ASTM B633, Type III SC1 or SC3
In the electroplating process, the part to be zinc coated is immersed in a solution of zinc ions.
An electric current causes the zinc to be deposited on the part.
SC1 (mild) has a Zinc coating of 0.2 and is recommended for dry indoor use. SC1 is the standard finish thickness.
SC3 (Severe) has a Zinc coating of 0.5 mill and is the standard finish thickness only on UL Listed raceway products.
Unistrut products are available in three types of zinc coatings:
- Electroplated (EG)
- Perma-Gold (ZD)
- Pregalvanized (PG)
- Hot Dip Galvanized (HG)
Zinc coatings offer two types of protection:
- Barrier: The zinc coating protects the steel substrate from direct contact with the environment.
- Sacrificial: The zinc coating will protect scratches, cut edges, etc. through an anodic sacrificial process.
The service life of zinc coating is directly related to the zinc coating thickness as shown below.
Comparison of Zinc Galvanized Finishes
- Hot Dip Galvanized - 2.6 MIL
- Pregalvanized - 0.75 MIL
- Electro-Galvanized (SC1) - 0.2 MIL
- Electro-Galvanized (SC3) - 0.5 MIL
- Perma-Gold (SC1) - 0.5 MIL
- Perma-Gold (SC3) - 0.5 MIL
As shown in the graph, when the zinc coating is double, the service life is double under most conditions.