The Global Standard for Regular Metric Hex Nuts in Mechanical, Structural, and Process Industry Applications.
ISO 4032 Hexagon Nuts are the most widely used metric regular hexagon nuts in the world, defined as hexagon regular nuts (style 1) in steel property classes 5, 6, 8 and 10, plus 12 up to M16, covering all critical dimensional requirements including width across flats, width across corners, nut height, thread pitch, and chamfer specifications for coarse pitch sizes M5 to M39, with historical sizes M1.6 to M4 and M42 to M64 kept only in informative Annex A, making them the standard mating nut for metric hex bolts, hex cap screws, and stud bolts in virtually every engineering sector globally. The ISO 4032 standard ensures full dimensional interchangeability across all compliant nut manufacturers worldwide, which is essential for global procurement projects, maintenance operations, and assembly lines sourcing fasteners from multiple vendors simultaneously. These hexagon nuts are manufactured to ASTM A1082, the specification for high-strength stainless steel bolting material, providing superior corrosion resistance and excellent mechanical performance, making ASTM A1082 ISO 4032 hex nuts the preferred choice for chemical processing equipment, marine structures, food and beverage processing machinery, water treatment plants, and pharmaceutical facilities where hygiene, corrosion resistance, and long service life are mandatory requirements. The combination of ISO 4032 dimensional precision and ASTM A1082 material performance ensures consistent preload development, reliable joint clamping, and extended service life without maintenance intervention. Full material traceability per EN 10204 Type 3.1 is available for all ASTM A1082 ISO 4032 hex nut lots.
| Nominal Size | c | da | e | m | s | Weight Per Pc | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Max | Min | Max | Min | Min | Max | Min | Max | Min | ||
| M1.6 | 0.2 | 0.1 | 2.42 | 2 | 3.41 | 1.3 | 1.05 | 3.2 | 3.02 | - |
| M2 | 0.2 | 0.1 | 3.07 | 2.5 | 4.32 | 1.6 | 1.35 | 4 | 3.82 | - |
| M2.5 | 0.3 | 0.1 | 4.07 | 3.5 | 5.45 | 2 | 1.75 | 5 | 4.82 | - |
| M3 | 0.4 | 0.15 | 4.57 | 4 | 6.01 | 2.4 | 2.15 | 5.5 | 5.32 | - |
| M4 | 0.4 | 0.15 | 5.88 | 5 | 7.66 | 3.2 | 2.9 | 7 | 6.78 | - |
| M5 | 0.5 | 0.15 | 6.88 | 6 | 8.79 | 4.7 | 4.5 | 8 | 7.78 | - |
| M6 | 0.50 | 0.15 | 6.75 | 6.00 | 11.05 | 5.20 | 4.90 | 10.00 | 9.78 | - |
| M8 | 0.60 | 0.15 | 8.75 | 8.00 | 14.38 | 6.80 | 6.44 | 13.00 | 12.73 | 0.0046 |
| M10 | 0.60 | 0.15 | 10.80 | 10.00 | 17.77 | 8.40 | 8.04 | 16.00 | 15.73 | 0.0100 |
| M12 | 0.60 | 0.15 | 13.00 | 12.00 | 20.03 | 10.80 | 10.37 | 18.00 | 17.73 | 0.0151 |
| M14 | 0.60 | 0.15 | 15.10 | 14.00 | 23.36 | 12.80 | 12.10 | 21.00 | 20.67 | 0.0235 |
| M16 | 0.80 | 0.20 | 17.30 | 16.00 | 26.75 | 14.80 | 14.10 | 24.00 | 23.67 | 0.0304 |
| M18 | 0.80 | 0.20 | 19.50 | 18.00 | 29.56 | 15.80 | 15.10 | 27.00 | 26.16 | 0.0435 |
| M20 | 0.80 | 0.20 | 21.60 | 20.00 | 32.95 | 18.00 | 16.90 | 30.00 | 29.16 | 0.0587 |
| M22 | 0.80 | 0.20 | 23.70 | 22.00 | 37.29 | 19.40 | 18.10 | 34.00 | 33.00 | 0.0720 |
| M24 | 0.80 | 0.20 | 25.90 | 24.00 | 39.55 | 21.50 | 20.20 | 36.00 | 35.00 | 0.0983 |
