What is stainless steel pipe passivation?

What is stainless steel pipe passivation? Passivation is the method to turn the metal surface into a state that is not easily oxidized, and slows the corrosion rate of the metal.In addition, a kind of active metal or alloy, in which the chemical activity is greatly reduced, and becomes the phenomenon of precious metal state, also called passivation. The passivation of metals may also be spontaneous processes, such as the formation of an insoluble compound on the surface of a metal, the oxide film. In industry, passivating agents (mainly oxidants) are used to passivate the metal to form a protective film.

Common examples: cold concentrated sulfuric acid, cold concentrated nitric acid and iron, aluminum can occur passivation.

What is the operation method of stainless steel tube pickling passivation? The stainless steel tube factory -zheheng steel introduces the following:

1. Preparation

2. Chemical degreasing
1) the chemical degreasing method is used in the tank for soaking, and the oil tank is made of steel plate, and the inner wall is covered with PVC or polyethylene.
2) use 12 ~ 15% (by volume) of nitric acid chemical degreasing treatment, temperature of 40 ℃ ~ 60 ℃, time is 2 ~ 4 hours.
3) when the pipe is immersed in the tank, it should pay attention to the position of placement and avoid the remaining air in the pipe.
4) the inner cavity solution should be constantly changed to improve the effect by moving or turning the tube up and down in the process of soaking.When necessary, take out the fittings and rinse them with water and then soak them.
5) chemical oil removal until the surface of the pipe is completely wetted by water.

3. Rinse stainless steel tube with hot water
1) in addition to the oil pipe fittings are taken from the in addition to the oil tank, soak in about 40 ℃ ~ 60 ℃ hot water tank inside the rinse, 5 ~ 20 minutes.
2) the hot water tank is made of steel plate, and the inner wall is covered with PVC or polyethylene.
3) chlorine ion content in water is less than 25ppm.

4. Flush with water
1) water rinsed pipe fitting is washed with pressure water (pressure P > 0.1mpa).
2) the chloride content in water is less than 25ppm.

5. Passivation
1) passivation is used in the tank, the passivation liquid formulation and soaking time are selected according to the 2.3 table.
2) made of passivated channel steel plate, and the inner wall is made of acid plastic.
3) when soaking in the tank, pay attention to the position of placement and avoid the remaining air in the pipe.
4) the inner cavity solution should be constantly changed to improve the effect by moving or turning the tube up and down in the process of soaking.When necessary, take out the fittings and rinse them with water and then soak them.

6. Dry
After passivated pipe fitting, clean compressed air or nitrogen to blow dry, and must have enough time (at least 2 hours) to make it naturally passivated in the air.

7. Inspection
After being passivated, the pipe should be self-checked and checked, and then submitted to the quality inspector for acceptance.

8. To protect
1) if the outer surface needs to be painted, it shall be carried out according to the coating requirements.
2) the qualified pipe fitting shall be sealed with a plastic stopper, and the protection shall be protected by three proofs, and the identification shall be carried out.

Zheheng steel is mainly engaged in all kinds of super long, thin, super thick or large diameter stainless steel pipe special use stainless steel tube manufacturers, such as stainless steel pipe products have passed the eu PED pressure equipment directive, national a-level special equipment manufacturing license, Lloyd's ISO9001:2008 system certification; The from zheheng steel, mail:[email protected]