S-91257A637 3/8"-16 x 3 1/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Maximum load-bearing capacity with 150,000 psi tensile strength for critical structural applications
• Superior corrosion resistance through zinc yellow-chromate plating in demanding environments
• Enhanced durability with Rockwell C33 hardness to withstand repeated stress and vibration
• Reliable thread engagement featuring Class 2A fit and UNC coarse threads for secure fastening
• Optimized torque transmission with external hex drive and 9/16" head width
• Versatile partial threading allowing for both clamping and alignment functions
• Full regulatory compliance meeting ASME, SAE, RoHS 3, and REACH standards

Professional Applications & Engineering Value

These Grade 8 hex head screws deliver exceptional engineering value in heavy machinery, construction equipment, and industrial assembly applications. The zinc yellow-chromate plated steel construction provides superior protection against corrosion while maintaining 150,000 psi tensile strength for high-stress connections. The 3/8"-16 UNC coarse threads with Class 2A fit ensure rapid installation and reliable performance in vibration-prone environments. The partially threaded design offers precise clamping control where full thread engagement isn't required, making these external hex drive fasteners ideal for structural frameworks, equipment mounting, and mechanical assemblies demanding ASME B18.2.1 compliance.

Specification Summary & Compliance

Manufactured to precise inch system dimensions with Class 2A thread fit tolerance and UNC coarse threading. Complies with ASME B18.2.1 and SAE J429 Grade 8 specifications for mechanical properties and dimensional standards. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance requirements. Features 3-1/4" length with 1" minimum thread length and Rockwell C33 hardness verification.