What is the role of pickling passivation of stainless steel tube?

Stainless steel tube in the production and processing is completed after a process - pickling passivation, then the stainless steel tube pickling passivation is how to operate? What role does it play?

Stainless steel tube pickling passivation operation steps are divided into the following 8 points:

Preparation

Chemical degreasing

Learn to degrease by immersion in the tank, degreasing tank made of steel plate, the inner wall of PVC or polyethylene.

Use 12~15% nitric acid (by volume) for chemical degreasing treatment at 40℃~60℃ for 2~4 hours.

When the pipe fittings are immersed in the tank, attention should be paid to the position of placing to avoid the air stored in the pipe.

Soaking process should be up and down before and after moving or turning the fittings, so that the inner cavity solution is constantly replaced to mention the fruit. If necessary, remove the fittings, rinse with water and air before soaking.

Chemical degreasing until the surface of the tubing is completely wetted with water.

Hot water rinsing

Degreasing pipe fittings from the degreasing tank removed, immersed in 40 ℃ ~ 60 ℃ about the hot water tank rinsing, time 5 ~ 20 minutes.

The hot water tank is made of steel plate and the inner wall is covered with PVC or polyethylene.

The chlorine ion content of the water is less than 25ppm.

Rinsing with water

Rinse the rinsed fittings with pressurized water (pressure P≥0.1Mpa).

The chlorine ion content in the water is less than 25ppm.

Passivation

Passivation is carried out by means of tank bubbling in the pool.

The passivation tank is made of steel plate, and the inner wall is covered with acid-proof plastic.

When soaking in the tank, attention should be paid to the location of the placement, to avoid retaining air in the tube.

Soaking process should be up and down before and after moving or turning the fittings, so that the inner cavity solution is constantly replaced to mention the fruit. Remove the fittings if necessary and rinse with water and air before soaking.

Drying

After passivation of the fittings, to catch with clean compressed air or nitrogen blow-drying, and must have enough time (at least 2 hours) to make it in the air natural passivation.

Inspection

After passivation, the pipe fittings should be self-inspected and mutually inspected, and then submitted to the quality inspector for acceptance as required.

Protection

If the outer surface of the pipe fittings need to be painted, then according to the painting requirements.

The pipe fittings after passing the inspection shall be sealed with plastic plugs, wrapped and protected with three-proof cloths, and labeled.