Heavy Hex Nuts
Heavy hex nuts are sized and dimensioned for structural work when a standard hex nut doesn't provide enough thread engagement or bearing area to do the job right. Compared to a standard hex nut, a heavy hex nut is taller and wider across the flats, which translates directly into more thread contact, a larger bearing surface, and better clamp load at the joint. Valley Nut & Bolt manufactures and stocks heavy hex nuts in carbon steel, alloy, and stainless steel, and we perform hot-dip galvanizing in-house, so the coating is consistent and matched to the bolt it threads onto.
One Source for Heavy Hex Nuts and the Hardware to Match
Valley Nut & Bolt manufactures heavy hex nuts in every grade and finish and stocks the matching anchor bolts, all-thread rod, and plate washers in the same shop.
Heavy Hex Nuts vs. Standard Hex Nuts
It's all about geometry. A heavy hex nut gives you more thread engagement than a standard nut by design, which is important when you're torquing to specification on a structural connection. The wider wrenching surface also reduces the chance of the nut slipping or rounding during installation, particularly on galvanized fasteners where the coating adds friction to the threads.
Where heavy hex nuts are most commonly specified:
- Structural steel connections, including beams, columns, and base plates
- Anchor bolt installations for column footings, equipment pads, and sign structures
- Bridge and infrastructure work, including DOT projects
- High-pressure and high-temperature flanged connections
- Utility pole line hardware and public works applications in the Pacific Northwest, where heavy hex nuts are a standard pairing for the pole line bolts we manufacture
If your plans or your inspector calls out heavy hex, there is a reason. The nut geometry and grade work together, and substituting a standard nut or an incorrect grade affects both the joint capacity and your compliance documentation.
Materials and Grades
The grade has to match the bolt it threads onto. We manufacture heavy hex nuts from carbon steel, alloy steel, and stainless steel, and we finish them to withstand the environment in which the connection operates.
| Material / Grade | Specification | Typical Use |
|---|---|---|
| Medium carbon steel, quenched and tempered | ASTM A194 Grade 2H | High-strength structural and flange connections; pairs with A193 B7, A325, A490, and F1554 Grade 105 |
| Carbon and alloy steel | ASTM A563 Grade DH | General structural use; commonly specified alongside F1554 anchor bolts |
| Stainless steel | 304, 316 | Corrosion-critical environments including marine, waterfront, and chemical applications |
For galvanized applications, we hot-dip galvanize in-house and tap the nuts oversize after coating to maintain a proper thread fit on the mating bolt. That step is important but often gets missed when galvanizing is farmed out to a separate shop.
Standards and Specifications
Heavy hex nuts are governed by published standards that define geometry, mechanical properties, and proof load. Common specifications we work to:
| Specification | What It Covers |
|---|---|
| ASTM A194 | Carbon, alloy, and stainless steel nuts for high-pressure and high-temperature service, including Grade 2H |
| ASTM A563 | Carbon and alloy steel nuts in Grades A, B, C, and DH for structural and general use |
| ASME B18.2.2 | Dimensional standard for heavy hex nut geometry, including width across flats and nut height |
Every order ships with mill test reports and full product traceability back to the heat number, so you can document compliance without chasing paperwork after the fact.
Common Applications
Heavy hex nuts show up wherever the connection has to be verified. We supply them for:
- Structural steel in buildings and bridges
- Anchor bolts for concrete footings
- DOT and public infrastructure work
- Industrial piping and pressure flanges
Fabricators, general contractors, and project teams across Washington and the Pacific Northwest have been sourcing from our Olympia shop since 1969.
If you need the matching anchor bolts, we manufacture those here, too. And if your project calls for a nonstandard size, special thread, or a production run that does not fit a catalog part, we make it in-house.
Get a Quote on Heavy Hex Nuts
Send us your size, grade, thread, and quantity, and we'll turn around pricing the same day for standard configurations. Pacific Northwest customers can count on fast delivery, and galvanized orders are coated and tapped in-house so you're not coordinating with a third party to get a complete fastener package.
If you're looking for a heavy hex nuts supplier that also manufactures the anchor bolts, all-thread rod, and plate washers to match, that's exactly what we do. Send us the spec, and we will handle the rest.
Can an ASTM A194 Grade 2H heavy hex nut substitute for an ASTM A563 Grade DH nut?
Yes, and ASTM A563 explicitly permits it. A194 Grade 2H nuts go through additional heat treating and testing that Grade DH nuts do not, which is why A194 2H is the required nut specification when paired with A193 B7 bolts used in high-temperature or high-pressure service. ASTM A563 Grade DH is acceptable for most structural applications, but it cannot substitute in the other direction when A194 2H is required by the bolt specification or the application conditions.
Do galvanized heavy hex nuts need to be tapped oversize?
Yes. After hot-dip galvanizing, the zinc coating adds enough material to the nut threads that a standard-tapped nut will not run freely on a galvanized bolt. The correct process is to tap the nut oversize after galvanizing so the thread fit works properly on the mating fastener. At Valley Nut & Bolt, we galvanize in-house, which means tapping and coating happen as part of the same controlled process rather than being coordinated across two separate shops. The result is a consistent fit across the lot.
What size heavy hex nut do I need for an F1554 anchor bolt?
It depends on the anchor bolt diameter and grade. Both F1554 Grade 36 and Grade 55 anchor bolts call for ASTM A563 Grade A heavy hex nuts. F1554 Grade 105 requires A563 Grade DH or A194 Grade 2H, and in practice, A194 Grade 2H is the more common choice because Grade DH nuts are hard to source in larger diameters and galvanized finishes. Nut dimensions follow ASME B18.2.2, so the width across flats and nut height are set by the nominal bolt diameter. If you send us your bolt spec, diameter, and thread series, we can confirm the correct nut and get you a quote quickly.
Ask Our Team
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