Can I get Grade 8 heavy hex anchor bolts?
It not uncommon for us to get requests or for bolt configurations that don’t match the specifications. Anchor bolts called out as headed Grade 8 bolts are only available with a hex head. From your description ASTM A354 BD would be the correct fastener. This specification has mechanical properties that are very similar to SAE Grade 8 bolts, 150 ksi minimum tensile and 130 ksi minimum yield. A354 BD indicates a hex head unless otherwise specified. So you can work with a manufacturer to meet the requirements of your prints to supply an A354 BD bolt with a heavy hex head. A490 bolts are meant for structural steel connections and have specific thread lengths. For example, a 1” diameter A490 will have 1-3/4” of thread, where as an A354 BD bolt has 2-1/2” of thread or you can specify longer threads as necessary.
The industry standard thread length for fasteners over 6” long is 2 times the diameter plus ½” and twice the diameter plus 1/4″ for anything shorter. Structural bolts, like A490, have special thread lengths that are shorter since they are used in structural connections.
Here’s a chart that highlights some of the differences between these three specifications.
|Specification||Diameter Range||Min. Tensile Strength Range||Min. Yield Strength Range||Head Pattern||Thread Length|
|ASTM A354-BD||¼ – 4”||150 ksi, 140 ksi (2-5/8”+)||130 ksi, 115 ksi (2-5/8”+)||Hex Head or as specified.||2 X Diameter Plus ½” or as specified.|
|ASTM A490||½ – 1-1/2”||150 ksi||130 ksi||Heavy Hex Head||Specified Per Diameter|
|SAE Grade 8||¼ – 1-1/2”||150 ksi||130 ksi||Hex Head||2 X Diameter Plus ½”|