Study On Corrosion Behavior Of X65 Steel Under Stray Current

The research on pipeline corrosion caused by stray current enjoys the history of more than120 years.As far as the long-term research is concerned,the topic of stray current corrosion studies is mostly about buried pipelines in cities.However,in recent years,with the popular of Marine engineering construction in China,people begin to pay more attention to the corrosion of Marine structures.Parts of these offshore platform structures are in seawater and they work with subsea pipelines.Therefore,this paper aims to provide an effective reference for offshore platforms and submarine pipelines to cope with the corrosion caused by stray current.In general,offshore flexible transmission system;nearshore electrified railways;large power plants near the sea and the ICCP system of the platform are the main source of stray current which can obviously affect the corrosion of the underwater structure of the platform.The collection of offshore oil and gas is generally an engineering project with more obvious planning and investment.Once these oil and gas pipelines under the sea are damaged by corrosion,they will cause irreversible economic losses and serious environmental pollution to us.In this paper,immersion experiment,numerical simulation,wire electrode experiment,electrochemical workstation and other methods were used to investigate the corrosion of X65steel in seawater under the action of different stray current.The main contents of this paper include:(1)Immersion experiments were used to study the corrosion morphology and characteristics of X65 steel under the action of 100A/m~2,300A/m~2 direct current and 400A/m~2alternating current respectively in seawater environment.(2)Through numerical simulation,different types and sizes of currents were loaded on both ends of the seawater simulation fluid to obtain the electric field distribution of X65specimen and provide a comparison for the experimental results.(3)The wire beam electrode was used to explore the corrosion characteristics of X65specimen under the action of 50-100A/m~2 alternating stray current in seawater environment.(4)With the help of electrochemical workstation,this paper explored the effects of ac electric fields of 100A/m~2,200A/m~2,300A/m~2 and 400A/m~2 on X65 specimen in seawater environment,and effectively quantified the change trend of corrosion tendency and rate of X65specimen.In this paper,the corrosion of X65 steel in seawater under the action of stray currents of various intensities has been investigated comprehensively through a variety of research methods.The following conclusions are obtained:after 20 to 30 days,under the continuous action of 100A/m~2 to 300A/m~2 DC or 400A/m~2 AC,no pitting phenomenon occurs in X65specimen.Moreover,the current inflow point,flow point and outflow point of X65 material have obvious corrosion rules.In addition,after the stray current of 50-100A/m~2 is applied for12h,the possibility of pitting of X65 specimen is low.The stronger the stray current,the more obvious the corrosion tendency and the faster the corrosion rate of X65 test pieces.