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ASME B18.2.3.3M Metric Heavy Hex Screws
Metric structural bolts with enlarged heads designed for heavy-duty steel construction and infrastructure projects worldwide.
ASME B18.2.3.3M Metric Heavy Hex Screws are metric fasteners featuring a larger head width and bearing surface, specifically engineered for structural steel connections in metric-based construction projects. Similar to their inch-series counterparts, these screws provide a larger wrenching surface for high-torque installation and a wider bearing area to distribute loads effectively on steel plates and beams. They are essential for the assembly of bridges, high-rise buildings, and industrial structures where metric specifications are mandated. The dimensions conform to international norms such as ISO 4016, ensuring compatibility with metric heavy hex nuts and washers. These screws are typically manufactured from high-strength steel grades (e.g., Property Class 8.8 or 10.9) to withstand the rigorous shear and tensile forces encountered in structural frameworks, offering a reliable and standardized solution for global engineering challenges.
| Nominal Dia., D , and Thread Pitch | Body Diameter.,D s | Width Across Flats,S | Width Across Corners, E | Head Height, K | Wrenching Height, K 1 | Washer Face Thickness,C | Washer FaceDia.,D w | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Max | Min | Max | Min | Max | Min | Max | Min | Min | Max | Min | Min | |
| M12 × 1.75 | 12 | 11.73 | 21 | 20.67 | 24.25 | 23.35 | 7.76 | 7.24 | 5.2 | 0.6 | 0.3 | 19.6 |
| M14 × 2 | 14 | 13.73 | 24 | 23.67 | 27.71 | 26.75 | 9.09 | 8.51 | 6.2 | 0.6 | 0.3 | 22.5 |
| M16 × 2 | 16 | 15.73 | 27 | 26.67 | 31.18 | 30.14 | 10.32 | 9.68 | 7 | 0.8 | 0.4 | 25.3 |
| M20 × 2.5 | 20 | 19.67 | 34 | 33 | 39.26 | 37.29 | 12.88 | 12.12 | 8.8 | 0.8 | 0.4 | 31.4 |
| M24 × 3 | 24 | 23.67 | 41 | 40 | 47.34 | 45.2 | 15.44 | 14.56 | 10.5 | 0.8 | 0.4 | 38 |
| M30 × 3.5 | 30 | 29.67 | 50 | 49 | 57.74 | 55.37 | 19.48 | 17.92 | 13.1 | 0.8 | 0.4 | 46.6 |
| M36 × 4 | 36 | 35.61 | 60 | 58.8 | 69.28 | 66.44 | 23.38 | 21.72 | 15.8 | 0.8 | 0.4 | 55.9 |
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Frequently Asked Questions
- What does ASME B18.2.3.3M metric heavy hex screws cover?
- ASME B18.2.3.3M is the metric dimensional standard for metric heavy hex screws. It defines head dimensions, body diameter, thread length, total length, drive recess, and tolerances so any compliant metric heavy hex screws interchanges with standard nuts, washers and wrenches across manufacturers.
- What size range is available for metric heavy hex screws under ASME B18.2.3.3M?
- metric heavy hex screws under ASME B18.2.3.3M covers M5 through M48 nominal diameter, heavy series. TorqBolt manufactures the full range in ASTM A193 Grades B7, B7M, B8, B8M and the full ASTM A320 cryogenic counterpart on customer specification.
- What is the metric/inch counterpart of ASME B18.2.3.3M metric heavy hex screws?
- The companion specification for metric heavy hex screws is ASME B18.2.1 inch heavy hex screws. Both standards share equivalent functional dimensions but use the corresponding measurement system (inch vs metric ISO M-series).
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