Method and apparatus for measuring curvature and curvature variations in pipelines and the like

• US 3,882,606 A
• Filed: 05/16/1973
• Issued: 05/13/1975
• Est. Priority Date: 05/16/1973
• Status: Expired due to Term

• Current Assignee: Tuboscope Vetco International, Inc. (NOV, Inc.)
• Original Assignee: Alfred E. Crouch, Reginald A. Kaenel
• Inventors: Kaenel, Reginald A., Crouch, Alfred E.
• Primary Examiner(s): Aegerter, Richard E.
• Assistant Examiner(s): Stearns, Richard R.
• Application Number:
  US05/360,899
• Time in Patent Office: 727 Days
• Field of Search: 33/174R,174L,174P,141.5,142,1H,141R,141G
• US Class Current: 33/544
• CPC Class Codes: G01B 7/281 for measuring contour or curvature along an axis, e.g. axial curvature of a pipeline or along a series of feeder rollers
• CPC Class Codes: G01M 3/005 using pigs or moles G01M3/246, G01M3/2823 take precedence

Abstract

Pipeline curvature is detected, measured and recorded by an instrumented pig carrying an array of sensing wheels down a length of pipeline with the sensing wheels engaging the inner wall of the pipeline in a symmetrical configuration about the axis of the pipeline. The rotation of the sensing wheels is encoded as a function of the distance travelled by each wheel over predetermined increments of axial travel of the array down the pipeline to provide periodic readout of curvature parameters between known positions (over known increments of length) of the run of pipeline traversed by the pig. A magnetic tape recorder in the pig records the curvature readout for each incremental length of pipeline traversed to provide a recorded profile of curvature correlated to position along the run to establish initial acceptable curvature conditions therefor. A succeeding run of the pig through the same run of pipeline results in a second profile which can be compared with the first profile in a computer to determine variations in curvature from the initial conditions together with the location of such variations along the run.

Claims

1. moving an array of sensing wheels of predetermined relative orientation and symmetrical disposition about the longitudinal axis of said pipe section in a transverse plane perpendicular to said axis and with said wheels in rolling contact with the inner wall of said pipe section, through said pipe section with said wheels rolling in paths substantially parallel to said axis;

2. sensing the actual distance travelled by each of said sensing wheels over predetermined incremental distances travelled by said sensing array along the length of said pipe section as the parameters of curvature over said incremental distances;

3. The invention defined in claim 1, wherein said encoder means comprises:

first and second wheel encoder means for providing distance output signals representing respective quantities A and B as a function of the respective distances travelled by said first and second sensing wheels;

first signal encoding means for summing the quantities A and B and providing a control output signal representative of a preselected magnitude of said sum thereby functionally defining a predetermined incremented distance traversed by said sensing wheels axially of said pipe; and

second signal encoding means responsive to said distance signals for generating first and second counts representative of the quantities A and B, respectively, and for transmitting same to said recorder means;

said second signal encoding means including reset means responsive to said control signal to reset said second signal encoding means at the termination of each said incremental distance traversed by said sensing wheels.

4. converting said first profile to a second profile of the magnitude and direction of resultant curvatures and the position thereof over the length of the pipe section by converting said distance parameters to magnitude and direction of resultant curvature over each said incremental length and recording said second profile on a second recording medium;

5. repeating steps (1), (2), (3) and (4), in that order, at a later time to provide a fourth profile of the magnitude and direction of resultant curvatures and the position thereof over the length of said pipe section;

and

6. Transducer means for generating and retaining data represenTative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of at least three sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

encoder means for generating counts representative of the distance travelled by each said sensing wheel along a predetermined incremental length of said pipe section; and

recording means for receiving and retaining said counts for subsequent calculation.

7. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of at least three sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

wheel encoding means for providing distance output signals representative of the distance travelled by each of said sensing wheels along said inner wall;

control means responsive to said distance signals for providing a control output signal upon the occurence of each predetermined incremental distance of travel of said sensing array axially of said pipe;

counting means responsive to said distance signals for generating a count for each said sensing wheels representative of the actual distance travelled thereby over the incremental axial distance of travel of said sensing array;

said counting means including reset means responsive to said control signal to reset said counting means at the occurrence of each predetermined increment of travel of said sensing array; and

recorder means receiving said counts from said counting means and responsive to said control signal to provide a record of curvature parameters for each predetermined incremental distance along a given length of pipe.

8. The invention defined in claim 7, wherein said control means comprises averaging means for deriving the average distance of travel of all said sensing wheels to determine said predetermined incremental distance of travel of said sensing array axially of said pipe.

9. The invention defined in claim 7, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means;

and magnetic tape recording means for recording said encoded counts in said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of curvature parameters for each incremental distance traversed along the axis of said pipe section by said sensing array.

10. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial Planes of said pipe section;

wheel encoding means providing distance output signals representative of the distance travelled by each of said sensing wheels along said inner wall;

control means responsive to said distance signals for providing a control output signal upon the occurrence of each predetermined incremental distance of travel of said sensing array axially of said pipe;

counting means responsive to said distance signals for generating a count for each said sensing wheel representative of the actual distance travelled thereby over the incremental axial distance of travel of said sensing array;

said counting means including reset means responsive to said control signal to reset said counting means at the occurrence of each predetermined increment of travel of said sensing array; and

recorder means receiving said counts from said counting means and responsive to said control signal for recording the magnitude of said counts upon each occurrence of a said control signal to provide a record of curvature parameters for each predetermined incremental distance along a given length of pipe.

11. The invention defined in claim 10, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means;

and magnetic tape recording means for recording said encoded counts in said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of curvature parameters for each incremental distance traversed along the axis of said pipe section by said sensing array.

12. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

first, second, third and fourth wheel encoding means providing distance output signals representative of the quantities A, B, C and D as a function of the respective distances travelled by the first, second, third and fourth sensing wheels along said inner wall, said first and second wheels comprising the first and said third and fourth wheels comprising the second of said orthogonally disposed pairs of wheels;

control means for summing the quantities A, B, C and D and providing a control output signal representative of a predetermined magnitude of said sum and thereby functionally defining said predetermined axial increment traversed by said sensing array;

counting means for providing encoded counts representative of said quantities A, B, C and D;

said counting means including reset means responsive to said control signal to reset said counting means at the occurrence of each predetermined axial increment; and

recorder means receiving said counts from said counting means and responsive to said control signal for recording the magnitude of said counts to provide a record of the quantities A, B, C and D as the parameters of magnitude and direction of curvature of said pipe section for each predetermined axial increment along a given length of said pipe section.

13. The invention defined in claim 12, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means;

and magnetic tape recording means for recording said encoded counts iN said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of curvature parameters for each incremental distance traversed along the axis of said pipe section by said sensing array.

14. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

first, second, third and fourth wheel encoding means for providing distance output signals representative of the quantities A, B, C and D as a function of the respective distances travelled by the first, second, third and fourth sensing wheels along said inner wall, said first and second wheels comprising the first pair and said third and fourth wheels comprising the second pair of said orthogonally disposed pairs of wheels;

control means for deriving the average of the quantities A, B, C and D as a determination of axial distance traversed by said sensing array and providing a control output signal when said average equals said predetermined axial increment;

counting means for providing encoded counts representative of said quantities A, B, C and D;

said counting means including reset means responsive to said control signal to reset said counting means at the occurrence of each predetermined axial increment; and

recorder means receiving said counts from said counting means and responsive to said control signal for recording the magnitude of said counts to provide a record of the quantities A, B, C and D as the parameters of magnitude and direction of curvature of said pipe section for each predetermined axial increment along a given length of said pipe section.

15. The invention defined in claim 14, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means;

and magnetic tape recording means for recording said encoded counts in said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of curvature parameters for each incremental distance traversed along the axis of said pipe section by said sensing array.

16. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and adapted to be placed in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

first, second, third and fourth wheel encoding means for providing distance output signals representative of the quantities A, B, C and D as a function of the respective distances travelled by the first, second, third and fourth sensing wheels along said inner wall, said first and second wheels comprising the first pair and said third and fourth wheels comprising the second pair of said orthogonally disposed pairs of wheels;

said pipe section having a cross-sectional radius r;

control means responsive to said distance signals for deriving the function r(A+B+C+D) and for providing a control output signal when said function equals a predetermined power of ten;

counting means responsive to said distance signals for deriving the functions (A-B) and (C-D);

said counting means including reset means responsive to said control signal to reset said counting means upon the occurrence of said control signal whereupon the functions (A-B) and (C-D), respectively, comprise direct readouts of the magnitude of first and second orthogonally disposed components of curvature in the plane of said sensing array over a fixed axial increment achieved between the occurrence of successive control signals; and

recorder means for receiving said functions (A-B) and (C-D) from said counting means and responsive to said control signal for recording the magnitudes of said functions (A-B) and (C-D) to provide a record of the magnitudes of the orthogonal components of curvature of said pipe section for each predetermined axial increment along a given length of said pipe section.

17. The invention defined in claim 16, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means;

and magnetic tape recording means for recording said encoded counts in said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of curvature parameters for each incremental distance traversed along the axis of said pipe section by said sensing array.

18. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and adapted to engage the inner wall of said pipe section in rolling contact;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

first, second, third and fourth wheel encoding means for providing distance output signals representative of the quantities A, B, C and D as a function of the respective distances travelled by the first, second, third and fourth sensing wheels along said inner wall, said first and second wheels comprising the first pair and said third and fourth wheels comprising the second pair of said orthogonally disposed pairs of wheels;

said pipe section having a cross-sectional radius r;

control means responsive to said distance signals for deriving the function r(A+B+C+D) Divided by N where N is any number selected to constitute a predetermined axial increment of travel of said array when the function r(A+B+C+D) Divided by N is equal to a predetermined power of ten and said control means providing a control output signal when said function equals said predetermined power of ten;

counting means responsive to said distance signals for deriving the functions (A-B) and (C-D);

said counting means including reset means responsive to said control signal to reset said counting means upon the occurrence of said control signal whereupon the functions (A-B) and (C-D), respectively, comprise direct readouts of the magnitude of first and second orthogonally disposed components of curvature in the plane of said sensing array over said axial increment as determined by the value of N; and

recorder means receiving said functions (A-B) and (C-D) from said counting means and responsive to said control signal for recording the magnitude of said functions (A-B) and (C-D) to provide a record of the magnitude of the orthogonal components of curvature of said pipe section for each predetermined axial increment along a given length of said pipe section.

