Process of pickling and passivation of seamless steel pipe

Eight processes necessary for pickling and passivation of seamless steel pipes:

1.  Preparation

2.  The organic chemical degreasing, the organic chemical degreasing adopts the tank body soaking method, the degreasing tank is made of thick steel plate, and the inner cavity is covered with PVC or high pressure polyethylene. When the seamless steel pipe is soaked in the tank, attention should be paid to the place where it is placed to prevent gas from remaining in the pipe. During the whole soaking process, the seamless steel pipe should be moved or rolled left and right, so that the inner wall aqueous solution can be continuously replaced and replaced, which can improve the actual effect. When necessary, remove the seamless steel pipe, wash it with water, and then carry out soaking.

3. Immersion in boiling water, the welded steel pipe after degreasing is removed from the degreasing tank, soaked in the boiling water tank body around 40 degrees Celsius to 60 degrees Celsius, and the time is 5 to 20 minutes. The boiling water tank is made of thick steel plate, and the inner cavity is Lay PVC or high pressure polyethylene. The chloride ion content in the water is less than 25ppm.

4. Cleaning with tap water. The seamless steel pipe that has been soaked in water is cleaned with working pressure water (working pressure p is greater than or equal to 0.1Mpa).

5. Passivation

6. Drying The passivated seamless steel pipe should be compressed with clean air or dried with N2 immediately, and there must be sufficient time (at least 2 minutes) to passivate it in the air.

7. Inspection After passivation of seamless steel pipe, self-inspection and mutual inspection should be carried out, and then submitted to the inspector for project acceptance as required.

8. Maintenance       

1) If the welded steel pipe of which the outer layer must be painted, it shall be carried out in accordance with the painting regulations.        

2) After the inspection, the seamless steel pipe is sealed with a plastic plug, and the three-proof cloth is used for bundling and maintenance, and marking is carried out.