Taller-Profile Metric Hex Nuts for Superior Thread Engagement in High-Tension Coarse-Pitch Bolted Assemblies.
ISO 4033 Hexagon High Nuts are metric-series internally threaded fasteners with a taller body height than standard ISO 4032 regular hexagon nuts, providing greater thread engagement length which increases the stripping strength of the bolted joint and makes them particularly suitable for use in applications where soft base materials or high-tension bolting demand more thread engagement than a standard nut height can offer. ISO 4033 defines dimensional requirements for high hexagon nuts in property classes 8, 10, and 12, covering width across flats, width across corners, nut height, thread pitch, and chamfer dimensions for metric coarse pitch sizes M5 to M39, ensuring full dimensional interchangeability across global nut suppliers. These hexagon high nuts are manufactured to ASTM A1082, the specification for high-strength stainless steel bolting material, providing superior corrosion resistance and excellent mechanical performance, making them the preferred choice for chemical processing equipment, marine structures, food and beverage processing machinery, water treatment plants, and pharmaceutical facilities where hygiene and corrosion resistance are mandatory requirements. The ISO 4033 high nut is widely used in combination with ISO 4014 and ISO 4017 metric hex bolts and hex cap screws in assemblies where full thread utilization and reliable anti-loosening performance are key design requirements. Pairing ISO 4033 dimensional compliance with ASTM A1082 material requirements gives engineers a fully defined, high-performance metric nut specification for critical corrosion-resistant service.
| Nominal Size | c | da | e | s | m | Weight Per Pc (H=D) | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Max | Min | Max | Min | Min | Max | Min | Max | Min | ||
| M1.6 | 0.2 | 0.1 | 2.42 | 2 | 3.41 | 3.2 | 3.02 | - | - | - |
| M2 | 0.2 | 0.1 | 3.07 | 2.5 | 4.32 | 4 | 3.82 | - | - | - |
| M2.5 | 0.3 | 0.1 | 4.07 | 3.5 | 5.45 | 5 | 4.82 | - | - | - |
| M3 | 0.4 | 0.15 | 4.57 | 4 | 6.01 | 5.5 | 5.32 | - | - | - |
| M4 | 0.4 | 0.15 | 5.88 | 5 | 7.66 | 7 | 6.78 | - | - | - |
| M5 | 0.5 | 0.15 | 6.88 | 6 | 8.79 | 8 | 7.78 | 5.10 | 4.80 | - |
| M6 | 0.50 | 0.15 | 6.75 | 6.00 | 11.05 | 10.00 | 9.78 | 5.70 | 5.40 | 0.0028 |
| M8 | 0.60 | 0.15 | 8.75 | 8.00 | 14.38 | 13.00 | 12.73 | 7.50 | 7.14 | 0.0057 |
| M10 | 0.60 | 0.15 | 10.80 | 10.00 | 17.77 | 16.00 | 15.73 | 9.30 | 8.94 | 0.0126 |
| M12 | 0.60 | 0.15 | 13.00 | 12.00 | 20.03 | 18.00 | 17.73 | 12.00 | 11.57 | 0.0181 |
| M14 | 0.60 | 0.15 | 15.10 | 14.00 | 23.36 | 21.00 | 20.67 | 14.10 | 13.40 | 0.0300 |
| M16 | 0.80 | 0.20 | 17.30 | 16.00 | 26.75 | 24.00 | 23.67 | 16.40 | 15.70 | 0.0374 |
| M18 | 0.80 | 0.20 | 19.50 | 18.00 | 29.56 | 27.00 | 26.16 | 17.60 | 16.90 | 0.0522 |
| M20 | 0.80 | 0.20 | 21.60 | 20.00 | 32.95 | 30.00 | 29.16 | 20.30 | 19.00 | 0.0734 |
| M22 | 0.80 | 0.20 | 23.70 | 22.00 | 37.29 | 34.00 | 33.00 | 21.80 | 20.50 | 0.0880 |
| M24 | 0.80 | 0.20 | 25.90 | 24.00 | 39.55 | 36.00 | 35.00 | 23.90 | 22.60 | 0.1242 |
| M27 | 0.80 | 0.20 | 29.10 | 27.00 | 45.20 | 41.00 | 40.00 | 26.70 | 25.40 | 0.1770 |
| M30 | 0.80 | 0.20 | 32.40 | 30.00 | 50.85 | 46.00 | 45.00 | 28.60 | 27.30 | 0.2528 |
| M33 | 0.80 | 0.20 | 35.60 | 33.00 | 55.37 | 50.00 | 49.00 | 32.50 | 30.90 | 0.3280 |
| M36 | 0.80 | 0.20 | 38.90 | 36.00 | 60.79 | 55.00 | 53.80 | 34.70 | 33.10 | 0.4452 |
| M39 | 1.00 | 0.30 | 42.10 | 39.00 | 66.44 | 60.00 | 58.80 | 37.50 | 35.90 | 0.5885 |
| M42 | 1.00 | 0.30 | 45.40 | 42.00 | 71.30 | 65.00 | 63.10 | - | - | 0.7298 |
| M45 | 1.00 | 0.30 | 48.60 | 45.00 | 76.95 | 70.00 | 68.10 | - | - | 0.9410 |
| M48 | 1.00 | 0.30 | 51.80 | 48.00 | 82.60 | 75.00 | 73.10 | - | - | 1.1354 |
| M52 | 1.00 | 0.30 | 56.20 | 52.00 | 88.25 | 80.00 | 78.10 | - | - | 1.3930 |
| M56 | 1.00 | 0.30 | 60.50 | 56.00 | 93.56 | 85.00 | 82.80 | - | - | 1.6460 |
| M60 | 1.00 | 0.30 | 64.80 | 60.00 | 99.21 | 90.00 | 87.80 | - | - | 1.9688 |
| M64 | 1.00 | 0.30 | 69.10 | 64.00 | 104.86 | 95.00 | 92.80 | - | - | 2.2827 |
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 4033, 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).
