An evaluation system and method for dynamic direct current corrosion risk of buried metal pipelines

Abstract

The invention provides a system and method for judging the risk of dynamic DC corrosion of buried metal pipelines. The method monitors the corrosion of the pipeline through a corrosion inspection sheet or a corrosion rate probe to obtain the corrosion rate. Under the high frequency, the DC parameters of the pipeline are continuously monitored to obtain dynamic DC potential data, and then judge whether to include the corrosion rate and whether to apply cathodic protection according to the acquired data, and evaluate the corrosion risk of the buried metal pipeline. The method of the present invention comprehensively Whether the pipeline is cathodically protected or not, and the difference in the minimum protection potential criterion for cathodic protection in different environmental media, and the dynamic fluctuation of the pipeline-ground potential under the interference condition of rail transit stray current are considered.

Description

【Technical field】 [0001] The invention relates to the field of stray current detection and evaluation of oil and gas pipelines, in particular to a system and method for evaluating dynamic DC corrosion risks of buried metal pipelines. 【Background technique】 [0002] With the rapid development of the transportation and energy industries, more and more cases of buried metal pipelines being laid parallel to or crossed with rail transit lines have caused the problem of dynamic DC stray current interference of buried metal pipelines to become increasingly serious. Due to the complexity and unpredictability of the DC stray current leakage path in the rail transit system, and the constantly changing position of the train on the track during operation, the DC stray current generated by the rail transit system has dynamic fluctuation characteristics, the direction and magnitude of the current Random changes. For buried metal pipelines, in the same area, there are alternating inflow a...

AI Technical Summary

Problems solved by technology

Existing standards and evaluation methods such as "GB50991-2014 Technical Standard for DC Interference Protection of Buried Steel Pipelines" put forward corresponding evaluation indicators for the identification and evaluation of DC interference of pipelines, but for pipelines without cathodic protection, it is proposed to use pipe-ground potential The interference intensity is judged relative to the offset value of the natural potential, but the potential offset evaluation index is suitable for the interference situation of the steady-state DC stray current. The standard does not specify which time to select the pipe-to-ground potential or how to deal with the pipe-to-ground potential for evaluation; for pipelines that implement cathodic protection, although an index for judging by whether the pipeline polarization potential meets the cathodic protection standard is proposed , but for buried pipelines that are disturbed by dynamic DC stray currents, the polarization potential of the pipeline is generally obtained by instantaneous power-off of the inspection sheet. There is a situation where the instantaneous power-off potential of the inspection sheet is higher than the minimum protection potential. At this time, how to judge the interference intensity of stray currents, and how many ranges and degrees of potentials that do not meet the requirements of the standard are acceptable. The standard does not specify

At the same time, the national standard GB50991-2014 only divides the severity of DC interference into acceptable and unacceptable. When the severity of DC interference is unacceptable, it does not further divide the corrosion risk of pipelines.

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