S-91286A156 5/16"-18 x 1 1/8" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Maximum Load-Bearing Capacity: Grade 8 classification and 150,000 PSI tensile strength ensure reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior Corrosion Resistance: Zinc-flake coating provides excellent protection against rust and environmental degradation, extending service life in harsh industrial conditions.
• Optimized Thread Engagement: UNC coarse thread design and Class 2A thread fit enable faster installation and secure holding power in a wide range of materials.
• Enhanced Durability: Rockwell C33 hardness and high-strength steel construction resist wear, deformation, and stripping under heavy loads.
• Efficient Installation & Removal: External hex drive and standard 1/2" head width allow for easy access with common tools, reducing assembly time.
• Full Thread Coverage: 1-1/8" fully threaded length ensures consistent clamping force and versatility across various material thicknesses.
• Regulatory Compliance: Meets ASME B18.2.1 and SAE J429 specifications, with RoHS 3 and REACH compliance for safe use in regulated industries.

Professional Applications & Engineering Value

These Grade 8 hex head screws are engineered to address critical fastening challenges in demanding environments. The high-strength steel construction, combined with Rockwell C33 hardness, provides exceptional resistance to shear and tensile forces, making them ideal for heavy machinery, structural assemblies, and automotive applications where vibration and dynamic loads are common. The zinc-flake coating offers superior corrosion protection, significantly outperforming standard zinc plating in salt spray and chemical exposure scenarios. With UNC coarse threads and Class 2A thread fit, these screws deliver reliable engagement in both metallic and non-metallic substrates, reducing the risk of cross-threading while maintaining precise torque-tension relationships. The fully threaded design ensures maximum grip length variability, providing engineers with flexible solutions for varying material thicknesses without compromising joint integrity.

Specification Summary & Compliance

This fastener maintains Class 2A thread fit tolerances per UNC thread standards, ensuring consistent threading compatibility. Manufacturing complies with ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. The product is fully RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting current environmental and safety regulations for industrial use.