Method of health status diagnosis, early warning and fault location for protective layer of buried metal pipeline

Abstract

The invention relates to a method of health status diagnosis, early warning and fault location for a protective layer of a buried metal pipeline, which comprises an accurate measurement method of a cathode protection potential of the buried metal pipeline, a reliable evaluation method of the transverse insulation resistance of the protective layer per unit length, a safety pre-warning and fault location method of the protective layer, and an implementation method of the micro power consumption of a measuring instrument. On the basis of the methods, the invention provides a quality evaluation method for the protective layer of the buried metal pipeline.

Description

technical field [0001] The invention relates to the field of detection, diagnosis and early warning of the health status of the protective layer of buried metal pipelines. Background technique [0002] The health diagnosis technology of the protective layer of buried metal pipelines is of great significance to the safe operation of metal pipelines. Over the years, anti-corrosion workers in various countries have studied many methods and technologies for detecting defects in the protective layer of metal pipelines, mainly inputting DC signals or AC signals to pipelines. Electrical signals are realized by detecting changes in potential, current or magnetic field strength along the pipeline. Commonly used techniques include pipe-to-ground potential method (P / S), close interval potential test method (CIPS), direct current potential gradient method (DCVG), Pearson PEARSON method, magnetic field method, potential difference method, tube current method, frequency conversion frequen...

AI Technical Summary

Problems solved by technology

This working method has the following disadvantages: 1) The cathodic protection potential measured by the manual line inspection method is all using a portable copper sulfate reference electrode. Different buried positions and depths, as well as changes in soil moisture content at different times, changes in the potential of the energized point, different measurement times, etc., will cause large differences in the measured cathodic protection potentials, and the measured results are not comparable; 2) It is unscientific to judge whether the buried metal pipeline is protected or not based only on whether the cathodic protection potential on the test pile is lower than -0.85V

In fact, this situation exists: due to the negative potential of the energized point, even if the protective layer falls off between the two test piles, the cathodic protection potential on all test piles is lower than -0.85V, so the pipeline protective layer defect cannot be found ; 3) There is a measurement error in the cathodic protection potential measurement. Different measurement errors are introduced into different pipe sections, and the calculation error of the resistance of the protective layer transverse insulation layer per unit length is different. Simply by the cathodic protection potential on two adjacent test piles The calculated transverse insulation resistance of the protective layer per unit length of the pipe section to evaluate the health of the protective layer of the pipe section will introduce a large evaluation error, so that it is impossible to make a correct evaluation of the health of the protective layer of the pipeline; positioning

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