Heavy Hex Nuts

Heavy hex nuts are larger across the flats and thicker than standard hex nuts of the same thread size, providing greater bearing area and strength to match high-strength and structural bolts. They are specified for A325/A490 structural connections and demanding industrial joints. We stock heavy hex nuts in the structural grades and materials that pair with high-strength bolts.

Why Heavy Hex

The larger, thicker body develops the full strength of a high-strength bolt without stripping, and the wider flats accept the larger wrenches used in structural work. Pairing a structural bolt with a standard nut risks thread stripping under high preload — heavy hex nuts are sized to carry the load.

Grades

ASTM A563 Grade DH: the structural standard, matched to A325 and A490 bolts. ASTM A194 Grade 2H: high-temperature, high-pressure service, paired with B7 stud bolts in flanges. A563 Grade A/B/C: lower grades for less demanding joints. Always match the nut grade to the bolt grade.

Finishes

Plain for protected structural use and hot-dip galvanized for exterior exposure. Galvanized structural nuts are over-tapped to fit galvanized bolts — match galvanized nuts with galvanized bolts.

Dimensional Standards

Heavy hex nuts conform to ASME B18.2.2 for dimensions, with grades per ASTM A563 (structural) and A194 (high-temp/pressure).

Selecting the Right Heavy Hex Nut

Match the nut grade to the bolt — A563 DH for A325/A490 structural, 2H for B7 studs. Choose galvanized to match galvanized bolts, and use the correct hardened washer for structural joints. Verify thread pitch and follow the specified installation method for proper preload.

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