Super-hydrophobic molecular film on the inner wall surface of steel for natural gas pipelines and its corrosion

In this paper, the complex of siloxanes was used as the modifying agent to form a dense layer of anticorrosion film upon the inner wall surface of steel for natural gas pipeline by direct spraying process. The testing of infra-red spectrometry and contact angle revealed that the inner wall surface of steels which were taken from the field natural gas pipeline was composed of multiform FeOOH, FeCO₃, α-Fe₂O₃ and a trace of Fe₃O₄. After being modified, the steel inner wall surface was coupled with a layer of super-hydrophobic film with alkyl chains towards the surface by the chemical reaction of steel surface and siloxanes. The average contact angle of the super-hydrophobic film was over 160°. The results of corrosions around the modified steel inner surfaces by 5wt% NaCl aqueous solution with different acidities indicated that the formed super-hydrophobic film was dense and stable, and had excellent anticorrosion properties. The complex of siloxanes used here is easily atomized and has a potential in corrosion inhibition or anticorrosion for wet gas transmission pipelines and natural gas pipelines with certain humidity.