PIPELINE INSPECTION PIG

• US 3,786,684 A
• Filed: 12/27/1971
• Issued: 01/22/1974
• Est. Priority Date: 12/27/1971
• Status: Expired due to Term

• Current Assignee: Vetco Services Incorporated
• Original Assignee: David A. Warren, James R. Sullins, William C. Wiers
• Inventors: Wiers, William C., Sullins, James R., Warren, David A.
• Primary Examiner(s): Swisher, S. Clement
• Application Number:
  US05/211,910
• Time in Patent Office: 757 Days
• Field of Search: 73/432,67.15 324/37,40,178,179,180
• US Class Current: 73/866.5
• CPC Class Codes: G01M 3/005 using pigs or moles G01M3/246, G01M3/2823 take precedence

Abstract

A self-contained, fully instrumented pipeline inspection pig is disclosed herein. The pig is particularly adapted to be (1) placed in a cross-country or transmission pipeline at a first location such as a pumping station, (2) carried a long distance through the pipeline by the products being pumped therethrough, and (3) eventually retrieved at a second location such as a subsequent pumping station. The pig includes an assortment of instruments for scanning the inside of the pipeline as it is being carried therethrough. These instruments detect various types of discontinuities such as cracks and other defects in the wall of the pipeline. The results of the inspection are stored in an onboard recorder carried by the pig whereby the results can be analyzed after the pig has traversed the pipeline and has been removed therefrom.

Claims

1. A pipeline inspection apparatus for traveling through a pipeline including the combination of a first array of pickups, said array having permanent magnetic means therein effective to create a magnetic field in the wall of the pipeline spirally disposed relative to the axis of the pipeline, each of said pickups in said array being aligned with said field and effective to individually scan a preselected segment of the inside surface of the pipeline and produce an individual signal corresponding to certain preselected characteristics of said segment, a second array of pickups, said second array having permanent magnetic means therein effective to create a magnetic field in said wall at substantially right angles to the first field, each of said pickups in said second array being effective to individually scan a preselected segment of the inside surface of the pipeline and produce an individual signal corresponding to certain preselected characteristics of said segments, the individual pickups in the second array being substantially aligned with the respective individual pickups in the first array whereby the respective pickups in the two arrays scan the same segment and the individual signals produced by the respective pickups correspond to the characteristics of said segment, and means coupled to said pickups and responsive to the individual signals therefrom to produce a signal corresponding to the characteristics of the pipeline.

2. A pipeline inspection apparatus for traveling through a pipeline including the combination of first means effective to produce a first magnetic field in the wall of said pipeline, said field extending in a first direction and producing stray flux fields adjacent the surface of the pipeline, a first array of pickups effective to scan said surface and produce first signals corresponding to said stray fields, second means effective to produce a second magnetic field in the wall of said pipeline, said second field extending in a second direction and producing stray fields adjacent the surface of the pipeline, a second array of pickups effective to scan said surface and produce second signals corresponding to said second stray fields, third means coupled to the pickups in the first and second arrays and responsive to the first and second signals, said third means being effective to produce a signal corresponding to said first and second signals, and fourth means coupled to said fIrst and second means, said fourth means being responsive to the time delay between the first and second signals and effective to produce a speed signal.

3. A pipeline inspection apparatus for traveling through a pipeline including the combination of a set of detector shoes arranged in an annular array, said shoes being adapted to be positioned adjacent the inside surface of the pipeline to scan adjacent circumferential segments on the inside surface of the pipeline, a permanent magnet in each of said shoes, each of said permanent magnets having an air gap positioned to produce a magnetic flux field in the wall of the pipeline which extends oblique to the axis thereof, and a plurality of pickup probes in said shoes positioned in said air gap.

4. The combination of claim 3 including a second set of detector shoes arranged in a second annular array, the shoes in the second set being adapted to be positioned adjacent the inside surface of the pipeline to scan adjacent circumferential segments on the inside surface of the pipeline, a permanent magnet in each of the shoes in said second set, each of said second permanent magnets having an air gap positioned to produce a magnetic flux field in the wall of the pipeline at substantially right angles to the first flux field, and a plurality of pickup probes in said second shoes positioned in said air gap.

