S-90311A172 5/16"-18 ASME B18.3 Shoulder Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with integrated nylon patch that maintains secure fastening from -50° to 250°F, preventing loosening in dynamic applications
• Superior corrosion resistance provided by 316 stainless steel construction, ideal for harsh chemical and marine environments
• Precision alignment capability with Class 3A thread fit and controlled shoulder diameter tolerances ensuring accurate component positioning
• High mechanical strength delivering 70,000 psi tensile and 35,000 psi shear strength for demanding industrial applications
• Enhanced grip and torque transmission through knurled socket head design, reducing tool slippage during installation
• Industry-standard compliance with ASME B18.3 specifications, guaranteeing interchangeability and reliability
• Environmental responsibility through RoHS 3 and REACH compliance, meeting modern regulatory requirements

Professional Applications & Engineering Value

This 316 stainless steel shoulder screw addresses critical engineering challenges in precision machinery and industrial equipment. The 5/16"-18 UNC coarse thread with Class 3A fit provides exceptional engagement strength while the integrated nylon patch thread locker eliminates vibration-induced loosening in rotating assemblies. The precisely machined shoulder with tight diameter tolerance (-0.004" to -0.002") serves as both an alignment feature and bearing surface, preventing component misalignment in pulley systems, gear mechanisms, and rotating shafts. The combination of hex socket drive and knurled head texture ensures secure tool engagement during high-torque installation, while the material's inherent corrosion resistance makes it suitable for food processing, chemical handling, and marine applications where environmental factors would compromise ordinary fasteners.

Specification Summary & Compliance

This shoulder screw maintains Class 3A thread fit per UNC standards with precise shoulder diameter tolerance of -0.004" to -0.002" and shoulder length tolerance of -0.005" to 0.005". Manufactured to ASME B18.3 specifications for dimensional consistency and mechanical performance. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use in regulated industries. The thread locker maintains effectiveness across the specified temperature range of -50° to 250°F while the Rockwell B79 hardness provides optimal balance between strength and machinability.