Stainless steel pipe sanitary seamless pipe corrosion resistance in sulfuric acid and nitric acid

1. Atmospheric corrosion of sanitary stainless steel pipe seamless pipe

 

The resistance of stainless steel to atmospheric corrosion basically changes with the chloride content in the atmosphere. Corrosion of stainless steel near the ocean or other sources of chloride pollution is therefore extremely important. A certain amount of rainwater is only important if it affects the chloride concentration on the steel surface. 1Cr13, 1 Cr 17 and austenitic stainless steels can be adapted to a variety of applications without significant changes in appearance. therefore,

 

The stainless steel used in rural areas can be selected according to price, market supply, mechanical properties, manufacturing and processing properties, and appearance. Industrial environment In an industrial environment without chloride pollution, 1Cr17 and austenitic stainless steels can work for a long time, basically remain free of rust, and may form a dirt film on the surface, but when the dirt film is removed, the original Glossy appearance. In industrial rings with chlorides

 

In the environment, it will cause stainless steel corrosion. Sanitary stainless steel pipe seamless pipe marine environment 1Cr13 and 1 Cr 17 stainless steel will form a thin rust film in a short period of time, but will not cause significant dimensional changes. Austenitic stainless steels such as 1 Cr 17Ni7, 1 Cr 18Ni9, and 0 Cr 18Ni9 may show some rust when exposed to the marine environment. Rust is usually shallow and can be easily removed. 0

 

Cr 17 Ni 12M 02 stainless steel containing molybdenum is basically resistant to corrosion in marine environments. In addition to atmospheric conditions, sanitary stainless steel seamless pipes have two other factors that affect the stainless steel's resistance to atmospheric corrosion, namely surface conditions and manufacturing processes. The finishing level affects the corrosion resistance of stainless steels in chloride environments. The matte surface (matte surface) is very sensitive to corrosion, that is, normal industrial finishing

 

The surface is less sensitive to rust. Surface finish levels also affect the removal of dirt and rust. Dirt and rust are easy to remove from highly finished surfaces, but difficult to remove from matte surfaces. For matte surfaces, more frequent cleaning is required if the original surface condition is to be maintained.

 

2.Sanitary stainless steel pipe seamless pipe for fresh water

 

Fresh water can be defined as water from rivers, lakes, ponds or wells, regardless of acidity, salinity or brackishness. The corrosivity of fresh water in sanitary stainless steel seamless pipes is affected by the pH value, oxygen content, and tendency to scale of the water. Scale (hard) water, its corrosiveness is mainly determined by the amount and type of scale formed on the metal surface. The formation of this scale is due to the presence of minerals and temperature. Non-fouling

 

(Soft) water, which is generally more corrosive than hard water. Corrosion can be reduced by increasing the pH or reducing the oxygen content. 1Cr13 stainless steel is significantly more resistant to freshwater corrosion than carbon steel, and has very good characteristics when used in fresh water. This steel is widely used in applications such as shipyards and dams that require high strength and corrosion resistance. However, it should be taken into account that in some cases 1Cr13 may be aligned in fresh water

 

Degree pitting sensitivity. But pitting corrosion can be completely avoided by cathodic corrosion protection. 1Cr17 and austenitic stainless steel are almost completely resistant to fresh water corrosion at room temperature (ambient temperature).

 

3.Sanitary stainless steel pipe seamless pipe nitric acid

 

Ferritic stainless steel and austenitic stainless steel containing chromium not less than 14% have good resistance to nitric acid corrosion. 1Cr17 stainless steel has been widely used in processing equipment of nitric acid plants. However, because 0 Cr 18 Ni 9 usually has good formability and welding performance, it has largely replaced 1Cr17 stainless steel in the above applications.

 

The nitric acid corrosion resistance of other austenitic stainless steels is similar to that of 0 Cr 18 Ni 9. 1Cr17 stainless steel usually has a slightly higher corrosion rate than 0 Cr 18 Ni 9 and higher temperatures and concentrations have a greater harmful effect on it.

 

If the heat treatment of the steel is not performed properly, hot nitric acid will cause intergranular corrosion of austenitic and ferritic stainless steels. Therefore, appropriate heat treatment can be used to prevent this type of corrosion, or use stainless steel that is resistant to this type of corrosion.

 

4 sanitary stainless steel pipe seamless pipe sulfuric acid

 

Standard stainless steel grades are rarely used in sulfuric acid solutions because they can be used in a narrow range. At room temperature, 0Cr17Ni12Mo2 stainless steel (more standard grade resistant to sulfuric acid corrosion) is resistant to sulfuric acid when the sulfuric acid concentration is less than 15%, or greater than 85%. However, in the higher concentration range, carbon steel is usually used. Martensitic and ferritic stainless steels are generally not resistant to corrosion by sulfuric acid solutions. As in the case of nitric acid

 

Similarly, without proper heat treatment of stainless steel, sulfuric acid can cause intergranular corrosion. For welded structures that cannot be heat treated after welding, low carbon grades 00Cr19Ni10 or 00Cr17Ni14Mo2, or stabilized grades 0Cr18Ni11Ti or 0Cr18Ni11Nb stainless steel should be used.