S-91286A517 3/4"-16 x 4 1/2" 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 the zinc-flake coating extends service life in harsh industrial environments, minimizing maintenance and replacement costs.
• Precise Class 2A thread fit with UNF fine threading provides secure, vibration-resistant connections, enhancing assembly integrity.
• High hardness (Rockwell C33) offers excellent wear resistance, maintaining thread integrity through repeated use and heavy loads.
• Partially threaded design allows for optimal clamping force distribution, ideal for applications requiring precise grip length.
• External hex drive enables easy installation and removal with standard tools, improving workflow efficiency.
• Compliance with major standards including ASME B18.2.1 and SAE J429 ensures consistent quality and interoperability in regulated industries.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical challenges in heavy machinery, construction, and automotive assemblies where high tensile strength and durability are paramount. The zinc-flake coated steel construction provides robust protection against corrosion, significantly extending service life in exposed or chemically aggressive environments. Featuring UNF fine threading with a Class 2A fit, it ensures tight, secure fastening that resists loosening under vibration and dynamic loads. The partially threaded shank design concentrates clamping force where needed, making it ideal for structural connections and equipment requiring precise load distribution. These screws deliver reliable performance in demanding applications, from industrial machinery to infrastructure projects, reducing downtime and maintenance costs.

Specification Summary & Compliance

This screw meets ASME B18.2.1 and SAE J429 Grade 8 specifications, with Class 2A thread fit ensuring dimensional accuracy and interchangeability. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing environmental safety and material restrictions adherence. The UNF fine thread with a diameter of 0.75" and spacing of 16 TPI provides precise engagement, while the Rockwell C33 hardness and 150,000 PSI tensile strength confirm its suitability for high-stress industrial use.