A hex style with a wider across-flats dimension and, for nuts, greater thickness than the regular series of the same thread size. A 3/4 in heavy hex structural bolt takes a 1-1/4 in wrench, against 1-1/8 in for a standard hex cap screw. The extra bearing area spreads load over oversized or slotted holes and softer materials, and heavy hex nuts are specified with structural bolts, B7 studs and other high-strength bolting.
Structural bolts are heavy hex, so grab the inch and a quarter sockets for the three-quarter connections.
Also heard as
- heavy hex nut
- heavy hex bolt
Related terms
A325
The workhorse high-strength structural bolt: heavy hex, quenched and tempered, 120 ksi minimum tensile.
B7
The chromium-molybdenum alloy stud grade that is the default for pipe flange and pressure vessel bolting.
Cap screw
A precision-headed screw, hex or socket, made to close tolerances and usually driven into a tapped hole.
Nut
An internally threaded part that mates with a bolt or stud, graded so the bolt breaks before the nut strips.