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 Square Nuts Dimension Standard
Inch-Series Square Nuts with Wide Bearing Face for Anti-Rotation and Structural Timber Fastening Applications.
ASME B18.2.2 Square Nuts are inch-series internally threaded fasteners with a four-sided square profile that provides a wider bearing surface and natural anti-rotation behavior when seated against flat stock, timber, or square-punched holes — making them a preferred nut choice in structural timber connections, agricultural equipment, railroad hardware, anchor bolt assemblies, and specialty industrial fastening where the square geometry locks the nut against spinning during tightening without the need for a secondary wrench or tool. The ASME B18.2.2 standard governs all critical dimensional requirements for square nuts including width across flats, width across corners, nut thickness, chamfer, and thread specifications for nominal sizes ranging from 1/4 inch to 2 inches — ensuring consistent dimensional interchangeability across all compliant manufacturers within the American National Standard framework. When manufactured to ASTM A1082, the specification for high-strength stainless steel bolting material, these square nuts provide the corrosion resistance, non-magnetic performance, and long service life required in outdoor structural assemblies, coastal timber construction, marine dock hardware, agricultural facility framing, and chemical plant structural connections where standard carbon steel nuts would rust aggressively and eventually seize or fail. ASME B18.2.2 square nuts in ASTM A1082 stainless steel are fully compatible with ASME B18.2.1 hex bolts and square bolts in matching stainless steel material, providing complete corrosion-resistant bolted assemblies for the most demanding outdoor and industrial service environments. Full EN 10204 Type 3.1 material certification is available for all ASTM A1082 square nut lots for quality-controlled project supply.
ASME B18.2.2 Square Nuts Dimensions (mm)
| Nominal Size (in) | Basic Major Diameter | Width Across Flats, F | Width Across Corners, G | Thickness | Runout to Thread Axis, FIM | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Basic | Min. | Max. | Min. | Max. | Basic | Min. | Max. | |||
| 1/4 | 6.350 | 11.11 | 10.80 | 11.13 | 14.07 | 15.72 | 5.56 | 5.16 | 5.97 | 0.28 |
| 5/16 | 7.938 | 14.29 | 13.89 | 14.27 | 18.31 | 20.19 | 6.75 | 6.32 | 7.19 | 0.38 |
| 3/8 | 9.525 | 15.88 | 15.39 | 15.88 | 20.37 | 22.45 | 8.33 | 7.87 | 8.79 | 0.41 |
| 7/16 | 11.113 | 19.05 | 18.49 | 19.05 | 24.64 | 26.95 | 9.53 | 9.04 | 10.01 | 0.48 |
| 1/2 | 12.700 | 20.64 | 20.02 | 20.62 | 26.72 | 29.18 | 11.11 | 10.62 | 11.63 | 0.56 |
| 5/8 | 15.875 | 25.40 | 24.61 | 25.40 | 33.02 | 35.92 | 13.89 | 13.34 | 14.45 | 0.66 |
| 3/4 | 19.050 | 28.58 | 27.64 | 28.58 | 37.19 | 40.41 | 16.67 | 16.05 | 17.27 | 0.74 |
| 7/8 | 22.225 | 33.34 | 32.23 | 33.32 | 43.48 | 47.14 | 19.45 | 18.80 | 20.12 | 0.86 |
| 1 | 25.400 | 38.10 | 36.83 | 38.10 | 49.81 | 53.87 | 22.23 | 21.51 | 22.94 | 0.99 |
| 1 1/8 | 28.575 | 42.86 | 41.43 | 42.88 | 56.11 | 60.60 | 25.40 | 24.64 | 26.16 | 0.74 |
| 1 1/4 | 31.750 | 47.63 | 46.02 | 47.63 | 62.43 | 67.36 | 27.78 | 26.97 | 28.60 | 0.81 |
| 1 3/8 | 34.925 | 52.39 | 50.65 | 52.37 | 68.78 | 74.09 | 30.56 | 29.69 | 31.42 | 0.89 |
| 1 1/2 | 38.100 | 57.15 | 55.25 | 57.15 | 75.08 | 80.82 | 33.34 | 32.41 | 34.24 | 0.99 |
ASME B18.2.2 Square Nuts Dimensions (Inch)
| Nominal Size | Basic Major Diameter of Thread | Width Across Flats, F | Width Across Corners, G | Thickness | Bearing Surface Runout to Thread Axis, FIM | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Basic | Min. | Max. | Min. | Max. | Basic | Min. | Max. | |||
| 1/4 | 0.2500 | 7/16 | 0.425 | 0.438 | 0.554 | 0.619 | 7/32 | 0.203 | 0.235 | 0.011 |
| 5/16 | 0.3125 | 9/16 | 0.547 | 0.562 | 0.721 | 0.795 | 17/64 | 0.249 | 0.283 | 0.015 |
| 3/8 | 0.3750 | 5/8 | 0.606 | 0.625 | 0.802 | 0.884 | 21/64 | 0.310 | 0.346 | 0.016 |
| 7/16 | 0.4375 | 3/4 | 0.728 | 0.750 | 0.970 | 1.061 | 3/8 | 0.356 | 0.394 | 0.019 |
| 1/2 | 0.5000 | 13/16 | 0.788 | 0.812 | 1.052 | 1.149 | 7/16 | 0.418 | 0.458 | 0.022 |
| 5/8 | 0.6250 | 1 | 0.969 | 1.000 | 1.300 | 1.414 | 35/64 | 0.525 | 0.569 | 0.026 |
| 3/4 | 0.7500 | 1 1/8 | 1.088 | 1.125 | 1.464 | 1.591 | 21/32 | 0.632 | 0.680 | 0.029 |
| 7/8 | 0.8750 | 1 5/16 | 1.269 | 1.312 | 1.712 | 1.856 | 49/64 | 0.740 | 0.792 | 0.034 |
| 1 | 1.0000 | 1 1/2 | 1.450 | 1.500 | 1.961 | 2.121 | 7/8 | 0.847 | 0.903 | 0.039 |
| 1 1/8 | 1.1250 | 1 11/16 | 1.631 | 1.688 | 2.209 | 2.386 | 1 | 0.970 | 1.030 | 0.029 |
| 1 1/4 | 1.2500 | 1 7/8 | 1.812 | 1.875 | 2.458 | 2.652 | 1 3/32 | 1.062 | 1.126 | 0.032 |
| 1 3/8 | 1.3750 | 2 1/16 | 1.994 | 2.062 | 2.708 | 2.917 | 1 13/64 | 1.169 | 1.237 | 0.035 |
| 1 1/2 | 1.5000 | 2 1/4 | 2.175 | 2.250 | 2.956 | 3.182 | 1 5/16 | 1.276 | 1.348 | 0.039 |
Frequently Asked Questions
What stainless steel grades does ASTM A1082 cover for square 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 square nuts?
This product follows ASME B18.2 2, the dimensional standard for square 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 square 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) square 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
Satisfaction Survey
