A307 Heavy Hex Head

[dozer]

I work for a firm that always specs A307 as heavy hex head bolts. These are for items like stairs and handrails. Before coming here I had always just specified A307 Gr A for such things which by default comes as standard hex.

I have a few questions.

Is specifying A307 heavy hex in structures a common practice?

What is the extra cost? (I already contacted a vendor. He was no help.)

Why would you want a heavy hex head to bolt a stair tread to stringer (as an example) anyway?

 

[cancmm]

Somebody correct me if I'm wrong, but I believe it simply depends on what type of bolt or threaded rod you're using. High-strength and/or large diameter bolts/rods will typically require heavy nuts. It would be overkill for lower strength bolt/rod applications.

Not sure about the extra cost, but I'm sure you'd have to take other factors into account such as galvanizing, dimension of nut considered, etc.

 

[ToadJones]

might just be specifying practice to avoid confusion or winding up with the wrong spec for A325 bolts or A490.

 

[ToadJones]

A307 Heavy Hex Bolt is specified as A307 Grade B.

Depending on size, say 1/4" to 1 1/2", A307 Gr A Bolts use a Standard A563 Hex Nut. From 1 5/8" up, A307 Gr A Bolts use a A563 Heavy Hex Nut.

All A307 Gr B Bolts are Heavy Hex Bolts and require A563 Heavy Hex Nuts for all sizes.

I don't think I answered any of your questions but I am sure I confused the hell out of the topic !!!!

 

[dik]

I stipulate heavy hex in general for all bolts and in particular for anchor rods...

Dik

 

[BAretired]

In Canada, 5/8" ASTM A307 bolts with standard hex head are commonly used for light steel framing such as girts, purlins, etc. For structural steel in buildings, 3/4" ASTM A325 bolts are usually used.

The following link suggests where A307 Heavy Hex Head are used:

http://www.portlandbolt.com/technicalinformation/astm/ASTM_A307.html

BA

 

[dozer]

Dik, do specify A307 Grade A with Heavy Hex (which is not the standard but possible to get as I understand) or A307 Grade B which comes with heavy hex head as the default?

BAretired, I agree with that. Yes, I'm aware of using Grade B for cast iron flanges.

 

[bridgebuster]

BAretired - thanks for the link; a lot of useful info.