Coatings and surface protection
Zinc plating
Electrolytic zinc plating
A thin, even zinc layer deposited in an electrolytic bath, followed by passivation (trivalent chromium). The Emsal standard for medium-size wafer check valve bodies.
- THICKNESS
- 8–12 µm
- APPLICATION
- By a subcontractor
- TEMPERATURE
- −40 … +120 °C
- COST
Surface preparation
Surface preparation: degreasing and pickling; electrolytic zinc; trivalent chromium passivation (free of Cr⁶⁺).
System and thickness
| SYSTEM | Thickness µm | Coats | Curing / process | Note |
|---|---|---|---|---|
| Fe/Zn 12 + passivation | 12 | 1 | Electroplating + passivation | Moderate environment; Emsal standard |
| Fe/Zn 8 + passivation | 8 | 1 | Electroplating + passivation | Indoor, bolts and small parts |
Thickness as dry film (µm). Emsal standard; binding values are set by the order specification.
Service temperature
−40 °C+120 °C−200−1000100200300400500600700800
Typically up to 120 °C (passivation layer).
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
- Even, thin layer that does not affect dimensions
- Bright appearance
- Suitable for threads and precision surfaces
Weaknesses
- Thin layer: short life outdoors and in water
- Not suitable for marine environments
Manufacturing and use
- ECONOMY
- Low.
- MANUFACTURING METHODS
- Electroplating · Passivation
- TYPICAL VALVE PARTS
- Body (medium sizes) · Bolts · Small parts
Emsal practice
- APPLIED BY
- By a subcontractor
- APPLIED TO
- Wafer check valve, carbon steel body, DN 200–400
- SYSTEM
- Fe/Zn 12 µm + trivalent chromium passivation
Used in 6 Emsal products
- 001Wafer check valveCoatings (iron-carbon parts)
- 005Short pattern swing check valveCoatings (iron-carbon parts)
- 311Rubber expansion jointCoatings (iron-carbon parts)
- 312Double sphere rubber expansion jointCoatings (iron-carbon parts)
- 313Externally pressurized expansion jointCoatings (iron-carbon parts)
- 314V-flex expansion jointCoatings (iron-carbon parts)
Source: ISO 2081 · EN ISO 4042. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.