Tools for Installation of bolts requiring Full Pre-Tensioning?

[ChuckerD]

Our company has provided a moment connection design using the minimum offset for entering and tightening clearances at 1 1/4" diameter bolts (1 11/16" side clears per pg 4-137 of the 1989 AISC ASD manual).

Lo and behold - the erector cannot complete full pre-tensioning of these bolts using standard equipment. His attempts to locate tools to tigthen the bolts adequately and that fit in this clear dimension have been unsuccessful.

Any suggestions?

 

[unclesyd]

Take a look at Ozat Sockets and a manual torque multiplier. Here are two companies I’ve worked with. This is the least expensive way, but if the number of fasteners is very high the pnenumatic route is the way to go.

http://www.newmantools.com/ozat/16lt.htm

http://www.norbar.com/NTTI/MainMenu.htm

 

[diamondjim]

How tight are you tightening the bolts?
Are you breaking the drive head off
when tightening or are you actually
breaking the sockets because of the
thin section?

 

[mloew]

How about Huck type fasteners from Alcoa Fastening Systems ?

Best regards,

Matthew Ian Loew
"Organizations cannot make a genius out of an incompetent. On the other hand, disorganization can scarcely fail to result in efficiency." -- Dwight D. Eisenhower

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Screwman]

What exactly is the problem that he is having? Is he trying to use power or manual tools? Power tools will be an issue on that clearance, but I think that you should be able to use a manual wrench with an appropriate handle extension to reach your target clamp value. One thing to try would be to use the best possible lube under the head and on the threads. If you do that and calibrate your torque values with the lubed fasteners, you will likely find that you will be able to use quite a bit lower torque than with the as-delivered parts. This may allow the use of smaller or shorter tools. I have even seen special, one use sockets made up by welding a 12 point armstrong socket (using appropriate pre-heat and post heat) to a 6 foot bar and then re-heat treating the tool to get the strength back up.

Dick

Dick

 

[unclesyd]

In the US OSHA frowns on welding on tools, especially wrenches and sockets. Not debating whether it can be done and isn't done, if you do alter an existing tool you had better have a written permission and a procedure from the OEM prior to use.

As someone stated in another post ask me how I know.

 

[ChuckerD]

Power tools have been impossible to find to fit the clearance. The estimated torque required to fully tension the A490 1 1/4" bolts is 2100 ft-lbs. The impact wrench that they have on-site can generate 800 ft-lbs. and using a standard wrench they will need an extremely long extender bar to create this kind of force.

It appears that snug tight installation will be an acceptable solution for the A325 bolts, but I'm still at a loss on the A490s.

Thanks to everyone for their responses.

ChuckerD

 

[HgTX]

Have you contacted AISC?

Hg

 

[Screwman]

Check into the manual torque multiplier. A 4:1 multiplier and a 1" ratchet head is not very big.
The welding process to change a tool can be done by one of the major tool companies. They will do that for you if you contact their engineering departments, but it is not an inexpensive thing to have them do. I would look at the torque multiplier and using lubrication. With the selection of the proper lubrication, you should be able to get the K factor on those parts down to the point where they can be fully tightened in the 1,400 ft. # range.

Dick