LI En-tian,ZHANG Jian-wei,ZHOU Hao,YANG Zu-ying,LIU Wen,WANG Lei,JIA Yong.Influences of NaCl Concentration on the Synergistic Action of Erosion-corrosion of Steel Used in Oil and Gas Gathering and Transportation Pipelines[J],49(5):279-284
Influences of NaCl Concentration on the Synergistic Action of Erosion-corrosion of Steel Used in Oil and Gas Gathering and Transportation Pipelines
Received:April 23, 2019  Revised:May 20, 2020
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DOI:10.16490/j.cnki.issn.1001-3660.2020.05.033
KeyWord:20 # steel  erosion-corrosion  synergy  quality loss  electrochemical experiment  morphology observation
                    
AuthorInstitution
LI En-tian 1.a.Jiangsu Key Laboratory of Oil-Gas Storage and Transportation Technology, Changzhou , China
ZHANG Jian-wei 1.a.Jiangsu Key Laboratory of Oil-Gas Storage and Transportation Technology, Changzhou , China
ZHOU Hao 1.a.Jiangsu Key Laboratory of Oil-Gas Storage and Transportation Technology, Changzhou , China
YANG Zu-ying 1.b.Business School, Changzhou University, Changzhou , China
LIU Wen 1.a.Jiangsu Key Laboratory of Oil-Gas Storage and Transportation Technology, Changzhou , China
WANG Lei 2.Gas Transportation Management Department of Petrochina Southwest Oil and Gasfield Company, Chengdu , China
JIA Yong 2.Gas Transportation Management Department of Petrochina Southwest Oil and Gasfield Company, Chengdu , China
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Abstract:
      The paper aims to quantify the synergistic effects of erosion-corrosion at different Cl– concentrations. The corrosion law of 20 # steel under different Cl– concentrations was obtained by means of corrosion weightlessness, morphology observation, electrochemical analysis (including Tafel curve test and impedance spectrum test) in simulated oilfield produced fluid with rotating cylindrical electrode experimental device. Based on the mass loss rates and electrochemical fitting results of pure erosion, pure corrosion and erosion-corrosion at different Cl– concentrations, the contributions of pure corrosion, pure erosion and their interactions to the total erosion-corrosion were obtained. In the simulated oilfield production fluid, when the NaCl concentration was less than 4.5%, the erosion and corrosion quality loss rate increased with the increase of Cl– concentration, and the highest rate increased to 0.44 mg/(cm2•h). Since the same potential protection was applied at each Cl– concentration, the mass loss due to erosion did not change much. It can be seen from the image that corrosion pits gradually appeared on the surface of the material with the increase of Cl– concentration. Cl– concentration has obvious promoting effect on material corrosion, and there is a critical Cl– concentration. The erosion-corrosion mass loss rate is in good consistency with the observation of morphology, and the erosion-corrosion under different Cl– concentrations is a mixed control of electrochemical corrosion-erosion, in which electrochemical corrosion dominates. As for the synergistic effect, with the increase of Cl– concentration, the corrosion promoting effect on scour gradually increases, while the erosion promoting effect on corrosion first increases and then decreases.
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