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Re: A490 bolts

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Javier,

The reason A490 bolts can not be galvanized is due to the possibility of hydrogen embrittlement.  This is a concern when tensile strengths approaches 200 ksi.  A490 bolts are specified at 170 ksi but due to manufacturing variances it was close enough to incorporate the restriction.

If your structure is inside a building then the bolts probably do not need to be coated at all.  If your structure is outside and the steel is galvanized then I would switch to A325 bolts which can be galvanized.  If your structure is outside and the steel is being painted then the A490 bolts can be spot painted after installation.

As a general comment, I would say you should be careful when specifying A490 bolts to make sure that the sizes you are specifying are readily available especial in remote areas and countries.  There is also a concern that if you are using both A325 and A490 bolts and your construction team is suspect then there is a possibility that they could be mis-installed.

Thomas Hunt, S.E.
ABS Consulting




"Javier Encinas" <jencinas(--nospam--at)coqui.net>

10/15/2002 06:19 PM
Please respond to seaint

       
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        Subject:        A490 bolts



Does anybody know why galvanizing A490 bolts is not allowed? Also, what measures are usually taken to protect these bolts against corrosion?
 
Javier Encinas
Encinas & Associates