Purpose of acid pickling and passivation
Standardize pipeline cleaning and passivation operations to form a dense oxide film on the surface of the pipeline and improve its service life.
Scope of use 
This specification applies to the chemical treatment operations of distribution systems such as purified water, injection water, pure steam, clean gas pipelines, and process pipelines. The pipelines and fittings used in these systems are made of stainless steel materials that have been mechanically polished or electropolished.
summary
The chemical treatment of the system includes the following steps:
1) Deionized water cleaning
2) Degreasing cleaning
3) Passivation cleaning
chemical treatment
1) Preparation and operation of degreasing solution:
Solution (W/V): 2% sodium hydroxide+98% deionized water;
(W=2% × V, W1 NaOH weight kg, V-Solution Volume L)
Cycle for 45 minutes at ambient temperature and pressure of 0.1-0.3 MPa (for the circulation system);
Soak for 60 minutes at ambient temperature and record the start and end times (for single pipeline systems);
System cleaning
Deionized water cleaning
Combine the passivation bucket, passivation pump, valve, pressure gauge, and connecting components with the cleaned system to form a circulating system. Use deionized water to circulate and clean for 30 minutes to remove metal shavings and other impurities from the system; For a single pipeline system, discharge for 3-5 minutes at each usage point and then close the valve.
Degreasing cleaning
1) Prepare the required solution in the passivation tank according to the degreasing solution preparation method;
2) When adding and dissolving chemicals, they should be dissolved while stirring. It is strictly prohibited to pour the required chemicals into the passivation bucket at once, which may cause the preparation solution to splash out and burn the on-site personnel;
3) During the process of preparing the solution, turn on the circulation pump and prepare while circulating, which is beneficial for the dilution and uniform concentration of chemicals.
4) For the circulatory system, cycle for 45 minutes at ambient temperature and pressure of 0.1-0.3 MPa; For a single pipeline system, fill each usage point with solution at ambient temperature, soak for 60 minutes, and keep records.
5) After cleaning, discharge the cleaning solution and rinse with deionized water until neutral (pH 6-8) is tested using pH test paper.
Passivation cleaning
1) Prepare the required solution in the passivation bucket according to the passivation solution preparation method;
2) When adding and dissolving chemicals, they should be dissolved while stirring. It is strictly prohibited to pour the required chemicals into the passivation bucket at once, which may cause the preparation solution to splash out and burn the on-site personnel;
3) During the process of preparing the solution, turn on the circulation pump and prepare while circulating, which is beneficial for the dilution and uniform concentration of chemicals;
4) To prevent operators from being poisoned by acid mist, if necessary, turn on the exhaust fan to blow away the acid mist in the air;
5) For a circulatory system, cycle for 60 minutes at ambient temperature and pressure of 0.1-0.3 MPa;
For single pipeline systems, fill each usage point with passivation solution at ambient temperature, soak for 120 minutes, and keep records;
6) After cleaning, neutralize the passivation solution with sodium hydroxide solution and then discharge it to the designated location;
7) Rinse with deionized water until neutral (pH 6-8) as measured by pH test paper.
After cleaning, restore the cleaned system to its original position; Wastewater should be taken away by the supplier themselves.