Precision stainless steel pipes are widely used. Some industrial equipment and production machinery working in harsh environments have very high requirements for pipe fittings because the acidity, alkalinity, or corrosive salts in the environment will threaten their lifespan; then, many people will question the stainless steel material and ask if the passivation layer of precision stainless steel pipes is corrosion-resistant? The answer is, of course, that it has excellent corrosion resistance!
Passivation is the process of electrochemically oxidizing stainless steel pipes to make the surface inactive and not easily oxidized, thereby slowing down the corrosion rate of stainless steel. Since stainless steel pipes contain chromium and nickel elements, they can react with the passivation solution to generate corrosion products, forming a film with a dense structure that tightly covers the surface of the steel pipe.
Slightly better stainless steels add elements such as titanium, molybdenum, silicon, and nitrogen, such as 321 stainless steel pipes, 316L stainless steel pipes, etc. After the surface is passivated, the protective layer is more stable, and the pipe fittings can withstand stronger corrosive media or more harsh environments.
When the components of our industrial equipment and production machinery use passivated precision stainless steel pipes, the protective film on its surface completely separates the steel pipe from the corrosive media in the environment, preventing the stainless steel precision pipe from contacting various corrosive media, thereby preventing the components from oxidation and corrosion, and extending the service life.
To ensure the corrosion resistance of pipe fittings, strict testing is required after passivation to ensure thorough passivation and avoid excessive passivation; the surface of the stainless steel workpiece after passivation should be clean and smooth, without pitting, pitting, foreign matter pollution, and loss of gloss. Corrosion resistance requires a high humidity test, salt spray test, or copper sulfate solution instead of a salt spray test.
High humidity test: First soak the precision stainless steel pipe in alcohol or acetone to clean it, then wipe it with gauze soaked in alcohol or acetone, and place it in a transfer atmosphere or a vacuum container to dry it. After drying, the pipe fittings must be placed in a high-humidity box with a relative humidity of 95%~100% and a temperature of 38℃~46℃ for 24~26 hours.
The salt spray test refers to the “GBT 2324.17-1993″ standard. The final test results show that no corrosive substances appear and no rust on the pipe fittings; the copper sulfate solution test refers to “GB/T 4334.5-2000″. After the test, no copper shall be precipitated, and there shall be no corrosive substances or rust on the surface.
Is the passivation layer of precision stainless steel pipe corrosion-resistant? Of course, it is corrosion-resistant. The passivation liquid and the surface of the stainless steel precision pipe produce a dense film that can isolate the external environment, play a protective, corrosion-resistant, and anti-oxidation role; and after humidity, electrolyte, and acid salt tests, it is guaranteed that the surface of the stainless steel pipe fittings will not produce corrosive substances, rust, oxidation and other phenomena; when used as a component in mechanical equipment, it is not affected by harsh environments, ensuring the service life.
Post time: Oct-29-2024