What changes have occurred to the ASTM A325 specification since it was incorporated into the F3125 specification?
In December 2015, ASTM committee F16 approved the new F3125 standard, which combined six structural bolt standards, A325, A325M, A490, A490M, F1852, and F2280. The goal was to clean up inconsistencies within those various standards and combine them, so that future updates would be easier and less costly.
The goal was not to drastically change any of the requirements of the bolts, as they had been used and functioning in the marketplace for decades without major issues. However, in order to better align with each other and with current design standards, minor changes were made. The most notable change was the increase in mechanical properties of large diameter A325 bolts. Originally, bolts ½” through 1” diameter had a minimum tensile requirement of 120ksi, whereas for bolts above 1” diameter, the requirement dropped to 105ksi. AISC design guides had used the 120ksi value for design loads all along regardless of bolt size, so this increase by ASTM aligns the design strength with the actual strength.
The table below outlines the mechanical changes. This is not meant to be a comprehensive comparison, there is much more information both on our website and within the F3125 standard at ASTM.org
Mechanical Requirements
| A325 ½” – 1” | A325 above 1” | F3125 Gr.A325, all sizes | |
|---|---|---|---|
| Tensile, min ksi | 120 | 105 | 120 |
| Yield, min ksi | 92 | 81 | 92 |
| Elongation, min % | 14 | 14 | 14 |
| RA, min % | 35 | 35 | 35 |
| Hardness, HBN | 253-319 | 223-286 | 253-319 |
Additional Revisions
After much clamoring by the industry, a supplemental requirement was added to address alternate bolt configurations. Supplement S2 allows the purchaser to specify nonstandard dimensions for thread length, head style, etc. Bolts ordered to S2 are marked with an “S” to signify that these bolts vary from the ASME B18.2.6 dimensional standard, for example A325S.
