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| The influence of Concrete counterweight layer on cathodic protection effect of nearshore submarine steel pipes |
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Cite this article:
. The influence of Concrete counterweight layer on cathodic protection effect of nearshore submarine steel pipes. Journal of Chinese Society for Corrosion and protection, 0, (): 0-0.
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Abstract To investigate the effect of concrete weighted layer on cathodic protection of submarine pipes in nearshore marine environments, steady-state constant potential polarization, electrochemical impedance spectroscopy (EIS), and numerical simulation methods were used to systematically study the cathodic polarization behavior of bare X60 steel and concrete weighted X60 steel in static seawater at different salinities (5 ‰, 16.8 ‰, 26.7 ‰) and mud, as well as 2m/s flowing seawater. The resistivity of the concrete weighted layer was also tested, and the cathodic protection potential distribution and sacrificial anode output current of the pipe under the influence of the concrete weighted layer were obtained. The results showed that when the polarization potential of -0.85V (CSE) was reached in static seawater with salinities of 5 ‰, 16.8 ‰, and 26.7 ‰ and mud, the cathodic polarization current density required for bare X60 steel was about 3.5-8 times that of X60 steel with a concrete weight layer. In 2m/s flowing seawater, the difference in cathodic polarization current density required for X60 steel with concrete weight layer under corresponding potential is relatively small compared to static seawater. The flow velocity will significantly increase the cathodic polarization current density required for bare X60 steel, which is related to the diffusion of oxygen and the destruction of calcium deposition layer due to the increase in flow velocity. However, the concrete weight layer hinders this effect of flow velocity. The change in polarization resistance measured by electrochemical impedance spectroscopy is consistent with the change in polarization current density. At the same time, the resistivity of the concrete weight layer in seawater is about 70 times that of the corresponding seawater resistivity, and the resistivity of the concrete weight layer in marine mud is about 37 times that of the corresponding marine mud resistivity. The numerical simulation results show that the concrete weight layer reduces the cathodic polarization current density, resulting in a significant negative shift and small potential attenuation of the cathodic protection potential. The concrete weight layer reduces the output current of the sacrificial anode, resulting in a slightly positive shift of the cathodic protection potential. The concrete weighted layer has a significant effect on improving the cathodic protection effect of submarine pipes.
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Received: 28 July 2025
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