ASTM A563/A194 Heavy Hex Structural Nuts

ASTM A563 grade DH & C as well as ASTM A194 grade 2H heavy structural nuts are essential components for establishing secure and dependable structural connections. These nuts adhere to rigorous ASTM standards and offer indispensable features for effective fastening solutions.


According to ASTM A563, both Grade DH and Grade C nuts are carbon steel fasteners used with bolts, studs, and threaded components. The key distinction lies in their mechanical properties. Grade DH nuts are crafted from carbon steel and undergo quenching and tempering, resulting in a minimum tensile strength of 150,000 psi and a minimum yield strength of 175,000 psi. Conversely, Grade C nuts are also made from carbon steel and can undergo quenching and tempering, offering a minimum tensile strength of 144,000 psi.

The primary disparity between ASTM A563 Grade DH and Grade C lies in their mechanical properties.

Both are available in Type 3 (Weathering Steel). This type is chosen for its corrosion-resistant properties, which eliminate the need for coatings in certain environments.

Similarly, ASTM A194-2H nuts are frequently paired with high-strength steel bolts. They are made using high-strength alloy steel and they undergo a heat treatment to achieve specific mechanical properties, guaranteeing superior load-bearing capabilities. Coating options include plain finish and zinc-coated to combat corrosion effectively.

These structural nuts are indispensable for distributing loads evenly and upholding connection integrity in construction and industrial applications. When sourced from Boulons Plus, you can rely on the quality, mechanical properties, and a variety of permitted coatings that meet or exceed industry standards. This assurance translates into the safety, durability, and success of your projects. 



A note on substituing A563-DH by A194-2H when used with ASTM F3125 bolt sets

ASTM A194 Grade 2H nuts and ASTM A563 Grade DH nuts share high-strength characteristics achieved through heat treatment but are not always interchangeable. A194 Grade 2H nuts can substitute for A563 Grade DH nuts, as specified by ASTM A563, ensuring their equivalence.

ASTM A563, Table 3, Note D:
“Nuts made in accordance with the requirements of Specification A194/A194M, Grade 2H, and marked with its grade symbol are an acceptable equivalent for Grade DH nuts. When A194 zinc-coated inch series nuts are supplied, the zinc coating, overtapping, lubrication and rotational capacity testing shall be in accordance with Specification A563.”

Nonetheless, it’s essential to note that substituting A563 Grade DH nuts for A194 Grade 2H nuts is generally acceptable, but the reverse is not always true. A194 Grade 2H nuts undergo additional heat treatment and testing, making them suitable for high-temperature applications.