EngiRef / UNC Bolt Specification
5/16-18
5/16-18 coarse UNC bolt: 18 threads per inch, 7.94 mm major diameter. Tensile stress area 33.8 mm² per ASME B1.1. Takes a 12.7 mm wrench. Free imperial…
Specification
- Size
- 5/16-18
- Threads per inch (TPI)
- 18
- Major diameter D (mm)
- 7.94
- Minor diameter D₁ (mm, internal thread)
- 6.4
- Tensile stress area (mm²)
- 33.8
- Wrench size (mm)
- 12.7
Tensile stress area follows ASME B1.1, At = 0.7854(D − 0.9743/n)² in², converted at 645.16 mm²/in². Verify against the current standard and the fastener manufacturer's data before safety-critical design.