ANSI/ASME B 18.2.3.1M (ANSI) and UNI 5739 (UNI) are equivalent fastener standards that specify the same or very similar products. Both standards cover 11 fastener types in our database.
ANSI/ASME B 18.2.3.1M (ANSI standard) and UNI 5739 (UNI standard) are equivalent standards that define the same fastener geometry and mechanical requirements. Minor differences may exist in tolerances, marking requirements, or referenced test methods, but the products are interchangeable in most applications. Always verify specific project requirements with your engineer.
| Property | ANSI/ASME B 18.2.3.1M | UNI 5739 |
|---|---|---|
| Standard Body | ANSI | UNI |
| Product Types | 11 fastener types | |
| Interchangeable? | Yes — equivalent standard | |
From: Hexagon Head Bolts - Product Grades A and B — applies to both ANSI/ASME B 18.2.3.1M and UNI 5739
| Size | P | k_max | k_min | s_max | s_min | ds_max | ds_min | k_nominal | ds_nominal |
|---|---|---|---|---|---|---|---|---|---|
| M1.6 | 0.40 | 1.2 | 4 | 1.525 | 1.275 | 4 | 3.7 | 1.6 | 3.82 |
| M2 | 0.50 | 1.8 | 5.5 | 2.125 | 1.875 | 5.5 | 5.2 | 2.2 |
Both ANSI/ASME B 18.2.3.1M and UNI 5739 fasteners are available with various surface treatments. Common options for these standards include:
Request detailed technical specifications, material certifications, and availability information for your application requirements. Our engineering team can provide product recommendations, custom specifications, and technical documentation.
| ✓ |
| Hexagon Head Bolts - Full Thread - Product Grade A and B | ✓ |
| Hexagon Head Screws - Product Grade A and B | ✓ |
| Hexagon Head Screws (Size Range M1.6 - M64) | ✓ |
| Hexagon Head Screws with Full Thread - Product Grade A and B | ✓ |
| 5.32 |
| M2.5 | 0.80 | 3.26 | 8 | 3.65 | 3.35 | 8 | 7.64 | 3.74 | 7.78 |
| M3 | 1.25 | 5.06 | 13 | 5.45 | 5.15 | 13 | 12.57 | 5.54 | 12.73 |
| M4 | 1.75 | 7.21 | 18 | 7.68 | 7.32 | 18 | 17.57 | 7.79 | 17.73 |
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