Last edited 23 Feb 2021

Structural fasteners

Structural fasteners are strong, heavy-duty fasteners that are necessary for the construction of structures which include steel to steel connections. In other words, they are used when one metal structure needs to be connected to another.

The typical application of structural fasteners is in bridge and building construction, where they are used to connect metal beams and girders. To be considered for structural purposes, fasteners need to be made of quenched and tempered steel with a minimal tensile strength of 120 ksi.

Some of the most commonly used structural fasteners are:

Heavy hex bolts. This type of bolt or cap screw comes with a hexagonal head, and is larger and thicker than standard hex bolts. A325 and A490 specifications are suitable in this application.
Heavy hex nuts, also known as finish nuts. Heavy hex nuts are used along with bolts - both for strength and for a thick finished look.
Flat washers. These high hardness and low-deformation plain washers, punched washers, or flat washers are used as spacers and load distributors.
Tension control bolts. TC bolts are extremely adept at handling vibrations and preventing load reversals and they eliminate slips in connections.

The quality of structural fasteners specified is of prime importance because they will be holding together heavy and crucial structures. Therefore, they must be durable, sturdy, rust-proof and corrosion-free for several years. Using poor quality structural fasteners not only reduces the durability of the overall structure but also puts lives at risk.