Related Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
ASME B18.2.2 Hex Nuts Dimension Standard
Standard Inch-Series Regular Hex Nuts for Structural, Mechanical, and Process Industry Bolted Connections.
ASME B18.2.2 Hex Nuts are the most widely used inch-series internally threaded fasteners in North American engineering, construction, and manufacturing — governing dimensional requirements for standard regular hexagonal nuts used as the primary mating nut for ASME B18.2.1 hex bolts, hex cap screws, and stud bolts across structural steel connections, mechanical assemblies, process piping, and pressure equipment applications throughout the full nominal size range from 1/4 inch through 4 inches. The ASME B18.2.2 standard defines precise dimensional requirements for regular hex nuts including width across flats, width across corners, nut thickness, bearing face, chamfer dimensions, and thread specifications — ensuring complete dimensional interchangeability across all compliant nut manufacturers and maintaining consistent clamping performance in bolted joint design calculations. When manufactured to ASTM A1082, the specification for high-strength stainless steel bolting material, ASME B18.2.2 Hex Nuts deliver excellent corrosion resistance, non-magnetic properties, and sustained mechanical performance in aggressive service environments including marine structures, chemical processing plants, coastal infrastructure, pharmaceutical manufacturing facilities, food and beverage processing buildings, and water treatment infrastructure where carbon steel hex nuts would suffer rapid surface corrosion, thread degradation, and eventual seizure under the combined effects of atmospheric moisture and chemical exposure. ASTM A1082 hex nuts per ASME B18.2.2 are the standard mating nut for ASME B18.2.1 hex bolts and cap screws in ASTM A1082 stainless steel, forming dimensionally matched and fully corrosion-resistant inch-series bolted assemblies for critical service applications. Full EN 10204 Type 3.1 material certification is available for all ASTM A1082 ASME B18.2.2 hex nut lots supplied to quality-critical projects.
ASME B18.2.2 Hex Nuts Dimensions (Inch)
| Nominal Size | Basic Major Diameter of Thread | Width Across Flats, F | Width Across Corners, G | Thickness, H |
Maximum Runout of Bearing Surface to Thread Axis, FIM |
||||
|---|---|---|---|---|---|---|---|---|---|
| Min. | Max | Min. | Max | Min. | Max | Up to 150,000 psi | 150,000 psi and Greater | ||
| 1/4 | 0.2500 | 0.428 | 0.438 | 0.488 | 0.505 | 0.212 | 0.226 | 0.015 | 0.010 |
| 5/16 | 0.3125 | 0.489 | 0.500 | 0.557 | 0.577 | 0.258 | 0.273 | 0.016 | 0.011 |
| 3/8 | 0.3750 | 0.551 | 0.563 | 0.628 | 0.650 | 0.320 | 0.337 | 0.017 | 0.012 |
| 7/16 | 0.4375 | 0.675 | 0.688 | 0.768 | 0.794 | 0.365 | 0.385 | 0.018 | 0.013 |
| 1/2 | 0.5000 | 0.736 | 0.750 | 0.840 | 0.866 | 0.427 | 0.448 | 0.019 | 0.014 |
| 9/16 | 0.5625 | 0.861 | 0.875 | 0.982 | 1.010 | 0.473 | 0.496 | 0.020 | 0.015 |
| 5/8 | 0.6250 | 0.922 | 0.938 | 1.051 | 1.083 | 0.535 | 0.559 | 0.021 | 0.016 |
| 3/4 | 0.7500 | 1.088 | 1.125 | 1.240 | 1.299 | 0.617 | 0.665 | 0.023 | 0.018 |
| 7/8 | 0.8750 | 1.269 | 1.312 | 1.447 | 1.516 | 0.724 | 0.776 | 0.025 | 0.020 |
| 1 | 1.0000 | 1.450 | 1.500 | 1.653 | 1.732 | 0.831 | 0.887 | 0.027 | 0.022 |
| 1 1/8 | 1.1250 | 1.631 | 1.688 | 1.859 | 1.949 | 0.939 | 0.999 | 0.030 | 0.025 |
| 1 1/4 | 1.2500 | 1.812 | 1.875 | 2.066 | 2.165 | 1.030 | 1.094 | 0.033 | 0.028 |
| 1 3/8 | 1.3750 | 1.994 | 2.062 | 2.273 | 2.382 | 1.138 | 1.206 | 0.036 | 0.031 |
| 1 1/2 | 1.5000 | 2.175 | 2.250 | 2.480 | 2.598 | 1.245 | 1.317 | 0.039 | 0.034 |
| 1 5/8 | 1.6250 | 2.35 | 2.43 | 2.679 | 2.805 | 1.364 | 1.416 | 0.044 | 0.038 |
| 1 3/4 | 1.7500 | 2.538 | 2.625 | 2.893 | 3.031 | 1.460 | 1.540 | 0.048 | 0.041 |
| 1 7/8 | 1.8750 | 2.722 | 2.813 | 3.103 | 3.247 | 1.567 | 1.651 | 0.051 | 0.044 |
| 2 | 2.0000 | 2.900 | 3.000 | 3.306 | 3.464 | 1.675 | 1.763 | 0.055 | 0.047 |
| 2 1/4 | 2.2500 | 3.263 | 3.375 | 3.719 | 3.897 | 1.890 | 1.986 | 0.061 | 0.052 |
| 2 1/2 | 2.5000 | 3.625 | 3.750 | 4.133 | 4.330 | 2.105 | 2.209 | 0.068 | 0.058 |
| 2 3/4 | 2.7500 | 3.988 | 4.125 | 4.546 | 4.763 | 2.319 | 2.431 | 0.074 | 0.064 |
| 3 | 3.0000 | 4.350 | 4.500 | 4.959 | 5.196 | 2.534 | 2.654 | 0.081 | 0.070 |
| 3 1/4 | 3.2500 | 4.713 | 4.875 | 5.373 | 5.629 | 2.749 | 2.877 | 0.087 | 0.075 |
| 3 1/2 | 3.5000 | 5.075 | 5.250 | 5.786 | 6.062 | 2.964 | 3.100 | 0.094 | 0.081 |
| 3 3/4 | 3.7500 | 5.438 | 5.625 | 6.199 | 6.495 | 3.178 | 3.322 | 0.100 | 0.087 |
| 4 | 4.0000 | 5.800 | 6.000 | 6.612 | 6.928 | 3.393 | 3.545 | 0.107 | 0.093 |
Frequently Asked Questions
What stainless steel grades does ASTM A1082 cover for hex nuts?
ASTM A1082 covers duplex grades (S31803/2205, S32205/2205, S32750/2507, S32760/Zeron 100, S39277/AL-6XN) and precipitation-hardening grades (S17400/17-4 PH, S17700/17-7 PH, S15700/15-7 PH, S35500/AM-355) - all available for this product family at TorqBolt.
What is the standard dimensional reference for these hex nuts?
This product follows ASME B18.2 2, the dimensional standard for hex nuts in stainless steel. Material chemistry, mechanical properties and heat treatment follow ASTM A1082/A1082M. TorqBolt supplies both inch-series and metric sizes per the applicable ASME or ISO drawing.
Are A1082 hex nuts suitable for sour service (NACE MR0175)?
Yes, with hardness control. NACE MR0175 / ISO 15156 permits duplex grades S31803, S32205, S32750, S32760 at 28 HRC max for sour service. 17-4 PH (S17400) at H1150 condition (28 HRC) is the most common PH grade qualified for sour service. TorqBolt provides NACE-MR0175 compliant heat-treat reports.
What is the typical strength of A1082 super-duplex 2507 (S32750) hex nuts?
Super-duplex 2507 (S32750) per A1082: tensile 116 ksi (800 MPa) min, yield 80 ksi (550 MPa) min, elongation 15% min, 32 HRC max. PREN ≈ 42 - suitable for seawater, brine and chloride-rich pressure-vessel service. Higher strength than austenitic A193 B8M while offering pitting resistance well above 304/316.
References & Standards
- ASTM A1082 / A1082M - Standard Specification for High-Strength Precipitation-Hardening and Duplex Stainless Steel Bolting for Special-Purpose Applications (current edition 2016, active)
- ASTM A962 / A962M - General Requirements for Special-Purpose Bolting Materials
- ASTM A370 - Mechanical Testing of Steel Products
- NACE MR0175 / ISO 15156 - Sour-service hardness limits for petroleum & natural gas industries
- ASME B18 series - Dimensional standards for bolts, screws, nuts, studs
- ISO 4032 / 4033 / 4035 - Metric hexagon nut dimensional standards
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