Non-invasive, high resolution detection of electrical currents and electrochemical impedances at spaced localities along a pipeline
April 2, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesMethod and apparatus for detecting faults in buried insulated conductors Method and apparatus for determining the presence of or absence of an underground body Method and apparatus for the detection of pipeline holidays Method for utilizing three-dimensional radiated magnetic field gradients for detecting serving faults in buried cables System for detecting a cable buried under the seabed Method and apparatus for electromagnetically surveying a remote elongate conductor employing a detector assembly having plural electromagnetic transducer assemblies Method and apparatus employing received independent magnetic field components of a transmitted alternating magnetic field for determining location Patent #: 4710708 InventorsAssigneeApplicationNo. 504100 filed on 04/02/1990US Classes:324/71.2, Erosion204/196.06, With measuring, testing, or sensing means204/196.36, Earth grounded object or protection means204/404, Corrosion324/263Current through test material forms test magnetic fieldExaminersPrimary: Harvey, Jack B.Attorney, Agent or FirmInternational ClassG01N 027/26AbstractElectrical current distribution in the soil surrounding a buried pipeline is detected by applying an AC electrical potential between the pipe and a buried electrode spaced from the pipe. The magnetic field at spaced localities along the pipe arising from currents transverse to the pipe is detected. Additionally, a potential containing a plurality of alternating frequencies is similarly applied to the pipe and the magnetic field induced by the resulting electrical current both along the pipe and transversely of the pipe is detected. The magnetic field is detected by correlation discrimination at spaced locations along the pipe and across the spectrum of the impressed frequencies. The detected data is used to determine the capacitance and resistance of the soil/pipe interface at localities along the pipe and to generate impedance plots which indicate characteristics of that interface.Other References
Field of SearchOf an applied test signalUsing a magnetic field sensor For insulation fault Insulation Of ground fault indication Erosion Inaccessible (at test point) conductor (e.g., buried in wall) For small object detection or location Current through test material forms test magnetic field Plural magnetic fields in material With phase sensitive element Magnetometers Nonparallel plural magnetic sensors CONDUCTOR IDENTIFICATION OR LOCATION (E.G., PHASE IDENTIFICATION) Magnetic field detection devices Corrosion |
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