Fasteners and Hardware
Keeping it all together
Fasteners and Hardware choices are many when considering construction hardware. Stitching light gauge sheet metal together, attaching sheet metal to structural steel.
Attaching sheet metal and other materials to substrates such as plywood, wood studs, brick, concrete masonry units and steel studs to name just a few. Then there is depth and sealing ability to consider. You can bet that there is a screw to suit every purpose you can come up with.
Engineers can calculate how much shear strength and pullout is required for fasteners and hardware but there are tests that can right in the field to be certain that a fastener will hold out under a given load.
Pullout testing involves using a special fixture to see how much force is required to pull out a screw that has been fastened into a substrate. It is especially important when fastening to old existing substrates where the actual strength may not be known.
There are several classes of commonly used fasteners and hardware for these purposes including screws, rivets as well as nuts & bolts.
There are different types of points such as Type A for drilling into light gauge sheet metal less than .060” thick. The Type B has a more blunted end and is intended for drilling into structural steel up to .200” in thickness. There is also a type AB point which is a type B with a sharper point to help locate the starter hole. For thicker materials a pilot hole and a thread cutting screw should be used.
Tapcon fasteners are used for attaching to concrete or brick and are available in 2 common diameters. The 3/16” diameter Tapcon is supplied with a 5/32” diameter drill bit for installation. The 1/4” diameter Tapcon comes with a 3/16” diameter drill bit. It is important to use these exact drill sizes when drilling holes for Tapcons.
Pop rivets blind rivets and more talks about how rivets fasten everything from your screen door handle to heavy panels many stories above the ground.
Nuts & Bolts
Used in sizes above 1/2” diameter. These are heavy duty structural steel bolts with tightly controlled specifications. The heads of the bolts are marked with 3 different grades in order of increasing tensile strength.
Materials for fasteners
Materials for fasteners can be very important. In North America materials have been standardized by the ASTM (American Society for Testing Materials) so that the yield strength is predictable. With screws that are too small to be marked, purchasers can get certificates of conformance and mill test reports to ensure specifications are met on critical applications.