S-91286A203 3/8"-16 x 1 3/8" 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 protection through zinc-flake coating that withstands harsh industrial environments
• Enhanced durability with Rockwell C33 hardness maintaining fastener integrity under repeated stress
• Reliable coarse threading using UNC 3/8"-16 pattern for faster installation and vibration resistance
• Precision fit with Class 2A thread tolerance ensuring consistent performance across assemblies
• High-torque capability through external hex drive design for secure tightening in confined spaces
• Full thread coverage along the 1-3/8" length providing maximum grip strength throughout the fastener

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers exceptional engineering value where failure is not an option. The combination of 150,000 PSI tensile strength and Rockwell C33 hardness provides critical load-bearing capacity for heavy machinery, structural steel connections, and industrial equipment subjected to extreme vibrations and dynamic loads. The zinc-flake coating offers superior corrosion resistance compared to standard platings, significantly extending service life in manufacturing facilities, outdoor applications, and chemical environments. The UNC coarse thread design ensures rapid installation while maintaining holding power, with Class 2A thread fit guaranteeing precise engagement in tapped holes. These fully threaded fasteners provide consistent clamping force across the entire 1-3/8" length, making them ideal for demanding applications in construction, automotive assembly, and heavy equipment manufacturing where reliability and durability are paramount.

Specification Summary & Compliance

Manufactured to exacting standards with Class 2A thread fit tolerance and UNC coarse thread spacing (3/8"-16). Complies with ASME B18.2.1 and SAE J429 Grade 8 specifications for dimensional accuracy and mechanical properties. Meets environmental regulations including RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant for restricted substance control. The external hex drive conforms to standard wrench sizes while the zinc-flake finish provides consistent corrosion protection meeting industrial fastener requirements.