Research On Inspection Method Of Underground Pipelines Anticorrosion Coating Conditions

Based on analyses of the current international anticorrosion inspection techniques, we proposed a novel inspection method for the status of the underground metal pipelines anticorrosion coating—the current gradient method.The development of this method is based on using the Underground Pipeline Measurement Instrument (Radio, UK). This instrument was originally used to detect the orientation of the underground metal pipelines or cable. It has no quality (coating broken point) or quantity (coating insulator resistance) inspection function of the anticorrosion coating of pipelines. Hence, we developed a novel pipeline anticorrosion coating inspection technique—the current gradient method. This method includes both quality and quantity inspection. The quality inspection is to locate the position of the broken point of the anticorrosion coating, and to determine the relative quality of different pipeline portions. The quantity inspection is the insulator resistance measurement of the anticorrosion coating. This number is a standard in reflecting the comprehensive quality of the coating. According to the resistance value and related standard, the quality of the coating can be evaluated and the coating grade can be determined.This method can be used for locating the pipelines and its broken point, evaluating the status of the anticorrosion coating without digging and affecting the normal production. It is convenient, fast, and accurate. This method can be used in testing and evaluating of new pipelines, as well as the periodical test of working pipelines. It provides important information for the maintenance and management of the pipelines, and it guarantees the safety performance of the underground metal pipelines.A number of experiments were carried out in the chemical plant and terylene plant of TPCC. Three positions were selected for comparison and proof, and results are satisfying.