5. The combination of claim 4 including means coupled to the pickups in said shoes and effective to produce signals corresponding to the characteristics of the wall of said pipeline.

6. A pipeline inspection apparatus for traveling through a pipeline including the combination of a plurality of pickups arranged to scan adjacent segments of the pipeline and generate signals corresponding to the characteristics of the wall being scanned by the pickups, means effective to produce a speed signal corresponding to the speed at which said pickups are scanning the segments, a multi-channel recorder, each of said channels being coupled to a separate one of said pickups for separately recording each of said signals, a drive coupled to said recorder, said drive being effective to produce a tachometer signal, and a speed control coupled to said drive and to said means, said speed control being effective to vary the drive to maintain the tachometer signal and the speed signal equal.

7. A pipeline inspection apparatus for traveling through a pipeline including the combination of detector means for scanning the inside surface of the pipeline and producing a first signal corresponding to the characteristics of the wall of the pipeline, and second means coupled to the detector means and responsive to said first signal, said second means being effective to produce a second signal which is a function of the speed at which said detector means is scanning said surface.

8. The combination of claim 7 including an accelerometer responsive to the changes in the speed of said apparatus to produce an acceleration signal, and third means coupled to said second means and to said accelerometer and responsive to the second signal and to said acceleration signal.

9. The combination of claim 7 wherein said detector means includes first and second parts, said parts being axially separated a predetermined distance whereby said first signal includes a first portion corresponding to a particular characteristics and a second portion corresponding to said particular characteristics, one of the portions of said signal being delayed from the other portion by an interval corresponding to the time required for the inspection apparatus to travel a distance equal to the distance between said two parts, and said second means is responsive to the time delay between said first and second portions of said first signal to produce said second signal.

10. A pipeline inspection apparatus for traveling through a pipeline including the combination of first detectoR means adapted to scan the inside surface of the pipeline as said apparatus travels therethrough, said first detector means being effective to provide a first signal corresponding to the characteristics of the wall of said pipeline, second detector means adapted to scan the inside surface of the pipeline as said apparatus travels therethrough, said second detector means being effective to provide a second signal corresponding to the characteristics of the wall of said pipeline, said first and second detector means being separated a predetermined distance from each other whereby the first and second signals are displaced timewise from each other by an interval which is a function of the time required for said apparatus to travel said distance, and means coupled to said first and second detector means and responsive to the time displacement between said first and second signals.

11. A pipeline inspection apparatus for traveling through a pipeline including the combination of first detector means for scanning the inside surface of the pipeline and producing a first signal each time said apparatus passes a girth weld in the pipeline, second detector means for scanning the inside surface of the pipeline and producing a second signal each time said apparatus passes a girth weld in the pipeline, third means coupled to the first and second detector means and responsive to said first and second signals said third means being effective to produce a third signal which is a function of the time delay between the first and second signals.

12. On a pipeline inspection apparatus for traveling through a pipeline the combination of a first array of pickups, the individual pickups in said first array being circumferentially spaced around said apparatus and effective to individually scan adjacent circumferential segments on the inside surface of the pipeline and produce a first series of individual signals corresponding to the characteristics of said segments, first means coupled to the pickups in said array and effective to produce a timing signal in response to certain preselected combinations of the individual signals in said first series, a second array of pickups axially spaced from the first array, the individual pickups in said second array being circumferentially spaced around said apparatus and effective to individually scan adjacent circumferential segments on the inside surface of the pipeline and produce a second series of individual signals corresponding to the characteristics of said segments, second means coupled to the pickups in the second array and effective to produce a second timing signal in response to certain preselected combinations of the individual signals in said second series, and third means coupled to said first and second means, said third means being responsive to the time delay between said timing signals to produce a speed signal.

