S-91257A613 5/16"-24 x 3" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 150,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior corrosion resistance from zinc yellow-chromate plating extends service life in harsh or outdoor industrial environments.
• High hardness (Rockwell C33) provides excellent wear resistance and durability under repetitive loading conditions.
• Precision Class 2A thread fit guarantees smooth assembly and secure fastening with consistent torque performance.
• Partially threaded UNF fine thread design offers optimal grip and vibration resistance in critical joints.
• External hex drive and hex head allow for easy installation and high torque application with standard tools.
• Compliance with ASME B18.2.1 and environmental standards ensures product reliability and safe use in regulated industries.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address demanding industrial fastening challenges where strength and durability are paramount. The steel construction combined with Rockwell C33 hardness and 150,000 psi tensile strength makes it ideal for heavy machinery, automotive assemblies, and structural applications subject to high vibration and dynamic loads. The zinc yellow-chromate plating provides a robust barrier against corrosion, significantly extending component life in exposed or chemically aggressive environments. Its 5/16"-24 UNF fine thread and partial threading ensure secure clamping force distribution, reducing the risk of loosening in critical joints. By meeting ASME B18.2.1 specifications, this fastener delivers consistent dimensional accuracy and performance, making it a trusted choice for engineers and maintenance professionals seeking reliable, high-strength industrial screws.

Specification Summary & Compliance

This fastener features a Class 2A thread fit for precise engagement and is manufactured in accordance with ASME B18.2.1 and SAE J429 Grade 8 standards, ensuring dimensional consistency and mechanical reliability. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its safety for use in environmentally conscious applications. With a thread size of 5/16"-24 UNF and a length of 3 inches, it is designed for high-strength, corrosion-resistant fastening solutions in industrial settings.