Hex Nuts 1

[jnich]

On a current project I'm working on, the lead is specifying jam nuts with anchor rods/bolts that connect multiple baseplates to their foundations on the latest drawings. At times he calls out two jam nuts to be used for conencting to the baseplates. I believe AISC code specifies that Heavy Hex Nuts (ASTM A563, Gr A) should be furnished with all anchor rods/bolts, if possible. Standard hex nuts are also acceptable, but not preferred. My question - how acceptable are jam nuts in this case? Any experience with this issue? I understand jam nuts have a thinner profile, but I cannot see any reason that would be required in this case.

Thanks in advance

 

[ishvaaag]

Maybe it is an attempt to prevent the nuts becoming loose, but better ask the director of the works if you think otherwise a better solution.

 

[Ron]

Jam nuts are about half the height of a standard nut and less than half the height of a heavy hex nut. Structurally, they are not equivalent to either the standard or heavy hex nut and should not be substituted.

Jam nuts are supplementary devices used to keep the primary nut from backing off. For static anchor bolts, they are not necessary.

 

[paddingtongreen]

Does the wording exclude the standard and heavy nuts. Normally, where jam nuts are called, I expect them to be in addition to a standard nut. It is not a jam nut unless it jams another nut, on it's own it is a "thin hex nut".

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[macmet]

Is it possible this is just a miscommunication or mix-up in terminology?

I would go back to the lead and make sure he is actually referring to a jam nut (if you have not already) and not the hex nuts you expect.

 

[dik]

FYI

 

[jnich]

Thanks guys. All of these posts have been helpful. After reading these posts, I'm going to approach the lead about the design basis for using only jam nuts to connect static anchor bolts to base plates.

 

[ToadJones]

I have specified jam nuts to be used as leveling nuts under "leveling plates" for grouted baseplate assemblies.
On large anchorages if I wanted to use a "jam nut" I often just used two heavy hex nuts.