19. The invention defined in claim 18, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means;

and magnetic tape recording means for recording said encoded counts in said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of curvature parameters for each incremental distance traversed along the axis of said pipe section by said sensing array.

20. An instrumented pig for measuring and recording a profile of variation in curvature over a length of pipeline traversed by said pig, comprising:

tractor means for causing said pig to travel through said length of pipeline;

transducer means coupled to said tractor means and including a housing, at least one sensing array comprising a plurality of sensing wheels mounted on said housing in symmetrical relationship to the longitudinal axis of a said pipeline, said sensing wheels being biased to engage the inner wall of said pipeline in rolling contact therewith for traversing said inner wall in respective paths substantially parallel to said axis and maintaining said transducer means substantially coaxially with said pipeline; and

instrument means coupled with said transducer means and including an instrument housing and at least one symmetrical array of tracking wheels on said instrument housing, said tracking wheels being biased to engage the inner wall of said pipeline in rolling contact therewith to traverse the said pipeline in substantially parallel paths with said axis and maintain said instrument means substantially coaxially with said pipeline;

said transducer means further including encoder means generating data as a function of the distance travelled along the said inner wall of said pipeline by each of said sensing wheels and along said axis of said pipeline by said sensing array; and

said instrument means further including recording means interconnected with said encoder means for receiving said data from said encoder means in correlation to the position of said sensing array along said length of pipeline to provide a record of curvature parameters and the position thereof along said length of pipeline traversed by said pig.

21. The invention defined in claim 20, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation.

22. The invention defined in claim 20, wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

23. The invention defined in claim 20, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation;

and wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

24. An instrumental pig for measuring and recording a profile of variation in curvature over a length of pipeline traversed by said pig, comprising:

tractor means for causing said pig to traverse said length of pipeline;

transducer means coupled to said tractor means and including a housing, at least one sensing array comprising first, second and third sensing wheelS mounted on said housing at symmetrical intervals about the longitudinal axis thereof, means biasing said sensing wheels to engage the inner wall of said pipeline in rolling contact therewith for traversing said pipeline in respective paths substantially parallel to the longitudinal axis of said pipeline and maintaining said housing substantially coaxially with said pipeline, said sensing wheels being disposed in a common transverse plane substantially perpendicular with said axis of said pipeline; and

instrument means coupled with said transducer means and including an instrument housing and at least one symmetrical array of tracking wheels on said instrument housing, said tracking wheels being biased to engage the inner wall of said pipeline in rolling contact therewith to traverse said pipeline in substantially parallel paths with said axis and maintain said instrument means substantially coaxially within said pipeline;

said transducer means further including encoder means for generating data as a function of the distance travelled along the said inner wall of said pipeline by each of said sensing wheels; and

said instrument means further including recording means interconnected with said encoder means for receiving said data from said encoder means in correlation to the position of said sensing array along said length of pipeline to provide a record of curvature parameters and the position thereof along said length of pipeline traversed by said pig.

25. The invention defined in claim 24, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation.

26. The invention defined in claim 24, wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

27. The invention defined in claim 24, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation;

and wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

28. An instrumented pig for measuring and recording a profile of variation in curvature over a length of a pipeline traversed by said pig, comprising:

tractor means for causing said pig to traverse said length of pipeline;

transducer means coupled to said tractor means and including a housing, at least one sensing array comprising first and second orthogonally disposed pairs of diametrically opposed sensing wheels mounted on said housing symmetrical with the longitudinal axis thereof, means biasing said sensing wheels to engage the inner wall of said pipeline in rolling contact therewith for traversing said pipeline in respective paths substantially parallel to the longitudinal axis of said pipeline and maintaining said housing substantially coaxial with said pipeline, said sensing wheels being disposed in a common transverse plane substantially perpendicular with said axis of said pipeline;

instrument means coupled with said transducer means and including an instrument housing and at least one symmetrical array of tracking wheels on said instrument housing, said tracking wheels being biased to engage the inner wall of said pipeline in rolling contact therewith to traverse said pipeline in substantially parallel paths with said axis and maintain said instrument means substantially coaxially within said pipeline;

said transducer means further including encoder means generating data as a function of the distance travelled along the said inner wall of said pipeline by each of said sensing wheels and along said axis of said pipeline by said sensing array; and

said instrument means further including recording means interconnected with said encoder means for receiving said data from said encoder means in correlation to the position of said sensing array along said length of pipeline to provide a record of curvature parameters and The position thereof along said length of pipeline by said pig.

