Soaking method of stainless steel welded pipe

There are the following 10 methods of immersing stainless steel welded pipes in liquid:
1. Ordinary processing, ordinary acid is enough, and then washed in clean water.
2. Deeper: there are more procedures, such as pickling, alkali washing, water washing, polishing, waxing, etc.
3. Precise: Ultrasonic degreasing and degreasing, surface spraying, grinding, oxidation, anti-rust treatment and:
Method 1: Common solvents for degreasing: trichloroethylene, acetone, butanone, benzene, ethyl acetate.
Method 2: Degrease after sandblasting or emery cloth polishing.
Method 3: Soak in the following solution at 70-85°C for 10 minutes: Sodium silicate 6.4 Sodium pyrophosphate 3.2 Sodium hydroxide 3.2 Detergent powder 1 Water 32 After washing with cold water, dry at 93°C.

Method 4: After degreasing, immerse in the following solution for 10 minutes, temperature 80°C, PH=12.65: sodium phosphate 8.5, sodium pyrophosphate 4.2 sodium hydroxide 4.2, surfactant 1.4, water 380, take out and wash, and then in the following solution at 65°C Immersion for 3 minutes: chromium oxide 20, water 380, washed with water and dried.

Method 5: Immerse in the following solution at 65-70°C for 5-10min: Hydrochloric acid (37%) 2 Hexamethylenetetramine 5 Water 20 Then add 30% hydrogen peroxide, take it out and wash it, and then dry it at 93°C .
Method 6: Immerse in the following solution at 50°C for 10 minutes: Potassium dichromate saturated solution 0.35 Sulfuric acid (d=1.84) 10 Then brush off the carbon residue, wash with distilled water, and dry at 70°C. This method is suitable for occasions where maximum peel strength is required.
Method 7: In the lead lining tank, the concentration of sulfuric acid is 500g/l, anodize for 90s, the voltage is 6V, rinse with water, wash with distilled water, dry at 70°C, the adhesive joint is the anode, after treatment, it is oxidized at 5-10% Passivation in chromium solution for 20min.
Method 8: Immerse in the following solution at 85-90°C for 10 minutes: oxalic acid 37 sulfuric acid (d=1.84) 36 water 300 After washing with distilled water, dry with warm air.
Method 9: After degreasing, immerse in the following solution at 65°C for 10 minutes: Hydrochloric acid (d=1.19 ) 52 Hydrogen peroxide (30%) 2 Formaldehyde (38%) 10 Water 45 After washing with water, then immerse in the following solution for 10 minutes, the temperature 65°C: Sulfuric acid (d=1.84) 100 Sodium dichromate 10 Water 30 After washing with distilled water, dry at 70°C.
Method 10: After washing with water-soluble industrial soap and alkali, washing with hot water at 40°C for 5 minutes, drying at 120°C, and then immersing in the following solution at 100°C for 2 minutes: hydrochloric acid 200, phosphoric acid 30, hydrofluoric acid 10, and then 40 C hot water washing 5min, 40 ℃ down drying 30min.