Harco Corporation

Harsco Technologies Corporation

Clark P Weldon

Stephen L Wolfson

James B Bushman

Marvin L Miller

Frank E Rizzo

Offshore or onshore electrical surveys of buried or submerged structures such as pipeline are conducted in a fixed-cell-to-moving-cell fashion either before or after one or more established pipe-to-electrolyte potentials can be obtained. The results of the fixed-cell-to-moving-cell survey are then corrected by a summation of the fixed-to-moving-cell recorded potential and the established potential at the location of the established potential to obtain a reliable electrical survey of the structure. As indicated, the fixed-cell-to-moving-cell survey may be conducted either before or after the established potential is obtained or either before or after a disposable wire survey using a direct connection to the structure.

Method and apparatus for electrical surveys of subsurface structures

An electrical survey of buried structures such as underwater or underground pipelines utilizes the steps of connecting one end of an economically disposable wire from a wire supply to the structure, either directly or through a heavier lead, the opposite end being electrically connected to a cell. The cell is moved along the structure together with a wire supply and a meter to obtain periodic measured structure-to-electrolyte potential values. If the wire is accidentally or intentionally disconnected during the survey, a stationary electrode is positioned at the wire break or last valid measured reading, such electrode being reconnected to the free end of the wire from the supply. The survey then continues periodically obtaining electrode-to-cell potential values. A structure-to-electrolyte potential profile is obtained by summing the last valid recorded structure-to-electrolyte potential value with each electrode-to-cell values. The summing may be done after the survey is completed by computer.

Electrical surveys of underwater or underground structures with

In the present invention a method and apparatus for electrical surveys of offshore metal structures includes measuring the electrical potential difference between the structure and an electrolyte, such as sea water and/or the sea bottom, in which the structure is contained. Such measurements are made at roughly approximated recorded distance locations along the structure and the approximate distance information is corrected based on periodically taken accurate distance measurements. Provision is also made to correct data for line currents in the structure, and a method is disclosed for examining the effectiveness of an electrically insulating member connected in the structure. Moreover, an improved insulated wire having minimum insulation holidays and a method for making the same are disclosed.

Method and apparatus for electrical surveys of offshore metal structures

A method and apparatus for conducting offshore pipeline electrical surveys is characterized by initially locating and marking the pipeline, traversing the length of the pipeline towing a reference electrode in close proximity to the structure, providing a supply of wire having one end electrically and mechanically connected to the pipeline at a reference location, playing out the wire along the length of the pipeline through a distance measuring device while transporting the supply of wire and towing the reference electrode, and measuring and recording the potential difference between the reference electrode and pipe either continuously or at spaced test locations along the length of the structure. The method and apparatus are further characterized by alternately connecting and disconnecting an electrical power source to the pipeline at the reference location, measuring and recording the potential difference in both connected and disconnected modes at the test locations, and measuring and recording the depolarization and/or polarization times when the power source is disconnected and/or connected, respectively, to the pipeline.

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Houston, TX, United States of America

Clark P Weldon