Detection of Coating Defects on Buried Pipelines Using Magnetic Field Variations Within the Pipeline

摘要

A method for in-situ detection of coating defects on a buried pipeline. The pipeline is under cathodic protection or otherwise carries a current applied to its pipe walls. A magnetic field sensor array is placed within the pipeline and moved along its length. As the sensor array travels, it detects the magnetic fields within the pipeline. The sensor output is compared with “expected” data, which represents interior magnetic fields of the pipeline without coating defects. Because electrical current leaks through a coating defect, the current is altered on the pipe wall at the defect. This in turn alters the interior magnetic fields, and a change in the interior magnetic fields indicates a coating defect.

主权项

1. A method for detecting coating defects in a coated and electrically conductive pipeline, the pipeline being under cathodic protection or otherwise carrying a current applied to its pipe walls, comprising:
placing a magnetic field sensor array within the pipeline; wherein the sensor array comprises a number of magnetic field sensors, arranged in a shape that generally matches but is smaller than the interior profile of the pipeline; moving the sensor array along a length of the pipeline; receiving output from each sensor of the array; comparing the output with the interior magnetic fields of a pipeline without coating defects; analyzing the results of the comparing step to determine if a coating defect is indicated.