Research On Corrosion And Anti-Corrosion Technology Of Buried Pipelines Of Compressor Stations In Xinjiang Section Of West-East Gas Pipeline

The main line of West-East gas pipeline, length 3900km, used the 3-layer PE and cathodic protection system, while solvent-free epoxy coatings are used on the buried pipelines of gas transmission stations for corrosion. The pipeline during the initial production run smoothly, but in 2007 and 2008 successively in Lunnan and Hami gas compressor station found a coating failure, corrosion and leakage of buried pipeline. And the soil situation and anti-corrosion program were similar to them; in the excavation of the survey a similar problem was also found. Although not leakage, but there have been more severe coating failures and corrosion, there was a big security risk. Therefore, against the external corrosion problems of the buried pipelines in Sidaoban gas compressor station, this thesis was studied, in order to identify the hidden causes of corrosion occurred, to understand the corrosion law, targeted for anti-corrosion, to ensure the West-East gas pipeline continuous operation in safety, extending the service life.The main research contents are as follows:(1) Surveys of corrosion status and soil analysis of Sidaoban gas compressor station. Through the excavation research of buried pipeline in Sidaoban gas compression station, their anti-corrosion technology and pipeline corrosion status were cognized; through the physical and chemical properties test analysis of soil, the soil corrosivity was studied.(2) Study on corrosion behavior of tubing of Sidaoban gas compressor station. Corrosion resistance of tubing was analyzed using electrochemical testing in lab; the influence on the corrosion of various factors in soil solution were analyzed using simulation experiments of the soil corrosion; the most direct corrosion data of tubing was obtained using coupon testing in situ, and the corrosion law was analyzed; each coupon's corrosion features were analyzed by using spectrum analysis and SEM.(3) Study on corrosion influence on the buried pipelines impacted by grounding grid. Bimetallic corrosion behavior, occurred when grounding grid contacted with the buried pipelines, was studied using electrochemical testing and immersion experiments. The results showed that the galvanic effect was obvious.(4) Study on bimetallic corrosion testing of blow-off pipe of compressor outlet. Bimetallic corrosion behavior, maybe occurred when the three different tubing connected successively, using immersion experiments. The results showed that the galvanic effect was obvious.(5) Evaluations of performance of solvent-free Epoxy coating used in the soil of Sidaoban gas compressor station. The evaluation of solvent-free epoxy coating on the corrosion performance was tested using immersion experiments with simulated soil solution. The results showed that the solvent-free epoxy coating, meeting design requirements, can provide good protection for pipe.(6) Study on anti-corrosion measures of buried pipeline in Sidaoban gas compressor station. Based on the research in the literature, type of coatings was recommended for Sidaoban station and, based on previous research results, the basic measures of corrosion control were put forward.