Stainless Steel Hex Nuts
Introduction
A Hex Nut is a six-sided fastener designed to mate with a bolt, screw, or threaded rod. Stainless steel hex nuts are manufactured from corrosion-resistant stainless steel, providing durability and reliability in harsh environments. These nuts are widely used across industries where resistance to rust, chemicals, and oxidation is critical. Their hexagonal design ensures easy installation with wrenches or sockets and secure fastening across diverse applications. Hex nuts play a crucial role in mechanical assemblies, structural frameworks, and high-performance machinery, ensuring joint integrity and long-term durability.
- Shape: Hexagonal (6 sides) for easy tool engagement.
- Function: Provides secure fastening by engaging with bolt threads, distributing load evenly.
- Materials: Primarily stainless steel; available in A2 (304), A4 (316), 430 ferritic, and duplex 2205 grades depending on corrosion resistance and mechanical requirements.
- Applications: Construction, marine, automotive, chemical industries, food processing, machinery, pipelines, structural components, and high-stress or vibration-prone environments.
| Type of Hex Nut | Description / Design | Function / Purpose | Advantages | Typical Applications |
|---|---|---|---|---|
| Standard Hex Nut | Regular six-sided nut with flat top and bottom | General fastening with bolts or threaded rods | Simple design, widely available, cost-effective | Construction, machinery, furniture, automotive |
| Heavy Hex Nut | Taller and thicker than standard hex nuts | Provides higher load-bearing capacity | Increased thread engagement, stronger joint | Structural steel connections, bridges, heavy machinery |
| Jam Nut (Thin Nut) | Thin nut, often used with a second nut | Locks another nut in place to prevent loosening | Prevents vibration loosening, lightweight | Machinery, automotive, vibration-prone assemblies |
| Flanged Hex Nut | Hex nut with an integrated flange (acts as built-in washer) | Distributes load over a larger surface | Reduces need for separate washers, prevents loosening | Automotive, machinery, construction, sheet metal assembly |
| Lock Nut (Nyloc / Serrated) | Nut with nylon insert (Nyloc) or serrated metal surface | Resists loosening under vibration or torque | High vibration resistance, secure fastening | Automotive, electronics, machinery, heavy equipment |
| Slotted Hex Nut (Castle Nut) | Nut with vertical slots on top, used with a cotter pin | Secures nut rotation using pin through bolt hole | Prevents accidental loosening, secure for critical joints | Automotive axles, heavy machinery, safety-critical applications |
| Wing Nut (Hand-Tightened) | Nut with two large protruding “wings” allowing hand tightening | Tool-free fastening and easy assembly/disassembly | Quick installation/removal, no tools required | Temporary setups, equipment covers, light machinery |
Notes: Material, thread types, and surface treatment considerations are critical for durability and corrosion resistance.
Material Grades of Stainless Steel Hex Nuts
| Grade | Common Name | Composition Highlights | Key Properties | Typical Use |
|---|---|---|---|---|
| A2 | 304 | Fe + 18% Cr + 8% Ni | Corrosion resistant, general-purpose | Marine, chemical, construction |
| A4 | 316 | Fe + 16–18% Cr + 10–14% Ni + 2–3% Mo | Excellent corrosion and pitting resistance | Saltwater, chemical plants, outdoors |
| 430 | Ferritic | Fe + 16–18% Cr | Magnetic, moderate corrosion resistance | Automotive, appliances |
| 2205 | Duplex | Fe + 22% Cr + 5% Ni + Mo | High strength, very high corrosion resistance | Oil & gas, marine, chemical industry |
Standards & Specifications
- ISO 4032: Hex nuts, ISO metric threads, regular height
- ISO 4033: Hex nuts, high strength, coarse threads
- DIN 934: German standard, general-purpose hex nuts
- ASTM A194 / A194M: Heavy hex nuts for high pressure or temperature, stainless steel grades
- ASTM A563: Carbon and alloy steel nuts, sometimes adapted for stainless steel
- ANSI / ASME B18.2.2: Hex nuts for industrial fasteners in the U.S.
Mechanical Properties
| Property | A2-70 (304) | A4-70 (316) | A2-80 |
|---|---|---|---|
| Tensile Strength | 700 MPa | 700 MPa | 800 MPa |
| Proof Load | 450 MPa | 450 MPa | 520 MPa |
| Hardness (HB) | 140–190 | 140–190 | 190–240 |
| Yield Strength | 450 MPa | 450 MPa | 520 MPa |
Thread Types
- Coarse (UNC / ISO Metric Coarse): Standard, fast installation, better resistance to stripping.
- Fine (UNF / ISO Metric Fine): Stronger engagement, suitable for thin materials.
- Extra Fine: Rare, high precision applications.
Surface Finish / Coatings
- Plain / Mill Finish: Natural stainless steel appearance.
- Polished / Bright: Decorative, smoother surface, easier cleaning.
- Passivated: Removes free iron, increases corrosion resistance.
- Electropolished: High corrosion resistance, smooth surface for hygienic applications.
Dimensions & Tolerances
Hex nuts conform to international size standards:
- Width Across Flats (WAF): Distance between parallel sides.
- Height / Thickness: Standard height or heavy hex.
- Thread Pitch: Coarse/fine metric or imperial.
- Tolerance Classes: ISO 898-2 defines tolerance for thread fit.
Example for M12 Hex Nut (ISO 4032): WAF: 19 mm | Height: 10 mm | Thread: M12 x 1.75 | Tolerance: 6H (internal thread)
Corrosion Resistance
Stainless steel hex nuts are highly corrosion resistant. Their resistance depends on chromium content, nickel, molybdenum, and environmental conditions.
| Environment | Best Grade |
|---|---|
| Marine / Saltwater | A4-316 |
| Food & Beverage | A2-304 / A4-316 |
| Chemical Industry | A4-316 / Duplex 2205 |
| Outdoor / Urban | A2-304 |
Applications
- Construction & Infrastructure: Fastening structural steel, beams, machinery.
