Method and apparatus for monitoring a cathodically protected corrodible hollow member

Claim 2

In a cathodic protection system for an elongate corrodible member routed through an electrolytic environment, said corrodible member having a longitudinally extending channel therethrough, said cathodic protection system including at least one sacrificial anode disposed within said electrolytic environment in spaced proximity to said elongate corrodible member, and connecting means for electrically connecting said sacrificial anode to said elongate corrodible member, an improved system for monitoring the condition of said cathodic protection system comprising: first means, responsive to electrical current flowing through said connecting means, for establishing an electromagnetic field within said channel of said corrodible member, said electromagnetic field being proportional to said electrical current flowing through said connecting means; and second means, positionable in said longitudinally extending channel of said corrodible member, for detecting the magnitude of said electromagnetic field established within said channel of said corrodible member and for supplying a signal representative of the magnitude of said electromagnetic field.

Claim 3

The monitoring system of claim 1 wherein said first means comprises an electrical coil, said coil being located in close proximity to the exterior of said corrodible member to establish said electromagnetic field within said channel.

Claim 4

The monitoring system of claim 1 further comprising: third means for transporting said second means through said channel, said second means detecting said electromagnetic field as said third means transports said second means within proximity of said electromagnetic field.

Claim 5

The monitoring system of claim 3 further comprising: fourth means carried by said third means for recording said signal representative of said electromagnetic field.

Claim 6

In a cathodic protection system including a cathodically protected corrodible member having an interior channel and at least one sacrifical metal anode, the improvement comprising: connection means electrically connected between said corrodible member and said anodes for establishing an electromagnetic field proportional to the current flow therethrough, said connection means being so positioned and oriented relative to said corrodible member as to cause said electromagnetic field to penetrate through said corrodible member into the interior channel thereof, and detection means for determining the field strength of said electromagnetic field in said interior channel, said detection means being positionable within said interior channel of said corrodible member.

Claim 7

In a cathodic protection system including a cathodically protected corrodible member having an interior channel and at least one sacrifical metal anode, the improvement comprising: connection means electrically connected between said corrodible member and said anodes for establishing an electromagnetic field proportional to the current flow therethrough, said connection means being so positioned and oriented relative to said corrodible member as to cause said electromagnetic field to penetrate through said corrodible member into the interior channel thereof, and detection means for determining the field strength of said electromagnetic field in said interior channel, said detection means being positionable within said interior channel of said corrodible member.

Claim 8

The improvement of claim 5 wherein said connection means comprises: an electrical coil electrically connected between said corrodible member and said sacrificial anode.

Claim 9

The improvement of claim 6 further comprising: traveling means for transporting said detection means through the interior channel of said cathodically protected member.

Claim 10

The improvement of claim 6 wherein said detection means includes means for supplying an electrical signal representative of said electromagnetic field strength, and means for relaying said representative signal to a location remote from said detection means.

Claim 11

The improvement of claim 6 wherein said detection means includes means for supplying an electrical signal representative of said electromagnetic field strength and means for recording said electrical signal.

Claim 12

A cathodically protected pipeline system comprising: a length of corrodible pipe routed through an electrolytic environment; at least one electrically continuous metallic conductor having a higher electromotive potential than the material forming said pipe, said conductor being routed through said electrolytic environment in spaced relationship with said length of pipe; a plurality of electrical coils, each of said electrical coils electrically connecting said metallic conductor and said pipe at predetermined positions spaced along the length of said pipe, each of said electrical coils being so positioned and so oriented relative to said pipe so as to establish an electromagnetic field within the interior of said pipe at the particular location of said electrical coil, said electromagnetic field being proportional to the current flow through said coil between said pipe and said metallic conductor; carrier means for traversing through the interior of said pipe, said carrier means being propelled by a fluid flowing through said pipe; means carried by said carrier means for supplying a signal representative of the strength of the electromagnetic field established by each of said electrical coils as said carrier means traverses past each of said predetermined positions; and means carried by said carrier means for conveying each of said representative signals to a predetermined remote location.

Claim 13

A cathodically protected pipeline system comprising: a length of corrodible pipe routed through an electrolytic environment; at least one electrically continuous metallic conductor having a higher electromotive potential than the material forming said pipe, said conductor being routed through said electrolytic environment in spaced relationship with said length of pipe; a plurality of electrical coils, each of said electrical coils electrically connecting said metallic conductor and said pipe at predetermined positions spaced along the length of said pipe, each of said electrical coils being so positioned and so oriented relative to said pipe so as to establish an electromagnetic field within the interior of said pipe at the particular location of said electrical coil, said electromagnetic field being proportional to the current flow through said coil between said pipe and said metallic conductor; carrier means for traversing through the interior of said pipe, said carrier means being propelled by a fluid flowing through said pipe; means carried by said carrier means for supplying a signal representative of the strength of the electromagnetic field established by each of said electrical coils as said carrier means traverses past each of said predetermined positions; and means carried by said carrier means for conveying each of said representative signals to a predetermined remote location.

Claim 14

The cathodically protected pipeline system of claim 10 wherein said means for supplying said signal representative of the strength of said electromagnetic field includes at least one electromagnetic detector means for supplying an electrical signal as said detector means travels through the electromagnetic field supplied by each of said electrical coils and circuit means responsive to said signal supplied by said detector means for supplying said signal representative of said strength of said electromagnetic field to said conveying means.

Claim 15

The cathodically protected pipeline system of claim 11 wherein said means for conveying each of said representative signals includes recording means carried by said carrier means, said recording means responsive to the electrical signal supplied by said circuit means as said electromagnetic detector means travels through said electromagnetic field established by each of said electrical coils.

Claim 18

The method of claim 13 further comprising the steps of: generating a signal representative of the magnitude of said electromagnetic field; and recording said representative signal.

Claim 19

The method of claim 13 wherein the potential between the pipeline and the surrounding electrolytic environment is monitored, said method further comprising the steps of: determining the electrical potential between said pipe and said sacrificial anode from said detected electromagnetic field and the resistance characteristic of said electrical connections; and determining the pipeline-to-electrolytic potential by subtracting said potential between said pipeline and said sacrificial anode from the electrical potential of said sacrificial anode.

Claim 20

The method of claim 13, wherein said cathodic protection system includes a plurality of said electrical connections, each of said electrical connections being positioned at predetermined locations along the corrodible member, further comprising the step of comparing the detected magnitude of the electromagnetic field caused by a particular electrical connection with the magnitude of the electromagnetic field caused by at least one other of said electrical connections to determine the relative condition of said cathodic protection system adjacent respective ones of said electrical connections.

Claim 23

The method of claim 17 wherein said device is conveyed through said pipeline by: positioning said device in a carrier sized to move through said pipeline; inserting said carrier in said pipeline; and pumping a fluid through said pipeline to urge said carrier through said pipeline.

Claim 24

The method of claim 18 further comprising the steps of: electrically coupling a signal recording apparatus to said device and positioning said signal recording apparatus in said carrier with said device; and recording said representative signal as it is generated.