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 B18.2.1 Askew Head Bolts Dimension Standard
Inch-Series Askew Head Bolts with Skewed Bearing Face for Structural Beam and Sloped Flange Connections.
ASME B18.2.1 Askew Head Bolts are a specialized inch-series fastener featuring a head skewed at a specific angle — typically 14° or 22.5° — relative to the bolt axis, designed to provide full bearing contact against sloped beam flanges in structural steel connections where a standard flat-seated bolt would bear unevenly and compromise clamping integrity. The dimensional standard governs all critical parameters including head dimensions, body diameter, thread length, width across flats, and head skew angle tolerances, ensuring consistent dimensional performance across all manufacturing sources. These bolts are manufactured in compliance with ASTM A1082, the specification for high-strength stainless steel bolting material, delivering excellent corrosion resistance and reliable mechanical performance in demanding structural environments. The use of ASTM A1082 material in ASME B18.2.1 Askew Head Bolts is particularly advantageous in marine, coastal, and industrial structures where carbon steel would be susceptible to severe atmospheric corrosion, significantly extending service life and reducing long-term maintenance costs. Procuring askew head bolts to both ASME B18.2.1 for dimensions and ASTM A1082 for material ensures a fully defined and traceable fastener for critical structural bolted connections.
ASME B18.2.1 Askew Head Bolts Dimensions (mm)
| Nominal Size | Body Diameter, E | Width Across Flats, F | Width Across Corners, G | Head Height, H1 | Mid height, H | Radius of Fillet, R | Maximum Unthreaded Length, S | Nominal Thread Length for Bolt Lengths, LT | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Max. | Min. | Basic | Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | 152.4mm and Shorter | Over 152.4mm | ||||
| 3/8 | 0.3750 | 9.855 | 9.144 | 14.288 | 14.275 | 13.818 | 20.193 | 18.974 | 8.052 | 7.036 | 6.350 | 0.762 | 0.254 | 6.350 | 25.400 | 31.750 |
| 1/2 | 0.5000 | 13.081 | 12.243 | 19.050 | 19.050 | 18.415 | 26.949 | 25.273 | 10.439 | 9.423 | 8.331 | 0.762 | 0.254 | 7.925 | 31.750 | 38.100 |
| 5/8 | 0.6250 | 16.307 | 15.367 | 23.813 | 23.825 | 23.012 | 33.680 | 31.598 | 13.208 | 12.192 | 10.719 | 1.524 | 0.508 | 8.738 | 38.100 | 44.450 |
| 3/4 | 0.7500 | 19.507 | 18.517 | 28.575 | 28.575 | 27.635 | 40.411 | 37.948 | 15.596 | 14.580 | 12.700 | 1.524 | 0.508 | 10.312 | 44.450 | 50.800 |
| 7/8 | 0.8750 | 22.733 | 21.641 | 33.338 | 33.325 | 32.233 | 47.142 | 44.247 | 18.364 | 17.348 | 15.088 | 1.524 | 0.508 | 11.125 | 50.800 | 57.150 |
| 1 | 1.0000 | 25.959 | 24.790 | 38.100 | 38.100 | 36.830 | 53.873 | 50.571 | 20.345 | 19.329 | 16.662 | 2.286 | 0.762 | 12.700 | 57.150 | 63.500 |
ASME B18.2.1 Askew Head Bolts Length Tolerance (mm)
| Nominal Length | Nominal Size (inches) | |||
|---|---|---|---|---|
| 1/4 to 3/8 | 7/16 and 1/2 | 9/16 to 3/4 | 7/8 and 1 | |
| Up to 25.4 mm, incl. | +0.508 0.762 |
+0.508 0.762 |
+0.508 0.762 |
... |
| Over 25.4 mm to 63.5 mm, incl. | +0.508 1.016 |
+1.016 1.524 |
+1.524 2.032 |
+2.032 2.54 |
| Over 63.5 mm to 101.6 mm, incl. | +1.016 1.524 |
+1.524 2.032 |
+2.032 2.54 |
+2.54 3.556 |
| Over 101.6 mm to 152.4 mm, incl. | +1.524 2.54 |
+2.032 2.54 |
+2.54 2.54 |
+3.048 4.064 |
| Longer than 152.4 mm | +2.54 4.572 |
+3.048 4.572 |
+3.556 4.572 |
+4.064 5.08 |
ASME B18.2.1 Askew Head Bolts Dimensions (Inch)
| Nominal Size | Body Diameter, E | Width Across Flats, F | Width Across Corners, G | Head Height, H1 | Mid height, H | Radius of Fillet, R | Maximum Unthreaded Length, S | Nominal Thread Length for Bolt Lengths, LT | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Max. | Min. | Basic | Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | 6 in. and Shorter | Over 6 in. | ||||
| 3/8 | 0.3750 | 0.388 | 0.360 | 9/16 | 0.562 | 0.544 | 0.795 | 0.747 | 0.317 | 0.277 | 0.250 | 0.03 | 0.01 | 0.250 | 1.000 | 1.250 |
| 1/2 | 0.5000 | 0.515 | 0.482 | 3/4 | 0.750 | 0.725 | 1.061 | 0.995 | 0.411 | 0.371 | 0.328 | 0.03 | 0.01 | 0.312 | 1.250 | 1.500 |
| 5/8 | 0.6250 | 0.642 | 0.605 | 15/16 | 0.938 | 0.906 | 1.326 | 1.244 | 0.520 | 0.480 | 0.422 | 0.06 | 0.02 | 0.344 | 1.500 | 1.750 |
| 3/4 | 0.7500 | 0.768 | 0.729 | 1 1/8 | 1.125 | 1.088 | 1.591 | 1.494 | 0.614 | 0.574 | 0.500 | 0.06 | 0.02 | 0.406 | 1.750 | 2.000 |
| 7/8 | 0.8750 | 0.895 | 0.852 | 1 5/16 | 1.312 | 1.269 | 1.856 | 1.742 | 0.723 | 0.683 | 0.594 | 0.06 | 0.02 | 0.438 | 2.000 | 2.250 |
| 1 | 1.0000 | 1.022 | 0.976 | 1 1/2 | 1.500 | 1.450 | 2.121 | 1.991 | 0.801 | 0.761 | 0.656 | 0.09 | 0.03 | 0.500 | 2.250 | 2.500 |
ASME B18.2.1 Askew Head Bolts Length Tolerance (Inch)
| Nominal Length | Nominal Size | |||
|---|---|---|---|---|
| 1/4 to 3/8 | 7/16 and 1/2 | 9/16 to 3/4 | 7/8 and 1 | |
| Up to 1 in., incl. | +0.02 0.03 |
+0.02 0.03 |
+0.02 0.03 |
... |
| Over 1 in. to 2 1/2 in., incl. | +0.02 0.04 |
+0.04 0.06 |
+0.06 0.08 |
+0.08 0.10 |
| Over 2 1/2 in. to 4 in., incl. | +0.04 0.06 |
+0.06 0.08 |
+0.08 0.10 |
+0.10 0.14 |
| Over 4 in. to 6 in., incl. | +0.06 0.10 |
+0.08 0.10 |
+0.10 0.10 |
+0.12 0.16 |
| Longer than 6 in. | +0.10 0.18 |
+0.12 0.18 |
+0.14 0.18 |
+0.16 0.20 |
Frequently Asked Questions
What stainless steel grades does ASTM A1082 cover for askew head bolts?
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 askew head bolts?
This product follows ASME B18.2 1, the dimensional standard for askew head bolts 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 askew head bolts 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) askew head bolts?
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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