Evaluation Of Corrosion And Residual Strength Of Natural Gas Pipeline In West Second Line

With the service time of long-distance pipeline is increasing, the internal corrosion problem is getting increasingly worse. If the condition of corrosion reach to a certain degree, it may cause pipe crackle or the pipeline perforation which lead to the nature gas leakage even bring about explosion.the Sulfur components of the nature gas transported by the The second west to east gas pipeline(WEPP II), makes not only more complicated of the internal corrosion situation, but also more serious of the consequences caused by internal corrosion.Therefore, it is necessary to evaluate the condition of internal corrosion and study on the residual intensity of the WEPP Ⅱ in order to ensure the safety and efficient operation of the WEPP Ⅱ. The main contents as follows:Firstly,identified the key pipeline which is extraordinarily prone to internal corrosion and the two most significant pipelines to research for this paper by using the method of laboratory experiment to test the total sulfur content in12groups of pigging-internal corrosion products and39groups gas sample of the WEPP Ⅱ while combined with the research of elevation along the pipeline, temperament components etc.Secondly,the paper researched the electrochemical effects of different concentration(w%) Cl-and SO42-on internal corrosion behavior of X80pipeline steel in stimulated solution for pigging-internal corrosion product and the internal corrosion mechanism of WEPP II by the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) experimental.Third,using the High temperature high pressure(HTHP) reactor to test the internal corrosion rate of X80steel in stimulated solution for the internal corrosionenvironment of WEPP II.Fourthly,determinethe three representative forms of internal defects of WEPP II through analysis and statistics for the Internal inspection report of the two most significant pipelines.Using software fitting defect discrete points to get the corresponding distribution and distribution function.Fifthly,using ANSYS(finite element modeling software) to assess the residual intensity assessment of WEPP Ⅱ, then, compared The settlement results of three different models.lastly,the paper reached the remaining life of the two target pipelines of WEPP II based on the residual strength and corrosion rate of the two target pipelines and combined with the operating conditions and environment conditions.The conclusions of this study have certain guiding significance to the internal corrosion status and residual strength evaluation for High strength steel natural gas pipelines.