1. Overview

1. Scope of cleaning and passivation: Stainless steel pipes, pipe fittings, valves, etc.

2. Water requirements: Deionized water shall be used for all the following process operations.

3. Safety protection measures: The following safety precautions have been adopted for the acid cleaning solution:

(1) Operators shall wear clean, transparent gas masks, acid-proof clothing and gloves.

(2) For all operations, add water to the container first, then add chemicals (never the reverse), and stir while adding.

(3) The cleaning and passivation solution can only be discharged when it reaches neutrality, and shall be discharged from the sewage outlet of the water preparation room to facilitate environmental protection.

2. Cleaning Plan

1. Pre-cleaning

(1) Formula: Room temperature deionized water.

(2) Operating procedure: Use a circulating water pump to maintain circulation at a pressure of 2/3 bar for 15 minutes, then open the drain valve and discharge while circulating.

(3) Temperature: Room temperature

(4) Time: 15 minutes

(5) Drain the deionized water used for cleaning.

2. Alkaline solution cleaning

(1) Formula: Prepare chemically pure sodium hydrogen fluoride reagent, add hot water (temperature not lower than 70℃) to prepare 1% (volume concentration) alkaline solution.

(2) Operating procedure: Circulate with a pump for no less than 30 minutes, then discharge.

(3) Temperature: 70℃

(4) Time: 30 minutes

(5) Drain the cleaning solution.

3. Passivation Method

1. Acid solution passivation

2. Purified water rinsing