Can A325 and A490 structural bolts be supplied with fine thread?
No. The specification calls out that those bolts must be Unified National Coarse thread and have class 2A tolerances.
The F3125/F3125M specification reads:
4.2.1 Uncoated bolt threads shall be as specified in Table 1.
4.2.2 Coated bolts shall have threads meeting Table 1 requirements before coating.
|Thread Fit, ASME||120 ksi Min Tensile Strength
|150 ksi Min Tensile Strength
|Type 1||Type 3||Type 1||Type 3|
|B1.1 UNC 2A||B1.1 UNC 2A||B1.1 UNC 2A||B1.1 UNC 2A|