29. The invention defined in claim 28, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation.

30. The invention defined in claim 28, wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

31. The invention defined in claim 28, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation;

and wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

32. An instrument pig for measuring and recording a profile of variation in curvature over a length of pipeline traversed by said pig, comprising:

tractor means for causing said pig to traverse said length of pipeline;

transducer means coupled to said tractor means and including a housing, at least one sensing array comprising a plurality of sensing wheels mounted on said housing in symmetrical relationship to the longitudinal axis of a said pipeline, said sensing wheel being biased to engage the inner wall of a said pipeline in rolling contact therewith for traversing said inner wall in respective paths substantially parallel to said axis and maintaining said transducer means substantially coaxially within said pipeline; and

instrument means coupled with said transducer means and including an instrument housing and at least one symmetrical array of tracking wheels on said instrument housing, said tracking wheels being biased to engage the inner wall of said pipeline in rolling contact therewith to traverse said pipeline in substantially parallel paths with said axis and maintain said instrument means substantially coaxially within said pipeline;

said transducer means further including first encoder means for generating data as a function of the distance travelled along said inner wall of said pipeline by each of said sensing wheels and along said axis of said pipeline by said sensing array, and second encoder means for sensing the direction of gravity with reference to the orientation of said sensing array and for generating data as a function of that orientation; and

said instrument means further including recording means interconnected with said first and second encoder means for receiving data from said encoder means in correlation to the position of said sensing array along said length of pipeline to provide a record of curvature parameters and gravitational reference parameters of said array in said pipeline and the position of said sensing wheels along said length of pipeline.

33. The invention defined in claim 32, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation;

and wherein said second encoder means senses the direction of gravity with reference to the orientation of each said sensing array and generates data as a function of said direction and relative orientation.

34. The invention defined in claim 32, wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

35. The invention defined in claim 32, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation;

wherein said second encoder means senses the direction of gravity with reference to the orientation of each said sensing array and generates data as a function of said direction and relative orientation; and

wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

36. An instrument pig for measuring and recording a profile of variation in curvature over a length of a pipeline traversed by said pig;

comprising;

tractor means for causing sAid pig to traverse said length of pipeline;

transducer means coupled to said tractor means and including a housing, at least one sensing array comprising first, second and third sensing wheels mounted on said housing at symmetrical intervals about the longitudinal axis thereof, means biasing said sensing wheels to engage the inner wall of said pipeline in rolling contact therewith for traversing said pipeline in respective paths substantially parallel to the longitudinal axis of said pipeline and maintaining said housing substantially coaxially with said pipeline, said sensing wheels being disposed in a common transverse plane substantially perpendicular with said axis of said pipeline;

instrument means coupled with said transducer means and including an instrument housing and at least one symmetrical array of tracking wheels on said instrument housing, said tracking wheels being biased to engage the inner wall of said pipeline in rolling contact therewith to traverse said pipeline in substantially parallel paths with said axis and maintain said instrument means substantially coaxially within said pipeline;

said transducer means further including first encoder means generating data as a function of the distance travelled along said inner wall of said pipeline by each of said sensing wheels and along said axis of said pipeline by said sensing array, and second encoder means for sensing the direction of gravity with reference to the orientation of said sensing array and generating data as a function of that orientation; and

said instrument means further including recording means, interconnected with said first and second encoder means for receiving data from said encoder means in correlation to the position of said sensing array along said length of pipeline to provide a record of curvature parameters and gravitational reference parameters of said array in said pipeline and the position of said sensing wheels along said length of pipeline.

37. The invention defined in claim 36, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation;

and wherein said second encoder means senses the direction of gravity with reference to the orientation of each said sensing array and generates data as a function of said direction and relative orientation.

38. The invention defined in claim 36, wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

39. The invention defined in claim 36, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation;

wherein said second encoder means senses the direction of gravity with reference to the orientation of each said sensing array and generates data as a function of said direction and relative orientation; and

wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

40. An instrumented pig for measuring and recording a profile of variation in curvature over a length of a pipeline traversed by said pig, comprising:

tractor means for causing said pig to traverse said length of pipeline;

transducer means coupled to said tractor means and including a housing, at least one sensing array comprising first and second orthogonally disposed pairs of diametrically opposed sensing wheels mounted on said housing symmetrical with the longitudinal axis thereof, means biasing said sensing wheels to engage the inner wall of said pipeline in rolling contact therewith for traversing said pipeline in respective paths substantially parallel to the longitudinal axis of said pipeline and maintaining said housing substantially coaxial with said pipeline, said sensing wheels being disposed in a common transverse plane substantially perpendicular with said axis of said pipeline;

instrument means coupled with said transducer means And including an instrument housing and at least one symmetrical array of tracking wheels on said instrument housing, said tracking wheels being biased to engage the inner wall of said pipeline in rolling contact therewith to traverse said pipeline in substantially parallel paths with said axis and maintain said instrument means substantially coaxially within said pipeline;

said transducer means further including first encoder means for generating data as a function of the distance travelled along the said inner wall of said pipeline by each of said sensing wheels and along said axis of said pipeline by said sensing array, and second encoder means for sensing the direction of gravity with reference to the orientation said sensing array and for generating data as a function of that orientation; and

said instrument means further including recording means interconnected with said first and second encoder means for receiving data therefrom in correlation with the position of said sensing array along said length of pipeline to provide a record of curvature parameters and gravitational reference parameters of said array in said pipeline and the position of said sensing wheels along said length of pipeline.

