Grade 8 Heavy Hex Nuts
Grade 8 heavy hex nuts are high-strength fasteners designed for demanding applications where superior load capacity, durability, and vibration resistance are essential. Manufactured to meet strict industry standards, Grade 8 heavy hex nuts are commonly used in heavy equipment, structural assemblies, industrial machinery, and high-stress bolting applications. Their larger bearing surface provides improved load distribution, making them ideal for critical connections that require strength and reliability.
At RAM Threading, we supply precision-manufactured Grade 8 heavy hex nuts built for performance in challenging environments. Whether your application requires standard carbon steel, specialty coatings, or custom sizes, our team helps ensure the right fit for your project
Key Features
- High-strength design for demanding, high-load applications
- Heavy hex shape provides increased wrenching surface and better torque control
- Larger bearing surface helps distribute load more evenly
- Heat-treated for improved hardness, durability, and wear resistance
- Precision-machined threads for secure fit and consistent engagement
- Helps resist loosening in vibration-prone assemblies
- Available in multiple sizes, thread pitches, and configurations
- Offered with plain, zinc, PTFE/Xylan, and other finish options
Common Applications
- Heavy equipment and construction machinery
- Agricultural and farm equipment
- Structural steel assemblies
- Industrial manufacturing equipment
- Transportation and trailer systems
- Oil and gas equipment
- Mining and earthmoving machinery
- Power generation equipment
- High-load mechanical assemblies
- General industrial maintenance and repair operations
Commonly Paired with Grade 8 Stud Bolt
Grade 8 heavy hex nuts are most commonly paired with Grade 8 hex head cap screws, heavy hex bolts, and threaded studs in high-strength fastening applications. Using matched Grade 8 components helps maintain proper load capacity, secure thread engagement, and long-term joint integrity under heavy loads and vibration.
They are also frequently used with hardened flat washers, such as ASTM F436 hardened flat washers, to help distribute load evenly and protect the mating surface. This combination is ideal for construction equipment, trailers, industrial machinery, structural assemblies, and other demanding bolted connections.
At RAM Threading, we supply Grade 8 heavy hex nuts along with compatible bolts, studs, and washers to help ensure full compatibility and dependable performance in critical applications.
Per ASTM A193/A193M-16
| Diameter | Proof Load Stress (Min psi) | Core Hardness (Rockwell) |
|---|---|---|
| 1/4″ thru 4″ | 80,000 | C32 max |
Per ASTM A193/A193M-16
| Grade | Material | Carbon % by weight |
Manganese % by weight |
Phosphorus % by weight |
Sulfur (1) % by weight |
Silicon % by weight |
Chromium % by weight |
Nickel % by weight |
|---|---|---|---|---|---|---|---|---|
| 8 | Type 304 Stainless Steel | 0.08 max | 2.00 max | 0.045 max | 0.030 max | 1.00 max | 18.0–20.0 | 8.0–11.0 |
ASTM A194
This specification covers a variety of carbon, alloy, and martensitic stainless steel nuts in the size range
1⁄4 through 4 in. and metric M6 through M100 nominal. It also covers austenitic stainless steel nuts in the
size range 1⁄4 in. and M6 nominal and above. These nuts are intended for high-pressure or high-temperature
service, or both. Grade substitutions without the purchaser’s permission are not allowed.
ASME B18.2.2
Covers the complete general and dimensional data for the various types of inch series square and hex nuts,
including machine screw nuts and coupling nuts.
ASME B1.1 UNC & UNF Class 2B
Specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads.
