Corrosion Detection And Electrochemical Anticorrosion Of Concentrated Seawater Pipeline

As a relatively safe and economical conveying method,pipeline has been widely applied in various fields.The damage and aging of the anticorrosion coating on the inner and outer walls of the pipeline are widespread due to various factors,which shorten the service life and increase the operating cost of the pipeline,meanwhile causing serious economic losses and pollution to the ecological environment.Based on the buried pipeline transporting concentrated seawater as a by-product after seawater desalination from a soda ash company in Tangshan,the anticorrosion effect of the inner and outer walls of the pipeline was tested,and the electrochemical anticorrosion of the inner wall was studied,whose research results were applied on the anticorrosion of the inner wall of the enterprise pipeline.Firstly,taking the 20000 m DN800 carbon steel pipeline conveying concentrated seawater as the research object,the corrosion performance detection method was designed for the anticorrosion coating of the crossing section,which was applied to the anticorrosion effect detection of coating of pipeline inner wall.The analysis showed that,the resistivity of the anticorrosion layer on the inner and outer walls of the pipeline crossing was 45282?·m2 and 1462?·m2 respectively.It showed that there are weak and damage points on the inner and outer wall of the pipeline,so that the anticorrosion coating could not effectively isolate the corrosive medium near the pipeline.Electrochemical corrosion was prone to occur in the weak and damaged area of the anticorrosion coating,which caused corrosion perforation and leakage of the pipeline..Then,the electrochemical corrosion protection of the inner and outer walls of the pipeline was studied based on the electrochemical principle.Selecting the representative pipe section in the plant as the test object,a set of electrochemical corrosion protection cathodic protection devices were designed.Through macroscopic observation,weight loss test of corrosion coupon,ultrasonic thickness measurement and ultrasonic guided wave detection,the anti-corrosion effect of test pipe section and blank pipe section were compared.The results showed that the wall thickness of the blank section without anticorrosion device was 0.60 mm less than that of the test section with anti-corrosion device,and the average corrosion weight loss of the test section was 1.98%,which was significantly lower than that of the blank section by 6.15%.Macroscopic observation showed that a layer of uniform protective film was formed on the inner wall of the pipeline in which the current cathodic protection device was installed.The inner wall of the untreated pipe was seriously corroded.Multiple tests showed that cathodic protection technology could effectively slow down the corrosion rate of medium carbon steel pipe line.Finally,the research results were applied on the inner wall electrochemical protection of the 1100 m concentrated sea water pipeline as the circulating cooling system.The results showed that the polarization potential was between-0.85 v ?-0.93 v,and all polarization potentials met the requirements of cathodic polarization potential,which indicated that the anti-corrosion effect was remarkable and could be widely promoted.Figure22;Table11;Reference 48...