SS in Concrete - Corrosion

[JLB23]

We've been installing aluminum poles (6063-T5) in concrete footings. We'd like to switch to SS poles as the contractors keep damaging the tar and ZRC (zinc rich compound) that we've been applying over the aluminum tubing to keep it from corroding.

Is there one SS that would be better in this application? SS304? SS316?

 

[Metalguy]

*IF* you can use very low Cl water in the concrete, and there is no road salt around, the 316 might be OK. If not, try 2205 or even something with a lot of Mo, like 254SMO.

 

[CdotS]

What kind of poles are they? Are they utility poles on the side of streets/roads? Of the stainless steels, 304 is cheaper than 316. If you have normal environment (away from the coast), these low-cost stainless should do the job.

Did you consider galvanized steel poles? Now-a-days they have long expected life over 30 years(it depends on the thickness of the zinc coating and atmosphere). Zinc should provide cathodic protection even if it gets scratched during installation.

 

[metengr]

There is an interesting technical paper titled " Use of Stainless Steel Reinforcement Bars for Concrete Structures" that outlines extensive testing of stainless steel rebar (304, 316 and a Duplex alloy) in various chloride environments. Despite the fact that this is for rebar, and you have poles embedded within concrete footings, similar correlations can be drawn;

http://www.indianengineer.com/Steel/Use_of_Stainless_steel.htm

 

[mcguire]

Note that for structural applications pitting corrosion is inconsequential, unless aesthetics are of major concern. Therefore a stainless that is normally not recommended, such as 304 in sea coast environments, can actually perform quite satisfactorily, because its weight loss to corrosion via pitting is minor. Explore nickel-free grades, such as 409 and 439, which are commonly available in tubing due to their extensive use in automotive applications.