- Marine & Offshore: Corrosion-resistant fastening for ships, docks, and platforms.
- Automotive & Machinery: Engine components, exhaust systems.
- Food Processing / Pharma: Hygienic applications with electropolished nuts.
- Electronics / Appliances: Durable fastening in humid environments.
- Oil & Gas / Chemical Plants: High-strength, corrosion-resistant fasteners.
Installation & Torque Guidelines
- Lubricated vs Dry: Stainless steel nuts may gall; anti-seize compounds prevent seizing.
- Torque values depend on grade and bolt size. Example: ISO 898-2, A2-70, M12 torque ≈ 66 Nm.
- Avoid over-tightening to prevent thread galling.
- Use washers to distribute load when needed.
- Use lock nuts or lock washers in vibration-prone environments.
Manufacturing Process
- Cold Forging / Hot Forging: Shapes hex nut from stainless steel bar stock.
- Thread Cutting / Rolling: Internal threads are cut or rolled.
- Heat Treatment (optional) for high-strength grades.
- Surface Treatment: Passivation, polishing, or plating if required.
- Inspection: Dimensions, thread gauge, hardness, and corrosion testing.
Advantages of Stainless Steel Hex Nuts
- Excellent corrosion and rust resistance.
- High mechanical strength.
- Wide temperature range (-200°C to 800°C depending on grade).
- Durable and long-lasting.
- Hygienic and easy to clean (especially for food and pharma industries).
- Compatible with stainless steel bolts to avoid galvanic corrosion.
Limitations
- Higher cost compared to carbon steel.
- Susceptible to galling if threaded with stainless steel bolts.
- Lower tensile strength than some alloy steels (unless high-grade like A2-80, A4-80, or duplex).
Quick Reference Table
| Feature | Stainless Steel Hex Nut |
|---|---|
| Shape | Hexagonal (6-sided) |
| Materials | A2 (304), A4 (316), 2205 duplex, 430 ferritic |
| Standards | ISO 4032, DIN 934, ASTM A194, ASME B18.2.2 |
| Thread Types | Coarse, Fine, Extra Fine |
| Strength | A2-70: 700 MPa tensile, A2-80: 800 MPa tensile |
| Corrosion | Excellent; better with A4 or duplex |
| Applications | Marine, automotive, food, chemical, construction |
Stainless Steel Hex Nuts – Materials and Grades
| Material / Grade | Description / Type |
|---|---|
| A4 Hex Nuts | Corrosion-resistant stainless steel hex nuts |
| 310 Stainless Steel Hex Nuts | High-temperature resistant stainless steel |
| ASTM A194 Grade 8M Hex Nuts (316) | Marine-grade stainless steel nuts |
| 304 Stainless Steel Hex Nuts | Standard corrosion-resistant stainless steel |
| 316 Stainless Steel Hex Nuts | High corrosion resistance, marine applications |
| 304H Stainless Steel Hex Nuts | High-temperature 304 stainless steel |
| 18-8 Stainless Steel Hex Nuts | Classic austenitic stainless steel |
| 317L Stainless Steel Hex Nuts | Low-carbon, highly corrosion-resistant stainless steel |
| 316L Stainless Steel Hex Nuts | Low-carbon version of 316 stainless steel |
| 347 Stainless Steel Hex Nuts | Stabilized stainless steel for high-temperature service |
| 17-4 PH Hex Nuts | Precipitation-hardened stainless steel |
| ASTM A194 Grade 8 Hex Nuts (304) | High-strength stainless steel nuts |
| 18-8 Stainless Steel Hex Nuts | Common stainless steel for general applications |
| A2-70 Hex Nuts | Metric stainless steel, moderate strength |
| A4-50 Hex Nuts | Metric stainless steel, corrosion-resistant |
| Heavy Hex Nuts | Extra-thick, heavy-duty nuts for structural use |
| Slotted Hex Nuts | Nuts with slots for locking or cotter pins |
| Large Hex Nuts | Oversized nuts for heavy machinery or structural bolts |
| Duplex 2205 Hex Nuts | Duplex stainless steel with high strength & corrosion resistance |
| ASTM A194 Grade 6 Hex Nuts (410) | High-strength martensitic stainless steel |
| 304L Stainless Steel Hex Nuts | Low-carbon 304 stainless steel |
| 904L Stainless Steel Hex Nuts | High-alloy austenitic stainless steel, excellent corrosion resistance |
| A4-80 Hex Nuts | Metric stainless steel, high-strength |
| 410 Stainless Steel Hex Nuts | Martensitic stainless steel, moderate corrosion resistance |
| A2 Hex Nuts | Standard metric stainless steel nuts |
| 4.8 Hex Nuts | Low-strength carbon steel nut (for reference) |
| ASTM A194 8C Hex Nuts (347) | High-temperature, stabilized stainless steel |
| 316 Stainless Hex Nuts | Standard marine-grade stainless steel |
| 8.8 Hex Nuts | Medium-strength carbon steel nut (metric standard) |
| 317 Stainless Steel Hex Nuts | High corrosion-resistant stainless steel |
| 321 Stainless Steel Hex Nuts | Titanium-stabilized stainless steel |
| A4-70 Hex Nuts | Metric stainless steel, high-strength |
| A2-50 Hex Nuts | Metric stainless steel, moderate strength |
| Long Hex Nuts | Extended length hex nuts for deep-thread applications |
| Thin Hex Nuts | Reduced thickness nuts for space-limited applications |
| Finished Hex Nuts | Precision-machined, ready-to-use hex nuts |
Stainless Steel Hex Nuts Testing Tools & Equipment
- Micrometer
- Smooth Plug Gauge
- Thread Gauge
- Coordinate Measuring Machine (CMM)
- Roughness Tester
- Image Measuring Instrument
- Routine Inspection of Calipers
Material Grades & Standards
Common Stainless Steel Grades:
- A2 (304), A4 (316) – General-purpose, excellent corrosion resistance
- A2-50, A2-70, A2-80, A4-50, A4-70, A4-80 – High-strength variants
- Duplex 2205, 410, 431, 416, 440C – Specialty or high-strength applications
Other Material Variants:
- Carbon Steel: ASTM A194 Grades 1, 2, 2HM, 4, 7M, 8M
- Alloy Steel: SCM435, C10B21, C10B33
- High Tensile: 8.8, 10.9, 12.9
- Non-ferrous: Brass, Bronze, Aluminum, Titanium
Standards Compliance:
- DIN: 934, 982, 985, 936, 929, 1587, 439, 315
- BS: BS 57, BS6105 (A2-70, A4-70, A4-80, A2-50)
- ISO: ISO 4014, ISO 4017, ISO 4032, ISO 4161, ISO 4162
- ANSI / ASME / SAE: B18.2.2, B18.2.4, UNC/UNF/UNEF etc.