41. The invention defined in claim 40, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation;

and wherein said second encoder means senses the direction of gravity with reference to the orientation of each said sensing array and generates data as a function of said direction and relative orientation.

42. The invention defined in claim 40, wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

43. The invention defined in claim 40, wherein said transducer means includes a plurality of said sensing arrays axially spaced on said housing in predetermined relative orientation;

wherein said second encoder means senses the direction of gravity with reference to the orientation of each said sensing array and generates data as a function of said direction and relative orientation; and

wherein said instrument means includes a plurality of said tracking arrays axially spaced on said instrument housing.

44. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of at least three sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

encoder means for generating counts representative of the distance travelled by each said sensing wheel along a predetermined incremental length of said pipe section;

gravitational reference means for sensing the relative orientation of said sensing array with reference to the direction of gravity in the plane of said sensing wheels and for generating encoded data as a function of said relative orientation; and

recorder means for receiving and retaining said counts and said encoded gravitational reference data for subsequent calculation.

45. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of at least three sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll aLong said inner wall in respective axial planes of said pipe section;

wheel encoding means for providing distance output signals representative of the distance travelled by each of said sensing wheels along said inner wall;

control means responsive to said distance signals for providing a control output signal upon the occurrence of each predetermined incremental distance of travel of said sensing array axially of said pipe;

counting means responsive to said distance signals for generating a count for each said sensing wheel representative of the actual distance travelled thereby over the incremental axial distance of travel of said sensing array;

said counting means including reset means responsive to said control signal to reset said counting means at the occurrence of each predetermined increment of travel of said sensing array;

gravitational reference means for sensing the relative orientation of said sensing array with reference to the direction of gravity and for generating encoded data as a function of said relative orientation; and

recorder means receiving said counts from said counting means and said encoded data from said gravitational reference means and responsive to said control signal for recording the magnitude of said counts and said encoded gravitational reference data upon each occurrence of said control signal, thereby to provide a record of parameters defining the curvature, and the orientation of such curvature with reference to the direction of gravity for each predetermined incremental distance along a given length of pipe.

46. The invention defined in claim 45, wherein said control means comprises averaging means for deriving the average distance of travel of all said sensing wheels to determine said predetermined incremental distance of travel of said sensing array axially of said pipe.

47. The invention defined in claim 45, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means, and for receiving said encoded gravitational reference data;

and magnetic tape recording means for recording said encoded counts and said encoded gravitational reference data from said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts and encoded gravitational reference data to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of parameters defining the curvature and the direction of such curvature with reference to the direction of gravity for each incremental distance traversed along the axis of said pipe section by said sensing array.

48. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

wheel encoding means for providing distance output signals representative of the distance travelled by each of said sensing wheels along said inner wall;

control means responsive to said distance signals for providing a control output signal upon the occurrence of each predetermined incremental distance of travel of said sensing array axially of said pipe;

counting means responsive to said distance signals for generating a count for each said sensing wheel representative of the actual distance travelled thereby over the incremental axial distance of travel of saId sensing array;

said counting means including reset means responsive to said control signal to reset said counting means at the occurrence of each predetermined increment of travel of said sensing array;

gravitational reference means for sensing the relative orientation of said sensing array with reference to the direction of gravity and for generating encoded data as a function of said relative orientation; and

recorder means for receiving said counts from said counting means and said encoded data from said gravitational reference means and responsive to said control signal for recording the magnitude of said counts and said encoded gravitational data upon each occurrence of said control signal to provide a record of parameters defining the curvature and the orientation of such curvature with reference to the direction of gravity for each predetermined incremental distance along a given length of pipe.

49. The invention defined in claim 48, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means and for receiving said encoded gravitational reference data;

and magnetic tape recording means for recording said encoded counts and said encoded gravitational reference data in said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts and encoded gravitational reference data to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of parameters defining the curvature and the direction of such curvature with reference to the direction of gravity for each incremental distance traversed along the axis of said pipe section by said sensing array.

50. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising;

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

first, second, third and fourth wheel encoding means providing distance output signals representative of the quantities A, B, C and D as a function of the respective distances travelled by the first, second, third and fourth sensing wheels along said inner wall, said first and second wheels comprising the first pair and said third and fourth wheels comprising the second pair of said orthogonally disposed pairs of wheels;

control means for summing the quantities A, B, C and D and providing a control output signal representative of a predetermined sum of said quantities and thereby functionally defining said predetermined axial increment traversed by said sensing array;

counting means for providing respective encoded counts representative of said quantities A, B, C and D;

said counting means including reset means responsive to said control signal to reset said counting means at the occurrence of each one of said predetermined axial increments;

gravitational reference means for sensing the relative orientation of said sensing array with reference to the direction of gravity and for generating encoded data as a function of said relative orientation; and

recorder means for receiving said encoded gravitational reference data from said gravitational reference means and said counts from said counting means and responsive to said control signal for recording said encoded gravitational reference data and the magnitude of said counts to provide a record of the quantities A, B, C and D and said encoded gravitational reference data as the parameters of magnitude and direction of curvature of said pipe section referenced to the direction of gravity for each predetermined axial increment along a given length of said pipe section.

