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Re: Hot-Dip Galvanizing of A 307 Bolts and Related Nuts

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I missed the remainder of the day's responses, so your question may have already been answered by one of the "heavies".
If not, to put the process in terms with which you may be familiar, mechanical galvanizing is performed in much the same manner as "moly" is applied to "moly coated" bullets.  It is a "cold" process.
Regarding "fit" problems with hot dip galvanized fasteners, I have minimized this as a field issue by specifying that the fasteners (at least the bolts and nuts) be supplied as an assembled unit when HDG is required and specified.  Thus if there are fit problems, they must be addressed by the supplier, who can employ relatively inexpensive labor in the warehouse to perform the assembly prior to shipment.
Mark D. Anderson  PE
----- Original Message -----
Sent: Monday, December 08, 2003 8:09 AM
Subject: Q: Hot-Dip Galvanizing of A 307 Bolts and Related Nuts

I have a job going for purchasing. I got shop drawings on miscellaneous steel which will be connected to some timber members using A 307 bolts.


The bolts were shown on the shop drawings as ?hot-dip galvanized.? I changed it to read ?mechanically galvanized.? Now the supplier claims it will take them over a week to get those.


The contractor wants me to ?handle it? (implying ?use hot-dip galvanized bolts?). I am uncomfortable with this because of past reading where hot-dip galvanizing of bolts caused fit-up problems and heat-related problems with the bolt material.


However, A 307 is not considered ?high strength? I believe, so it may be all right to hot-dip galvanize.

Comments, please.


William L. Polhemus, Jr. P.E.

Polhemus Engineering Company

Katy, Texas USA