- GB / IS / JIS / UNI / PN / EU – International standards
Size Range & Manufacturing
Metric Hex Nuts:
- Cold Forming: M2 – M24
- Hot Forging: M24 – M100, 1½” dia., up to 1100 mm length
- CNC Machining: M100 / 4” dia., up to 1500 mm length
Typical Sizes: M2 – M160 (custom sizes)
Inch Hex Nuts: Diameter: ½” – 4”, Length: ½” – 52”
Thread & Nut Types
- Metric / US Threads: UNC, UNF, UNEF, UNJC, UNJF, UNK, UNR
- Special Threads: Acme, Trapezoidal
- Hex Nut Variants: Long Hex, Heavy Hex, Flanged, Lock Nuts, Slotted (Castle)
- Thread Tolerances: Metric ±0.01 mm to ±0.05 mm
Surface Finishes & Coatings
- Finishes: Passivated, Self-color, Electropolished, Bright Finish
- Coatings: Zinc, Dacromet, HDG, Zinc-Nickel, Nickel, PTFE, Teflon, Anodizing, Black Oxide
Dimensions & Standards
- Hex Nut Dimensions: ASME B18.2.2 / DIN 934
- Machine Nut Length: 3 mm – 200 mm
- Hex Nut Size: M10 – M110 (Metric), ½” – 4” (Imperial)
- Head Drives: Phillips, Slot, Six-Lobe
Packaging & Logistics
- Standard Packaging: Cartons, Wooden Pallets, Euro Pallets
- Carton Sizes: 36×24×16 cm / 36×24×12 cm
- Pallet Size: 110×80×90 cm
- Port of Dispatch: Mumbai / Kalamboli, Maharashtra, India
Stainless Steel Hex Nuts Dimensions (inches) & Weight
| Nominal Thread Size | Width Across Flats (F) Basic | Width Across Flats Max | Width Across Flats Min | Width Across Corners (C) Max | Width Across Corners Min | Thickness (H) Max | Thickness Min | Approx. Weight/Nut (lbs) |
|---|---|---|---|---|---|---|---|---|
| 3/8 | 11/16 | 0.688 | 0.669 | 0.794 | 0.763 | 0.377 | 0.341 | 0.03 |
| 1/2 | 7/8 | 0.875 | 0.850 | 1.010 | 0.969 | 0.504 | 0.464 | 0.07 |
| 5/8 | 1-1/16 | 1.062 | 1.031 | 1.227 | 1.175 | 0.631 | 0.587 | 0.12 |
| 3/4 | 1-1/4 | 1.250 | 1.212 | 1.443 | 1.382 | 0.758 | 0.710 | 0.20 |
| 7/8 | 1-7/16 | 1.438 | 1.394 | 1.660 | 1.589 | 0.885 | 0.833 | 0.30 |
| 1 | 1-5/8 | 1.625 | 1.575 | 1.876 | 1.796 | 1.012 | 0.956 | 0.43 |
| 1-1/8 | 1-13/16 | 1.812 | 1.756 | 2.093 | 2.002 | 1.139 | 1.079 | 0.59 |
| 1-1/4 | 2 | 2.000 | 1.938 | 2.309 | 2.209 | 1.251 | 1.187 | 0.79 |
| 1-3/8 | 2-3/16 | 2.188 | 2.119 | 2.526 | 2.416 | 1.378 | 1.310 | 1.02 |
| 1-1/2 | 2-3/8 | 2.375 | 2.300 | 2.742 | 2.622 | 1.505 | 1.433 | 1.31 |
| 1-5/8 | 2-9/16 | 2.562 | 2.481 | 2.959 | 2.828 | 1.632 | 1.556 | 1.62 |
| 1-3/4 | 2-3/4 | 2.750 | 2.662 | 3.175 | 3.035 | 1.759 | 1.679 | 2.04 |
| 1-7/8 | 2-15/16 | 2.938 | 2.844 | 3.392 | 3.242 | 1.886 | 1.802 | 2.41 |
| 2 | 3-1/8 | 3.125 | 3.025 | 3.608 | 3.449 | 2.013 | 1.925 | 2.99 |
| 2-1/4 | 3-1/2 | 3.500 | 3.388 | 4.041 | 3.862 | 2.251 | 2.155 | 4.19 |
| 2-1/2 | 3-7/8 | 3.875 | 3.750 | 4.474 | 4.275 | 2.505 | 2.401 | 5.64 |
| 2-3/4 | 4-1/4 | 4.250 | 4.112 | 4.907 | 4.688 | 2.759 | 2.647 | 7.38 |
| 3 | 4-5/8 | 4.625 | 4.475 | 5.340 | 5.102 | 3.013 | 2.893 | 9.50 |
| 3-1/4 | 5 | 5.000 | 4.838 | 5.774 | 5.515 | 3.252 | 3.124 | 11.94 |
| 3-1/2 | 5-3/8 | 5.375 | 5.200 | 6.207 | 5.928 | 3.506 | 3.370 | 15.26 |
| 3-3/4 | 5-3/4 | 5.750 | 5.562 | 6.640 | 6.341 | 3.760 | 3.616 | 18.12 |
