APPENDIX F: TORQUE UNITS TM 9-2350-256-20F-5 FASTENER GRADEIn addition to being classified by thread type, threaded fasteners are also classified by material. The most familiarfastener classification system is the SAE grading system (see Table F-5).TABLE F-5. SAE SCREW AND BOLT MARKINGS.ScrewsBoltsSAE Grade 2SAE Grade 6No Marking4 Radial Dashes90° ApartSAE Grade 3SAE Grade 72 Radial Dashes5 Radial Dashes180° Apart72° ApartSAE Grade 5SAE Grade 83 Radial Dashes6 Radial Dashes120° Apart60° ApartNOTEThe following is a listing of various manufacturer markings on hex locknuts:Grade A— No Marks/No Notches/No LetterGrade B— 3 Marks/One Notch/Letter BGrade C— 6 Marks/Two Notches/Letter CF-6
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