13. A pipeline inspection apparatus for traveling through a pipeline including the combination of a first array of pickups, the individual pickups in said array being circumferentially spaced around said apparatus and effective to individually scan adjacent circumferential segments on the inside surface of the pipeline and produce individual signals corresponding to the characteristics of said segments, first means coupled to the pickups in said array and effective to produce a timing signal in response to certain preselected combinations of said individual signals, a second array of pickups circumferentially spaced around said apparatus and axially spaced from the first array, the pickups in said second array being effective to individually scan adjacent circumferential segments on the inside surface of the pipeline and produce individual signals corresponding to the characteristics of said segments, second means coupled to the pickups in the second array and effective to produce a second timing signal in response to certain preselected combinations of said individual signals, and third means coupled to said first and second means, said third means being responsive to the time delay between said timing signals to produce a speed signal.

14. A pipeline inspection apparatus for traveling through a pipeline including the combination of an accelerometer responsive to the acceleration of the apparatus in a direction parallel to the axis of the pipeline to produce a signal corresponding to the changes in the speed of the apparatus through the pipeline, and speed signal means effective to provide a speed signal which is a function of the speed of said apparatus, said speed signal means being coupled to the accelerometer and effective to change said speed signal as a function of the acceleration signal.

15. On a pipeline inspection apparatus for traveling through a pipeline the combination of pickup means positioned to scan the inside surface of the pipeline and provide a speed signal which is a function of the speed of said apparatus through the pipeline, an accelerometer responsive to the acceleration of the apparatus in a direction parallel to the axis of the pipeline, said accelerometer being effective to produce an acceleration signal corresponding to the changes in the speed of the apparatus through the pipeline, and speed signal means coupled to said pickup means and to said accelerometer and responsive to the speed signal and to the acceleration signal.

16. A pipeline inspection apparatus for traveling through a pipeline including the combination of pickup means positoned to scan the inside surface of the pipeline s said apparatus travels through the pipeline, said pickup means being responsive to certain preselected characteristics in the wall of said pipeline and effective to intermittently produce a signal which is a function of the speed at which said apparatus passes over the characteristics, an accelerometer responsive to the acceleration of the apparatus in a direction parallel to the axis of the pipeline, said accelerometer being effective to produce an acceleration signal corresponding to the changes in the speed of the apparatus through the pipeline, speed signal means effective to provide a speed signal which is a function of the speed of said apparatus, means coupled to said speed signal means and responsive to the as produced speed signals and the acceleration signal, said last means being effective to intermittently correct said speed signal whenever said intermittent signal occurs and to vary said speed signal in accordance with the acceleration signal therebetween.

17. A pipeline inspection apparatus for traveling through a pipeline including the combination of a vehicle adapted to travel through the pipeline, a first array of detector shoes mounted on said vehicle to travel therewith, each of the shoes in said array being adapted to be positioned adjacent the inside surface of the pipeline and to scan adjacent circumferential segments on the inside of the pipeline, a permanent magnet in each of said shoes, each of said permanent magnets having an air gap positioned to produce a magnetic flux field in the wall of the extending oblique to the axis thereof, a plurality of pickup probes in each of said shoes, said pickup probes being positoned to scan stray fields resulting from the permanent magnets and to produce signals corresponding thereto, a second array of detector shoes mounted on said vehicle to travel therewith and being spaced a predetermined distance from the first array, a permanent magnet in each of the shoes in the second array, each of said permanent magnets having an air gap positioned to produce a magnetic flux field in the wall of the pipeline which extends at substantially right angles to the first field, a plurality of pickup probes in each of the shoes in the second array positioned in the respective air gaps, said pickup probes being positioned to scan the stray fields resultiNg from the respective permanent magnets and to produce electrical signals corresponding thereto, recording means carried upon the vehicle and coupled to the pickups for recording each of the individual signals, means responsive to the time delay between corresponding signals from the two arrays to produce a speed signal, and speed control means coupled to said last means and the recording means, said speed control means being responsive to the speed signal.