S-91259A214 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Enhanced Durability – Alloy steel construction with black oxide finish provides superior corrosion resistance and extends service life in demanding environments.
• High Tensile Strength – 140,000 psi tensile strength ensures reliable performance under heavy loads and prevents failure in critical applications.
• Precision Shoulder Fit – 6" shoulder length with tight tolerances (±0.005") allows for accurate alignment and smooth rotation in assemblies.
• Secure Fastening – Class 3A thread fit and coarse UNC thread design offer excellent vibration resistance and quick installation.
• Easy Installation & Removal – Hex socket drive and knurled head enable firm grip and efficient torque application with standard tools.
• Hardened for Wear Resistance – Rockwell C32 hardness minimizes wear and maintains dimensional stability over repeated use.
• Broad Compliance – Meets ASME B18.3 specifications and RoHS 3/REACH regulations, ensuring quality and environmental safety.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address common industrial challenges such as misalignment, component wear, and vibration-induced loosening. The 6" shoulder length with precise diameter tolerance provides a stable pivot or bearing surface, ideal for machinery linkages, conveyor systems, and robotic arms where smooth rotational movement is critical. The black oxide finish enhances corrosion resistance, while the coarse UNC thread and Class 3A fit ensure secure fastening even in high-vibration settings like automotive or heavy equipment assemblies. With a 140,000 psi tensile strength and Rockwell C32 hardness, it delivers long-term reliability in demanding applications, reducing maintenance downtime and improving operational efficiency.

Specification Summary & Compliance

This shoulder screw features a 5/16"-18 UNC coarse thread with Class 3A fit for precise engagement, and a shoulder diameter tolerance of -0.004" to -0.002" for consistent alignment. It is manufactured in compliance with ASME B18.3 standards and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring it is free from hazardous substances and suitable for global industrial use.