S-91264A593 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Load-Bearing Capacity – With 140,000 psi tensile and 84,000 psi shear strength, this screw reliably handles high-stress applications without failure.
• Vibration-Resistant Locking – Integrated nylon pellet thread locker ensures secure fastening, maintaining clamp force in dynamic environments from -50° to 250°F.
• Precision Shoulder Alignment – 2-1/2" shoulder length with tight diameter and length tolerances provides accurate component positioning and smooth pivot or bearing surfaces.
• Durable Corrosion Protection – Black oxide finish on alloy steel resists rust and wear, extending service life in demanding industrial conditions.
• High-Strength Material – Alloy steel with Rockwell C32 hardness offers excellent toughness and fatigue resistance for long-term reliability.
• Secure Hex Drive Engagement – 3/16" hex socket drive with knurled head allows for high-torque installation and easy handling, even with gloves.
• Industry-Standard Compliance – Meets ASME B18.3 and ASTM A574 specifications, ensuring interchangeability and consistent performance in OEM and MRO applications.

Professional Applications & Engineering Value

This 5/16"-18 UNC shoulder screw is engineered to address critical alignment and retention challenges in machinery assembly. The precision-machined alloy steel shoulder serves as a dependable axle or spacer, eliminating misalignment in rotating parts like gears, pulleys, and linkages. Its Class 3A thread fit and coarse UNC thread provide rapid assembly and high resistance to loosening under vibration. The black oxide finish enhances corrosion resistance, making it suitable for industrial environments where exposure to moisture or chemicals is a concern. Combined with the integrated nylon pellet thread locker, this screw delivers reliable performance in automotive, aerospace, and heavy equipment applications, reducing maintenance downtime and ensuring operational safety.

Specification Summary & Compliance

The screw features a 2-1/2" shoulder length with diameter tolerance of -0.004" to -0.002" and length tolerance of -0.005" to 0.005", ensuring precise fit. Threads conform to UNC coarse thread standards with Class 3A fit for superior engagement. Manufactured in compliance with ASME B18.3 and ASTM A574 specifications, it is also RoHS 3 and REACH compliant, meeting environmental and safety regulations for global industrial use.