1. Range of cleaning passivation: pipelines, fittings, valves, etc. belonging to the purified water pipes constructed by our company.
2. Water requirements: The water used in all the following process operations is deionized water, and Party A is required to cooperate in water production operations.
3. Safety precautions: The following safety precautions are adopted in the pickling liquid:
(1) The operator wears a clean, transparent gas mask, acid-proof clothing, and gloves.
(2) All operations are to add water to the container first, and then add chemicals, not the other way around, and stir while adding.
(3) The cleaning and passivation liquid must be discharged when it is neutral, and the discharge must be discharged from the sewage outlet of the water production room to benefit the environment.

Cleaning plan
1. Pre-cleaning
(1) Formula: Deionized water at room temperature.
(2) Operation procedure: Use a circulating water pump to keep the pressure at 2/3bar and circulate with a water pump. After 15 minutes, open the drain valve and discharge while circulating.
(3) Temperature: room temperature
(4) Time: 15 minutes
(5) Drain the deionized water for cleaning.

2. Lye cleaning
(1) Formula: Prepare a pure chemical reagent of sodium hydrochloride, add hot water (temperature not lower than 70℃) to make 1% (volume concentration) lye.
(2) Operating procedure: Circulate with a pump for no less than 30 minutes, and then discharge.
(3) Temperature: 70℃
(4) Time: 30 minutes
(5) Drain the cleaning solution.

3. Rinse with deionized water:
(1) Formula: Deionized water at room temperature.
(2) Operation procedure: Use a circulating water pump to keep the pressure at 2/3bar to circulate with a water pump. After 30 minutes, open the drain valve and discharge while circulating.
(3) Temperature: room temperature
(4) Time: 15 minutes
(5) Drain the deionized water for cleaning.

Passivation scheme
1. Acid passivation
(1) Formula: Use deionized water and chemically pure nitric acid to prepare an 8% acid solution.
(2) Operation procedure: Keep the circulating water pump at 2/3bar pressure and circulate for 60min. After 60 minutes, add proper sodium hydroxide until the PH value is equal to 7, open the drain valve, and discharge while circulating.
(3) Temperature: 49℃-52℃
(4) Time: 60 minutes
(5) Let go of the passivation solution.

2. Purified water rinse
(1) Formula: Deionized water at room temperature.
(2) Operation procedure: Use a circulating water pump to keep the pressure at 2/3bar to circulate with a water pump, open the drain valve after 5 minutes, and discharge while circulating.
(3) Temperature: room temperature
(4) Time: 5 minutes
(5) Drain the deionized water for cleaning.

3. Rinse with purified water
(1) Formula: Deionized water at room temperature.
(2) Operation procedure: Keep the circulating water pump at 2/3bar pressure and circulate with the water pump until the effluent pH is neutral.
(3) Temperature: room temperature
(4) Time: no less than 30 minutes
(5) Drain the deionized water for cleaning.

Note: When cleaning and passivating, the filter element of the precision filter must be removed to avoid damage to the filter element