A325 bolts
A325 bolts
(OP)
I have a situation in which i totally rely on the tension capacity of some a325 bolts. and the failure of the connection would be fatal. does anyone see it is a problem to weld the nut and bolts to the steel plates. although the bolts would be tightened to full pretensin force, as time goes by i worry about it will get loose especially if we get some kind of dynamic loads. thanks.






RE: A325 bolts
RE: A325 bolts
High strength nuts and bolts aren't intended to be welded, and you don't really know what kind of strength you have left after you weld them, so I would avoid that on a critical application.
RE: A325 bolts
You mean to bent it after it is installed?
RE: A325 bolts
You should never use a single bolt in a critical connection for this reason. I have seen slip critical bolts come loose on a portal frame, though unlikely, it can happen.
RE: A325 bolts
RE: A325 bolts
Dik
RE: A325 bolts
RE: A325 bolts
Pretensioned bolts will not loosen under service loads because the tensioning imparts a large static friction force on the threads. For extra peace-of-mind, you could spike the threads or add a jam nut. If it's that critical, you could use the bolts just for erection purposes and use welds for the permanent connection.
RE: A325 bolts
Welding the nut to an A325 grade bolt is a definite "no-no". The use of locking nuts,double jam nuts, lok-tite are all good options, but I would agree with Taro's post regarding the welding.
As a footnote, I personally avoid(fatal as you put it)tension only connections wherever possible. I go for the gravity type connection where the bolts simply are for erection and or to avoid displacement.
Best regards, registeredpe in AZ
RE: A325 bolts
This is what I was thinking. Ironically, welding is being considered to make it safer?!
More bolts, double nut, booger the threads, etc. are better IMO.
RE: A325 bolts
271828, the welding Taro was referring to was to weld the structural member to the supporting member, not welding the nut to the bolts! This redundancy would indeed make the connection safer!
Best regards, registeredpe in AZ
RE: A325 bolts
RE: A325 bolts
RE: A325 bolts
I'd also like to pile on with everyone who said not to weld the nut. Don't weld the nut.
I would vote against the A 490 option. They're more brittle and can't be retightened.
Whether you should make this a welded or bolted connection depends on which you feel more paranoid about and which you think the workers are more likely to accomplish in accordance with design assumptions. There are ways to screw up both.
Hg
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RE: A325 bolts
RE: A325 bolts
To answer your section post, he didn't mean to bend the bolt. He just meant to foul the threads beyond the nuts by taking a big hammer and cole chisel to them.
RE: A325 bolts