| 4 | 6-1/8 | 6.125 | 5.925 | 7.073 | 6.755 | 4.014 | 3.862 | 21.80 |
Stainless Steel Hex Nut & Screw Nut Heights (Imperial)
| Nominal Size | Across Flats (Diameter) | Hex Nut Height | Machine Screw Nut | Jam Nut | Nylock Nut | MS Nut Height |
|---|---|---|---|---|---|---|
| #0 | — | — | 5/32" | — | — | 3/64" |
| #1 | — | — | 5/32" | — | — | 3/64" |
| #2 | — | — | 3/16" | — | 9/64" | 1/16" |
| #3 | — | — | 3/16" | — | 9/64" | 1/16" |
| #4 | — | — | 1/4" | — | 9/64" | 3/32" |
| #6 | — | — | 5/16" | — | 11/64" | 7/64" |
| #8 | — | — | 11/32" | — | 15/64" | 1/8" |
| #10 | — | — | 3/8" | — | 15/64" | 1/8" |
| #12 | — | — | 7/16" | — | 5/16" | 5/32" |
| 1/4" | 7/16" | 7/32" | 7/16" | 5/32" | 5/16" | 3/16" |
| 5/16" | 1/2" | 17/64" | 9/16" | 3/16" | 11/32" | 7/32" |
| 3/8" | 9/16" | 21/64" | 5/8" | 7/32" | 29/64" | 1/4" |
| 7/16" | 11/16" | 3/8" | — | 1/4" | 29/64" | — |
| 1/2" | 3/4" | 7/16" | — | 5/16" | 19/32" | — |
| 9/16" | 7/8" | 31/64" | — | 5/16" | 41/64" | — |
| 5/8" | 15/16" | 35/64" | — | 3/8" | 3/4" | — |
| 3/4" | 1-1/8" | 41/64" | — | 27/64" | 7/8" | — |
| 7/8" | 1-5/16" | 3/4" | — | 31/64" | 63/64" | — |
| 1" | 1-1/2" | 55/64" | — | 35/64" | 1-3/64" | — |
Note: Across flats = diameter for wrench size.
Stainless Steel Hex Nuts Dimensions (mm)
| Hex Nut Size | Thread Pitch | Width Across Flats (s) Max | Width Across Flats (s) Min | Width Across Corners (e) Min | Height of Nut (m) Max | Height of Nut (m) Min |
|---|---|---|---|---|---|---|
| M1.6 | 0.35 | 3.20 | 3.02 | 3.41 | 1.30 | 1.05 |
| M2 | 0.4 | 4.00 | 3.82 | 4.32 | 1.60 | 1.35 |
| M2.5 | 0.45 | 5.00 | 4.82 | 5.45 | 2.00 | 1.75 |
| M3 | 0.5 | 5.50 | 5.32 | 6.01 | 2.40 | 2.15 |
| M3.5* | 0.6 | 6.00 | 5.82 | 6.58 | 2.80 | 2.55 |
| M4 | 0.7 | 7.00 | 6.78 | 7.66 | 3.20 | 2.90 |
| M5 | 0.8 | 8.00 | 7.78 | 8.79 | 4.70 | 4.40 |
| M6 | 1 | 10.00 | 9.78 | 11.05 | 5.20 | 4.90 |
| M8 | 1.25 | 13.00 | 12.73 | 14.38 | 6.80 | 6.44 |
| M10 | 1.5 | 16.00 | 15.73 | 17.77 | 8.40 | 8.04 |
| M12 | 1.75 | 18.00 | 17.73 | 20.03 | 10.80 | 10.37 |
| M14* | 2 | 21.00 | 20.67 | 23.36 | 12.80 | 12.10 |
| M16 | 2 | 24.00 | 23.67 | 26.75 | 14.80 | 14.10 |
| M18* | 2.5 | 27.00 | 26.16 | 29.56 | 15.80 | 15.10 |
| M20 | 2.5 | 30.00 | 29.16 | 32.95 | 18.00 | 16.90 |
| M22* | 2.5 | 34.00 | 33.00 | 37.29 | 19.40 | 18.10 |
| M24 | 3 | 36.00 | 35.00 | 39.55 | 21.50 | 20.20 |
| M27* | 3 | 41.00 | 40.00 | 45.20 | 23.80 | 22.50 |
| M30 | 3.5 | 46.00 | 45.00 | 50.85 | 25.60 | 24.30 |
| M33* | 3.5 | 50.00 | 49.00 | 55.37 | 28.70 | 27.40 |
| M36 | 4 | 55.00 | 53.80 | 60.79 | 31.00 | 29.40 |
| M39* | 4 | 60.00 | 58.80 | 66.44 | 33.40 | 31.80 |
| M42 | 4.5 | 65.00 | 63.10 | 71.30 | 34.00 | 32.40 |
| M45* | 4.5 | 70.00 | 68.10 | 76.95 | 36.00 | 34.40 |
| M48 | 5 | 75.00 | 73.10 | 82.60 | 38.00 | 36.40 |
| M52* | 5 | 80.00 | 78.10 | 88.25 | 42.00 | 40.40 |
| M56 | 5.5 | 85.00 | 82.80 | 93.56 | 45.00 | 43.40 |
| M60* | 5.5 | 90.00 | 87.80 | 99.21 | 48.00 | 46.40 |
| M64 | 6 | 95.00 | 92.80 | 104.86 | 51.00 | 49.10 |
*Note: Diameter across flats = wrench size.