51. The invention defined in claim 50, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means and for receiving said encoded gravitational reference data;

and magnetic tape recording means for recording said encoded counts and said encoded gravitational reference data in said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts and encoded gravitational reference data to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of parameters defining the pipe curvature and the direction of such curvature with reference to the direction of gravity for each incremental distance traversed along the axis of said pipe section by said sensing array.

52. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

first, second, third and fourth wheel encoding means for providing distance output signals representative of the quantities A, B, C and D as a function of the respective distances travelled by the first, second, third and fourth sensing wheels along said inner wall, said first and second wheels comprising the first pair and said third and fourth wheels comprising the second pair of said orthogonally disposed pairs of wheels;

control means for deriving the average of the quantities A, B, C and D as a determination of axial distance traversed by said sensing array and providing a control output signal when said average equals said predetermined axial increment;

counting means for providing encoded counts representative of said quantities A, B, C and D;

said counting means including reset means responsive to said control signal to reset said counting means at the occurrence of each predetermined axial increment;

gravitational reference means for sensing the relative orientation of said sensing array with reference to the direction of gravity and for generating encoded data as a function of said relative orientation; and

recorder means for recording said encoded gravitational reference data and the magnitude of said counts to provide a record of the quantities A, B, C and D and said encoded gravitational reference data as the parameters of magnitude and direction of curvature of said pipe section referenced to the direction of gravity for each predetermined axial increment along a given length of said pipe section.

53. The invention defined in claim 52, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means and for receiving said encoded gravitational reference data;

and magnetic tape recording means for recording said encoded counts and said encoded gravitational reference data in said register means;

said register means being responsive to said control signal to transmit said accumulated and encoded counts and encoded gravitational reference data to said magnetic tape recording means at the conclusion of each predetermined increment of travel Of said sensing array to provide in said magnetic tape recording means a recorded profile of parameters defining the pipe curvature and the direction of such curvature with reference to the direction of gravity for each incremental distance traversed along the axis of said pipe section by said sensing array.

54. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

first, second, third and fourth wheel encoding means for providing distance output signals representative of the quantities A, B, C and D as a function of the respective distances travelled by the first, second, third and fourth sensing wheels along said inner wall, said first and second wheels comprising the first pair and said third and fourth wheels comprising the seond pair of said orthogonally disposed pairs of sensing wheels;

said pipe section having a cross-sectional radius r;

control means responsive to said distance signals for deriving the function r(A+B+C+D) and for providing a control output signal when said function equals a predetermined power of ten;

counting means responsive to said distance signals for deriving the functions (A-B) and (C-D);

said counting means including reset means responsive to said control signal to reset said counting means upon the occurrence of said control signal, whereupon the functions (A-B) and (C-D), respectively, comprise direct readouts of the magnitude of first and second orthogonally disposed components of curvature in the plane of said sensing array over a fixed axial increment achieved between the occurrence of successive control signals;

gravitational reference means for sensing the relative orientation of at least one of said components of curvature with reference to the direction of gravity and for generating encoded data as a function of said relative orientation; and

recorder means receiving said functions (A-B) and (C-D) from said counting means and said encoded gravitational reference data from said gravitational reference means and responsive to said control signal for recording said functions (A-B) and (C-D) and said gravitational reference data to provide a record of the magnitude of the orthogonal components of curvature of said pipe section and the direction of the resultant curvature of said components referenced to the direction of gravity for each predetermined axial increment along a given length of said pipe section.

55. The invention defined in claim 54, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means and for receiving said encoded gravitational reference data;

and magnetic tape recording means for recording said encoded counts and said encoded gravitational reference data in said register means; and

said register means being responsive to said control signal to transmit said accumulated and encoded counts and encoded gravitational reference data to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of parameters defining the pipe curvature and the direction of such curvature with reference to the direction of gravity for each incremental distance traversed along the axis of said pipe section by said sensing array.

