|
Hot-dip galvanizing |
Electro-galvanizing |
Paint |
Corrosion Protection |
Cathodic & barrier |
Cathodic & barrier |
Barrier |
Coverage on corners/edges |
Uniform coverage including corners, edges, and threads |
Maybe thin or no coating in difficult to access areas |
Holidays and pin holes possible, coating tends to thin on edges/corners |
Coating thickness |
1.7 to 3.4 mils |
0.2 mils |
1-3 mils |
Bond strength |
3,600 psi |
300-600 psi |
300-600 psi |
Hardness |
Alloy layer harder than base steel, with DPN hardness ranging from 179-250 |
50% as hard as base steel |
Soft & susceptible to handling damage |
Temperature range |
-100 C to 200 C |
-100 C to 200 C |
Dependent on formulation |
Paintability |
Can be painted |
Can be painted |
n/a |
Application |
Shop |
Shop |
Shop or field |
Conditions |
Independent of weather |
Independent of weather |
Temperature & humidity restrictions |
Procedure |
After cleaning with series of chemicals, dipped in molten zinc bath, then spun to remove excess zinc |
Clean steel, immerse parts in a zinc acid bath, and drive current through bath |
Clean steel rinse, dry, brush or spray multiple coats |
Performance: Time to first maintenance |
50+ years |
10+ years |
10-20 years |
Suitability |
Outdoor and indoor, applications |
Outdoor sparingly, indoor main applications |
Outdoor and indoor applications |