S-91211A213 5/8"-11 x 3" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Thread-Locking Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 150,000 psi tensile strength for reliable performance in high-stress industrial environments
• Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in demanding conditions
• Vibration-resistant locking capability through nylon patch thread locker, maintaining secure fastening from -55° to 250°F
• Optimized torque transmission via external hex drive design, enabling efficient installation with standard tools
• Precision thread engagement with Class 2A thread fit and UNC coarse threading, ensuring consistent assembly quality
• Enhanced durability from Rockwell C33 hardness, providing excellent wear resistance in heavy-duty applications
• Strategic partial threading design allowing for precise clamping force distribution across connected components

Professional Applications & Engineering Value

Engineered for demanding industrial applications, these Grade 8 hex head screws deliver exceptional performance in heavy machinery, structural assemblies, and equipment manufacturing. The zinc yellow-chromate plated steel construction provides superior corrosion protection in harsh environments, while the nylon patch thread locker ensures vibration-resistant fastening across extreme temperature ranges from -55° to 250°F. The 5/8"-11 UNC coarse thread configuration offers rapid installation and reliable holding power, complemented by the partially threaded design that concentrates clamping force precisely where needed. These high-strength fasteners solve critical challenges in applications requiring maintained tension under dynamic loads, making them ideal for construction equipment, automotive systems, and industrial machinery where failure is not an option.

Specification Summary & Compliance

Manufactured to exacting standards with Class 2A thread fit tolerance for consistent engagement and UNC coarse threading for rapid assembly. Complies with ASME B18.2.1 and SAE J429 specifications, ensuring dimensional accuracy and performance reliability. The Grade 8 classification guarantees minimum tensile strength of 150,000 psi and Rockwell C33 hardness, meeting rigorous industrial requirements for heavy-duty fastening applications.