×
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

shim plates under structures
4

shim plates under structures

shim plates under structures

(OP)
Please anybody advice .. Are shim plates under structural steel should be galvanized?? .. as it`s required by my client and
i dont find any reference standard for such requirement ?

RE: shim plates under structures

Is the structural steel you are shimming galvanized?

RE: shim plates under structures

(OP)
yes, its galvanized

RE: shim plates under structures

Its expensive to galvanize shim... you will have to pay a significant premium for galvanizing small flat pieces like shims, but if its your client requirement i guess you have to provide galvanized shims.

RE: shim plates under structures

(OP)
totally appreciate your answer .. but my question is regardless my client requirements, is it required or recommended by any
international standard or code.
as i see that shim plates anyway will be embedded under grouting and not exposed to air and rust, and in my previous projects i`ve never used galvanized shims under galvanized structures.

RE: shim plates under structures

If the client requires it and is paying for it, the shims have to be galvanized. There is no standard or code that requires the structure itself to be galvanized, but it is just common sense that if the structure is galvanized, all the components should be galvanized. The base of columns, the anchor bolts, etc., is usually where corrosion starts, so that is not the place to skimp.

RE: shim plates under structures

(OP)
hokie66, thx for ur valuable answer, but let me ask the question in a different way,

from metallurgical point of view .. "black steel in contact with galvanized steel embedded under grout" is there any probability to rust.

RE: shim plates under structures

I would galvanize them...no guarantee that the grout will be uniform and completely sealing the area in question...anyway, as hokie pointed out, this is an area prone to corrosion...

RE: shim plates under structures

StudB8 - Shims are not totally embedded in grout. Of course they are surrounded by grout on the sides and top, but most likely, are sitting on a concrete base that has a cold joint with the grout. If water wicks in through the cold joint, and that can happen, there can be a corrosion issue with black steel shims.

www.SlideRuleEra.net idea
www.VacuumTubeEra.net r2d2

RE: shim plates under structures

Would stainless shims be less expensive?

RE: shim plates under structures

Can you cut galvanized sheet or bar into shims? That might satisfy the requirement without having to galvanize a bunch of little pieces.

RE: shim plates under structures

I don't think you want to galvanize the bar and then cut it as the ends would be exposed. The galvanized process is a coating is my understanding.

RE: shim plates under structures

(OP)
Thank you all .. got the point.

RE: shim plates under structures

std88>> If the intent of your OP is metal compatatibility to resist corrosion then.....
Ref: AISC Steel Const. Manual 13th Ed., Table 2-6 : If base metal is galvanized steel and fastener metal is steel or cast iron,
then the corrosion of the galvanized base metal is marginally increased by the fastener.

RE: shim plates under structures

I've galvanized them in the past, just because I thought it a good practice. As JStephens suggested, Galv sheet metal up to 3/16" thick should be readily available, and depending your application, may be acceptable.

RE: shim plates under structures

Hokie66,

A little off topic.... and this may be a matter of interpretation, but I seem to remember ASCE24 having some requirements for galvanizing steel structures exposed to flood conditions.

RE: shim plates under structures

check the galvanic chart. carbon steel and galvanized (zinc) are some distance apart on the chart (300 - 400 millivolts) and zinc will tend to act as the anode. There may be some concentrated corrosion at the shim contact point. stainless steel will not improve this since it would be more noble than carbon steel.

RE: shim plates under structures

A quick check on Google turns up some ready-made galvanized shims, for what that is worth.

RE: shim plates under structures

IFRs, you do NOT want stainless in contact with galvanized. It will chew up your galvanizing quite quickly - if your environment is corrosive enough to warrant galvanizing, anyway. I most often see this with stainless bolts on galvanized items. Nice little halo of corrosion around each of the fasteners.

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