Fine Thread Stainless Steel Hex Nuts Dimensions (mm)
| Nominal Thread | Min Width Across Corners (e min) | Width Across Flats (s) | Max Height (m max) |
|---|---|---|---|
| MF3 × 0.3 | 6.01 | 5.5 | 2.4 |
| MF4 × 0.5 | 7.66 | 7 | 3.2 |
| MF5 × 0.5 | 8.79 | 8 | 4 |
| MF6 × 0.75 | 11.05 | 10 | 5 |
| MF8 × 1 | 14.38 | 13 | 6.5 |
| MF10 × 1 | 18.9 | 17 | 8 |
| MF10 × 1.25 | 18.9 | 17 | 8 |
| MF12 × 1 | 21.1 | 19 | 10 |
| MF12 × 1.25 | 21.1 | 19 | 10 |
| MF12 × 1.5 | 21.1 | 19 | 10 |
| MF14 × 1.5 | 24.49 | 22 | 11 |
| MF16 × 1.5 | 26.75 | 24 | 13 |
| MF18 × 1.5 | 29.56 | 27 | 15 |
| MF20 × 1.5 | 32.95 | 30 | 16 |
| MF22 × 1.5 | 35.03 | 32 | 18 |
| MF24 × 2 | 39.55 | 36 | 19 |
| MF27 × 2 | 45.2 | 41 | 22 |
| MF30 × 2 | 50.85 | 46 | 24 |
| MF36 × 3 | 60.79 | 55 | 29 |
| MF42 × 3 | 72.09 | 65 | 34 |
| MF48 × 3 | 82.6 | 75 | 38 |
Finished Hex Nut Dimensions
| Nominal Size | Thread Diameter | Width Across Flats (F) | Width Across Corners (G) | Thickness (H) |
|---|---|---|---|---|
| 1/4" | 0.2500 | 7/16" | 0.505 – 0.488 | 7/32" 0.226 – 0.212 |
| 5/16" | 0.3125 | 1/2" | 0.577 – 0.557 | 17/64" 0.273 – 0.258 |
| 3/8" | 0.3750 | 9/16" | 0.650 – 0.628 | 21/64" 0.337 – 0.320 |
| 7/16" | 0.4375 | 11/16" | 0.794 – 0.768 | 3/8" 0.385 – 0.365 |
| 1/2" | 0.5000 | 3/4" | 0.866 – 0.840 | 7/16" 0.448 – 0.427 |
| 9/16" | 0.5625 | 7/8" | 1.010 – 0.982 | 31/64" 0.496 – 0.473 |
| 5/8" | 0.6250 | 15/16" | 1.083 – 1.051 | 35/64" 0.559 – 0.535 |
| 3/4" | 0.7500 | 1-1/8" | 1.299 – 1.240 | 41/64" 0.665 – 0.617 |
| 7/8" | 0.8750 | 1-5/16" | 1.516 – 1.447 | 3/4" 0.776 – 0.724 |
| 1" | 1.0000 | 1-1/2" | 1.732 – 1.653 | 55/64" 0.887 – 0.831 |
| 1-1/8" | 1.1250 | 1-11/16" | 1.949 – 1.859 | 31/32" 0.999 – 0.939 |
| 1-3/8" | 1.3750 | 2-1/16" | 2.382 – 2.273 | 1-11/64" 1.206 – 1.138 |
| 1-1/2" | 1.5000 | 2-1/4" | 2.598 – 2.480 | 1-9/32" 1.317 – 1.245 |
| 1-5/8" | 1.6250 | 2-7/16" | 2.815 – 2.686 | 1-25/64" 1.429 – 1.353 |
| 1-3/4" | 1.7500 | 2-5/8" | 3.031 – 2.893 | 1-1/2" 1.540 – 1.460 |
| 2" | 2.0000 | 3" | 3.464 – 3.306 | 1-23/32" 1.763 – 1.675 |
| 2-1/4" | 2.2500 | 3-3/8" | 3.897 – 3.719 | 1-15/16" 1.986 – 1.890 |
| 2-1/2" | 2.5000 | 3-3/4" | 4.330 – 4.133 | 2-5/32" 2.209 – 2.105 |
| 2-3/4" | 2.7500 | 4-1/8" | 4.763 – 4.546 | 2-3/8" 2.431 – 2.319 |
Heavy Hex Nut Dimensions
| Nominal Size | Thread Diameter | Width Across Flats (F) | Width Across Corners (G) | Thickness (H) |
|---|---|---|---|---|
| 1/4" | 0.2500 | 1/2" | 0.577 – 0.556 | 15/64" 0.250 – 0.218 |
| 5/16" | 0.3125 | 9/16" | 0.650 – 0.622 | 19/64" 0.314 – 0.280 |
| 3/8" | 0.3750 | 11/16" | 0.794 – 0.763 | 23/64" 0.377 – 0.341 |
| 7/16" | 0.4375 | 3/4" | 0.866 – 0.830 | 27/64" 0.441 – 0.403 |
| 1/2" | 0.5000 | 7/8" | 1.010 – 0.969 | 31/64" 0.504 – 0.464 |
| 9/16" | 0.5625 | 15/16" | 1.083 – 1.037 | 35/64" 0.568 – 0.526 |
| 5/8" | 0.6250 | 1-1/16" | 1.227 – 1.175 | 39/64" 0.631 – 0.587 |
| 3/4" | 0.7500 | 1-1/4" | 1.443 – 1.382 | 47/64" 0.758 – 0.710 |
| 7/8" | 0.8750 | 1-7/16" | 1.660 – 1.589 | 55/64" 0.885 – 0.833 |
| 1" | 1.0000 | 1-5/8" | 1.876 – 1.796 | 63/64" 1.012 – 0.956 |
| 1-1/8" | 1.1250 | 1-13/16" | 2.093 – 2.002 | 1-7/64" 1.139 – 1.079 |
| 1-1/4" | 1.2500 | 2" | 2.309 – 2.209 | 1-7/32" 1.251 – 1.187 |
| 1-3/8" | 1.3750 | 2-3/16" | 2.526 – 2.416 | 1-11/32" 1.378 – 1.310 |
| 1-1/2" | 1.5000 | 2-3/8" | 2.742 – 2.622 | 1-15/32" 1.505 – 1.433 |
| 1-5/8" | 1.6250 | 2-9/16" | 2.959 – 2.828 | 1-19/32" 1.632 – 1.556 |
| 1-3/4" | 1.7500 | 2-3/4" | 3.175 – 3.035 | 1-23/32" 1.759 – 1.679 |
| 2" | 2.0000 | 3-1/8" | 3.608 – 3.449 | 1-31/32" 2.013 – 1.925 |
