The math, and where the numbers come from
Torque–tension calculator T = K · D · F
Filled from the result above: D is the bolt's major diameter, K is NASA's 0.20, F is the axial load at the assembly torque (65% of the interpolated pullout load), T is the assembly torque. Change any three and the fourth is worked out. A dry-steel K is assumed, and the formula ignores stiffness. The same calculator as Engineers Edge's.
Torques are from NASA/TM-2017-219475, Installation Torque Tables for Noncritical Applications (NTRS). They are for noncritical joints with no structural or vibration load: not for flight hardware, or anywhere a specific preload is needed. NASA assumes dry threads (K = 0.20), a bolt stronger than the material it threads into, no insert, and 3 threads minimum. The assembly torque is 65% of the torque that strips the parent threads, and the pullout load already includes a safety factor of 3. Thread data: ISO 261 metric and ASME B1.1 unified threads.
Click a row to add it to the comparison. Click a column heading to sort.