Galvanisation or galvanization or galvanizing as it is most commonly called is the process of applying a protective zinc coating to iron or steel, to prevent rusting. The most common method is hot dip galvanizing, in which steel sections are submerged in a bath of molten zinc. Types of Galvanizing and other Zinc Coatings Batch hot dip galvanizing. Prepared items are galvanized by immersion in molten zinc. Continuous galvanizing processes in-line galvanizing Thermal spray or metallising Sherardizing and thermal diffusion.
Mechanical plating. Zinc rich paints. Like all ferrous metals, zinc corrodes when exposed to air and water. Please enter your name. Please enter your mobile number. Please enter valid Mobile number. Select Class Please select the class. Forgot Password? OTP has been re-sent.
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Satyanarayana Prasad. But, hot dip galvanization is known to have very high life averaging between 20 to 50 years. Electro-galvanization comes with excellent finish. However, hot dip galvanization has dull, unpleasant finish. The coating thickness entirely depends upon the dipping duration. The latter has normal coat thickness that is much affordable. But, the cost is said to increase proportionately with higher coating thickness.
Hence, it becomes expensive. Hot dip galvanization is provided with non-uniform coating, while the other one with uniform coating. What is the minimum thickness for hot-dip galvanizing? We need an outdoor cabinet for about 25 years and dont want to renew it. We thought that building it with galvanized sheet metal is meaningless because zink will be gone from the welding points. Is it the best; hot-dip galvanizing after building the whole cabinet?
Abdullah- The minimum thickness for hot dip galvanizing of bolts and hardware, which is what we do, is 2. For structural members the thickness can vary from 1. There are different standards for sheet metal, and I am less familiar with what those requirements are. Galvanizing the cabinet after fabrication might be a good idea, but you would need to discuss dimensions and details with your galvanizer and make sure it is within their capabilities.
Khozema- No, hot dip galvanizing is a completely different coating than a zinc chromate. Chromates are simply a sealer on top of the metallic coating, whereas hot dip galvanizing actually bonds with the steel in order to protect it. Where can I get a swing set hot dipped galvanized again? It is about 60 years old and some places have rust showing. I am in the Houston , Texas area.
Robert- You would need to call around to some local galvanizers and find out what their largest item dimensions are. Your swing set would be much too large for our tank. For street light poles please give comparisons that hot dip galvanised poles are better than swedged poles. Kailas- Hot dip galvanized and swedged anchor bolts are not mutually exclusive — you can have both. Does it meet the same specs? Dan- Mechanical galvanizing is performed per ASTM B, and is tumbled with zinc dust and glass beads in a liquid medium, so the zinc is cold fused onto the steel.
Hot dip galvanizing is just that, dipped into hot molten zinc. For wedge anchors mechanical galvanizing is more commonly available, although I believe some manufacturers make hot dip galvanized anchors. Dear Sir now i planed to purchase the electroplated Swivel coupler for scaffolding purchase. Rabindra- Hot dip galvanizing is a much thicker coating and will provide a longer service life than electroplating.
Your descriptions above indicate that electroplating is not suitable for outdoor applications. Would that include underwater applications? Ramsey- Electroplating is a very thin coating 0. Hot dip galvanizing is roughly 10 times that thick approx 0. We cannot make any recommendations for your specific application, but caution should be used with electroplating if corrosion protection is a concern.
During Electro Galvanizing of CS fittings why the coating thickness on the outer surface is more than the inner surface.? Is it not possible to achieve same coating thickness on both outer and inner surfaces? Jabin- I am sorry, but we are not experts in electro plating, you will need to contact an electro plater in order to determine why that is. Is there a dissimilar issue when using different kinds of galvanizing?
Thanks, Danny. For many grades of bolt, ASTM specifies that the plating types be the same. In addition, nuts for use with HDG bolts are tapped oversize to accommodate the thickness of the zinc. For electro plated nuts, this is not the case, so you could run into thread fit issues. Is a 85um layer a problem to achieve? We should be able to get that thickness on our fasteners as an average thickness, but we could not guarantee that there would not be spots that were thinner than 85um.
Can electroplating be done after hot dipped galvanizing for shinier surface? Will the galvanizing still hold after the plating top coat? The zinc plating covered only the outside surface but not the threaded area.
Rita — electro-zinc plating should be on all surfaces of the nut, including the threads. Thicker coatings, like hot dip galvanizing require that the threads be overtapped after coating, so those threads are bare. If so, what are the possible thickness can be coated? What about their lives? Can we heat the coated SS upto deg C?
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