Cor-ten weathering steel 1

[csd72]

Does anyone know of any additional issues associated with the use of cor-ten weathering steel? Are there any compatibility issues with welds/fasteners e.t.c?

Will galvanised bolts work?

I havent been able to find much info on the US steel site.

 

[csd72]

I actually found the answer to my own question:

http://www.aisc.org/MSCTemplate.cfm...tomSource/Faq/SteelInterchange.cfm&FaqID=2311

 

[dik]

Corten can cause staining of concrete surfaces and the initial weathering may not be uniform.

Dik

 

[HgTX]

There are inaccuracies in that AISC article. I've tried to get them to take it down but they won't.

There are a number of resources linked from the Wikipedia article:

http://en.wikipedia.org/wiki/Weathering_steel

Hg

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[UcfSE]

You would use a different type of bolt, nut and washer (I believe all three). For instance, typical A325 bolts are usually type 1. For weathering steel you would use type 3. If I remember correctly you would specify these types instead of galvanizing.

 

[bridgebuster]

Take a look at the FHWA guidelines

http://www.fhwa.dot.gov/legsregs/directives/techadvs/t514022.htm

 

[NITTANYRAY]

Do not use Cor-Ten steel in areas where moisture can collect such as ledge angles. A couple years ago we had to replace channels and ledge angles supporting balcony slabs. They rusted badly. If the Cor-Ten doesn't dry-out occasionally the protective coating will not form.

 

[JedClampett]

When I was a student, this was marketed as the greatest thing since sliced bread. Fifty ksi and no coating! How could you go wrong?
AS I remember, there was also an issue with the corrosion weathering off due to wind and other wear and the sections being eventually reduced to an unacceptable section.
Well, as the links above show, there's no such a thing as a free lunch. Why do you want to use it anyway?

 

[gr2vessels]

csd72,
Type Corten in the search box, in top of this page and select Search Posts in the advanced search box. This steel has been detailed to extreme end in the last few years, happy perusal for you. You'll find everything you need to know.
cheers,
gr2vessels

 

[HgTX]

It's used quite sucessfully for bridges.

Hg

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[Robertmet]

Long ago it was found that if concrete is below ,the concrete can be stained with rust.Water must not collect on the steel....Our new bridge on the Delaware River I found was made of Corten while I was photographing it.I asked the engineer why , if it was made of Corten, were some , not all ,of the girders painted ??? He said that only the outer girders, which would be easily seen were painted because people didn't want to see a brand new bridge rusting !!! LOL LOL. ...The only thing left to do on the bridge is to put in the railings .But why has there been a delay ? Architect [??] didn't want to use standard shapes etc. so he designed something different ! That aluminum railing was cracking during fabrication so it was back to square one .The railing might be available early next year !!!

 

[HgTX]

Robertmet, I don't really understand what you think is so LOLable.

Often the ends of all the girders are painted where the bridge joint is, both because the steel may need some extra protection from an open or leaking joint and to prevent the water from carrying rust down the support. They try to match the color of that end paint to what they think the weathered color will be, but it's hard to get that match. So sometimes they paint the fascia girders so they don't have to worry about the color match.

Other times, it's been decided (by whoever) that a green, beige, blue, whatever color bridge is what is wanted. Not everyone likes brown for their infrastructural monuments. If you asked the public to vote on a color for their bridge, I doubt brown would be in the top 5 choices--and a major span across the Delaware River had better take aesthetics into account. An economical approach in that case, rather than painting the whole bridge just for aesthetic reasons, is to use weathering steel and paint just the fascia girders.

So what's so funny?

Hg

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[Robertmet]

HgTX, If you were here and watched the bridge over the construction ,now going into the fifth year You'd also be looking for some comic relief !!! Looking for indian artifacts ,$$$ and one or more year. Study fresh water mussels ,$$$ at least one year .Then start bridge and work bit by bit into five years !

 

[rootsxrocks]

I have seen cor-ten rust completely through when it was used in an environment were frequent high winds blew sand.
This was an incident were it was used as the foundation for a house and had to be replaced with an engineered laminate beam. Had it not been spotted during a plumbing repair it could have been a disaster for the homeowners.

 

[csd72]

rootsxrocks,

yes, the above mentioned articles go through where the steel is appropriate/innapropriate.

HgTx,

What innacuracies are there in the AISC article? It all seems pretty reasonable stuff to me, but I have never used this material before.

csd

 

[HgTX]

The Steel Interchange article had a lot of claims about painting that just aren't true and didn't match what was in the ISG publication they cited (which is now a Mittal brochure).

Here's the Mittal brochure (formerly the ISG Cor-ten brochure):

http://www.mittalsteel.com/documents/en/Inlandflats/ProductBrochure/weathering.pdf

The Cor-ten info they have in the Steel Interchange article seems almost to imply that Cor-ten needs to be painted even more than regular steel does, since it stresses that any surface "not boldly exposed to the weather" must be painted. Faying surfaces, non-fascia surfaces of bridges, indoor applications, etc.

That just ain't so, and the Mittal publication doesn't say it. There are two different ways "proper oxide formation" can be prevented. One is in a highly corrosive wet environment where the steel will continue to corrode, lose corrosion product, corrode again, etc. (The building foundation mentioned in another post would be a prime example.) But then there are areas in which nothing much happens to it--like a properly detailed faying surface (the Mittal flyer does say to keep bolt spacing close enough to exclude water) or the underbelly of a highway overpass in moderate climate (not a lot of salt spray kicked up from underneath). For example, there is a 40-year-old WS bridge in Austin, TX (eastbound 51st St. over I-35, I believe), that never even formed the patina on its non-fascia surfaces. It's flaky, but shows negligible section loss. Austin isn't as humid as Houston, but it's not Phoenix either; relative humidity in the mornings is around 80-90% year-round. For interior exposure, if you wouldn't paint your non-weathering steel, you have no reason to paint your weathering steel either.

The USS literature cited by AISC deals excessively with when WS needs to be painted; as I said, it almost implies that it needs to be painted more than ordinary carbon steel. In reality, if you're going to paint WS, you might as well not use it. It won't do its weathering thing under the paint, and will corrode through a paint pinhole just as badly as ordinary carbon steel will. Paint on WS is not a case of belt and suspenders.

Hg

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