S-91327A155 5/16"-18 ASME B18.3 Shoulder Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with permanent nylon patch that maintains integrity across a wide temperature range from -50° to 250°F, preventing loosening in dynamic applications
• Superior corrosion resistance from 18-8 stainless steel construction with passivated finish, ensuring long-term reliability in harsh industrial environments
• Precision thread engagement with Class 3A fit and UNC coarse threads providing consistent, reliable fastening with reduced assembly time
• Enhanced installation control through knurled socket head design offering superior grip and torque transmission during driving operations
• High mechanical strength with 70,000 psi tensile strength and Rockwell B55 hardness, capable of withstanding heavy loads and stress
• Accurate shoulder positioning featuring tight diameter tolerance (-0.004" to -0.002") for precise component alignment and spacing
• Industry compliance assurance meeting ASME B18.3 specifications and environmental regulations including RoHS 3 and REACH

Professional Applications & Engineering Value

This 5/16"-18 UNC shoulder screw delivers exceptional engineering value in demanding industrial applications where vibration resistance and precise alignment are critical. The 18-8 stainless steel construction with passivated finish provides superior corrosion protection for machinery operating in humid or chemically aggressive environments. The integrated nylon patch thread locker eliminates the need for separate locking compounds, streamlining assembly while maintaining secure fastening under constant vibration in automotive, aerospace, and heavy equipment applications. The knurled socket head ensures positive driver engagement, reducing slippage and tool damage during high-torque installation. With its Class 3A thread fit and precisely controlled shoulder dimensions, this fastener enables accurate component positioning in rotating assemblies, pivoting mechanisms, and precision instruments where dimensional stability is paramount.

Specification Summary & Compliance

This shoulder screw maintains Class 3A thread fit with UNC coarse thread profile (5/16"-18) and features precise shoulder diameter tolerance of -0.004" to -0.002" with shoulder length tolerance of -0.005" to 0.005". Manufactured in compliance with ASME B18.3 specifications and certified RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring environmental regulatory adherence for global industrial applications.