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 Hex Lag Screws Dimensions
Inch-Series Corrosion-Resistant Lag Fasteners for Wood, Composite, and Structural Substrate Anchoring.
ASME B18.2.1 Hex Lag Screws are inch-series threaded fasteners featuring a hexagonal head and a coarse gimlet-point thread that self-taps into wood, composite timber, and other substrate materials without requiring a pre-drilled through-hole — making them the standard heavy-duty fastener for structural timber connections, deck framing, fence posts, marine dock structures, and outdoor construction applications where a screw-type fastener must develop high withdrawal and lateral load resistance directly in the base material. The ASME B18.2.1 standard covers dimensional requirements for hex lag screws ranging from No. 10 to 1-1/4 inch diameter, defining body diameter, head dimensions, width across flats, head height, thread length, and gimlet point dimensions with all associated manufacturing tolerances to ensure consistent dimensional performance. When manufactured to ASTM A1082, the specification for high-strength stainless steel bolting material, these hex lag screws provide outstanding corrosion resistance in outdoor, marine, and chemical environments where conventional galvanized or hot-dip zinc-coated lag screws would fail prematurely due to corrosion of the zinc coating in aggressive saline, acidic timber preservative, or high-humidity conditions. This makes ASTM A1082 stainless steel lag screws the preferred choice for coastal construction, marine dock assemblies, pressure-treated timber structures, swimming pool surrounds, and chemical plant grating installations. ASTM A1082 hex lag screws are available with EN 10204 Type 3.1 material certification for specification-controlled projects.
ASME B18.2.1 Hex Lag Screws Dimensions (mm)
| Nominal Size or Basic Product Diameter | Body or Shoulder Diameter, E | Width Across Flats, F | Width Across Corners, G | Head Height, H | Minimum Shoulder Length, S | Radius of Fillet, R | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Max. | Min. | Basic | Max. | Min. | Max. | Min. | Basic | Max. | Min. | Max. | Min. | |||
| #10 | 4.826 | 5.055 | 4.521 | 7.144 | 7.137 | 6.883 | 8.204 | 7.849 | 3.175 | 3.556 | 2.794 | 2.388 | 0.762 | 0.254 |
| 1/4 | 6.350 | 6.604 | 6.020 | 11.113 | 11.125 | 10.795 | 12.827 | 12.294 | 4.366 | 4.775 | 3.810 | 2.388 | 0.762 | 0.254 |
| 5/16 | 7.938 | 8.230 | 7.569 | 12.700 | 12.700 | 12.294 | 14.656 | 14.021 | 5.556 | 5.969 | 4.953 | 3.175 | 0.762 | 0.254 |
| 3/8 | 9.525 | 9.855 | 9.144 | 14.288 | 14.275 | 13.818 | 16.510 | 15.748 | 6.350 | 6.807 | 5.740 | 3.175 | 0.762 | 0.254 |
| 7/16 | 11.113 | 11.481 | 10.693 | 15.875 | 15.875 | 15.316 | 18.339 | 17.450 | 7.541 | 8.026 | 6.909 | 3.962 | 0.762 | 0.254 |
| 1/2 | 12.700 | 13.081 | 12.243 | 19.050 | 19.050 | 18.415 | 21.996 | 20.980 | 8.731 | 9.246 | 7.671 | 3.962 | 0.762 | 0.254 |
| 5/8 | 15.875 | 16.307 | 15.367 | 23.813 | 23.825 | 23.012 | 27.508 | 26.238 | 10.716 | 11.278 | 9.601 | 7.925 | 1.524 | 0.508 |
| 3/4 | 19.050 | 19.507 | 18.517 | 28.575 | 28.575 | 27.635 | 32.995 | 31.496 | 12.700 | 13.310 | 11.557 | 9.525 | 1.524 | 0.508 |
| 7/8 | 22.225 | 22.733 | 21.641 | 33.338 | 33.325 | 32.233 | 38.506 | 36.754 | 14.684 | 15.342 | 13.487 | 9.525 | 1.524 | 0.508 |
| 1 | 25.400 | 25.959 | 24.790 | 38.100 | 38.100 | 36.830 | 43.993 | 41.986 | 17.066 | 17.780 | 15.011 | 15.875 | 2.286 | 0.762 |
| 1 1/8 | 28.575 | 29.185 | 27.889 | 42.863 | 42.875 | 41.427 | 49.505 | 47.219 | 19.050 | 19.812 | 16.713 | 15.875 | 2.286 | 0.762 |
| 1 1/4 | 31.750 | 32.436 | 31.064 | 47.625 | 47.625 | 46.025 | 54.991 | 52.476 | 21.431 | 22.250 | 19.025 | 15.875 | 2.286 | 0.762 |
ASME B18.2.1 Hex Lag Screws 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 | 1 1/8 to 1 1/2 | Over 1 1/2 | |
| Up to 25.4 mm, incl. | +0.000 0.762 |
+0.000 0.762 |
+0.000 0.762 |
... | ... | ... |
| Over 25.4 mm to 63.5 mm, incl. | +0.000 1.016 |
+0.000 1.524 |
+0.000 2.032 |
+0.000 2.540 |
+0.000 3.048 |
+0.000 4.572 |
| Over 63.5 mm to 101.6 mm, incl. | +0.000 1.524 |
+0.000 2.032 |
+0.000 2.540 |
+0.000 3.556 |
+0.000 4.064 |
+0.000 5.080 |
| Over 101.6 mm to 152.4 mm, incl. | +0.000 2.540 |
+0.000 2.540 |
+0.000 2.540 |
+0.000 4.064 |
+0.000 4.572 |
+0.000 5.588 |
| Longer than 152.4 mm | +0.000 4.572 |
+0.000 4.572 |
+0.000 4.572 |
+0.000 5.080 |
+0.000 5.588 |
+0.000 6.096 |
Frequently Asked Questions
What stainless steel grades does ASTM A1082 cover for lag 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 lag bolts?
This product follows ASME B18.2 1, the dimensional standard for lag 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 lag 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) lag 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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