1. Chemical method
Use pickling paste or spray to assist the rusted parts to passivate again to form a chromium oxide film to restore its corrosion resistance. After pickling, it is very important to rinse with clean water properly to remove all pollutants and acid residues. After all treatments, re-polish with polishing equipment and seal with polishing wax. For local slight rust, you can also use a 1:1 gasoline and engine oil mixture with a clean rag to wipe off the rust.

2. Mechanical method
Sandblasting, cleaning with glass or ceramic particles, annihilation, brushing, and polishing. Mechanical methods may wipe off the pollution caused by previously removed materials, polishing materials, or annihilation materials. All kinds of pollution, especially foreign iron particles, may become a source of corrosion, especially in humid environments. Therefore, the mechanically cleaned surface should preferably be cleaned formally under dry conditions. The use of mechanical methods can only clean the surface and cannot change the corrosion resistance of the material itself. Therefore, it is recommended to re-polish with polishing equipment after mechanical cleaning and seal with polishing wax.

The reason why stainless steel does not easily rust is that there are two core alloying elements, namely chromium (Cr) and nickel (Ni). Cr is the element that allows stainless steel to stabilize its own structure in a high temperature environment and not oxidize and fall off. Ni can enhance the stability of its own structure and improve the comprehensive mechanical properties of stainless steel itself, ensuring its good welding performance.
310 stainless steel contains a high amount of chromium (Cr) element, up to 24%~26%. When chromium encounters an oxidizing medium, it can combine with oxygen to form a dense Cr2O3 oxide film. As long as the chromium content is sufficient, this oxide film can continuously cover the surface of 310 stainless steel, effectively preventing its internal metal from contacting the outside world, thereby achieving the purpose of high temperature resistance. This oxide film can also provide protection for 310 stainless steel, preventing its internal alloy elements from being further oxidized.
Secondly, the nickel (Ni) content in 310 stainless steel is also quite high, reaching 19%~22%. Nickel not only enhances the organizational stability of stainless steel but also improves its comprehensive mechanical properties and ensures good welding performance. In a high temperature environment, the presence of nickel enables 310 stainless steel to maintain the stability of its various performances and is not easily affected by external corrosion or oxidizing media.
The high chromium and nickel content of 310 stainless steel plate and the addition of other alloying elements together give it excellent high temperature resistance.

310 is often used as a high-temperature resistant material because of its good high-temperature strength and low oxidation resistance at high temperatures.
In high-temperature environments, 310 heat-resistant stainless steel can maintain the stability of its own performance in all aspects and is not easily affected by some external corrosion, oxidation, and other media. This is mainly due to the high Cr content in 310 stainless steel itself. Because of the oxidizing medium, the Cr in the metal on the surface of 310 can combine with oxygen to form Cr₂O₃, and this oxide film can prevent oxidation and corrosion.
As long as the Cr content in stainless steel is sufficient, the Cr₂O₃ oxide film can continuously cover the surface of 310 steel. As the film becomes thicker and thicker, it will eventually put on a "protective coat" for 310 steel, which can prevent the internal 310 metal from contacting the outside world, thereby preventing further oxidation. This is also the main reason why 310 steel can have good anti-oxidation properties at high temperatures.

Since spiral welded pipes are piled outdoors and most of them are buried underground when in use, they are very easy to corrode and rust. In order to ensure the smooth flow of the pipeline, the spiral welded pipe must have strong corrosion resistance.
The influence of external conditions will cause spiral welded pipe corrosion. It mainly depends on the medium characteristics and temperature around the pipeline, and whether the medium around the pipeline is corrosive. Because the degree of medium corrosiveness is closely related to the various microorganisms contained in the soil. And if it is a long-distance pipeline, the soil environment is more complicated. In addition, the temperature of the environment in which the pipeline is located will also affect the corrosion of the spiral welded pipe. If the temperature is high, the corrosion rate will also accelerate, while the corrosion rate will slow down at a low temperature.