| M27 | 0.80 | 0.20 | 29.10 | 27.00 | 45.20 | 23.80 | 22.50 | 41.00 | 40.00 | 0.1442 |
| M30 | 0.80 | 0.20 | 32.40 | 30.00 | 50.85 | 25.60 | 24.30 | 46.00 | 45.00 | 0.2022 |
| M33 | 0.80 | 0.20 | 35.60 | 33.00 | 55.37 | 28.70 | 27.40 | 50.00 | 49.00 | 0.2584 |
| M36 | 0.80 | 0.20 | 38.90 | 36.00 | 60.79 | 31.00 | 29.40 | 55.00 | 53.80 | 0.3586 |
| M39 | 1.00 | 0.30 | 42.10 | 39.00 | 66.44 | 33.40 | 31.80 | 60.00 | 58.80 | 0.4678 |
| M42 | 1.00 | 0.30 | 45.40 | 42.00 | 71.30 | 34.00 | 32.40 | 65.00 | 63.10 | 0.5908 |
| M45 | 1.00 | 0.30 | 48.60 | 45.00 | 76.95 | 36.00 | 34.40 | 70.00 | 68.10 | 0.7528 |
| M48 | 1.00 | 0.30 | 51.80 | 48.00 | 82.60 | 38.00 | 36.40 | 75.00 | 73.10 | 0.8989 |
| M52 | 1.00 | 0.30 | 56.20 | 52.00 | 88.25 | 42.00 | 40.40 | 80.00 | 78.10 | 1.1251 |
| M56 | 1.00 | 0.30 | 60.50 | 56.00 | 93.56 | 45.00 | 43.40 | 85.00 | 82.80 | 1.3227 |
| M60 | 1.00 | 0.30 | 64.80 | 60.00 | 99.21 | 48.00 | 46.40 | 90.00 | 87.80 | 1.5750 |
| M64 | 1.00 | 0.30 | 69.10 | 64.00 | 104.86 | 51.00 | 49.10 | 95.00 | 92.80 | 1.8190 |
ASTM A1082/A1082M (2016) Table 1 lists 14 duplex (ferritic-austenitic) grades, S31100, S31260, S31803, S32101, S32202, S32205 (2205), S32304 (2304), S32506, S32550 (255), S32750 (2507), S32760, S32906, S32950 and S39277, and 5 precipitation-hardening grades, S15700 (Type 632), S17400 (Type 630), S17600 (Type 635), S17700 (Type 631) and S35500 (Type 634). Grade selection depends on design, service conditions and the mechanical properties required.
Dimensions follow ISO 4032, tabulated on this page. ASTM A1082/A1082M sets chemistry (Table 1), heat treatment and mechanical properties (Tables 2 to 4) and marking (Table 5). ASTM A962/A962M general requirements also apply, and A1082 prevails where the two conflict (clause 4.1). Inch-pound units apply unless the order specifies A1082M (clause 1.4).
ISO 15156-3 Table A.24 accepts wrought duplex stainless steel for any equipment when it is solution-annealed and liquid-quenched or rapidly cooled, has 35 % to 65 % ferrite and has had no ageing heat treatment. With 30 ≤ PREN ≤ 40 and Mo ≥ 1.5 % the limit is 232 °C (450 °F) and 10 kPa (1.5 psi) H2S partial pressure; with 40 < PREN ≤ 45 it is 232 °C (450 °F) and 20 kPa (3 psi). Table A.27 accepts wrought 17-4 PH (S17400) at 33 HRC max after a double age at 620 °C (1150 °F) or a modified double age, for named wellhead, valve and subsurface components, up to 3.4 kPa (0.5 psi) H2S and pH 4.5 or above.
Two supplementary requirements apply to nuts when the purchaser specifies them. S5 requires proof load testing of nuts, with the number of tests and the proof loads agreed between purchaser and manufacturer. S6 requires cross-sectional hardness testing of nuts per ASTM A370 Annex A3, with the number of tests agreed. Certification reports chemical analysis, mechanical tests and the heat treatment method (clause 10.1).
Table 4: solution annealed at 1880 to 2060 °F [1025 to 1125 °C], water quenched. Up to and including 2 in.: tensile 116 ksi [800 MPa] and yield 80 ksi [550 MPa] min. Over 2 in.: 110 ksi [760 MPa] and 75 ksi [515 MPa] min. Elongation 15 % min and hardness 33 HRC or 310 HB max for both. The marking grade symbol is 32750 (Table 5).
