S-94705A781 7/8"-9 x 4 1/2" ASTM A193 Steel Heavy Hex Head Screws for High-Pressure Applications

Key Features & Benefits at a Glance

• Exceptional tensile strength of 125,000 PSI ensures reliable performance under extreme mechanical loads and prevents fastener failure in critical applications.
• High material durability from Grade B7 steel and Rockwell C35 hardness provides excellent resistance to wear, deformation, and stress corrosion cracking.
• Superior coarse UNC threading with Class 2A fit offers faster assembly, easier engagement, and reduced risk of cross-threading in rugged industrial environments.
• Optimized grip and thread length (both 2 1/4") ensures maximum clamping force and secure fastening in thick materials or complex assemblies.
• External hex drive design allows for high-torque installation with standard tools, facilitating quick maintenance and disassembly.
• Compliance with ASTM A193 specifications guarantees material quality, manufacturing consistency, and suitability for high-pressure and high-temperature services.
• Partially threaded shank concentrates strength where needed and provides an unthreaded bearing surface for improved shear resistance.

Professional Applications & Engineering Value

This 7/8"-9 UNC Hex Head Screw is engineered to address the demanding requirements of heavy-duty industrial applications, including pressure vessel systems, valve assemblies, and structural fabrications. The Grade B7 steel construction, combined with a Rockwell C35 hardness, ensures long-term integrity in environments subject to high stress, vibration, and thermal cycling. The coarse thread spacing and Class 2A thread fit provide reliable engagement even in applications where debris or minor misalignment is a concern, reducing installation time and maintenance costs. Its partially threaded design and substantial grip length make it ideal for securing flanges, machinery bases, and other components where precise clamp load and joint stability are critical to operational safety and efficiency.

Specification Summary & Compliance

This fastener adheres to ASTM A193 specifications for high-temperature or high-pressure service. It features UNC coarse threading with a Class 2A thread fit for standard tolerance and interchangeability. The screw is manufactured in the inch system with a thread size of 7/8"-9, a thread length of 2 1/4", and an overall length of 4 1/2". The material and manufacturing process comply with industry standards for high-strength applications.