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 B18.3 Hexagon Socket Head Cap Screws Dimensions
High-Strength Inch-Series Allen Drive Cap Screws for Confined-Space and Precision Mechanical Bolting.
ASME B18.3 Hexagon Socket Head Cap Screws are inch-series precision fasteners featuring a cylindrical head with an internal hexagonal Allen drive socket, engineered to develop high clamping forces in applications where external wrench access is restricted by surrounding components — making them the standard fastener choice in precision machine tools, hydraulic manifolds, dies and molds, aerospace structures, robotics, and automated assembly equipment where compact fastening with maximum strength in minimum space is a design imperative. The ASME B18.3 standard establishes dimensional requirements for head diameter, head height, hexagonal socket size, key engagement depth, body diameter, thread length, and all associated tolerances, ensuring precise dimensional interchangeability and consistent performance across all compliant manufacturers. When manufactured to ASTM A1082, the specification for high-strength stainless steel bolting material, these socket head cap screws deliver high tensile strength, excellent fatigue resistance, and outstanding corrosion resistance in aggressive service environments including chemical process equipment, marine hardware, food and pharmaceutical machinery, and high-humidity industrial settings where standard alloy steel socket screws would suffer from surface rust and corrosion-induced galling. The internal socket drive allows tightening with a hex key in applications where open-end or box wrenches physically cannot be used, providing exceptional versatility in compact mechanical assembly designs. Every ASTM A1082 socket head cap screw lot is backed by full EN 10204 Type 3.1 material certification for quality-assured procurement.
ASME B18.3 Hexagon Socket Head Cap Screw Dimensions (mm)
| Nominal Size | Basic Screw Diameter | Body Diameter, D (mm) | Head Diameter, A (mm) | Head Height, H (mm) | Maximum Chamfer or Radius, C (mm) | Nominal Hexagon Socket Size, J | Socket Width Across Flats, J (mm) | Minimum Key Engagement, T (mm) | Minimum Wall Thickness, G (mm) | Maximum Chamfer or Radius, K (mm) | Fillet Juncture Diameter, F (mm) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Max. | Min. | Max. | Min. | Max. | Min. | Nom. | Dec. (mm) | Max. | Min. | Max. | Min. | ||||||
| #0 | 0.0600 | 1.524 | 1.443 | 2.438 | 2.311 | 1.524 | 1.448 | 0.102 | ... | 1.27 | 1.295 | 1.27 | 0.635 | 0.508 | 0.178 | 1.88 | 1.575 |
| #1 | 0.0730 | 1.854 | 1.765 | 2.997 | 2.845 | 1.854 | 1.778 | 0.127 | 1/16 | 1.575 | 1.613 | 1.588 | 0.787 | 0.635 | 0.178 | 2.21 | 1.905 |
| #2 | 0.0860 | 2.184 | 2.088 | 3.556 | 3.404 | 2.184 | 2.108 | 0.203 | 5/64 | 1.981 | 2.009 | 1.984 | 0.965 | 0.737 | 0.178 | 2.591 | 2.286 |
