If, during the course of your inspection, you encountered unspecified tack welds between grade-8 bolts and A36 plate washers, what would you do?
Would this require qualification?
C C,
If the tacks are unspecified as you mentioned, then they are also undocumented and most likely made by unqualified personnel.
I would photograph them and make an informal report to the Engineer.
Why are grade 8 bolts being used? In most applications for anything structural....OOOPPPS..... SSSOOOO... What Code are we dealing with?? What type of project is it? What more can you tell us?
NOW, if this is a stuctural application to D1.1 and AISC then more than likely there should not be grade 8 bolts in use. Also, welding to any bolt, in ALMOST any application is non-compliant.
There are some ways of getting a procedure qualified to tack bolts in place in certain applications for certain codes. You won't see it often as the bolt is no longer qualified for it's part of the job. Especially a grade 8 bolt. Once you weld on it you change it's mechanical properties.
Have a Great Day, Brent
The grade 8 bolts are being used to fasten precast concrete members to structural steel. Both the steel and precast welded connections are subject to D1.1. The drawings call for ASTM A193, grade B5, bolts, with only the plate washer tacked to the steel.
In addition to what Brent has posted....I doubt that you will find any of the bolt ASTM materials listed in any pre-qualified list of materials(ie D1.1)...so if using D1.1, it would require a "qualified by testing" welding procedure. I can tell you before you call any high strength bolt mfg to ask about welding on their high strength fastener, that they will not recommend welding in any way shape of form due to the heat treating of the bolt. After they have heat treated the bolt to get the strength required to meet the ASTM specification for that grade of bolt, any further heat added will destroy the original heat treating.
Tack welds are even worst than a fillet weld in that there is a quick quenching of the area that has been tack welded and the result is a brittle area that is prone to cracking...
By MBSims 
Date 06-17-2011 02:13
Edited 06-17-2011 02:17
This would be a rejectable condition. Grade 8 bolts are quenched and tempered, and welding affects the strength of the bolt. We recently had this occur on some 4130 Q&T anchor bolts we ordered. Our initial attempt was to do metallurgical examination and attempt to use a portion of the anchors to qualify the welding. However, every one we examined had cracks in the bolt HAZ under the tack welds. I would expect the same or worse for A193-B5, since this is a 5%CrMo steel. We wound up sending our whole shipment back to the bolt mfr. to be replaced with new bolts.
Thanks to all for your replies. Today I reexamined the welds in question and noted several which were cracked. Problem solved--they all come out.
