EngiRef / UNC Bolt Specification
7/8-9
7/8-9 coarse UNC bolt: 9 threads per inch, 22.23 mm major diameter. Tensile stress area 298 mm² per ASME B1.1. Takes a 33.34 mm wrench. Free imperial fastener…
Specification
- Size
- 7/8-9
- Threads per inch (TPI)
- 9
- Major diameter D (mm)
- 22.23
- Minor diameter D₁ (mm, internal thread)
- 19.18
- Tensile stress area (mm²)
- 298
- Wrench size (mm)
- 33.34
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.