S-91772A557 1/4"-28 x 1/2" ASME B18.6.3 Stainless Steel Pan Head Phillips Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with passivated 18-8 stainless steel construction, ideal for harsh industrial environments
• Exceptional mechanical strength delivering 70,000 psi tensile strength and Rockwell B70 hardness for reliable load-bearing performance
• Precision thread engagement with Class 2A fit and UNF fine threads ensuring vibration-resistant, secure fastening
• Optimized drive efficiency featuring No. 3 Phillips drive and pan head design for streamlined installation and torque control
• Full-threaded design maximizing grip length and distribution of clamping force across the entire fastener
• Regulatory compliance assurance meeting ASME B18.6.3 standards and environmental directives (RoHS 3, REACH)
• Consistent dimensional accuracy with 0.492" head diameter and standardized geometry for repeatable assembly results

Professional Applications & Engineering Value

Engineered for demanding industrial fastening applications, these passivated 18-8 stainless steel screws combine material durability with precision threading to address critical assembly challenges. The UNF fine thread spacing and Class 2A thread fit provide superior resistance to loosening under vibration, making them ideal for machinery, electronic enclosures, and precision equipment where reliable thread engagement is paramount. The pan head design with Phillips drive facilitates efficient installation in confined spaces while maintaining consistent clamp load. With full threading along the 1/2" length, these rounded head screws ensure maximum surface contact and stress distribution, reducing the risk of joint failure in high-stress environments.

Specification Summary & Compliance

These 1/4"-28 UNF screws maintain Class 2A thread fit tolerances per unified thread standards, ensuring precise compatibility with matched components. Manufacturing conforms to ASME B18.6.3 specifications for dimensional consistency and mechanical performance. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations confirms environmental responsibility and material safety for global supply chain integration.