Oil pipe is mainly used for oil and gas well drilling and oil and gas transportation, which including oil drill pipe, oil casing, OTCG. Corrosion has become the major problem affecting the reliability and service life of pipeline system and the main cause of pipeline safety accidents. The presence of CO2, H2S and free water will cause severe internal corrosion problems in oil and gas pipelines, which is also influenced by temperature, CO2 and H2S content, PH, water chemistry, flow velocity, oil or water wetting and composition and surface condition of the steel in wells and pipelines .
The corrosion of oil pipe is mainly caused by impurities in crude oil, which are mainly composed of sulfide and polysulfide. Sulfide can react with aquatic biochemistry to produce a large amount of reductive and acidic hydrogen sulfide, which causes serious corrosion of petroleum pipeline. In addition, a large number of chemical impurities in petroleum such CO2, H2S and naphthenic acids, also contribute to the corrosion of petroleum equipment. It is known to all that the water and salt in crude oil exist on the surface of petroleum piping will lead to oxidation reaction, which is an important reason for corrosion on the surface of petroleum pipe. Naphthenic acid is a type of an organic acid, is a strong corrosive acid to iron products.
The surface is the most prone to corrosion of oil casing parts,to improve the corrosion resistance of the machinery, you need the process such as addition of surface anti-corrosion materials, the use of surface anti-corrosion layer of thtubing. The general anti-corrosion methods of well tube are: nitriding, epoxy powder spraying, titanium nano spraying, carbon zirconium coating, PE pipe lining and fiberglass tubing, etc.
Coating anticorrosion technology is the most widely used measure in pipeline anticorrosion. Anticorrosive coatings such as petroleum bitumen, paint or anticorrosive coatings made of acid-resistant and inorganic polymers are applied on the outer layer of the machinery to insulate the surface of the steel pipe from the air to avoid oxidation reactions, thus protecting the pipe from corrosion.
In addition to being able to resist corrosion chemically, there are physical methods. Electroplating is one of the most common corrosion protection methods used on the surface of oil casing, which is equivalent to mechanically adding a metal surface to the metal pipe. In addition, the methods like current cathodic protection, electric couple effect inhibition and corrosion inhibitor addition are the effective corrosion protection.