High Strength Bolts In Tension

[STEVE97]

Hello all! I have been looking for and answer to this question and cannot seem to find it anywhere. I am designing a rigging system and need to use (1) 1 1/2" diameter A490 bolt that will be fully in tension (hanger connection) My question is do I need to install double heavy hex nuts to to achieve the full tensile load of the bolt. My load is 57 kips and the bolt is no problem for the tensile load but I am concerned about the shear produced on the bolts threads within the nut. Is this correct thinking or does (1) nut have the capacity to resist the 57 kips? Thanks

 

[CoryPad]

You only need a single nut, but it must be the proper one. When using ASTM A 490 Type 1 bolts, you must use ASTM A 563 Grade DH nuts. When using ASTM A 490 Type 3 bolts, you must use ASTM A 563 Grade DH3 nuts.

 

[STEVE97]

Thanks Cory. Do you know where I can find that written?

 

[CoryPad]

http://www.boltcouncil.org/files/2004RCSCSpecification.pdf

 

[paddingtongreen]

I always worry, when I hear of bolts being used in direct tension, if the designer has allowed for load intensification.

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

 

[Tmoose]

An table in an old Sturtevant manual lists 3780 lb-ft torque for an 1-1/2 A 490 bolt (unlisted pitch), which would exert something like 160,000 lbs of clamping force. Similar to a grade 8 nut, so a high quality nut should handle that torque and load OK.