| 2-1/4" | 2.2500 | 3-1/2" | 4.041 – 3.862 | 2-13/64" 2.251 – 2.155 |
| 2-1/2" | 2.5000 | 3-7/8" | 4.474 – 4.275 | 2-29/64" 2.505 – 2.401 |
| 2-3/4" | 2.7500 | 4-1/4" | 4.907 – 4.688 | 2-45/64" 2.759 – 2.647 |
| 3" | 3.0000 | 4-5/8" | 5.340 – 5.102 | 2-61/64" 3.013 – 2.893 |
| 3-1/4" | 3.2500 | 5" | 5.774 – 5.515 | 3-3/16" 3.252 – 3.124 |
| 3-1/2" | 3.5000 | 5-3/8" | 6.207 – 5.928 | 3-7/16" 3.506 – 3.370 |
| 3-3/4" | 3.7500 | 5-3/4" | 6.640 – 6.341 | 3-11/16" 3.670 – 3.616 |
| 4" | 4.0000 | 6-1/8" | 7.073 – 6.755 | 3-15/16" 4.014 – 3.862 |
Stainless Steel Hex Nuts Torque Chart
| Nominal Thread | Width Across Flats (S, mm) | Width Across Corners (E, mm) | Property Class 5 & 10 | Property Class 9 | Bearing Face Diameter (Dw, mm) | Top Insert | Thickness / Wrench Height (M / M1, mm) |
|---|---|---|---|---|---|---|---|
| M3 × 0.5 | 5.50 – 5.32 | 6.35 – 6.01 | 3.10 – 2.65 | 4.50 – 3.90 | 3.10 – 2.65 | 4.50 – 3.90 | 1.4 / 1.4 / 4.6 |
| M3.5 × 0.6 | 6.00 – 5.82 | 6.93 – 6.58 | 3.50 – 3.00 | 5.00 – 4.30 | 3.50 – 3.00 | 5.00 – 4.30 | 1.7 / 1.7 / 5.1 |
| M4 × 0.7 | 7.00 – 6.78 | 8.08 – 7.66 | 4.00 – 3.50 | 6.00 – 5.30 | 4.00 – 3.50 | 6.00 – 5.30 | 1.9 / 1.9 / 5.9 |
| M5 × 0.8 | 8.00 – 7.78 | 9.24 – 8.79 | 5.30 – 4.80 | 6.80 – 6.00 | 5.30 – 4.80 | 7.20 – 6.40 | 2.7 / 2.7 / 6.9 |
| M6 × 1 | 10.00 – 9.78 | 11.55 – 11.05 | 5.90 – 5.40 | 8.00 – 7.20 | 6.70 – 5.40 | 8.50 – 7.70 | 3.0 / 3.0 / 8.9 |
| M8 × 1.25 | 13.00 – 12.73 | 15.01 – 14.38 | 7.10 – 6.44 | 9.50 – 8.50 | 8.00 – 7.14 | 10.20 – 9.20 | 3.7 / 4.3 / 11.6 |
| M10 × 1.5 | 15.00 – 14.73 | 17.32 – 16.64 | 9.70 – 8.70 | 12.50 – 11.50 | 11.20 – 9.60 | 13.50 – 12.50 | 5.6 / 6.2 / 13.6 |
| M10 × 1.5 | 16.00 – 15.73 | 18.48 – 17.77 | 9.00 – 8.04 | 11.90 – 10.90 | 10.50 – 8.94 | 12.80 – 11.80 | 4.8 / 5.6 / 14.6 |
| M12 × 1.75 | 18.00 – 17.73 | 20.78 – 20.03 | 11.60 – 10.37 | 14.90 – 13.90 | 13.30 – 11.57 | 16.10 – 15.10 | 6.7 / 7.7 / 16.6 |
| M14 × 2 | 21.00 – 20.67 | 24.25 – 23.35 | 13.20 – 12.10 | 17.00 – 15.80 | 15.40 – 13.40 | 18.30 – 17.10 | 7.8 / 8.9 / 19.6 |
| M16 × 2 | 24.00 – 23.67 | 27.71 – 26.75 | 15.20 – 14.10 | 19.10 – 17.90 | 17.90 – 15.70 | 20.70 – 19.50 | 9.1 / 10.5 / 22.5 |
| M20 × 2.5 | 30.00 – 29.16 | 34.64 – 32.95 | 19.00 – 16.90 | 22.80 – 21.50 | 21.80 – 19.00 | 25.10 – 23.80 | 10.9 / 12.7 / 27.7 |
| M24 × 3 | 36.00 – 35.00 | 41.57 – 39.55 | 23.00 – 20.20 | 27.10 – 25.60 | 26.40 – 22.60 | 29.50 – 28.00 | 13.0 / 15.1 / 33.2 |
| M30 × 3.5 | 46.00 – 45.00 | 53.12 – 50.85 | 26.90 – 24.30 | 32.60 – 30.60 | 31.80 – 27.30 | 35.60 – 33.60 | 15.7 / 18.2 / 42.7 |
| M36 × 4 | 55.00 – 53.80 | 63.51 – 60.79 | 32.50 – 29.40 | 38.90 – 36.90 | 38.50 – 33.10 | 42.60 – 40.60 | 19.0 / 22.1 / 51.1 |
Hex vs Heavy Hex Nuts
| Hex Nut Grade | Nut Style | Size (inches) | Proof Load (ksi) | Hardness (HBN) |
|---|---|---|---|---|
| Plain / Galvanized A | Hex | 1/4 – 1-1/2 | 90 | 68 / 116 – 302 |
| Heavy Hex A | Heavy Hex | 1/4 – 4 | 100 | 75 / 116 – 302 |
| B | Heavy Hex | 1/4 – 1 | 133 | 100 / 121 – 302 |
| B | Heavy Hex | 1-1/8 – 1-1/2 | 116 | 87 / 121 – 302 |
| C / C3 | Heavy Hex | 1/4 – 4 | 144 | 144 / 143 – 352 |
| D | Heavy Hex | 1/4 – 4 | 150 | 150 / 248 – 352 |
| DH / DH3 | Heavy Hex | 1/4 – 4 | 175 | 150 / 248 – 352 |
Hex Nut Standards
| Standard / Specification | Description |
|---|---|
| AS 1112.1 | Hexagon nuts, style 1, grade A & B |
| AS 1112.2 | Hexagon nuts, style 2, grade A & B |
| AS 1112.3 | Hexagon nuts, grade C |
| AS 1112.4 | Hexagon thin nuts (chamfered), grades A & B |
| AS 1252 | High strength large hexagon nuts |
| AS 2451 | Hexagon nuts with BSW threads |
