LOKRON Engineering Reference

Stud Bolt Torque Chart: B7, B8, B8M and L7

Indicative torque ranges for common inch-size stud bolts under lubricated assembly conditions. Use the project specification, approved lubricant and calibrated tooling for final tightening.

Important: Torque is an indirect method of controlling preload. Actual results depend on nut factor, thread condition, nut-face friction, temperature and tool calibration. For critical joints, verify preload with an approved procedure such as hydraulic tensioning or ultrasonic measurement.

Indicative chart, lubricated assembly

Stud size	TPI	A193 B7 / A320 L7 (ft-lb)	A193 B8 / B8M (ft-lb)	B7 / L7 approximate (N·m)
1/2 in	13	45	27	61
5/8 in	11	90	54	122
3/4 in	10	160	96	217
7/8 in	9	260	156	353
1 in	8	390	234	529
1-1/8 in	8	560	336	759
1-1/4 in	8	780	468	1,057
1-1/2 in	8	1,370	822	1,857

Calculation basis

The starting relationship is T = K × D × F, where T is torque, K is the nut factor, D is nominal diameter and F is target preload. The values above are reference values, not a replacement for the approved flange assembly procedure.

Use with LOKRON resources

Open the interactive torque calculator

A193 B7 stud bolts · A320 L7 stud bolts · Request a technical quote

LOKRON · ASTM A193/A320 stud bolts and ASTM A194 heavy hex nuts · Reference updated 2026-07-20