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Re: Tack-welding nuts of high strength bolts

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On Jun 13, 2006, at 10:00 AM, Garner, Robert wrote:

I would appreciate any opinions on tack-welding these nuts.
I don't think it's such a great idea. No doubt your fabricator does it all the time without any problems, but tack welds are simply crack starters waiting for the right load to fracture. That's especially true if you're using heat-treated or medium carbon steel nuts as required by the bolting spec. The starting and stopping points of welds are always prone to cracking and tack welds are just starts and stops with no actual weld between.

The A-194 grade 2 nuts specified for A-325 bolts have a carbon level of 0.40 which is not permitted for welding at least by the ASME Code, which is another red flag for me.

I've also run into distortion problems with tack welds in smaller bolt sizes. You can get around distortion if you assemble the joint before you tack it, but then you can get into problems with disassembly.
Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)skypoint.com   | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw/


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