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Minimum Prevailing Torque For ANSI Inch Size Hardware

Engineering Hardware Design Guide

Minimum Prevailing Torque Values for ANSI Inch Nuts Fine and Course threads.

PREVAILING TORQUE . The torque required to run a nut down a thread on certain types of nuts designed to resist vibration loosening. The resistance can be provided by a plastic insert or a noncircular head. PREVAILING TORQUE NUT. A type of lock nut which has a prevailing torque to assist in preventing self loosening.

FINE THREAD SERIES PREVAILING TORQUE
THREAD SIZE
MINIMUM PREVAILING TORQUE
7/16 -20
8 inch-pounds
1/2 -20
10 inch-pounds
9/16 -18
13 inch-pounds
5/8 -18
18 inch-pounds
3/4 -16
27 inch-pounds
7/8 -14
40 inch-pounds
1 -14
55 inch-pounds
1-1/8 -12
73 inch-pounds
1-1/4 -12
94 inch-pounds
COARSE THREAD SERIES PREVAILING TORQUE
THREAD SIZE
MINIMUM PREVAILING TORQUE
7/16 -14
8 inch-pounds
1/2 -13
10 inch-pounds
9/16 -12
14 inch-pounds
5/8 -11
20 inch-pounds
3/4 -10
27 inch-pounds
7/8 -9
40 inch-pounds
1 -8
51 inch-pounds
1-1/8 -8
68 inch-pounds
1-1/4 -8
88 inch-pounds