| #3 | 0.0990 | 2.515 | 2.41 | 4.089 | 3.912 | 2.515 | 2.413 | 0.203 | 5/64 | 1.981 | 2.009 | 1.984 | 1.118 | 0.864 | 0.178 | 2.921 | 2.591 |
| #4 | 0.1120 | 2.845 | 2.731 | 4.648 | 4.47 | 2.845 | 2.743 | 0.229 | 3/32 | 2.388 | 2.418 | 2.38 | 1.295 | 0.965 | 0.203 | 3.302 | 2.972 |
| #5 | 0.1250 | 3.175 | 3.053 | 5.207 | 5.029 | 3.175 | 3.073 | 0.305 | 3/32 | 2.388 | 2.418 | 2.38 | 1.448 | 1.092 | 0.203 | 3.683 | 3.353 |
| #6 | 0.1380 | 3.505 | 3.376 | 5.74 | 5.486 | 3.505 | 3.404 | 0.33 | 7/64 | 2.769 | 2.822 | 2.779 | 1.626 | 1.194 | 0.203 | 4.013 | 3.658 |
| #8 | 0.1640 | 4.166 | 4.026 | 6.858 | 6.528 | 4.166 | 4.039 | 0.356 | 9/64 | 3.581 | 3.622 | 3.571 | 1.956 | 1.422 | 0.203 | 4.775 | 4.369 |
| #10 | 0.1900 | 4.826 | 4.674 | 7.925 | 7.569 | 4.826 | 4.699 | 0.457 | 5/32 | 3.962 | 4.031 | 3.967 | 2.286 | 1.651 | 0.203 | 5.537 | 5.131 |
| #12 | 0.2160 | 5.486 | 5.321 | 8.23 | 7.976 | 5.486 | 5.334 | 0.559 | 5/32 | 3.962 | 4.031 | 3.967 | 2.616 | 2.083 | 0.254 | - | - |
| 1/4 | 0.2500 | 6.35 | 6.185 | 9.525 | 8.992 | 6.35 | 6.198 | 0.635 | 3/16 | 4.775 | 4.826 | 4.763 | 3.048 | 2.413 | 0.254 | 7.061 | 6.63 |
| 5/16 | 0.3125 | 7.938 | 7.755 | 11.913 | 11.328 | 7.925 | 7.772 | 0.838 | 1/4 | 6.35 | 6.426 | 6.35 | 3.835 | 3.023 | 0.254 | 8.814 | 8.357 |
| 3/8 | 0.3750 | 9.525 | 9.342 | 14.275 | 13.716 | 9.525 | 9.347 | 1.016 | 5/16 | 7.925 | 8.026 | 7.938 | 4.623 | 3.632 | 0.254 | 10.541 | 10.084 |
| 7/16 | 0.4375 | 11.113 | 10.907 | 16.662 | 16.027 | 11.125 | 10.922 | 1.194 | 3/8 | 9.525 | 9.627 | 9.525 | 5.41 | 4.216 | 0.381 | 12.294 | 11.811 |
| 1/2 | 0.5000 | 12.7 | 12.494 | 19.05 | 18.415 | 12.7 | 12.497 | 1.397 | 3/8 | 9.525 | 9.627 | 9.525 | 6.223 | 4.826 | 0.381 | 14.021 | 13.487 |
| 9/16 | 0.5625 | 14.288 | 14.067 | 21.412 | 21.006 | 14.275 | 14.072 | 1.575 | 7/16 | 11.1 | 11.227 | 11.113 | 7.01 | 5.436 | 0.381 | - | - |
| 5/8 | 0.6250 | 15.875 | 15.654 | 23.825 | 23.216 | 15.875 | 15.647 | 1.778 | 1/2 | 12.7 | 12.827 | 12.7 | 7.798 | 6.045 | 0.381 | 17.501 | 16.866 |
| 3/4 | 0.7500 | 19.05 | 18.811 | 28.575 | 27.788 | 19.05 | 18.796 | 2.159 | 5/8 | 15.875 | 16.027 | 15.875 | 9.398 | 7.239 | 0.381 | 21.031 | 20.32 |
| 7/8 | 0.8750 | 22.225 | 21.963 | 33.325 | 32.791 | 22.225 | 21.946 | 2.54 | 3/4 | 19.05 | 19.228 | 19.05 | 10.973 | 8.458 | 0.508 | 24.46 | 23.673 |
| 1 | 1.0000 | 25.4 | 25.11 | 38.1 | 37.49 | 25.4 | 25.095 | 2.896 | 3/4 | 19.05 | 19.228 | 19.05 | 12.573 | 9.652 | 0.508 | 27.94 | 27.127 |
| 1 1/8 | 1.1250 | 28.575 | 28.158 | 42.875 | 42.291 | 28.575 | 28.219 | 3.277 | 7/8 | 22.225 | 22.479 | 22.225 | 14.148 | 10.871 | 0.508 | 31.369 | 30.429 |
| 1 1/4 | 1.2500 | 31.75 | 31.333 | 47.625 | 47.041 | 31.75 | 31.394 | 3.658 | 7/8 | 22.225 | 22.479 | 22.225 | 15.748 | 12.065 | 0.508 | 34.798 | 33.858 |
