Interpretation of corrosion profile of anticorrosive spiral steel tube used in pipelines
Most of the pipelines are buried anticorrosive pipes, namely anti-corrosion spiral steel pipes. Enough attention should be paid to the anti-corrosion protection of buried anticorrosive spiral steel pipes.Therefore, the research on pipeline corrosion is extremely urgent, and to study corrosion protection, it is necessary to first understand the principle of pipeline corrosion, and then carry out targeted corrosion protection. Anticorrosive spiral steel pipe pipe corrosion is in the soil, the ocean, the atmosphere, under the action of the surrounding medium damage and corrosion.According to the corroded parts, there are inner wall corrosion and outer wall corrosion;According to the degree of corrosion to be divided into comprehensive corrosion and local corrosion;According to the corrosion mechanism, can be divided into chemical corrosion, electrochemical corrosion, biochemical corrosion.
Pipeline inner wall corrosion is the corrosion of metal pipeline inner wall due to the effect of medium, mainly water corrosion and medium corrosion.Water corrosion and medium corrosion generally exist in the inner wall of long-distance transportation pipeline.The corrosion of pipeline outer wall is mainly represented by atmospheric corrosion, soil corrosion, bacterial corrosion and stray current corrosion.Chemical corrosion is caused by the chemical reaction between the soil, air or the chemical medium in the pipeline and the metal. Generally, the corrosion is relatively light, and there is no electric current generated in the corrosion caused by chemical action.Electrochemical corrosion is a type of corrosion that occurs in the electrolyte of a metal that is associated with the flow of electric current. Biochemical corrosion is mainly due to the bacterial life of life activities caused by metal corrosion.Pipeline corrosion is generally the most serious electrochemical corrosion, LPG pipelines are made of steel, steel corrosion is a natural phenomenon of electrochemical changes.
Generally speaking, the condition of steel corrosion is to have a cathode and an anode, and the two should be connected by a conductive circuit, there is a potential difference, are in the conductive medium.When the current flows from the anode to the cathode, the metal atoms will be separated from the anode surface into positively charged ions and enter the electrolyte. This means that the metal will be corroded in the electrolyte. The degree of corrosion depends on the material of the metal. For LPG pipeline, corrosion of anticorrosive spiral steel pipe pipe is very harmful, which affects the safe transportation of LPG.It is mainly manifested in the corrosion pits formed on the surface of metal pipes, resulting in the thinness of pipes and the bulging or bursting of pipes under the action of internal pressure.Also can make the organization of place of material decarburization, corrode produces a change, more serious when, can make conduit blowout directly.