Are 9/16” diameter F3125 Grades A325 and A490 structural bolts readily available?
No. The specification moves up in 1/8” increments starting at ½” diameter and maxing out at 1-1/2”.
Under the old A325 – 09 specification, there was a reference about oversize limits on bolts and listed 9/16” diameter as a size. Since A325 bolts have been reclassified under the new F3125 specification, there is no longer a reference to 9/16” diameter. In addition, none of the mass bolt producers make a structural bolt in 9/16” diameter.
The F3125/F3125M-19 specification reads:
1.2.2 Bolts in this specification are furnished in sizes from 1⁄2 to 1-1⁄2 in. inclusive and from M12 to M36 inclusive.