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TM 9-2350-287-20-2
C-6.
FASTENER GRADE.
In addition to being classified by thread type, thread fasteners are also classified by material. The most familiar
fastener classification system is the SAE grading system (Table C-5).
Table C-5. SAE Screw and Bolt Markings
SCREWS
BOLTS
SAE GRADE 2
SAE GRADE 6
NO MARKING
4 RADIAL DASHES
90° APART
SAE GRADE 3
2 RADIAL DASHES
SAE GRADE 7
180° APART
5 RADIAL DASHES
72° APART
SAE GRADE 5
3 RADIAL DASHES
SAE GRADE 8
120° APART
6 RADIAL DASHES
60° APART
GRADE A - No Marks
GRADE B -3 Marks
GRADE C -6 Marks
GRADE A - No Notches
GRADE B - One Notch
GRADE C - Two Notches
Markings on Hex Locknuts
GRADE A - No Marks
GRADE B - Letter B
GRADE C - Letter C
C-5/(C-6 blank)
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