S-91205A541 1/4"-20 x 7/8" ASME B18.3, ASTM A574 Alloy Steel Thread-Locking Socket Head Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with integrated nylon patch maintains secure fastening in temperatures from -70° to 250°F, preventing loosening in dynamic applications
• Exceptional strength-to-weight ratio from alloy steel construction delivers 170,000 psi tensile strength for heavy-duty mechanical assemblies
• Precision thread engagement with Class 3A UNC coarse threads ensures reliable mating and reduced cross-threading risk
• Superior corrosion protection through black-oxide surface treatment extends service life in demanding industrial environments
• Optimized torque transmission via 3/16" hex drive socket head prevents tool slippage and enables high tightening forces
• Full regulatory compliance with ASME B18.3, ASTM A574, RoHS 3, and REACH standards guarantees quality and environmental safety
• Consistent performance backed by Rockwell C37 hardness rating ensures dimensional stability under load

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw addresses critical vibration and thermal stability challenges in industrial equipment. The nylon patch thread locking system provides permanent fastener security without compromising disassembly capability, making it ideal for machinery subjected to continuous operation or thermal cycling. Engineered with Class 3A UNC coarse threads, the screw delivers superior engagement in tapped holes while resisting stripping in high-vibration environments like automotive assemblies, manufacturing equipment, and heavy machinery. The combination of 170,000 psi tensile strength and corrosion-resistant black-oxide finish ensures long-term reliability in applications where fastener failure could lead to costly downtime or safety concerns.

Specification Summary & Compliance

Manufactured to ASME B18.3 specifications with ASTM A574 material standards, this socket head cap screw features precision Class 3A thread fit with UNC coarse threading (1/4"-20) and 7/8" fully threaded length. The component meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance requirements, ensuring environmental safety while maintaining 170,000 psi tensile strength and Rockwell C37 hardness throughout its operational temperature range of -70° to 250°F.