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Hot dipped galvanized vs. electrogalvanized



(-----) 2006

Clevis hangers that are to be used to support piping are available in hot dipped galvanized finish or Electro- Galvanized. My question is which coating is the better?

Graeme Mc Dougall
Construction - Austin, Texas
^


2006

Hello, Graeme. Electrogalvanized just means zinc electroplated. Either electroplating or hot dipping can be used to apply the coating of zinc to steel (and there are other methods as well). Zinc electroplating has a definite advantage in appearance and for close fitting parts, but hot dipping will give much better corrosion resistance because the zinc coating will be about five times thicker.

Very similar questions have been asked and answered many times on this site. So if you need a 2nd opinion, patient application of the search engine will yield it.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


June 5, 2008

I am planning a fence that will incorporate stringer hangers that are either hot dipped galvanized or electro galvanized. Can I use hot dipped galvanized nails with electro galvanized hangers and visa versa?

Daniel Wilkinson
- Boulder, Colorado, USA
^


June 5, 2008

Hi, Daniel. "Electro galvanized" means zinc electroplated. I don't know the origin of the term but it may have simply been an invention by a marketing manager to attempt to ride the coattails of the more expensive and more durable finish through obfuscation :-)

There should be no compatibility problem between the two finishes but the electroplated parts may not prove very durable in outdoor exposure as the protective zinc coating will only be perhaps a fifth as thick as the hot dipped coating. There is nothing intrinsically questionable about electroplating; it can be an outstanding finish. But zinc electroplating is no substitute for galvanizing in outdoor exposure. Good luck.

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


July 7, 2008

I am re-roofing my house. The local code calls for 8D ring-shanked roofing nails to re-nail the plywood decking which, in my case, is 1/2 inch plywood. The re-roof will be premium material: 30 # standard felt but then 170 # with 250 # in the valleys and at penetrations. Accordingly, I spec'ed premium nails even though roof will be hot-mopped with premium 170 modified SBS underlayment/250 as above and then tile roof. I wanted Maze of Peru, Illinois, double-hot dipped galvanized 8D nails (Maze product # R107A)but it turns out that Maze nail must be hand-driven and my roofer uses an Hitachi 75 AG nail coil gun. He is proposing to use Hitachi ring-shanked diamond point "electro-galvanized" nails---made in the United Arab Emirates. Is this excellent or is there a better product out there for my application which can be used with a coil gun? Or is this UAE-manufactured nail a pretty good product? (I recognize it is not as corrosion-resistant as double hot-dipped and CORROSION is my prime quality issue for the nails). Shall I just go with the flow or can I get something REALLY good which works in a gun? The hand-driving will add about two man days at $ 55/hour to my cost (almost $1000) I am told. What should I do?
THANK YOU VERY MUCH!

James Bell
- Naples, Florida, USA
^


August 20, 2009

Hi, James. As long as this plywood is not pressure treated (and it shouldn't be), and as long as the nails are not exposed, I would think that you can let the builder use the nails that he must use for power tools (hot dip galvanized coatings are probably too thick and drippy to use in these machines). But where you have exposed nails, like the top course of shingles at the peak of the roof, you could ask him to hand drive hot dip galvanized nails.

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


April 7, 2011

Ted,

Great insight on these questions. My company works as a manufacturer of custom roofing materials. We have sources for hot-dip galvanizing and electro-galvanizing. Our electro-galvanizer has two types he refers to as yellow zinc and white zinc. The products we manufacture are of course used for outdoor applications. Can you provide some insight into the different types of zinc and if one coating is preferred in an outdoor setting.

Thanks

Jacob Anderson
employee - American Fork, Utah
^


April 7, 2011

Hi, Jacob. Zinc plated materials are invariably chromate conversion coated to deter white rust. Traditionally these chromates were hexavalent chrome based, and hexavalent chrome is yellow-amber in color. Hence the name "yellow zinc". The color could be leached out in hot water, or the coating applied very thin, or trivalent chromate used instead so that it was more clear or more like "white zinc".

Yellow zinc traditionally had much more hexavalent chrome and offered better corrosion resistance. But today there is significant environmental pressure to stop using hexavalent chromates, and in many industries (like the auto industry) only trivalent chromates are used anymore. Some say today's trivalent chromates are the equal of yesteryear's hexavalent chromates.

n the auto industry today the trivalent chromates are simply dyed yellow and are otherwise exactly equal to the "white". Sorry, I don't know whether your yellow roofing material is hexavalent chromated or trivalent chromated and dyed, but that's the short term answer anyway. Eventually there will be no more hexavalent chromium in roofing material and there will be no performance difference between yellow and white. Good luck.

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


August 29, 2013

Q. I am looking to purchase Galvanized Zinc coated Hexagonal mesh wire (Chicken wire) to make fish traps for fishing in the ocean/sea.

I would like to know the life expectancy of electro galvanized steel wire versus hot dipped galvanized steel wire versus PVC coated.

I know that hot dipped last longer as it is thicker but I only need something that will last 5-8 months when immersed in salt water and that will not be too expensive.

Best regards.

Dereck Lambert
Tropical Sea Foods Distributor - Hollywood, Florida, U.S.
^


August 30, 2013

A. Hi. PVC will last "forever" until it is cut, but it will be, then it won't last long. I think electrogalvanizing will be completely worthless in the ocean. Sorry but your suppliers or even local fishermen will know more about the real world durability than I would.

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^

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