Letter 8075

Conductivity - Galvanized / Galvanealed 

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I am a custom job shop, primary product is cabinet and case work for the telecom industry. We have an application for a client requesting galvanealed or galvanized material. I understand that one is more accepting of paint finishing while the other is not.

My question is do both materials carry the same conductivity charastictics? Are they both conductive? I always thought they were but I am told otherwise.

Michael Lozy
- Warwick, RI, USA

Galvanneal is merely galvanized steel which has been annealled. The annealling furnace is downstream, from the zinc bath. Galvanneal is easier to paint. The surface is a smooth, dull grey. Usually, it is lightly oiled or even dry.

Galvanize sheets have a bright zinc finish (like garbage cans). The surface is not smooth. Zinc crystals may show through the paint. The surface is normally treated with a chromate solution which is for rust protection. This solution prevents good paint adhesion.

Terry T. Magyar
steel - Gahanna, OH usa

The galvanneal process converts most of the zinc and some of the iron at the substrate surface to an intermetallic iron-zinc compound. The electrical conductivity for the intermetallic probably is not as great as that for the zinc or iron metal. Thus, the surface conductivity may not be as high for the galvanneal.

Larry Hanke materials testing laboratory Minneapolis, Minnesota

What is the difference between Galvanealed, Galvanized and pre-galvanized.

Eileen Travis
- S Attleboro, MA, USA

Pre-galvanized means that the item in question is made by bending, punching, and otherwise working sheet steel that was galvanized before the working began, rather than galvanizing the item after the other fabrication steps are completed.

Pregalvanized material is used for economy (because it is far less labor intensive to galvanize a continuous sheet than individual fabricated items). If it is integrated correctly into the design, the product should be just as good as a post-galvanized item. But if the design is not so good, there will be rusting at the edges and around any holes because there will be no galvanizing on edges that have been created after the galvanizing process.

 
Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

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