I have read similar threads on this and other forums. I also read this report from Euro Inox (though too advanced for me to understand everything) "Stainless Steel in Contact with Other Metallic Materials" https://www.worldstainless.org/Files/issf/non-image-files/PDF/Euro_Inox/Contact_with_Other_SW.pdf.
Briefly, I am going to attach a larger hot-dip galvanized concrete angle/L-profile to the underside of my balcony (concrete) to mount a post for the railing. https://www.joma.se/byggbeslag/vinkelbeslag/betongvinklar-10-mm/betongvinkel-18
Since the concrete in the balcony is slightly "attacked" I will not use an expansion anchor but instead use anchoring adhesive and threaded rod. I thought I would use a stainless steel threaded rod rather than a hot-dip galvanized one. The mounting of the threaded rod will take place on the underside of the balcony and thus it is relatively protected from water except for condensation and other water that makes its way via the concrete angle/L-profile to the underside of the balcony.
Do I need to worry about galvanic corrosion when attaching this hot-dip galvanized fitting with a stainless steel threaded rod, washer, and nut? Should I also choose a hot-dip galvanized threaded rod, washer, and nut instead?
If I read the document I referred to above at the bottom of page 8, next to image 8a, it states:
"Fasteners of stainless steel on significantly larger components of galvanized steel normally cause no corrosion."
I think it's a similar scenario for me, i.e., the concrete angles/L-brackets are quite sturdy (10.0x310x210x50mm) so maybe I don’t need to worry about mixing with stainless steel.
Briefly, I am going to attach a larger hot-dip galvanized concrete angle/L-profile to the underside of my balcony (concrete) to mount a post for the railing. https://www.joma.se/byggbeslag/vinkelbeslag/betongvinklar-10-mm/betongvinkel-18
Since the concrete in the balcony is slightly "attacked" I will not use an expansion anchor but instead use anchoring adhesive and threaded rod. I thought I would use a stainless steel threaded rod rather than a hot-dip galvanized one. The mounting of the threaded rod will take place on the underside of the balcony and thus it is relatively protected from water except for condensation and other water that makes its way via the concrete angle/L-profile to the underside of the balcony.
Do I need to worry about galvanic corrosion when attaching this hot-dip galvanized fitting with a stainless steel threaded rod, washer, and nut? Should I also choose a hot-dip galvanized threaded rod, washer, and nut instead?
If I read the document I referred to above at the bottom of page 8, next to image 8a, it states:
"Fasteners of stainless steel on significantly larger components of galvanized steel normally cause no corrosion."
I think it's a similar scenario for me, i.e., the concrete angles/L-brackets are quite sturdy (10.0x310x210x50mm) so maybe I don’t need to worry about mixing with stainless steel.
Member
· Västernorrland
· 12 029 posts
Reports are all well and good, but it might be like this........The galvanized lasts for 100 years, the stainless maybe 120 years. The balcony overall maybe 50 years.
You gain nothing by thinking this way and it is probably very Swedish, I think...........In other countries, they just slap things together with whatever and deal with the next problem when it comes, and in your case, what I mean is that it's probably likely the balcony itself might be considered worn out long before what you install is affected.
You gain nothing by thinking this way and it is probably very Swedish, I think...........In other countries, they just slap things together with whatever and deal with the next problem when it comes, and in your case, what I mean is that it's probably likely the balcony itself might be considered worn out long before what you install is affected.
Homeowner
· Klagshamn
· 285 posts
Galvanic corrosion is something that occurs when metals with different galvanic potentials are in contact with each other, and the more humid the conditions, the more corrosion. I would definitely avoid the risk by using galvanized components throughout. If, as you write, it is not a particularly exposed place, I see no advantage with stainless steel. Hot-dip galvanized works excellently, just look at all the lampposts and electrical cabinets that stand outside without rusting.
I built a structure outside with galvanized steel, galvanized threaded rods, and RF nuts. It has been standing there now 30 m from the sea without any problem.
Thanks for the response.
So some would not worry, and some would avoid mixing different metals.
If I could easily replace it in case of corrosion, it wouldn't be a problem, but once the threaded rods are fastened in the anchor mass under the balcony, it's not something I can change.
It wasn't entirely straightforward either with galvanized threaded rods/bolts. "Electro galvanizing is often called bright galvanizing and abbreviated as FZB, whereas hot-dip galvanizing is abbreviated as FZV".
I have found hot-dip galvanized (FZV) threaded rods/bolts where it explicitly states for indoor use and cold galvanized (FZB) where it states for outdoor use. If you read generally about FZV vs FZB, FZV should have higher corrosion protection and be more suitable for outdoor use.
So some would not worry, and some would avoid mixing different metals.
If I could easily replace it in case of corrosion, it wouldn't be a problem, but once the threaded rods are fastened in the anchor mass under the balcony, it's not something I can change.
It wasn't entirely straightforward either with galvanized threaded rods/bolts. "Electro galvanizing is often called bright galvanizing and abbreviated as FZB, whereas hot-dip galvanizing is abbreviated as FZV".
I have found hot-dip galvanized (FZV) threaded rods/bolts where it explicitly states for indoor use and cold galvanized (FZB) where it states for outdoor use. If you read generally about FZV vs FZB, FZV should have higher corrosion protection and be more suitable for outdoor use.
I should have trusted the report. I've only heard of galvanic corrosion causing problems when it comes to copper against steel.
At my childhood home, a galvanized downpipe was installed to receive water from a copper roof. The pipe wasn't in contact with the roof, it was just water with copper ions reaching the pipe. The pipe was completely worn out after 8 years, essentially destroyed.
This was apparently a bit worse than one would expect chemically. My dad was a chemist, and he would usually strongly react to similar phenomena, like leaving metal cutlery in the herring jar on Christmas Eve, etc.
At my childhood home, a galvanized downpipe was installed to receive water from a copper roof. The pipe wasn't in contact with the roof, it was just water with copper ions reaching the pipe. The pipe was completely worn out after 8 years, essentially destroyed.
This was apparently a bit worse than one would expect chemically. My dad was a chemist, and he would usually strongly react to similar phenomena, like leaving metal cutlery in the herring jar on Christmas Eve, etc.