Dip-Type Derusting Chemical Concentrate Formulation (100 L Stock)
Designed for immersion applications on mild steel with heavy to moderate rust. Slower action than spray, but more thorough penetration.
Target Dilution Ratio: 1:10 (stock : water)
Stock Concentrate Composition
| Component | Qty (kg or L) | Purpose |
|---|
| Hydrochloric Acid (33%) | 50 L | Strong rust/scale removal |
| Phosphoric Acid (85%) | 20 L | Passivation, helps in mild derusting |
| Non-ionic Surfactant (e.g., NP-9) | 1.5 kg | Wetting, penetration |
| Corrosion Inhibitor (thiourea-based or amine blend) | 2.0 kg | Prevents flash rusting |
| Chelating Agent (NTA·3Na, 40% solution) | 3.0 L | Stabilizes dissolved metal ions |
| Deionized/Soft Water | Balance to 100 L | Carrier |
Operating Parameters (after dilution)
- pH: 1.5 – 2.5
- Temperature: Ambient to 40°C
- Immersion Time: 5 – 15 minutes
- Agitation: Recommended (air or pump recirculation)
- Post Treatment: Rinse thoroughly → phosphating or neutralizing rinse
Advantages
- Effective on deep pits and heavy rust.
- Longer contact ensures thorough derusting.
- Acid blend controls over-etching and ensures passivation.
Formula-2 – Non HCl Derusting Dip Type Chemical Concentrate formulation
| Component | Quantity (kg or L) | Purpose |
| Phosphoric Acid (85%) | 45 L | Primary rust removal and passivation |
| Organic Acid (Citric Acid, 50% solution) | 20 L | Mild acid derusting and chelation |
| Non-ionic Surfactant (e.g., NP-9) | 1.5 kg | Wetting, penetration |
| Corrosion Inhibitor (thiourea-based or amine blend) | 2.0 kg | Prevents flash rusting |
| Chelating Agent (NTA·3Na, 40% solution) | 3.0 L | Stabilizes dissolved metal ions |
| Deionized/Soft Water | Balance to 100 L | Carrier |
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