S-91259A651 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 strength and 84,000 psi shear strength for reliable performance in high-stress applications
• Precision thread engagement with Class 3A UNC coarse threads ensuring secure fastening and vibration resistance in industrial assemblies
• Enhanced corrosion protection through black oxide finish that provides durable surface resistance in demanding environments
• Superior material strength from alloy steel construction with Rockwell C32 hardness for long-term durability and wear resistance
• Secure installation and removal with hex socket drive and knurled head design that prevents tool slippage during torque application
• Accurate component alignment with precisely machined 5½" shoulder length maintaining consistent spacing in rotating assemblies
• Regulatory compliance assurance meeting ASME B18.3 standards and environmental regulations for global industrial applications

Professional Applications & Engineering Value

This alloy steel shoulder screw delivers critical engineering solutions for precision machinery and rotating assemblies where alignment accuracy and high tensile strength are paramount. The 5/16"-18 UNC coarse thread with Class 3A fit provides superior vibration resistance in dynamic applications, while the black oxide finish enhances corrosion protection in industrial environments. The precisely machined 5½" shoulder length maintains exact component spacing in gear assemblies, pivots, and rotating mechanisms, eliminating the need for additional spacing components. The socket head with hex drive and knurled texture ensures secure tool engagement during installation, preventing damage to fastener heads in high-torque applications. Engineered to ASME B18.3 specifications and manufactured from ASTM A574 alloy steel, this shoulder screw provides reliable performance in automotive, aerospace, and heavy machinery applications where failure is not an option.

Specification Summary & Compliance

This precision shoulder screw features Class 3A thread fit with UNC coarse thread profile maintaining tight tolerances for secure fastening. The shoulder diameter maintains -0.004" to -0.002" tolerance while shoulder length holds -0.005" to 0.005" precision. Manufactured to ASME B18.3 specifications using ASTM A574 alloy steel material standards. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use in global industrial markets.