What Is ASTM A563?

ASTM A563 defines the material, chemical, and mechanical requirements for carbon
and alloy steel nuts used in general structural and mechanical bolting applications.
In oil and gas and industrial work, crews typically use it for lower-pressure or
structural-grade fastening rather than high-temperature or pressure-containing flange service.

Who Sets This Specification?

ASTM International sets and maintains ASTM A563. It develops the specification
through a consensus process involving engineers, manufacturers, end users, and
industry committees. This process ensures the standard reflects real-world
performance and maintains compatibility across suppliers.

What It Covers

ASTM A563 includes several nut grades designed for different strength levels and
applications, including:

• Grade A: General-purpose carbon steel nuts
• Grade B: Higher strength carbon steel nuts for structural use
• Grade C: Heat-treated nuts for higher strength applications
• DH: Heavy hex high-strength nuts often used with ASTM A193 B7 studs in some applications

How It Is Used

Manufacturers produce ASTM A563 nuts to pair with compatible bolts and studs in
structural and mechanical assemblies. Technicians install the nuts and tighten
them to generate clamping force, which holds components together under load.

Common Applications

• Structural steel connections
• General industrial assemblies
• Non-critical oilfield equipment
• Machinery and fabricated steel systems
• Utility and support structures

Key Difference vs ASTM A194

ASTM A563 generally covers structural and general-purpose nuts, while ASTM A194
targets high-pressure and high-temperature service. As a result, A563 is more
common in structural steel work, whereas A194 appears in pressure-containing flange
joints in oil and gas systems.

Summary

ASTM A563 is a consensus-based ASTM International standard that defines carbon and
alloy steel nuts for structural and general industrial applications. It ensures
consistent nut performance in mechanical assemblies where high-pressure or
high-temperature requirements do not apply.