| 1 3/8 | 1.3750 | 34.925 | 34.463 | 52.375 | 51.765 | 34.925 | 34.544 | 4.064 | 1 | 25.4 | 25.908 | 25.4 | 17.323 | 13.284 | 0.508 | 38.227 | 37.236 |
| 1 1/2 | 1.5000 | 38.1 | 37.638 | 57.15 | 56.49 | 38.1 | 37.719 | 4.47 | 1 | 25.4 | 25.908 | 25.4 | 18.923 | 14.478 | 0.508 | 41.656 | 40.665 |
| 1 3/4 | 1.7500 | 44.45 | 43.929 | 66.675 | 65.964 | 44.45 | 44.044 | 5.258 | 1 1/4 | 31.75 | 32.385 | 31.75 | 22.098 | 16.891 | 0.508 | 48.514 | 47.473 |
| 2 | 2.0000 | 50.8 | 50.241 | 76.2 | 75.438 | 50.8 | 50.368 | 6.045 | 1 1/2 | 38.1 | 38.862 | 38.1 | 25.273 | 19.304 | 0.508 | 55.372 | 54.051 |
| 2 1/4 | 2.2500 | 57.15 | 56.591 | 85.725 | 84.938 | 57.15 | 56.693 | 6.833 | 1 3/4 | 44.45 | 45.339 | 44.45 | 28.448 | 21.717 | 0.914 | 62.23 | 60.909 |
| 2 1/2 | 2.5000 | 63.5 | 62.896 | 95.25 | 94.412 | 63.5 | 63.017 | 7.62 | 1 3/4 | 44.45 | 45.339 | 44.45 | 31.623 | 24.13 | 0.914 | 69.088 | 67.615 |
| 2 3/4 | 2.7500 | 69.85 | 69.246 | 104.775 | 103.886 | 69.85 | 69.342 | 8.433 | 2 | 50.8 | 51.816 | 50.8 | 34.798 | 26.543 | 0.914 | 75.946 | 74.574 |
| 3 | 3.0000 | 76.2 | 75.596 | 114.3 | 113.386 | 76.2 | 75.667 | 9.195 | 2 1/4 | 57.15 | 58.293 | 57.15 | 37.973 | 28.956 | 0.914 | 82.804 | 81.432 |
| 3 1/4 | 3.2500 | 82.55 | 81.946 | 123.825 | 122.86 | 82.55 | 81.991 | 10.008 | 2 1/4 | 57.15 | 58.293 | 57.15 | 41.148 | 31.369 | 0.914 | 89.662 | 88.29 |
| 3 1/2 | 3.5000 | 88.9 | 88.296 | 133.35 | 132.359 | 88.9 | 88.341 | 10.82 | 2 3/4 | 69.85 | 71.247 | 69.85 | 44.323 | 33.782 | 0.914 | 96.52 | 95.148 |
| 3 3/4 | 3.7500 | 95.25 | 94.646 | 142.875 | 141.834 | 95.25 | 94.666 | 11.633 | 2 3/4 | 69.85 | 71.247 | 69.85 | 47.498 | 36.195 | 0.914 | 103.378 | 102.006 |
| 4 | 4.0000 | 101.6 | 100.996 | 152.4 | 151.333 | 101.6 | 100.99 | 12.421 | 3 | 76.2 | 77.724 | 76.2 | 50.673 | 38.608 | 0.914 | 110.236 | 108.864 |
ASME B18.3 Hexagon Socket Head Cap Screw Length Tolerances(mm)
| Nominal Length | Nominal Size, Tolerances on Lengths (mm) | |||
|---|---|---|---|---|
| 0 Through 9.525, Incl. |
11.112 Through 19.05, Incl. |
22.225 Through 38.1, Incl. |
Over 38.1 | |
| Up to 25.4, incl. | -0.762 | -0.762 | -1.27 | ... |
| Over 25.4 to 63.5, incl. | -1.016 | -1.524 | -2.54 | -4.572 |
| Over 63.5 to 152.4, incl. | -1.524 | -2.032 | -3.556 | -5.08 |
| Over 152.4 | -3.048 | -3.048 | -5.08 | -6.096 |
Frequently Asked Questions
What stainless steel grades does ASTM A1082 cover for din 912?
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 din 912?
This product follows ASME B18.3, the dimensional standard for din 912 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 din 912 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) din 912?
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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