Torque Ratings for Grade 5 and Grade 8 Fasteners

To determine what fastener is right for the job, you must be able to identify what grade fastener and torque rating you are using. Fasteners are graded by tensile strength and are easily identified by the number of slash marks on the head of the fastener. Torque is measured in foot pounds.

  • Grade 5 fasteners have 3 lines or markings on the head resembling the shape of a “Y"
  • Grade 8 fasteners have 6 lines or markings on the head as displayed in the figure below

 

THREAD SIZE

SAE GRADE 5
75% YIELD STRENGTH (PSI) =69000

SAE GRADE 8
75% YIELD STRENGTH (PSI) = 98000

PLAIN
Ft. Lbs.

ZINC PLATED
Ft. Lbs.

PLAIN
Ft. Lbs.

ZINC PLATED
Ft. Lbs.

1/4 - 20 9 10 13 14
1/4 - 28 10 12 15 16
5/16 - 18 19 21 27 29
5/16 - 24 21 23 30 33
3/8 - 16 33 37 47 52
3/8 - 24 38 42 54 59
7/16 - 14 53 59 76 83
7/16 - 24 60 66 85 93
1/2 - 13 82 90 116 127
1/2 - 20 92 101 131 144
9/16 - 12 118 129 167 184
9/16 - 18 131 144 186 205
5/8 - 11 162 179 231 254
5/8 - 14 184 202 261 287
3/4 - 10 288 317 409 450
3/4 - 16 322 354 457 503