S-91211A159 3/8"-16 x 1 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Thread-Locking Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional vibration resistance with nylon patch thread locker maintaining secure fastening from -55° to 250°F
• Maximum load-bearing capability through Grade 8 classification with 150,000 psi tensile strength
• Superior corrosion protection via zinc yellow-chromate plating for extended service life in harsh environments
• Optimized torque application with external hex drive and 9/16" head width for reliable installation
• Precise thread engagement with Class 2A UNC coarse threads ensuring consistent performance
• Enhanced durability from Rockwell C33 hardness for repeated use in demanding applications
• Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for quality assurance

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, these Grade 8 hex head screws deliver reliable performance where vibration resistance and high tensile strength are critical. The nylon patch thread locking technology effectively prevents loosening under dynamic loads, making them ideal for machinery, equipment assembly, and structural applications exposed to constant motion or thermal cycling. The zinc yellow-chromate plated steel construction provides superior corrosion protection in demanding environments, while the 3/8"-16 UNC coarse thread design ensures quick installation and secure fastening in various materials. The partially threaded configuration allows for precise clamping force distribution, making these external hex drive fasteners essential components in automotive, manufacturing, and construction sectors where failure is not an option.

Specification Summary & Compliance

Manufactured to exacting standards with Class 2A thread fit and UNC coarse thread spacing for consistent performance. These inch system fasteners feature a 1 3/4" length with 1" minimum thread length and comply with ASME B18.2.1 and SAE J429 specifications. The Grade 8 strength classification ensures 150,000 psi tensile strength and Rockwell C33 hardness for maximum reliability in critical applications.