Detecting method of outer anti-corrosion layer of buried fuel gas steel pipeline

Abstract

The invention relates to the technical field of pipeline inspection, and particularly to a detecting method of an outer anti-corrosion layer of a buried fuel gas steel pipeline. The detecting method is characterized by comprising the following steps: a, dividing a detected pipeline into multiple sections for detection, wherein the distance between detecting points is 50 m; b, connecting two ends of the detected pipeline with insulating flanges; c, applying a low-frequency current signal to the pipeline by using a pipeline signal transmitter of a signal transmission machine, and then detecting the trend of the pipeline on the ground surface and detecting by using a reception machine; and d, transmitting an audio signal to the pipeline by utilizing a transmission machine of a buried pipeline outer anti-corrosion layer detection instrument, connecting an 1000 Hz AC signal with the pipeline, generating an alarm display for an obvious overflow signal by the reception machine when a detector holding the reception machine with a frequency-selective amplifier walks right above the pipeline, and determining the position of the damage of the anti-corrosion layer of the pipeline by the detector based on the audio alarm and the size of the current signal. The two detection technologies, namely, a PCM (Pulse Code Modulation) method and a PEARSON method, are combined for the pipeline detection, so that the detecting method of the outer anti-corrosion layer of the buried fuel gas steel pipeline is excellent in detection precision as well as sensitivity of the outer anti-corrosion layer.

Description

[technical field] [0001] The invention relates to the technical field of pipeline detection, in particular to a detection method for an external anticorrosion layer of a buried gas steel pipeline. [Background technique] [0002] Buried pipelines mainly include long-distance (oil and gas) pipelines and public gas pipelines. The buried pipelines in Shanghai mainly include more than 900 kilometers of long-distance (oil and gas) pipelines and thousands of kilometers of urban buried gas pipelines. Urban gas pipeline is one of the important infrastructures of urban construction and an important part of urban energy supply. The urban gas system consists of three parts: gas source production device, transmission and distribution pipeline network and application equipment. Urban buried gas pipeline is one of them. Transmission and distribution part. [0003] With the rapid development of my country's economy, my country's urban gas has been widely used. There are more than 300 citie...

AI Technical Summary

Problems solved by technology

In terms of detection methods, there are currently tube current and voltage methods, PEARSON detection method (PS), AC current attenuation method, frequency conversion-frequency selection method, and DC potential gradient detection method (DCVG), all of which have different degrees of defects when used alone Specifically, the current-voltage method in the tube is subject to objective constraints in use, such as AC-DC interference, specificity and response speed of the instrument, the setting of the current test pile, the error of the 20m tube length and the value of the steel resistivity, etc. ; PEARSON detection method needs to walk along the whole line to detect, can not indicate the severity of the defect, cannot indicate the CP efficiency, cannot indicate the peeling of the outer anti-corrosion layer, depends on the skills of the operator, and often gives non-existing defect information; the measurement of AC current attenuation method The result is not intuitive, cannot indicate the CP efficiency, cannot indicate the peeling of the outer anti-corrosion layer, and is easily disturbed by the external current; the calculation result of the frequency conversion-frequency selection method introduces many factors, the error is large, the size and location of the defect cannot be determined, and the external The peeling of the anti-corrosion layer cannot indicate the CP effect, which is greatly affected by the ground environment, but the anti-interference ability is limited; the DC potential gradient detection method cannot indicate the cathodic protection effect of the pipeline, and cannot indicate the peeling of the outer anti-corrosion layer, and needs to be detected along the line

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