Low Power Microprocessor Based Measurements System for Determining the Integrity of Coatings on Buried Pipelines

摘要

A hand held, low power consumption instrument (GASCOPLEX) for finding faults in coatings on underground pipelines was developed. It comprises a signal generator which supplies a crystal controlled, low frequency alternating current to the pipeline, and the receiver which is carried along the pipeline route. The receiver measures magnetic field strength due to the signal current in the pipe. The magnetic field values allow the magnitude of local pipe current, current gradient and pipe depth to be obtained. The values of current gradient are automatically compared with a preset threshold and values greater than this threshold initiate an audible warning to the operator, signifying a coating defect. An integral guidance system is incorporated in the receiver to keep the operator within an acceptable band over the pipeline.