Method, system and apparatus for ferromagnetic wall monitoring

• US 20040041560A1
• Filed: 08/28/2002
• Published: 03/04/2004
• Est. Priority Date: 08/28/2002
• Status: Active Grant

• Current Assignee: SCAN Systems Corporation
• Original Assignee: SCAN Systems Corporation
• Inventors: Walters, William T., Uselton, Danny J., Speiser, Robert W.
• Granted Patent: US 7,038,445 B2
• Time in Patent Office: Days
• US Class Current: 324/238
• CPC Class Codes: G01N 27/82 for investigating the presence of flaws

Abstract

A device and method is taught for detection of flaws and localized wall loss in pipes made of ferromagnetic-based material. The device utilizes a magnetic field generator to create a horizontal magnetic field of flux. A pipe is passed through the magnetic field where a magnetic fluctuation detector, for example multiple groups of hall units, identifies fluctuations in the magnetic field.

Claims

1. A device for ferromagnetic wall monitoring comprising:

a magnetic field generator for generating a magnetic field of flux, said magnetic field generator having an inner and outer circumference;

a plurality of groups of magnetic fluctuation detectors mounted about the magnetic field generator inner circumference; and

a summing circuit interconnected with said groups of magnetic fluctuation detectors for adding together the voltage output of each of the groups of magnetic fluctuation detectors.

2. The device for ferromagnetic wall monitoring of claim 1, wherein the magnetic field of flux is horizontal.

3. The device for ferromagnetic wall monitoring of claim 1, wherein the magnetic field generator is an encircling coil.

4. The device for ferromagnetic wall monitoring of claim 1, wherein the magnetic field generator is a circular coil having multi-turns of wire located in the coil.

5. The device for ferromagnetic wall monitoring of claim 1, further comprising a searching head mounted about the outer circumference of the magnetic field generator.

6. The device for ferromagnetic wall monitoring of claim 1, further comprising one or more magnetic fluctuation detectors mounted about the outer circumference of the magnetic field generator.

7. The device for ferromagnetic wall monitoring of claim 6, wherein the magnetic fluctuation detectors mounted about the outer circumference are hall units.

8. The device for ferromagnetic wall monitoring of claim 6, the magnetic fluctuation detectors mounted about the outer circumference are magneto resistors.

9. The device for ferromagnetic wall monitoring of claim 6, the magnetic fluctuation detectors mounted about the outer circumference are magneto diodes.

10. The device for ferromagnetic wall monitoring of claim 6, wherein the magnetic field fluctuation detectors mounted about the outer circumference are a combination of at least two of the following:

hall units, magneto, resistors and magneto diodes.

11. The device for ferromagnetic wall monitoring of claim 1, further comprising an ore circuit interconnected with each group of magnetic fluctuation detectors whereby a largest signal from the groups is determined.

12. The device for ferromagnetic wall monitoring of claim 1, further comprising a defect monitor interconnected with each group of the magnetic fluctuation detectors.

14. The device for ferromagnetic wall monitoring of claim 10, further comprising a searching head mounted about the outer circumference of the circular coil.

15. The device for ferromagnetic wall monitoring of claim 10, wherein said hall units within a group are mounted substantially equidistant from one another.

16. The device for ferromagnetic wall monitoring of claim 1, further comprising an ore circuit interconnected with each group of magnetic fluctuation detectors whereby a largest signal from the groups is determined.

17. The device for ferromagnetic wall monitoring of claim 1, further comprising a further comprising a defect monitor interconnected with each group of the magnetic fluctuation detectors.

13. A device for ferromagnetic wall monitoring comprising:

a circular coil having multi-turns of wire located in the coil for generating a horizontal magnetic field of flux, said circular coil having an inner and outer circumference;

a plurality of groups of hall units mounted about the circular coil inner circumference; and

a summing circuit interconnected with said groups of hall units for adding together the voltage output of each of the groups of hall units.

18. A method for ferromagnetic wall monitoring, comprising the steps of:

providing a magnetic field generator having a plurality of groups of magnetic field fluctuation detectors mounted about the inner circumference of the magnetic field generator;

generating a magnetic field of flux with said magnetic field generator;

passing a ferromagnetic object through said magnetic field of flux; and

determining flaws in said ferromagnetic objects by identifying magnetic field fluctuations with said plurality of magnetic field fluctuation detectors.

19. The method of claim 18, wherein the metallic object is a pipe.

20. The method of claim 18, wherein the magnetic field fluctuation detectors are hall units.

21. The method of claim 20, determining a sum of voltage from each of said hall units.

22. The method of claim 20, further comprising the step of monitoring a signal generated by said hall units when said metallic object passes near said hall units.

23. The method of claim 18, wherein the magnetic field fluctuation detectors are magneto resistors.

24. The method of claim 18, wherein the magnetic field fluctuation detectors are magneto diodes.

25. The method of claim 18, wherein the magnetic field generator is an encircling coil.

26. The method of claim 18, wherein the magnetic field generator is a circular coil having multi-turns of wire located in the coil.

27. The method of claim 18, wherein the magnetic field fluctuation detectors are a combination of at least two of the following:

hall units, magneto, resistors and magneto diodes.

28. The method of claim 18, further comprising exciting the magnetic field generator with a DC current for generating magnetic lines of flux that encircle the magnetic field generator.

29. The method of claim 20, further comprising detecting a change of voltage in said hall units when passing portion of pipe past hall units, said portion of pipe having a flaw.

30. The method of claim 20, further comprising identifying the greatest voltage signal from a group of magnetic field fluctuation detectors.