| AS 2465 | Hexagon nuts with Unified threads |
| ASME/ANSI B18.2.2 | Heavy hex nuts |
| ASME/ANSI B18.2 | Hex coupling nuts (Table 13) |
| ASME/ANSI B18.2.2 | Hex flat jam nuts |
| ASME/ANSI B18.2.2 | Hex flat nuts and hex flat jam nuts (Table 3) |
| ASME/ANSI B18.2.2 | Hex full nuts |
| ASME/ANSI B18.2.2 | Hex lock nuts |
| ASME/ANSI B18.2.2 | Hex nuts and hex jam nuts (Table 4) |
| ASME/ANSI B18.2.2 | Hex thick nuts |
| ASME/ANSI B18.2.2 | Hex thick nuts (Table 2) |
| ASME/ANSI B18.2.2 | Hexagon lock nuts - heavy duty |
| ASME/ANSI B18.2.4.1M | Hex full nuts, style 1 |
| ASME/ANSI B18.2.4.2M | Hex nuts, style 2 |
| ASME/ANSI B18.2.4.5M | Metric hex jam nuts |
| ASME/ANSI B18.2.4.5M | Metric hex thin nuts |
| ASME/ANSI B18.2.4.6M | Metric heavy hex nuts |
| ASME/ANSI B18.2.6 | Flat nuts and heavy hex flat jam nuts (Table 9) |
| ASME/ANSI B18.2.6 | Heavy hex flat nuts (Table 10) |
| ASME/ANSI B18.2.6 | Heavy hex nuts |
| EN 14399-3 | High strength nuts for preloading assemblies, HR system |
| EN 14399-4 | High strength nuts for preloading assemblies, HV system |
| EN 14399-7 | High strength nuts for preloading assemblies, HR system |
| BS 190 | Pre-war hexagon full nuts (Heavy series BSW or BSF) |
| BS 190 | Pre-war hexagon lock nuts (Heavy series BSW or BSF) |
| BS 1083 | Hexagon full nuts |
| BS 1083 | Hexagon lock nuts |
| BS 1768 | Hexagon full nuts - unified threads |
| BS 1768 | Hexagon lock nuts - unified threads |
| BS 1768 | Hexagon thick full nuts - unified threads |
| BS 1769 | Hexagon black full nuts - unified threads |
| BS 1769 | Hexagon heavy black full nuts - unified threads |
| BS 325 | Hexagon black full nuts |
| BS 3692 | Hexagon full nuts |
| BS 3692 | Hexagon lock nuts |
| BS 4190 | Hexagon thin lock nuts |
| BS 4395 | High strength large hex nuts |
| BS 916 | Hexagon black nuts |
| DIN 2510-5 | Reduced shank hexagon nuts |
| DIN 439-1 | Hexagon unchamfered thin lock nuts |
| DIN 439-2 | Hexagon thin lock nuts |
| DIN 555 | Hexagon nuts |
| DIN 6915 | Heavy hex nuts |
| DIN 74361-2A | Hexagon wheel nuts |
| DIN 74361-2F | Hexagon conical wheel nuts |
| DIN 934 | Hexagon nuts |
| DIN 936 | Hexagon nuts |
| DIN 970 | Hexagon nuts |
| DIN 971-1 | Hexagon nuts, style 1 |
| DIN 971-2 | Hexagon nuts, style 2 |
| EN 24035 | Hexagon thin nuts |
| EN 28673 | Hexagon nuts, style 1 |
| IFI 128 | Hexagon coupling nuts |
| ISO 13754 | Hexagon nuts |
| ISO 4032 | Hexagon nuts, style 1 |
| ISO 4033 | Hexagon nuts, style 1 |
| ISO 4034 | Hexagon nuts |
| ISO 4035 | Hexagon chamfered thin nuts |
| ISO 4036 | Hexagon unchamfered thin nuts |
| ISO 4775 | Heavy hexagon nuts |
| ISO 7413 | Galvanized hexagon nuts tapped oversize |
| ISO 7414 | Heavy hexagon nuts |
| ISO 7417 | Galvanized hexagon nuts tapped oversize |
| ISO 8673 | Hexagon nuts |
| ISO 8674 | Hexagon nuts |
| ISO 8675 | Hexagon thin lock nuts |
| NF E25-401 | Hexagon nuts, style 1 |
| NF E25-402 | Hexagon nuts |
| NF E25-405-1 | Hexagon chamfered thin lock nuts |
| NF E25-405-2 | Hexagon unchamfered thin lock nuts |
| NF E25-407 | Hexagon nuts, style 2 |
| NF E25-451 | Hexagon nuts, style 1 |
| NF E25-452 | Hexagon nuts, style 2 |
| NF E25-453 | Hexagon chamfered thin nuts |
| UNI 5587 | Hexagon nuts |
| UNI 5588 | Hexagon nuts |
| UNI 5589 | Hexagon nuts |
| UNI 5713 | Heavy hexagon nuts |
Accessories / Related Components for Stainless Steel Hex Nuts
Stainless steel hex nuts are often used with other fasteners and components to ensure secure assembly, load distribution, and proper alignment. The main accessories include washers, bolts, threaded rods, and more.
