Dissimilar metals
Dissimilar metals
(OP)
I know that in general dissimilar metals are problematic and to be avoided. My specific question is about the pair: zamac and stainless steel. The specific use is a zamac female nut body (Star threaded insert, similar to a closed barrel nut) embedded in concrete and receiving stainless steel threaded rod. Is this inadvisable?





RE: Dissimilar metals
RE: Dissimilar metals
This is a useful connection detail for us, but perhaps it is too risky. What extent of corrosion would you expect with a 3/8" diameter rod?
www.caryconcrete.com
RE: Dissimilar metals
http://www.ucanfast.com/cast_in_place_anchor.html
RE: Dissimilar metals
www.caryconcrete.com
RE: Dissimilar metals
One thing to be aware of is that as the Zn corrodes the corrosion products take up more space, so the anchor will swell. Could this cause cracking and lead to failure?
If this were at sidewalk level and there was a chance of salt water from deicing getting in then it might fail in a season or two.
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RE: Dissimilar metals
RE: Dissimilar metals
to be more clear about the detail. In terms of the potential for water to get to the insert, it is more extreme than typical because one side is below grade. I am concerned about the "decades" issue. I've never seen a visible problem, and I'd have to break one open to assess the extent or if corrosion was actually occurring. But it looks to me like we should avoid this in the future and use only a stainless insert with stainless rod. Is it true that if I used galvanized (hot dipped, not electroplated) threaded rod with the Zamak insert I should anticipate no problems? Thanks to everyone for their comments.
www.caryconcrete.com
RE: Dissimilar metals
If you have never seen one of these corrode enough to crack then maybe it isn't a big issue. These are usually not under much load, are they?
Yes, you right to be concerned about a below grade application. Being constantly wet will lead to early failures.
What comes to my mind is the use of galv parts in general construction. In areas that are near the coast even simple parts inside exterior walls will corrode an fail.
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Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm