×
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

Bolts dimensions change after galvanizing

Bolts dimensions change after galvanizing

Bolts dimensions change after galvanizing

(OP)
Hello All,

We have a problem with galvanized step bolts stripping from the nut. When we complained this situation to the manufacturer, they come up with an excuse to say that these bolts could have reduced dimentions (diameter) because of hot dip galvanizing or picking process. The lab. has done basic tests and found after removing the galvanized layer, the bolt diameter has reduced slightly compare to oroginal diameter of the bolt (before galvanizing). Can anyone tell me what is the scientific reason behind the phenomina?

Thanks in advance







RE: Bolts dimensions change after galvanizing

AISC/RCSC Section 2 (Para 2.1 Parge 16.2-5) is very specific on galvanized bolt because of this phenomena. It is a common complaint in the field. The manufacturer is required to test each lot of bolt assembly (bolt and nut) after galvanizing to verify that the galvanizing process has not reduced bolt tension ability
From AISC/RCSC
"This testing must show that the galvanized or Zn/AQl coated nut with the lubricant provided may be rotated from the snug-tight condition well in excess of the rotation required for pretensioned installation without stripping."

Was a Certificate of Conformance (C of C) provided for each lot showing the testing had been performed? Even if it was and you are stripping bolt during normal tensioning I would go back to supplier and have them replace lots affected based on AISC/RCSC.

Just as background on this. Bolts/nuts to be galvanized are machined slightly under size to accommodate addition of coating thickness to bring bolt/nut into the required fit tolerance that would prevent the stripping you are experiencing. That is why the Code requires the testing to verify the variables in the galvanizing process do not degrade the tension capability of the bolt/nut assembly.

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