Stainless steel thick wall pipe inside is direct contact with the medium , most of which mixed in a lot of corrosion medium gene, for example water of high salinity, dissolved oxygen, carbon dioxide, hydrogen sulfide and sulfate reducing bacteria and chloride ion...When temperature, pressure, flow rate and alternating stress are mixed and staggered, the corrosion of stainless steel thick wall pipe in some place will be seriously damaged.For example, crude oil contains sulfide, naphthenic acid, alkali metal salt (magnesium chloride and calcium chloride in oil field water) and other substances, which can make the inner wall of stainless steel pipe subject to chemical and electrochemical corrosion.Light petroleum products without stable treatment may also contain the above substances. These products also contain water and oxygen, so when the medium enters the pipeline, it will cause corrosion of stainless steel thick wall pipe.In the water supply and water injection pipelines of oil fields, electrochemical corrosion often occurs in the inner wall of the pipe due to the presence of oxygen or sulfate reducing bacteria.The gas pipeline contains moisture such as CO2 and H2S, which leads to electrochemical corrosion or stress corrosion cracking.

The corrosion of sulfate - reducing bacteria in stainless steel pipe is the same as that of soil bacteria, especially when the pipeline stops delivering.Because soil and water contain sulfate - reducing bacteria, it is hard to avoid them being carried into tanks and pipelines.Bacteria thrive quickly in the right conditions, dividing every cell every 20 seconds, so they can multiply in large Numbers in a short period of time after the shutdown.Bacteria to participate in the electrochemical reaction process, generate a lot of ferrous sulfide, within hours after the restart, ferrous sulfide everywhere can be in harmony with oxygen, began to oxidation of ferrous sulfide to accelerated corrosion process.Combined with the above factors, the solution is to increase the pH value of the medium or add fungicides to inhibit corrosion.

Methods to protect the inner wall of stainless steel thick-walled pipe:

Stainless steel thick-walled pipe inner wall protection can be classified into three major types of outer wall protection.Chemical agents such as corrosion inhibitor, bactericide, deoxidizer, etc.Stainless steel material with good corrosion resistance is adopted.At present, the most common application is to use the anti-corrosion layer in the interface protection, commonly known as the inner coating, to separate the corrosive medium from the steel pipe surface, in order to achieve the anti-corrosion purpose.

The anti-corrosion layer technology in stainless steel thick wall pipe can bring several major influences:
(1) the service life of stainless steel pipe is more than doubled, while the investment of anti-corrosion layer only accounts for 8% ~ 15% of the investment of pipeline construction.

(2) because the friction coefficient of coating surface in the pipe is small, and the friction resistance of fluid flow in the pipe is small, the conveying capacity of the pipe can be increased by 5% to 10%.

(3) reduce the sediment on the inner wall of the pipe, facilitate the pigging, reduce the number of pigging and reduce the production cost.Prevent the corrosion of the inner wall of the pipe from contaminating the transport medium.Stainless steel thick wall pipe, thick wall stainless steel pipe, large diameter thick wall pipe.