected at least from the outer and inner wall surfaces of said tubular material and means to provide relative rotation of the ultrasonic transducer means around the tubular material as said tubular material passes generally axially through said chamber, comprising:

a pulse generating source for the ultrasonic transducer means to provide pulses at a constant rate sufficiently frequent to permit examination of the entire tubular material;

a pulse receiving and interpreting means for effectively calculating wall thickness of the tubular material opposite a transducer location;

an out-of-tolerance comparison means to identify out-of-tolerance data in comparison to a predetermined in-tolerance standard,

a storage means to receive and store an out-of-tolerance output signal from the comparison means in a position representative of sensor and tubular location;

angular location means secured relative to said ultrasonic transducer means for rotation therewith, said angular location means having a repetitive pattern providing preselected number of pattern repetitions around its periphery;

stationary sensor means cooperating with the repetitive pattern on the angular location means to produce a repetitive wave-form output representative of transducer location;

means responsive to each wave of said repetitive wave-form output to count waves and thereby provide a basis for comparison of a stored out-of-tolerance signal at a predetermined position relative to the currently generated signal;

means for comparing said stored output signal with the output existing at the attainment of a preselected count of a number of waves from a counter corresponding to a comparison position for verification, and producing a verification signal upon comparison if the signals correspond within preset limits, and

out-of-tolerance indicator means receiving said verification of said out-of-tolerance signal from the comparison means and indicating the out-of-tolerance condition.

2. The system of claim 1 in which the counter counts for the equivalent of a complete revolution, or a predetermined limited number of counts before or after a full revolution, before making comparison.

3. The system of claim 1 in which the storage means is a shift register in which data is periodically shifted by the signals from the stationary sensor means and comparison is made at a predetermined comparison position for verification approximately one revolution later.

4. The system of claim 3 in which the angular location means is a toothed wheel.

5. The system of claim 4 in which the number of teeth on said wheel is 60 and said preselected number of waves is 60.

6. The system of claim 4 in which the number of teeth on said wheel is 60 and said preselected number of waves is 59.

7. The system of claim 4 in which the said constant rate of said pulse generating source is about 3,000 cycles per second.

8. A system for inspecting tubular material in which the tubular material passes through an inspection apparatus including a chamber supplied with liquid to fill the path between the tubular material and ultrasonic transducer means providing means to transmit ultrasonic pulses inwardly to the tubular material and receive pulses reflected at least from the outer and inner wall surfaces of said tubular material and means to provide relative rotation of the ultrasonic transducer means around the tubular material as said tubular material passes generally axially through said chamber, comprising:

a pulse generating source for the ultrasonic transducer means to provide pulses at a rate sufficiently frequent to permit examination of the entire tubular material;

a pulse receiving and interpreting means for generating a signal representative of rate-of-change of wall thickness of the tubular material at successive measurement intervals around the tube;

comparison means for comparing the dimensional wall thickness rate-of-change signals with at least one predetermined rate-of-change tolerance limit to identify flaws; and

out-of-tolerance indicator means receiving an output signal from the comparison means indicating a flaw.

9. The system of claim 8 in which a high pass filter is used to identify a flaw signal from passed high frequencies generated by a preselected rate-of-change of tubular wall thickness.

10. The system of claim 8 in which a plurality of tuned band pass filters are used in parallel to identify an array of flaw signals from passed high frequencies generated by a preselected rate-of-change of tubular wall thickness.

11. The system of claim 8 in which the comparison means includes a peak detector employed in obtaining maximum wall thickness signals and a storage device is provided to receive and hold at least previous maximum peak readings.

12. The system of claim 11 in which two stages of operational amplifiers are used with storage means between them and the second amplifier is used as a high impedance voltage-follower.

13. The system of claim 12 in which the first operational amplifier is used as a diode detector to permit precision rectification of small signals.

14. The system of claim 13 in which the second operational amplifier in combination with a diode and at least two resistors to produce a constant current discharge for the storage means.

15. The system of claim 14 in which a rate-of-change filter is employed at circuit output.

16. The system of claim 15 employs a peak detector at output for maximum wall thickness detection.

17. The system of claim 15 employs a peak detector at output for minimum wall thickness detection.

18. The system of claim 8 in which the comparison means includes a peak detector employed in obtaining minimum wall thickness signals and the storage device is provided to receive and hold at least minimum peak readings.

19. The system of claim 18 in which two stages of operational amplifiers are used with storage means between them and the second amplifier is used as a high impedance voltage-follower.

20. The system of claim 19 in which the first operational amplifier is used as a diode detector to permit precision rectification of small signals.

21. The system of claim 20 in which the second operational amplifier in combination with a diode and at least two resistors to produce a constant current discharge for the storage means.