Coatings and surface protection
Galvanizing
Hot-dip galvanizing
A metallurgical zinc-iron alloy layer formed by dipping the part into molten zinc at about 450 °C. Provides cathodic protection and protects the steel even where scratched.
- THICKNESS
- ≥ 70–85 µm
- APPLICATION
- By a subcontractor
- TEMPERATURE
- −40 … +200 °C
- COST
Surface preparation
Surface preparation: degreasing, pickling, fluxing; then dipping. Thickness increases with steel wall thickness.
System and thickness
| SYSTEM | Thickness µm | Coats | Curing / process | Note |
|---|---|---|---|---|
| Steel thickness > 6 mm | ≥ 85 (mean) · ≥ 70 (local) | 1 | Dipping ~450 °C | EN ISO 1461 minimum values |
| Steel thickness 3–6 mm | ≥ 70 (mean) · ≥ 55 (local) | 1 | Dipping ~450 °C | EN ISO 1461 minimum values |
Thickness as dry film (µm). Emsal standard; binding values are set by the order specification.
Service temperature
−40 °C+200 °C−200−1000100200300400500600700800
Typically up to 200 °C; above that the zinc layer can separate.
Media suitability GENERAL TREND
Indoor (C1–C2)
Urban, industrial (C3–C4)
Marine, coastal (C5)
Immersion in water (Im1)
Buried (Im3)
High temperature
Abrasion, impact
UV, sunlight
Emsal assessment. The final choice is made from corrosion tables, taking concentration, temperature, chloride content and flow velocity into account.
Strengths and weaknesses
Strengths
- Long life and cathodic protection (protects scratches too)
- Highly resistant to abrasion and impact
- Complete coverage including internal surfaces and corners
Weaknesses
- Precision surfaces and threads are affected
- No colour options (a duplex system with paint is possible)
- Depletes quickly in acids and strong bases
Manufacturing and use
- ECONOMY
- Medium.
- MANUFACTURING METHODS
- Degreasing and pickling · Hot dipping
- TYPICAL VALVE PARTS
- Flange · Bracket · Expansion joint flange
Emsal practice
- APPLIED BY
- By a subcontractor
- APPLIED TO
- Option for wafer and short-pattern swing check valves; flanges of supplied rubber expansion joints (supplier standard)
Used in 2 Emsal products
- 001Wafer check valveCoatings (iron-carbon parts)
- 005Short pattern swing check valveCoatings (iron-carbon parts)
Source: EN ISO 1461. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.