S-91286A153 1/4"-28 x 4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with Grade 8 classification and 150,000 psi tensile strength for reliable performance in high-stress environments
• Superior corrosion resistance through zinc-flake coating that provides long-lasting protection against harsh industrial conditions
• Precise thread engagement with Class 2A UNF fine threads ensuring secure fastening and vibration resistance
• Optimized strength-to-weight ratio through partial threading design that concentrates material where needed most
• Enhanced installation efficiency with external hex drive and standard head dimensions for quick assembly with common tools
• Consistent hardness performance at Rockwell C33 for maintained structural integrity under repeated stress
• Regulatory compliance assurance meeting ASME, SAE, RoHS 3, and REACH standards for global industrial applications

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions for heavy-duty applications where failure is not an option. The steel construction combined with Rockwell C33 hardness provides exceptional resistance to deformation under extreme loads, making it ideal for industrial machinery, automotive assemblies, and structural frameworks. The zinc-flake coated finish addresses corrosion concerns in challenging environments, while the 1/4"-28 UNF fine thread configuration ensures superior clamping force and vibration resistance compared to coarse-thread alternatives. The partial threading design optimizes strength distribution, preventing stress concentration at thread run-out points. These hex head screws are engineered to withstand the rigorous demands of heavy-duty applications where reliability and longevity are paramount.

Specification Summary & Compliance

Manufactured to precise Class 2A thread fit tolerances with UNF fine threading (1/4"-28) and 4" length with 3/4" minimum thread length. Complies with ASME B18.2.1 and SAE J429 Grade 8 specifications, ensuring dimensional accuracy and performance consistency. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance standards for safe use across global markets.