Standard Hex Nut
Direct Answer
The Standard Hex Nut (standardized under ISO 4032, DIN 934, and ASME B18.2.2) is a 6-sided internal-threaded mechanical fastener. Paired with mating machine screws and structural bolts, it converts rotational tightening torque into axial clamping preload across industrial and architectural assemblies.
Source: ISO 4032 / DIN 934 / ASME B18.2.2 / ISO 898-2
Specs
| Standard Specifications | ISO 4032 (Standard style 1) / DIN 934 / ASME B18.2.2 |
| Geometry | 6-sided regular hexagonal prism with internal tapped thread and double chamfered faces |
| Nominal Height Ratio | Height $\approx 0.8\times$ Nominal Diameter ($m \approx 0.8D$) |
| Metric Property Classes | Class 6, Class 8 (for 8.8 bolts), Class 10 (for 10.9 bolts), Class 12 (for 12.9 bolts) |
| Imperial Strength Grades | Grade 2 (plain), Grade 5 (dot markings), Grade 8 (corner dots/notches) |
| Jam Nut Variant | ISO 4035 / DIN 439 (Thin half-height hex nut used for locking) |
Strength Matching Rule (ISO 898-2)
In structural bolting, a nut must always possess a proof-load stress rating equal to or higher than the mating bolt (e.g. a Property Class 8.8 bolt must be paired with a Class 8 or Class 10 nut). Using a soft Class 4 nut on a Class 10.9 bolt will cause the internal nut threads to strip before the bolt reaches its required tension.
Jam Nut Locking Technique
When two standard hex nuts are tightened against each other on a threaded rod (a standard nut plus a thin DIN 439 'Jam Nut'), the opposing axial forces jam the thread flanks against each other, preventing vibrational loosening without liquid threadlockers.