Can ASTM A325 bolts be used as anchor bolts?
Engineers occasionally specify the use of F3125 Grade A325 heavy hex structural bolts as anchor bolts, but technically they are supposed to be used for structural steel connections only. Part of the problem is that the A325 specification is very specific as to the application and thread length. Because A325 bolts are typically used in structural steel connections, they have very short thread lengths. Often this thread length restriction is too short when the bolts are used as anchor bolts. Since the A325 specification was recategorized under the F3125 specification in 2016, extending the thread length is now allowed provided the heads are marked “A325S” to indicate a nonstandard thread length. Most A325 bolts used as anchor bolts will possess an extended thread length and be marked accordingly.
We occasionally see inquiries for A325 bent anchor bolts or straight anchor rods with anchor plates. Since the A325 specification is restricted to headed bolts only, the F3125 Grade A325 specification suggests moving to either ASTM A449 or A354 Grade BC in these instances. Since both A449 and A354 specifications are designed for general applications (including anchor bolts), engineers should consider these specifications for headed anchor bolts in lieu of F3125 Grade A325 when a similar strength and chemistry is desired. The F1554 specification was developed specifically for anchor bolts and may also be a more appropriate specification to consider when specifying anchor bolts. AISC also discusses which ASTM specifications should be used as anchor bolts.