S-91257A585 5/16"-18 x 1 3/8" 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 corrosion resistance provided by the zinc yellow-chromate plating, extending service life in harsh industrial and outdoor environments.
• Optimized for high-torque installation thanks to the external hex drive and hex head design, allowing for secure tightening with standard tools.
• Reliable thread engagement with UNC coarse threading and Class 2A thread fit, facilitating easier assembly and reducing cross-threading risks.
• Durable material construction using high-strength steel with Rockwell C33 hardness, offering excellent wear resistance and longevity.
• Versatile partial threading that provides a non-threaded shank for precise clamping in a wide range of assembly scenarios.
• Compliance with industry standards including ASME B18.2.1 and SAE J429, ensuring consistent quality and interchangeability in professional applications.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical fastening challenges in industrial machinery, construction frameworks, and heavy equipment assembly. The high-strength steel and Rockwell C33 hardness provide exceptional resistance to shear and tensile forces, preventing joint failure in high-vibration environments. The zinc yellow-chromate plating delivers robust protection against corrosion, making it ideal for outdoor or chemically exposed settings. With its 5/16"-18 UNC coarse thread and partial threading, it ensures quick installation and secure clamping in structural connections, reducing assembly time while maintaining integrity under dynamic loads. This combination of material properties and design meets the rigorous demands of ASME B18.2.1 and SAE J429 specifications, offering a dependable solution for engineers and procurement specialists seeking longevity and performance.

Specification Summary & Compliance

This fastener adheres to precise dimensional standards, including a Class 2A thread fit for consistent engagement and UNC coarse thread specifications. It is manufactured in compliance with ASME B18.2.1 and SAE J429 standards, ensuring reliability and interchangeability. The product meets common industry regulations for quality and safety, supporting use in regulated sectors without compromising on performance.