Some ASTM specifications might demand a hex head that is larger compared to a normal finished Hex head. The specifications include A320, A193 and A307B. It is true that A325 and A490 bolts also require a heavy hex head; but, it is crucial to refer to Structural Bolts in order to study the dimensional specifications as these bolts are known to possess shorter thread lengths in comparison with the standard heavy Hex bolts.
Applications
Heavy hex bolts sport a range of applications including fastening wood, steel, and different other construction materials, used largely in projects including bridges, buildings, docks, and highway structures. Sometimes, Hex bolts also come with forged heads and these are usually used as headed anchor bolts.
Standard Thread Lengths
Bolt lengths ≤ 6″: Thread length = (2 X diameter) + 1/4″
Bolt lengths > 6″: Thread length = (2 X diameter) + 1/2″