Closely spaced pipe-to-soil electrical survey method and apparatus

• US 4,151,458 A
• Filed: 07/29/1977
• Issued: 04/24/1979
• Est. Priority Date: 07/29/1977
• Status: Expired due to Term

• Current Assignee: Harsco Corporation
• Original Assignee: Harco Corporation
• Inventors: Seager, William H.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US05/820,379
• Time in Patent Office: 634 Days
• Field of Search: 324/1, 324/3, 324/9, 324/67, 324/54, 324/52, 324/71 R, 324/65 P, 324/65 CR, 324/72
• US Class Current: 324/357
• CPC Class Codes: G01N 17/02 Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement
• CPC Class Codes: G01R 31/08 Locating faults in cables, transmission lines, or networks
• CPC Class Codes: G01V 3/02 operating with propagation of electric current

Abstract

A method and apparatus for making relatively closely spaced pipe-to-soil potential difference measurements, the method and apparatus being characterized by a dual function economically disposable, relatively lightweight, flexible electrical wire that provides for the necessary electrical connection to a pipeline and also for accurate distance measurement at the test end of the wire along the pipeline. The wire is electrically connected at a test station or lead to the pipeline and is played out from a supply thereof carried by the surveyor along the length of the pipeline through distance measuring means. At each selected test location, the potential between the wire connected to the pipe and a reference electrode contacting the soil proximate the pipe are measured by a high resistance input meter. The wire is economically disposable and may be discarded when no longer used eliminating the need to rewind the wire.

Claims

1. A readily portable apparatus for making relatively closely spaced electrical surveys of sub-surface structures adapted to be manually transported therealong by a single person walking along such structures comprising a portable support, manually held reference electrode means contactible with the surface proximate the structure, a supply of lightweight, small gage, disposable elongate electrically conductive magnet wire means for electrically and mechanically connecting the apparatus with the structure at a reference location thereon, storage means for storing said supply of said wire means on said portable support, meter means electrically connected between said electrode means and said wire means for indicating the potential difference between said reference electrode means and said wire means, and distance measuring means mounted on said portable support and driven by said wire means for measuring the length of said wire means as it is played out from the apparatus as the latter is manually transported along the surface above the structure whereby the structure-to-surface potential difference may be determined by such single person at measured distances along the length of the structure.

2. The apparatus of claim 1 wherein said wire means comprises copper wire.

3. The apparatus of claim 1 wherein said wire means is enamel insulated copper magnet wire.

4. The apparatus of claim 1 wherein said reference electrode means comprises a copper-copper sulfate half cell.

5. The apparatus of claim 1 further comprising a manually held cane and wherein said reference electrode means is secured to the lower end of said cane to be manually placed to contact the surface and said meter means is supported by such single person for facile viewing.

6. The apparatus of claim 1 wherein said wire means is copper wire in a size range of from about No. 32 to about No. 36 A.W.G.

7. The apparatus of claim 1 wherein said storage means comprises an electrically conductive spool means, and further comprising means for supporting said spool means for rotation.

8. The apparatus of claim 7 wherein said means for supporting comprises electrically conductive U-shape spindle means.

9. The apparatus of claim 8 further comprising means for electrically connecting said wire means to said electrically conductive spool means, means for electrically connecting said spool means to said spindle means by mechanical engagement therewith, and means for electrically connecting said spindle means to said meter means to complete an electrical connection between said wire means and said meter means.

10. The apparatus of claim 9 wherein said means for electrically connecting said spool means and said spindle means comprises a soldered notch in the core of said spool means electrically connecting the inner layer of said wire means to said spool means.

11. The apparatus of claim 9, further comprising resilient means for urging said spool means into mechanical and electrical engagement with said spindle to improve electrical connection between said spool means and spindle means and to minimize backlash.

12. The apparatus of claim 9, further comprising a manually held cane and wherein said reference electrode means is secured to the lower end of said cane to be manually placed in contact with the surface, and said meter means is secured to the other end of said cane for facile viewing, said means for electrically connecting said spindle means to said meter means comprises an electrical connector having one portion mounted on said support and another portion electrically coupled to said meter and removably connectable with said one portion.

13. The apparatus of claim 9, said support comprising a housing, said wire means, spool means, and spindle means being mounted in said housing, and said distance measuring means being mounted on said housing to measure wire means played out from said housing.

14. The apparatus of claim 7 further comprising means for carrying additional spool means on said portable support.

15. The apparatus of claim 1, said portable apparatus being of a size and weight to be carried with facility by a person, said support comprising a housing, said storage means comprising a storage reel rotatably mounted in said housing for playing out said wire means as the portable apparatus is manually carried away from a point of connection of said wire means to the structure, and said distance measuring means comprising roller type measuring means for contacting said wire means and rotating as the latter is played out.

16. A method for making relatively closely spaced structure-to-soil potential difference surveys comprising the steps of:

(a) providing a portable supply of a lightweight small gage, disposable, flexible elongate electrical magnet wire conductor,

(b) electrically and mechanically connecting the conductor to the structure at a reference location thereon,

(c) playing out the conductor along the length of the structure through a distance measuring device while transporting the portable supply of the conductor to test locations along the structure,

(d) contacting the soil at such test locations proximate the structure with reference electrode,

(e) measuring and observing the potential difference at each such test location between the reference electrode and the conductor,

(f) recording the measured potential difference and distance indicated by the distance measuring device, and

(g) leaving the conductor when the survey is completed for disposal.

17. The method of claim 16 wherein such test locations are at closely spaced regular intervals along the structure.

18. The method of claim 16 further comprising the step of recording both such distance and potential measurements at such test location.

19. The method of claim 18 wherein both the distance and potential measurements at such test location are transmitted to a remote location for recording of the same.

20. The method of claim 16 wherein the conductor is stored on an electrically conductive spool, the method further comprising the step of mechanically treating the spool by filing a notch in the inner core to expose the interior layer of the electrical conductor and flooding such notch with solder to assure good electrical contact between the interior layer of the electrical conductor and spool at the notch.

21. The method of claim 16 further comprising the step of splicing a second lightweight elongate electrical conductor to the end of the first lightweight elongate electrical conductor when the latter is exhausted to maintain continuity of electrical connection with the structure.

22. The method of claim 16 wherein the step of measuring potential difference comprises measuring the same by a high resistance meter.

23. The method of claim 22 wherein such structure is a buried pipeline and the step of transporting comprises manually carrying such supply, reference electrode and meter by a single person walking along the pipeline right of way. f

24. The method of claim 23 further comprising the step of mounting the reference electrode and meter on a cane and wherein the step of transporting comprises manually carrying the cane in one hand of the person.