1/2 in. high strength bolts 3

[NS4U]

Someone told me awhile ago, that in any bolted connection, 3/4 in. high strength bolts at a minimum should be used.

My question, if A325 bolts are available in 1/2 in. diameters, why are they generally discouraged from being used?

 

[ChipB]

3/4" has pretty much been the industry standard since I've been in it.

If you go with a smaller bolt, say 1/2", and your material is at that thickness (or greater), most fabricators will have to drill the bolt holes instead of punching them. This increases the fabrication cost which would quickly offset the savings of a smaller bolt.

Rule of thumb is you can punch material up to the bolt diameter, after that you risk shattering your punch.

 

[ATSE]

You can get 1/2" diameter Grade 5 bolts, which are almost identical to A325 - both in black steel and HD galv.
With Gr 5, both fine and course threading is available (use course for structural applications).
A325 goes down to 5/8" diameter, and up over 1.25".
There's nothing wrong with a 1/2" diameter bolt for low loads and thin plies of steel.

 

[ChipB]

ATSE:
See the attached regarding other bolts.
Chip