| Nominal Diameter | UNC | UN8 | F Width Across Flats |
G Width Across Corners |
H Thickness |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Basic | Max | Min | Max | Min | Basic | Max | Min | ||||||
| Fraction | Decimal | ||||||||||||
| 1/4 | 0.250 | 20 | 1/2 | 0.500 | 0.488 | 0.577 | 0.556 | 15/64 | 0.250 | 0.218 | |||
| 5/16 | 0.313 | 18 | 9/16 | 0.562 | 0.546 | 0.650 | 0.220 | 19/64 | 0.314 | 0.280 | |||
| 3/8 | 0.375 | 16 | 11/16 | 0.688 | 0.669 | 0.794 | 0.763 | 23/64 | 0.377 | 0.341 | |||
| 7/16 | 0.438 | 14 | 3/4 | 0.750 | 0.728 | 0.866 | 0.830 | 27/64 | 0.441 | 0.403 | |||
| 1/2 | 0.500 | 13 | 7/8 | 0.875 | 0.850 | 1.010 | 0.990 | 31/64 | 0.504 | 0.464 | |||
| 9/16 | 0.563 | 12 | 15/16 | 0.938 | 0.909 | 1.083 | 1.037 | 35/64 | 0.568 | 0.526 | |||
| 5/8 | 0.625 | 11 | 1 1/16 | 1.062 | 1.031 | 1.227 | 1.175 | 39/64 | 0.631 | 0.587 | |||
| 3/4 | 0.750 | 10 | 1 1/4 | 0.250 | 1.212 | 1.443 | 1.382 | 47/64 | 0.758 | 0.710 | |||
| 7/8 | 0.875 | 9 | 1 7/16 | 1.438 | 1.394 | 1.660 | 1.589 | 55/64 | 0.885 | 0.833 | |||
| 1 | 1.000 | 8 | 1 5/8 | 1.625 | 1.575 | 1.876 | 1.796 | 63/64 | 1.012 | 0.956 | |||
| 1 1/8 | 1.125 | 7 | 8 | 1 13/16 | 1.812 | 1.756 | 2.093 | 2.002 | 1 7/64 | 1.139 | 1.079 | ||
| 1 1/4 | 1.250 | 7 | 8 | 2 | 2.000 | 1.380 | 2.309 | 2.209 | 1 7/32 | 1.251 | 1.187 | ||
| 1 3/8 | 1.375 | 6 | 8 | 2 3/16 | 2.188 | 2.119 | 2.526 | 2.416 | 1 11/32 | 1.378 | 1.310 | ||
| 1 1/2 | 1.500 | 6 | 8 | 2 3/8 | 2.375 | 2.300 | 2.742 | 2.622 | 1 15/32 | 1.505 | 1.433 | ||
| 1 5/8 | 1.625 | 5 1/2 | 8 | 2 9/16 | 2.562 | 2.481 | 2.959 | 2.828 | 1 19/32 | 1.632 | 1.556 | ||
| 1 3/4 | 1.750 | 5 | 8 | 2 3/4 | 2.750 | 2.662 | 3.175 | 3.035 | 1 23/32 | 1.759 | 1.679 | ||
| 1 7/8 | 1.875 | 5 | 8 | 2 15/16 | 2.938 | 2.844 | 3.392 | 3.242 | 1 27/32 | 1.886 | 1.802 | ||
| 2 | 2.000 | 4 1/2 | 8 | 3 1/8 | 3.125 | 3.025 | 3.608 | 3.449 | 1 31/32 | 2.013 | 1.925 | ||
| 2 1/4 | 2.250 | 4 1/2 | 8 | 3 1/2 | 3.500 | 3.388 | 4.041 | 3.862 | 2 13/64 | 2.251 | 2.155 | ||
| 2 1/2 | 2.500 | 4 | 8 | 3 7/8 | 3.875 | 3.750 | 4.474 | 4.275 | 2 29/64 | 2.505 | 2.401 | ||
| 2 3/4 | 2.750 | 4 | 8 | 4 1/4 | 4.250 | 4.112 | 4.907 | 4.688 | 2 45/64 | 2.759 | 2.647 | ||
| 3 | 3.000 | 4 | 8 | 4 5/8 | 4.625 | 4.475 | 5.340 | 5.102 | 2 61/64 | 3.013 | 2.893 | ||
| 3 1/4 | 3.250 | 4 | 8 | 5 | 5.000 | 4.838 | 5.774 | 5.515 | 3 3/16 | 3.252 | 3.124 | ||
| 3 1/2 | 3.500 | 4 | 8 | 5 3/8 | 5.375 | 5.200 | 6.207 | 5.928 | 3 7/16 | 3.506 | 3.370 | ||
| 3 3/4 | 3.750 | 4 | 8 | 5 3/4 | 5.750 | 5.562 | 5.562 | 6.341 | 3 11/16 | 3.670 | 3.616 | ||
| 4 | 4.000 | 4 | 8 | 6 1/8 | 6.125 | 5.925 | 5.925 | 6.755 | 3 15/16 | 4.014 | 3.862 | ||


