Method for evaluating corrosion of DC stray current on high strength steel for oil gas pipeline under stress condition

Abstract

The invention discloses a method for evaluating corrosion of DC stray current on high strength steel for oil gas pipeline under a stress condition, and belongs to the field of oil gas pipeline detection and evaluation. The method comprises the following steps: step one, managing the pipeline information; step two, evaluating the stress situation; step three, evaluating the stray current disturbance, wherein the stray current disturbance can be divided into DC interference and AC interference; step four, evaluating the soil corrosion performance; step five, predicting and evaluating the corrosion speed, namely processing the measured soil conductivity and soil pH value, and calculated DC stray current density and stress level to obtain a relationship between the corrosion speed and the factors mentioned above so as to carry out corrosion speed prediction and evaluation. The method carries out comprehensive evaluation on the detection results of soil corrosion and stray current according to the present standards and evaluation method, can carry out evaluation on the pipeline stress situation, can obtain the DC stray current density and stress level on the high strength steel pipeline, and is capable of predicting the corrosion speed and evaluating the corrosion level.

Description

technical field [0001] The invention relates to a method for evaluating DC stray current corrosion of high-strength steel for oil and gas pipelines under stress conditions, and belongs to the field of detection and evaluation of oil and gas pipelines. Background technique [0002] Due to the advantages of high efficiency, low cost, small land occupation, strong continuity, and not easily affected by the surrounding environment of transportation, pipeline transportation is more and more widely used in energy supply, petrochemical and residential life systems, and has become The preferred solution for oil and gas transportation is called the "lifeline" of the country. In recent years, in order to improve transportation efficiency and reduce energy consumption, long-distance pipeline transportation is developing in the direction of large diameter and high pressure, which makes high-strength pipeline steel widely used in long-distance oil and gas transportation pipelines. Durin...

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Problems solved by technology

[0004] In order to overcome the defects that the existing evaluation method does not consider the influence of the stress of the pipeline in service, cannot calculate and evaluate the DC stray current density, cannot predict the corrosion rate, and the evaluation results are unscientific, the present invention uses the basic information of the pipeline, pipeline faults and Maintenance information, evaluation results for overall management of the pipeline; use multiple linear regression to obtain the DC stray current corrosion rate of high-strength steel oil and gas pipelines under stress conditions and various environmental factors (soil conductivity, pH value, DC stray current density, stress level ), through which the corrosion rate of high-strength steel is predicted and the hazard of the corrosion rate is evaluated; the stress state of the pipeline is evaluated by calculating the stress level of the in-service pipeline combined with the evaluation index; the soil conductance obtained through testing Rate and pH value combined with evaluation indicators to evaluate soil corrosion; by investigating stray current interference sources, detecting pipe-ground potential offset or soil surface potential gradient, and calculating DC stray current density, stray current interference is evaluated and analyzed. Guidance on pipeline cathodic protection and drainage

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