Hot-dip galvanizing is a process of applying a protective zinc coating by dipping product in bath of molten zinc. Galvanizing is a favored method of protective coating due to its low cost, ease of application, and long maintenance-free service life. Generally applied at 830 to 870 degrees, the zinc will bond with the steel. It is the most common outdoor protective coating in use. When used on bolts, due to the thickness of the zinc coating, all galvanized nuts must be tapped oversize.
Zinc plating or electroplating is a process where zinc is applied by using a current of electricity. It is a thinner coating than hot-dip galvanizing making it unsuitable for outdoor applications. Its advantages are its brightness and uniform color making it more aesthetically appealing.
The ASTM specification covering hot-dip galvanized fasteners is F2329, while the specification covering zinc plated fasteners is F1941.
I need to specify exposed bolts for use on timbers in an indoor swimming pool area. Stainless, galvanized, or A307 zinc?
@Brian- there are pros and cons to all three of those options. The only one we’d caution against is zinc. Electro-zinc plating offers minimal corrosion resistance and is mostly aesthetic. As for stainless and galvanized, both offer significant corrosion protection, but since we do not employ any engineers on staff, we are unable to make any recommendations as to which is best for your application.
We have SG Iron casting products Insulator Metal Fittings and we do hot dip galvanizing but after machining Shine gone so I want to know if we do electroplating over hot dip galvanizing product what will happen it effect coating thickness or not.
One more thing how to increase hot dip galvanizing thickness we required over 150 micron
@Aman- We have not heard of anyone electroplating over galvanizing, so we are not sure if/how that would work or what the pros or cons could be. You probably want to discuss with your electroplater and galvanizer to see what your options are and if they are able to increase the thickness of their zinc.
I want to know if I can use galvanized in SAE grade 8. If I can’t, what surface coating are there on the market for grade 8?
@Walker- There is no specific prohibition against galvanizing SAE J429 gr.8 bolts, but we do not recommend it due to hydrogen embrittlement concerns. Zinc plating is typically acceptable and widely available, as are any number of metallic and non metallic coatings.
Does HDG hardware are suitable to use inside transformer with transformer oil?
Or it will create some chemical reaction with transformer oil.
@Chetan- Apologies, but we don’t have any information regarding zinc and transformer oil.
Dear Babu,Galvanizing is done on steel parts prone to rusting & corrosion.Where is the need to galvanize SS which are corrosion resistant by nature?
@A.S.- Not only is it unnecessary to galvanize stainless steel materials, the zinc will not properly adhere to the stainless steel, so it is impossible.