Can I order A490 Heavy Hex Structural Bolts larger than 1-1/2" diameter?
According to ASTM A490-11, the answer is no. The A490 specification only covers diameters from 1/2″ to 1-1/2″, inclusive. An A490 bolt cannot be made above 1-1/2″ diameter; ASTM does not allow it. Since there are no chemical requirements, hardness requirements, or strength requirements for A490 fasteners above 1-1/2″ diameter, no manufacturer would be able to certify a bolt above 1-1/2″ to ASTM A490. An alternative grade to consider in diameters above 1-1/2″ would be an ASTM A354 Grade BD. This grade of fastener can be manufactured in diameters from 1/4″ to 4″, inclusive, and is virtually identical to A490 in strength and chemistry through 1-1/2″ diameter. However, there is no way to compare the two grades above 1-1/2″ diameter, due to the fact that A490 does not have any strength requirements in diameters larger than 1-1/2″. Additionally, A354 Grade BD bolts do not require a Magnetic Particle Inspection, which is a requirement for ASTM A490 structural bolts. A490 bolts are only available in a heavy hex head configuration, while A354 Grade BD bolts are not restricted to a specific configuration. Because of these configuration restrictions, A490 bolts often readily available as stock items in certain diameter/length combinations, but A354 Grade BD bolts typically need to be made per order.
If the situations comes up where an A490 bolt is specified in a size larger than 1½” diameter, it is advisable to have the engineer of record specify a grade of fastener that is available in that diameter.