Patent
Method and apparatus for the detection of pipeline holidays
Charles R. Bruce,Irvin D Johnson +1 more
TLDR
In this article, a method and apparatus for detecting and locating holidays in an insulating coating of a subterranean pipeline is described, where an alternating current is induced in the portion of the pipeline being surveyed, and the electrical current signal is displayed to provide an indication of the location and magnitude of the holiday.Abstract:
A method and apparatus are provided for detecting and locating holidays in an insulating coating of a subterranean pipeline. An alternating current is induced in the portion of the pipeline being surveyed. The pipeline is tracked by sensing the normal electromagnetic field generated by the current flowing in the pipeline. Leakage current indicative of the location and magnitude of a holiday in the pipeline coating is sensed by a pair of coil members adapted to be located above the ground on opposite sides of a vertical plane including the longitudinal axis of the pipeline with the central axes of the coil members being oriented generally parallel to the central axis of the pipeline, whereby an electrical current signal is induced in the pair of coil members by an electromagnetic field generated by the leakage current. The electrical current signal is displayed to provide an indication of the location and magnitude of the holiday.read more
Citations
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References
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Patent
Magnetic field gradient apparatus and method for detecting pipe line corrosion
TL;DR: In this article, the magnetic fields produced by electrical current flowing into or exiting from a buried pipeline at the situs of a bare region of the pipeline at which corrosion may take place are detected.
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TL;DR: In this article, a method of detecting inaccessible metallic objects such as gas, electricity, water or telecommunications systems (lines) through which an alternating current is flowing, comprises making at least three spatially separated measurements of the magnetic field associated with the current.
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