APPENDIX F: TORQUE UNITS
TM 9-2350-256-20
F-5
FASTENER GRADE
In addition to being classified by thread type, threaded fasteners are also classified by material. The most familiar
fastener classification system is the SAE grading system (see Table F-5).
TABLE F-5. SAE SCREW AND BOLT MARKINGS.
Screws
Bolts
SAE Grade 2
SAE Grade 6
No Marking
4 Radial Dashes
90° Apart
SAE Grade 3
SAE Grade 7
2 Radial Dashes
5 Radial Dashes
180° Apart
72° Apart
SAE Grade 5
SAE Grade 8
3 Radial Dashes
6 Radial Dashes
120° Apart
60° Apart
NOTE
The following is a listing of various manufacturer markings on hex locknuts:
Grade A— No Marks/No Notches/No Letter
Grade B— 3 Marks/One Notch/Letter B
Grade C— 6 Marks/Two Notches/Letter C
F-6
