UNF Fasteners in Tension
 UNF thread :
 SAE Grade Number :
 Preload as percentage of proof strength :
 
 Major diameter d in
 Threads per inch N -
 Pitch P = 1/N in
 Pitch diameter dp = d - 0.649519/N in
 Minor diameter dr = d - 1.299038/N in
 Tensile stress area At = π/4 ((dp+dr)/2)2 10-3 in2
 Proof strength Sp kpsi
 Initial preload Fi lb
 
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