×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Steel Transfer Girder over Pool
2

Steel Transfer Girder over Pool

Steel Transfer Girder over Pool

(OP)
I am designing a 60 foot plate girder just below the 3rd floor of an 11 story hotel picking up a building column (supporting 8 floors and a roof) over a pool.

Any suggestions on how to provide corrosion protection on this very important structural member?

RE: Steel Transfer Girder over Pool

I would suggest:

It would be best to avoid the chlorides and vapors.

1. Hot Dip Galvanized
2. Inorganic zinc with three coats (prime, intermediate and finish) with each coat no less than 10 mills.
3. Cathodic protection (sacrificial anodes)

Regards,



Lutfi
www.cdeco.com

RE: Steel Transfer Girder over Pool

I agree with Lutfi.  Hot dip galvanizing is the way to go.  We design potable water reservoirs.  The atmosphere above the water has a very strong chlorine odor, much higher than you'd accept for the public.  We've been covering these reservoirs with hot dip galvanized framing for 40 years now.  I've done surveillances of these existing reservoirs and the galvanized steel is never a problem.  Sometimes we get mechanical wear of the galvanizing due to thermal movement of the metal roofs, but even that is unusual.

RE: Steel Transfer Girder over Pool

(OP)
At that length, there may need to be a field splice to get it into a dip tank. The bolted field splice will be a great place for corrosion to begin also. How do you protect the splice?

I will also need to fireproof this member. Is spray-on compatible with galvanizing?

RE: Steel Transfer Girder over Pool

What is Lutfi's #2, is that a paint-on protection of some sort?

RE: Steel Transfer Girder over Pool

I would try to avoid the splice.  If I recall correctly, plate girders can ship at more than double your length, so that shouldn't be a problem unless you have site specific access issues.

RE: Steel Transfer Girder over Pool

I know for a fact that in our area (with one 45 ft. kettle) that 60 ft. long members are not a problem.

RE: Steel Transfer Girder over Pool

I would contact local galvanizers and verify the longest piece that they can dip in the tank.

I have no issues with splicing. As a matter of fact, splicing may be required, as was mentioned by others, so that the steel can be maneuvered in the building. I would use bolted connections. One word of advice, account for the zinc coating for your holes. The standard AISC 1/16 larger than bolt does not apply unless you intend on hammering the bolts in!

UcfSE, the inorganic zinc is a nice coating that has been tested for the last 10 to 15 years here on the east coast of Florida. It requires steel to be blasted to near white metal according SSPC-SP10 which is expensive. The following link has more explanation of the cleaning specifications: http://www.nace.org/nacestore/assets/freestandardsreports/NACE2.pdf#search='sspc%2010'

 When paint is sprayed, it has to be done under environmentally controlled conditions (certain Relative Humidity (RH and temperature).
It works great. Basically the paint has zinc in it and acts as a sacrificial anode (as in HDG) and the zinc are expended with time.

I specify it a lot on the east coast of Florida for exposed steel frames.

Regards,

Lutfi
www.cdeco.com

RE: Steel Transfer Girder over Pool

What about the compatibility of spray on fireproofing?  I would have thought that the humidity alone would not be good for the bond to steel, then compounded by galvanizing.  This seems like a bigger problem to me.
 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources