TNA® can be used and specified in a few ways. The first way is a direct replacement for ASTM A325 and F1852 bolts. TNA® bolts are made of the same raw material and conform to the same dimensional standards. So using existing A325 design criteria will apply. The other way is to use A490 design criteria. This is where you get the full value of TNA®. The system is designed around capturing the inherent strength available in modern raw materials used to make A325 bolts. By making a small change to hardness and controlling both steps of the installation process we can achieve A490 tension values. Our minimum tension values are A490 tension values, so all existing software packages can make the switch without any outside calculation.