Simulation And Experimental Study On Erosion Corrosion Of Seawater Pipelines In Ships

Ships,serving as crucial apparatus in both the defense of maritime boundaries and the development and utilization of ocean resources,contribute significantly to national defense and economic growth.The seawater piping system is a key component of a ship,responsible for essential functions such as load adjustment,cooling,and fire suppression.Given the materials of the seawater pipelines are subjected to the harsh marine environment over extended periods,they often experience severe corrosion due to the combined effects of erosion and corrosion.Such corrosion,if it leads to leakage,could pose serious threats to ship safety.Both domestic and international research results and engineering practices underscore the significant issue of erosion-corrosion damage to pipeline materials,thereby drawing widespread attention.With the continuous advancements in marine ship equipment technology,the expectations for the service life and reliability of seawater pipeline materials are progressively increasing.Therefore,comprehensive research into the erosion-corrosion behavior of seawater pipelines is urgently needed.Over recent years,numerical simulation technology,capable of predicting and analyzing long-term corrosion behavior of materials under various operational conditions,has seen rapid development.Presently,this technology is broadly employed in the field of corrosion protection,offering a novel technical approach for investigating erosion-corrosion in seawater pipeline systems.Because of the technical needs of the research on erosion-corrosion of seawater pipelines,in this paper,B10 copper-nickel alloy was selected as the research object,and simulation and experimental research on erosioncorrosion behavior of seawater pipeline were carried out under the condition of single-phase flow and liquid-solid two-phase flow by combining simulation calculation and corrosion verification test.The research results are as follows:1.Based on the Fluent simulation platform,the corrosion electrochemical model was used to carry out simulation research on erosion-corrosion of four typical seawater piping systems under the condition of single-phase flow.The influences of seawater velocity,oxygen concentration,pipeline structure design,and other factors on erosioncorrosion rate of piping were analyzed,and the erosion-corrosion rate of each position of the piping system was obtained.The results showed that the corrosion rate was higher in the position where the fluid flow changes rapidly,such as bend pipe,three-way pipe,and reducing pipe,which became the key factor affecting the service life of the piping system.At the same time,the erosion-corrosion test of B10 alloy was carried out under the condition of single-phase flow(3.5wt.% Na Cl solution).Methods of electrochemical and microscopic characterization were used to test and analyze the erosion-corrosion behavior of B10 alloy at different flow rates,and the influence rule of flow rates on the erosion-corrosion behavior of B10 alloy was clarified.When the flow rate increased from 1 m/s to 6 m/s,the corrosion rate obtained by simulation increases from 0.0283 mm/a to0.1470 mm/a,and the corrosion rate obtained by corrosion test increases from 0.0315 mm/a to 0.1313 mm/a.The trend of simulation and experimental results were the same,and the error of both was 11.05 %.Therefore the simulation and experiment have a good consistency under the condition of single-phase flow.2.Based on the above simulation results and practical engineering experience of the seawater piping system,the numerical simulation platform was used to further study the more severely corroded bend pipe,reducing pipe,and three-way pipe,which to explore the erosion-corrosion law of the pipe system under more severe liquid-solid two-phase flow condition(3.5 wt.% Na Cl solution with 1.5% sand).By using the discrete phase model,the influence laws of pipe structure,fluid velocity,particle properties,confluence direction,and other factors on the erosion-corrosion behavior of typical pipe fitting were obtained,and the erosion rate of the pipe under different working conditions was calculated.At the same time,the corrosion test of B10 alloy was carried out under the condition of liquid-solid two-phase flow.Methods of electrochemical and microscopic characterization were used to test and analyze the erosion-corrosion behavior of B10 alloy at different flow rates.The results showed that the presence of sand can greatly increase the erosion corrosion rate of the alloy.When the flow rate increased from 1 m/s to 6 m/s,the corrosion rate obtained by simulation increases from 0.1812 mm/a to 0.6607 mm/a,and the corrosion rate obtained by corrosion test increases from 0.2061 mm/a to 0.5838 mm/a.The trend of simulation and experimental results were basically the same,the error of both was 12.21 %.Therefore the simulation and experiment have a good consistency under the condition of liquid-solid two-phase flow.