Bolts torque requirement ? 3

[Abdelrahman_Yousef]

Erection team are asking for these values and I was never asked for them before , I search in AISC and didn't find any related info.
Bolts used are A325M for bearing type connections, can someone tell me what exactly is required to provide this information ?

Thank you very much in advance.

 

[SlideRuleEra]

Current "RCSC Specification"

http://www.SlideRuleEra.net

 

[r13]

For tightening bolts in structural connections, search AISC topics on "turn of the nut method".

For pretension an embedded anchorages, the desirable pretension needs to be specified by the design engineer (20k, 30k, ...).

 

[Ron]

What SRE said!

 

[Geoff13]

I have a slightly different understanding of this question.
[ul][li]The words used by the OP are "Bolts used are A325M for bearing type connections, ...".[/li]
[li]Per AISC 360 clause J3.1 "Bolts are permiited to be installed to the snug-tight condition when used in bearing type connections.".[/li]
[li]The same clause also states "Bolts to be tightened to a condition other than snug tight shall be clearly identified on the design drawings."[/li][/ul]
It seems that the OP's drawings do not specify anything about the bolt tightening, and thus it should be assumed these are "snug-tight" bolts.

The definition of snug-tight is found in the RCSC specification linked above, but it says "The snug tightened condition is the tightness that is attained with a few impacts of an impact wrench or the full effort of an ironworker using an ordinary spud wrench to bring the plies into firm contact."

As the AISC Commentary for J3 notes "Snug-tightened installation is the most economical installation procedure ...". The field shouldn't be doing all the additional effort for turn-of-nut or calibrated torque unless called for by the design drawings.

 

[r13]

Geoff13, Thanks for the catch. My comment was a careless quick reaction drawn by the subject title.

 

[JLNJ]

I totally agree on the snug-tight possibility. The bolts may not need to be "torqued" at all.

It also worth noting again that for pretensioned high strength bolts we are looking for bolt tension, not torque, and the torque-to-tension relationship can vary widely.