Circulating pickling process and formulation for hydraulic system

Pipe pickling for Hydraulic System can effectively remove oxides from inner wall of pipe, 

prevent corrosion of inner wall of pipe, re-corrosion of inner wall of pipe and residual chemical reaction deposits in pipe, etc. 

The following is an introduction of the acid pickling process for hydraulic system.

Trough pickling process and formulation for hydraulic system:

(1) Degreasing. The formulation of degreasing liquid is (NaOH) = 9%~10%; (Na3PO4) = 3%; (NaHCO3) = 1.3%; (Na2SO3) = 2%; The rest is water. Operating process requirements are: liquid temperature 70-80 C, soaking for 4h.

(2) Water scouring. Clean water with pressure of 0.8MPa is flushed clean.

(3) Acid pickling. The formula of acid pickling solution is: HCl is 13%~14%; (CH2) 6N4 is 1%; The rest is water. Operating process requirements are: soak at normal temperature for 1.5-2 H.

(4) Water scouring. Rinse with clean water at a pressure of 0.8 MPa.

(5) Second pickling. The acid pickling solution formula is the same as above. Operating process requirements are: soak at normal temperature for 5 minutes.

(6) Neutralization. The formulation of the neutralizing solution is: NH4OH diluted to a solution with pH value of 10-11. Operating process requirements are: soak for 2 minutes at normal temperature.

(7) Passivation. The passivating liquid formulation is: NaNO2 is 8%~10%; NH4OH is 2%; The rest is water. Operating process requirements are: soak at normal temperature for 5 minutes.

(8) Water scouring. Rinse off with purified water with a pressure of 0.8MPa.

(9) Quick drying. Dry with steam, superheated steam or hot air

(10) Seal the nozzle. Secure with plastic pipe plugs or layers of plastic cloth. If the pipe is treated by the above method, it will be clean and bright, and it will keep rust free for about 2 months. It can also be prolonged if preserved.

Circulating pickling process and formulation for hydraulic system:

(1) Leak test. Fill the leak test with 1 MPa compressed air.

(2) Degreasing. The formulation of the degreasing liquid is the same as that of the tank pickling process. Operating process requirements are: liquid temperature 40-50 C, continuous circulation for 3h.

(3) Gas cap. The degreasing liquid is ejected with compressed air of 0.8MPa.

(4) Water scouring. Flush out the residue with clean water with a pressure of 0.8MPa.

(5) Acid pickling. The formula of acid pickling solution is: HCl is 9%~11%; (CH2) 6N4 is 1%; The rest is water. Operating process requirements are: normal temperature intermittent circulation for 50min.

(6) Neutralization. The formulation of the neutralizing solution is: NH4OH diluted to a solution with pH value of 9-10. Operating process requirements are: continuous circulation at room temperature for 25min.

(7) Passivation. The passivating liquid formulation is: (NaNO2) = 10% - 14%; The rest is water. Operating process requirements are: normal temperature intermittent circulation for 30 min.

(8) Water scouring. Rinse continuously with purified water with pressure of 0.8 MPa and temperature of 60 C for 10 minutes. (9) Drying. Dry with superheated steam.

(10) Oiling. Fill hydraulic oil with a hydraulic pump.

Pickling of hydraulic system is divided into tank-type pickling method and circulating pickling method. Different pickling methods have different characteristics. The former is generally applied to hydraulic system with small piping volume, while the latter is often used in pipeline construction of large hydraulic system.