S-91286A387 1/2"-20 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 load-bearing capacity with a 150,000 PSI tensile strength, ideal for high-stress structural and machinery applications.
• Superior corrosion resistance provided by the zinc-flake coating, extending service life in harsh industrial environments.
• Reliable, fine-thread engagement with the 1/2"-20 UNF and Class 2A thread fit, ensuring vibration resistance and secure fastening.
• High durability and wear resistance from the Grade 8 steel and Rockwell C33 hardness, minimizing deformation under heavy loads.
• Easy installation and removal with the external hex drive and 3/4" head width, compatible with standard wrenches for efficient maintenance.
• Optimized thread design as partially threaded, allowing for precise clamping force control and reduced risk of cross-threading.
• Compliance with major industry standards including ASME B18.2.1 and SAE J429, ensuring consistent quality and performance.

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 corrosion resistance are paramount. The zinc-flake coating provides a robust barrier against rust and chemical exposure, significantly reducing maintenance downtime. Its 1/2"-20 UNF fine thread and Class 2A fit deliver superior vibration resistance, preventing loosening in dynamic load conditions. The partially threaded shank allows for precise joint clamping, making it ideal for securing flanges, brackets, and structural frames. By integrating ASME B18.2.1 and SAE J429 specifications, this fastener ensures reliability in demanding applications, from industrial equipment to infrastructure projects, enhancing operational safety and longevity.

Specification Summary & Compliance

This fastener adheres to precise dimensional standards, including Class 2A thread fit for consistent engagement and UNF fine threading per inch system requirements. It meets ASME B18.2.1 and SAE J429 specifications for material and mechanical properties, ensuring high performance. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations confirms its environmental safety and suitability for global industrial use.