❮
Washers
Purpose: Distribute load, prevent damage, and reduce loosening.
Types:
Types:
- Flat Washers – Smooth surface, even load distribution
- Spring Washers – Prevent loosening due to vibration
- Fender Washers – Larger diameter for soft or thin surfaces
- Sealing Washers – Prevent leakage in fluid applications
Bolts
Purpose: Join components; hex nuts thread onto bolts for secure joints.
Types:
Types:
- Hex Bolts – Common pairing with hex nuts
- Carriage Bolts – Round head with square neck
- Stud Bolts – Threaded rods with nuts at both ends
- Machine Bolts – Precision applications
Threaded Rods
Purpose: Fully threaded rods cut to size; use nuts at both ends.
Applications:
Material: Stainless steel for corrosion resistance
Applications:
- Structural assemblies
- Machinery installation
- Electrical & plumbing systems
Material: Stainless steel for corrosion resistance
Additional Accessories
- Lock Nuts – Resist loosening under vibration
- Caps & Domed Nuts – Protect threads & provide aesthetic finish
- Coupling Nuts – Connect two threaded rods or bolts
Practical Tips
- Match material grade of nuts, bolts, and washers
- Use washers to protect surfaces and distribute load
- Ensure thread compatibility (metric or imperial)
- For high-vibration, use lock washers or nylon-insert nuts
❯
Frequently Asked Questions – Stainless Steel Hex Nuts
1. What are Stainless Steel Hex Nuts?
Stainless Steel Hex Nuts are six-sided fasteners used with bolts and screws to securely hold components together. They are resistant to corrosion, making them ideal for industrial, marine, and outdoor applications.
2. What materials and grades are available for stainless steel hex nuts?
Common materials and grades include:
- 304, 304L, 304H Stainless Steel
- 316, 316L, 317L Stainless Steel
- 317, 347 Stainless Steel
- 18-8 Stainless Steel
- Duplex 2205
- ASTM A194 Grade 6, 8, 8M, 8C
- 17-4 PH Stainless Steel
- A2 and A4 Hex Nuts
3. What are the different types of hex nuts?
- Standard Hex Nuts
- Heavy Hex Nuts
- Jam Nuts (thin hex nuts)
- Nylock Nuts (self-locking)
- Slotted Hex Nuts
- Large Hex Nuts
- Long Hex Nuts
- Thin Hex Nuts
- Acme Hex Nuts
4. What standards do stainless steel hex nuts follow?
Hex nuts follow international standards such as:
- AS: AS 1112, AS 1252, AS 2451, AS 2465
- ASME/ANSI: B18.2.2, B18.2.4, B18.2.6
- DIN: DIN 2510-5, DIN 439, DIN 555, DIN 6915, DIN 934
- ISO: ISO 4032, ISO 4033, ISO 4034, ISO 4035, ISO 4775
- EN: EN 14399-3, EN 14399-4, EN 14399-7, EN 24035, EN 28673
- BS: BS 190, BS 1083, BS 1768, BS 1769, BS 325, BS 3692
5. What sizes and dimensions are available?
Hex nuts come in a wide range of **nominal diameters**, thicknesses, and widths across flats and corners. Examples:
- Standard Hex Nut: 1/4" to 2-3/4"
- Heavy Hex Nut: 1/4" to 4"
- Fine Thread Hex Nuts: MF3x0.3 to MF48x3
- Acme Hex Nuts: 3/16”-20 TPI to 3-1/2”-2 TPI
6. What is the difference between standard and heavy hex nuts?
- Standard Hex Nuts: Used for general applications; smaller thickness and wrench sizes.
- Heavy Hex Nuts: Thicker and larger, designed for high-strength applications and heavy load-bearing.
7. How do I select the right hex nut for my application?
Consider:
- Bolt diameter and thread type
- Material and corrosion resistance
- Load and torque requirements
- Industry standards or specifications
8. What testing tools and equipment are used?
Quality control tools include:
- Micrometers
- Smooth Plug Gauges
- Thread Gauges
- Coordinate Measuring Machines (CMM)
- Roughness Testers
- Image Measuring Instruments
- Routine inspection using calipers
9. What is the torque specification for stainless steel hex nuts?
Torque depends on nut size, thread pitch, and material grade. Examples:
- M6 × 1 Hex Nut (Class 8) – Torque: 8.9 Nm
- M10 × 1.5 Hex Nut (Class 10) – Torque: 13.6 Nm
10. Can hex nuts be used in high-temperature or marine environments?
Yes. Grades like 316, 316L, 317L, and Duplex 2205 are suitable for corrosive environments, including marine applications and high-temperature conditions.
11. Difference between 304 and 316 stainless steel hex nuts?
- 304 Stainless Steel: General-purpose corrosion resistance, suitable for indoor use.
- 316 Stainless Steel: Superior corrosion resistance, ideal for marine or chemical environments.
12. What is a Nylock nut?
A Nylock nut is a self-locking hex nut with a nylon insert, preventing loosening due to vibrations.
13. Difference between finished and coarse hex nuts?
- Finished Hex Nuts: Precision-machined for exact fit and dimensions.
- Coarse Hex Nuts: Standard tolerances, commonly used for general applications.
14. Are hex nuts reusable?
Yes, but only if the nut has not been deformed, corroded, or subjected to excessive torque beyond its specification.
15. How do I maintain stainless steel hex nuts?
- Clean regularly to remove debris and prevent corrosion.
- Avoid exposure to harsh chemicals unless the grade supports it.
- Inspect for wear or deformation before reuse.