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 B18.2.4.6M Metric Heavy Hex Nuts Dimensions
Wide-Profile Metric Nuts for Superior Load Distribution in High-Pressure and Heavy Structural Bolted Assemblies.
ASME B18.2.4.6M Metric Heavy Hex Nuts are metric-series internally threaded fasteners featuring a significantly wider and taller profile compared to standard ASME B18.2.4.1M metric hex nuts, providing a greater bearing surface area that distributes clamping load across a larger footprint — reducing the risk of embedment into flange or structural steel bearing surfaces under high bolt preload. ASME B18.2.4.6M defines precise metric dimensions for width across flats, width across corners, nut height, chamfer angle, and thread pitch tolerances for all standard metric sizes, ensuring dimensional interchangeability between heavy hex nut suppliers on global metric-standard projects. When manufactured to ASTM A1082, the specification for high-strength stainless steel bolting material, these metric heavy hex nuts provide the combination of wide bearing surface, superior corrosion resistance, and maintained mechanical performance required for offshore structure flange bolting, LNG plant pressure equipment, desalination plant piping, and marine infrastructure assemblies. In applications involving softer flange materials such as aluminium, GRP, or duplex stainless steel, the larger bearing area of the heavy hex nut is particularly critical in preventing nut face embedment that would reduce bolt preload and compromise gasket seating stress over time. ASTM A1082 metric heavy hex nuts are supplied with EN 10204 Type 3.1 material certificates for all quality-controlled project requirements.
ASME B18.2.4.6M Metric Heavy Hex Nuts Dimensions (mm)
| Nominal Dia. | Width Across Flats, S | Width Across Corners, E | Thickness, M | Bearing Face Dia., Dw | Washer Face Thickness, C | Total Runout of Bearing Surface FIM | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Max. | Min. | Max. | Min. | Max. | Min. | Min. | Max. | Min. | Max. | |
| M12 | 21.00 | 20.16 | 24.25 | 22.78 | 12.3 | 11.9 | 19.2 | 0.8 | 0.4 | 0.38 |
| M14 | 24.00 | 23.16 | 27.71 | 26.17 | 14.3 | 13.6 | 22.0 | 0.8 | 0.4 | 0.42 |
| M16 | 27.00 | 26.16 | 31.18 | 29.56 | 17.1 | 16.4 | 24.9 | 0.8 | 0.4 | 0.47 |
| M20 | 34.00 | 33.00 | 39.26 | 37.29 | 20.7 | 19.4 | 31.4 | 0.8 | 0.4 | 0.58 |
| M22 | 36.00 | 35.00 | 41.57 | 39.55 | 23.6 | 22.3 | 33.3 | 0.8 | 0.4 | 0.63 |
| M24 | 41.00 | 40.00 | 47.34 | 45.20 | 24.2 | 22.9 | 38.0 | 0.8 | 0.4 | 0.72 |
| M27 | 46.00 | 45.00 | 53.12 | 50.85 | 27.5 | 26.3 | 42.8 | 0.8 | 0.4 | 0.80 |
| M30 | 50.00 | 49.00 | 57.74 | 55.37 | 30.7 | 29.1 | 45.6 | 0.8 | 0.4 | 0.87 |
| M36 | 60.00 | 58.80 | 69.28 | 66.44 | 36.6 | 35.0 | 55.9 | 0.8 | 0.4 | 1.05 |
| M42 | 70.00 | 67.90 | 80.83 | 77.41 | 42.0 | 40.4 | 64.5 | 1.0 | 0.5 | 1.22 |
| M48 | 80.00 | 77.60 | 92.38 | 88.46 | 48.0 | 46.4 | 73.7 | 1.0 | 0.5 | 1.40 |
| M56 | 90.00 | 87.20 | 103.92 | 99.41 | 56.0 | 54.1 | 82.8 | 1.0 | 0.5 | 1.57 |
| M64 | 100.00 | 96.80 | 115.47 | 110.35 | 64.0 | 62.1 | 92.0 | 1.0 | 0.5 | 1.75 |
| M72 | 110.00 | 106.40 | 127.02 | 121.30 | 72.0 | 70.1 | 101.1 | 1.2 | 0.6 | 1.92 |
| M80 | 120.00 | 116.00 | 138.56 | 132.24 | 80.0 | 78.1 | 110.2 | 1.2 | 0.6 | 2.09 |
| M90 | 135.00 | 130.50 | 155.88 | 148.77 | 90.0 | 87.8 | 124.0 | 1.2 | 0.6 | 2.36 |
| M100 | 150.00 | 145.00 | 173.21 | 165.30 | 100.0 | 97.8 | 137.8 | 1.2 | 0.6 | 2.62 |
Frequently Asked Questions
What stainless steel grades does ASTM A1082 cover for heavy hex nuts?
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 heavy hex nuts?
This product follows ASME B18.2 4 6M, the dimensional standard for heavy hex nuts 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 heavy hex nuts 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) heavy hex nuts?
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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