56. Transducer means for generating and retaining datA representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising;

at least one sensing array of two orthogonally disposed pairs of sensing wheels symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and in rolling contact with the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said sensing wheels to roll along said inner wall in respective axial planes of said pipe section;

first, second, third and fourth wheel encoding means for providing distance output signals representative of the quantities A, B, C and D as a function of the respective distances travelled by the first, second, third and fourth sensing wheels along said inner wall, said first and second wheels comprising the first pair and said third and fourth wheels comprising the second pair of said orthogonally disposed pairs of sensing wheels;

said pipe section having a cross-sectional radius r;

control means responsive to said distance signals for deriving the function r(A+B+C+D) Divided by N where N is any number selected to constitute a predetermined axial increment of travel of said array when the function r(A+B+C+D) Divided by N is equal to a predetermined power of ten, and said control means providing a control output signal when said function equals said predetermined power of ten;

counting means responsive to said distance signals for deriving the functions (A-B) and (C-D);

said counting means including reset means responsive to said control signal to reset said counting means upon the occurrence of said control signal, whereupon the functions (A-B) and (C-D), respectively, comprise direct readouts of the magnitude of first and second orthogonally disposed components of curvature in the plane of said sensing array over said axial increment;

gravitational reference means for sensing the relative orientation of at least one of said components of curvature with reference to the direction of gravity and for generating encoded data as a function of said relative orientation; and

recorder means receiving said functions (A-B) and (C-D) from said counting means and said encoded gravitational reference data from said gravitational reference means and responsive to said control signal for recording said functions (A-B) and (C-D) and said gravitational reference data to provide a record of the magnitude of the orthogonal components of curvature of said pipe section and the direction of the resultant curvature of said components referenced to the direction of gravity for each predetermined axial increment along a given length of said pipe section.

57. The invention defined in claim 56, wherein said recorder means comprises storage register means for receiving, accumulating and encoding said counts from said counting means and for receiving said encoded gravitational reference data;

and magnetic tape recording means for recording said encoded counts and said encoded gravitational reference data in said register means; and

said register means being responsive to said control signal to transmit said accumulated and encoded counts and encoded gravitational reference data to said magnetic tape recording means at the conclusion of each predetermined increment of travel of said sensing array to provide in said magnetic tape recording means a recorded profile of curvature parameters defining the curvature and the direction of such curvature with reference to the direction of gravity for each incremental distance traversed along the axis of said pipe section by said sensing array.

58. The method of measuring deviations in curvature of an elongated pipe section from an established curvature condition thereof over a finite length of said pipe section, comprising:

59. The method of measuring deviations in curvature of an elongated pipe section from an established curvature condition thereof over a finite length of said pipe section, comprising:

60. The method of measuring deviation in curvature of an elongated pipe section from an established curvature condition thereof over a finite length of said pipe section, comprising:

1 moving an array of sensing wheels of predetermined relative orientation and symmetrical disposition about the longitudinal axis of said pipe section in a transverse plane perpendicular to said axis and with said wheels in rolling contact with the inner wall of said pipe section, through said pipe section with said wheels rolling in paths substantially parallel to said axis;

2 generating a number of pulses in proportion to the distance travelled by each said sensing wheel;

3 counting said pulses to generate a like plurality of counts respectively representing the distance travelled by said Plurality of sensing wheels;

4 continuously averaging the sum of said counts until the average thereof is representative of a predetermined incremental length of travel of said sensing array axially of said pipe section;

5 recording said counts upon the occurrence of said representative average; and

6 repeating steps (2), (3), (4) and (5), in that order, for each succeeding incremental distance along the length of said pipe section to provide a recorded profile of the curvature parameters thereof, over each said incremental length, correlated to a known position along the length of said pipe section.

61. The method of claim 60, including the additional steps of:

7 repeating steps (1), (2), (3), (4), (5) and (6) in that order at a later time to provide a second recorded profile of curvature parameters correlated to a said known position along the length of said pipe section; and

8 comparing said first and second profiles in reference to a predetermined allowable deviation in said curvature parameters for each said incremental distance and detecting variations in said parameters of said profiles in excess of said deviation and the position of said variations over the length of said pipe section.

62. Transducer means for generating and retaining data representative of the curvature of a pipe section on a given cross-sectional diameter thereof comprising:

first and second distance sensing means positioned at the inner wall of said pipe section at opposite ends of said given diameter;

means for moving said distance sensing means through said pipe section to cause said distance sensing means to traverse said inner wall in a plane defined by said given diameter and the longitudinal axis of said pipe section;

encoder means for generating data representative of the distance travelled by each said distance sensing means along a predetermined finite length of said pipe section; and

recording means for receiving and retaining said data for subsequent calculation.

63. The invention defined in claim 62, wherein said transducer means further includes gravitational direction sensing means for sensing the direction of gravity, and wherein said encoder means further generates data representing the angular orientation of said internal wall length measuring means relative to said gravitational direction.

64. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of at least three distance sensing means symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and positioned at the inner wall of said pipe section;

encoder means for generating data representative of the distance travelled by each said distance sensing means along a predetermined incremental length of said pipe section; and

recording means for receiving and retaining said data for subsequent calculation.

65. The invention defined in claim 64, wherein said transducer means further includes gravitational direction sensing means for sensing the direction of gravity;

and wherein said encoder means further generates data representing said gravitational direction.

