S-91268A204 5/16"-18 x 3 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional strength for demanding applications with Grade 8 classification and 150,000 PSI tensile strength, ensuring reliable performance under high stress.
• Superior durability and wear resistance due to Rockwell C33 hardness, extending service life in harsh industrial environments.
• Secure and easy installation with an external hex drive and 1/2" head width, providing excellent torque transfer and reducing slippage.
• Optimized for quick assembly featuring coarse UNC threading and Class 2A thread fit, which minimizes cross-threading and speeds up fastening.
• Versatile partial threading design allows for precise clamping force control, ideal for applications where unthreaded shank strength is critical.
• Compliance with major industry standards including ASME B18.2.1 and SAE J429, guaranteeing consistent quality and interchangeability.
• Environmentally responsible manufacturing with RoHS 3 and REACH compliance, ensuring safety and regulatory adherence for global supply chains.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical challenges in heavy-duty industrial settings, such as machinery assembly, structural frameworks, and automotive components. The steel material and partial UNC threading provide a robust solution that resists vibration loosening and maintains clamp load under dynamic stresses. Its coarse thread design ensures reliable engagement in softer materials or where debris is present, reducing the risk of thread stripping. With a 3 1/2" length and right-hand thread, it offers versatility for applications requiring deep penetration and secure fastening. The external hex drive facilitates efficient installation with standard tools, enhancing productivity in maintenance and manufacturing operations where high tensile strength and durability are non-negotiable.

Specification Summary & Compliance

This fastener adheres to precise dimensional standards, including Class 2A thread fit for consistent assembly and UNC thread type with a size of 5/16"-18. It meets ASME B18.2.1 and SAE J429 specifications, ensuring reliability in mechanical and structural applications. Additionally, it is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), supporting environmentally safe and regulated use in various industries.