66. Transducer means for generating and retaining data representative of the magnitude and direction of curvature of a pipe section at predetermined increments of axial length thereof, comprising:

at least one sensing array of at least three distance sensing means symmetrically disposed about the longitudinal axis of said pipe in a cross-sectional plane perpendicular to said axis and positioned at the inner wall of said pipe section;

means for moving said sensing array through said pipe section to cause said distance sensing means to traverse said inner wall in respective axial planes of said pipe section;

encoding means fOr providing respective distance output signals representative of the distance travelled by each of said distance sensing means along said inner wall;

control means responsive to said distance signals for providing a control output signal upon the occurrence of each predetermined incremental distance of travel of said sensing array axially of said pipe;

counting means responsive to said distance signals for generating a count for each said distance sensing means representative of the actual length of said inner wall traversed thereby over the incremental axial distance of travel of said sensing array;

said counting means including reset means responsive to said control signal to reset said counting means at the occurrence of each predetermined increment of travel of said sensing array; and

recorder means for receiving said counts from said counting means and responsive to said control signal to provide a record of curvature parameters for each predetermined incremental distance along a given length of pipe.

67. The invention defined in claim 66, wherein said transducer means further includes gravitational direction sensing and encoding means for providing coded output data representative of said gravitational direction relative to the orientation said sensing array;

and wherein said recorder means further receives and records said gravitational data upon the occurrence of said control signal.

68. The invention defined in claim 66, wherein said control means comprises averaging means for deriving the average distance of travel of all said distance sensing means to determine said predetermined incremental distance of travel of said sensing array axially of said pipe.

69. The invention defined in claim 68, wherein said transducer means further includes gravitational direction sensing and encoding means for providing coded output data representative of said gravitational direction relative to said sensing array;

and wherein said recorder means further receives and records said gravitational data upon the occurrence of a said control signal.

70. Transducer means for generating and retaining data representative of the curvature of a pipe section at each of a plurality of incremental axial distances along the length thereof while axially traversing said pipe, comprising:

axial length measuring means for defining predetermined axial increments of distance;

internal wall length measuring means controlled by said axial length measuring means for defining the length of said internal wall of said pipe over each said axial increment in at least three axial planes of said pipe;

encoder means for generating data representing each occurrence of a said axial incremental distance and the respective lengths of said internal wall over said incremental distance; and

recording means responsive to said data to record the occurrence of each said incremental distance and the corresponding said internal wall lengths over said incremental distance at each such occurrence, over the length of said pipe section

71. The invention defined in claim 70, wherein said transducer means further includes gravitational direction sensing means for sensing the direction of gravity, and wherein said encoder means further generates data representing the angular orientation of said internal wall length measuring means relative to said gravitational direction;

and wherein said recorder means further records said gravitational orientation data at said occurrence of each said incremental distance.

72. The method of generating and collecting data for measuring the curvature of a finite length of pipe section, comprising:

1 moving an array of sensing wheels of predetermined relative orientation and symmetrical disposition about the longitudinal axis of said pipe section and with said wheels in rolling contact with the inner wall of said pipe section, through said pipe section with said wheels rolling in paths substantially pArallel to said axis;

2 for each sensing wheel, generating a number of pulses in proportion to the distance travelled by each wheel;

3 counting said pulses to generate a like plurality of counts respectively representing the distance travelled by each sensing wheel;

4 continuously averaging the sum of said counts until the average thereof is representative of a predetermined incremental length of travel of said sensing array axially of said pipe section; and

5 recording said counts upon the occurrence of said representative average.

73. The method of generating and collecting data for a profile of variations in curvature of a finite length of pipe section, comprising:

1 moving through said pipe section an array of sensing means of predetermined relative orientation and symmetrical disposition about the longitudinal axis of said pipe section in a plane substantially perpendicular to said axis;

2 sensing parametric variations caused by curvature in said pipe section at each said sensing means as said array is moved over predetermined incremental distances along the length of said pipe section; and

3 recording said parametric variations in correlation to each said predetermined incremental distance on a recording medium to provide a profile of variations in curvature and the position of such variations over the length of said pipe section.

74. Transducer means for generating and retaining data representative of the curvature of a pipe section comprising:

a multiplicity of sensing wheels of known dimensions adapted to be placed in rolling contact with the inner walls of said pipe section and arranged in angular spaced relationship about the longitudinal axis of the pipe section;

means for moving said sensing wheels through said pipe section to cause said sensing wheels to roll along said inner walls;

encoder means for generating counts representative of the distance travelled by each sensing wheel; and

means for receiving and retaining said counts for subsequent calculations.

75. Transducer means for producing information signals representative of the curvaturre along the length of a pipe section, comprising:

a plurality of rotatable wheels disposed in angular spaced relationship about the longitudinal axis of said pipe section and each adapted to contact the wall of said pipe section and to rotate when moved along said wall;

means for moving said wheels together along the length of said pipe section, means associated with each of said wheels for generating data as a function of the rotation of its respective wheel along the pipe section, and data processing means responsive to said data for providing information signals representing quantities determinative of pipe curvature at locations along the pipe section.

76. The combination claimed in claim 75, wherein said data processing means includes means for providing an information signal representing each given distance of movement of said wheels along the wall of the pipe section.

77. The combination claimed in claim 76 including means for providing information signals representative of the angular orientation of said wheels about the longitudinal axis of said pipe section relative to a fixed direction.

78. The combination claimed in claim 77 wherein said fixed direction is the direction of gravitational force.