S-91247A027 1/4"-28 x 3 3/4" ASME B18.2.1, SAE J429 Medium-Strength Grade 5 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Load-Bearing Performance – Grade 5 classification and 120,000 PSI tensile strength ensure reliable performance in high-stress industrial applications.
• Superior Corrosion Resistance – Zinc plating provides a durable protective layer, extending service life in harsh or outdoor environments.
• Precise & Secure Fastening – UNF fine threading and Class 2A thread fit offer excellent vibration resistance and reduced risk of loosening.
• Optimized Thread Engagement – Partially threaded design with a minimum 3/4" thread length allows for controlled clamping force and easier alignment.
• High Torque Application Ready – External hex drive and hex head design enable efficient installation with standard tools, even in confined spaces.
• Consistent Hardness & Durability – Rockwell C25 hardness ensures the screw maintains its structural integrity under repeated loads.
• Wide Industrial Compatibility – Manufactured to inch system standards, making it suitable for replacement and OEM use in North American machinery.

Professional Applications & Engineering Value

This 1/4"-28 UNF Grade 5 hex head screw is engineered to address common challenges in heavy machinery, automotive assemblies, and structural frameworks. The zinc plated steel construction combats rust and corrosion, crucial for equipment exposed to moisture or chemicals. Its fine UNF threading and Class 2A thread fit provide superior resistance to vibrational loosening—a frequent issue in dynamic load environments. The partially threaded shank allows the unthreaded portion to act as a precise dowel, improving shear strength and alignment in bolted joints. With a 3 3/4" length and external hex drive, it offers deep penetration and easy installation in hard-to-reach areas, making it a versatile choice for maintenance and manufacturing engineers seeking durability and compliance.

Specification Summary & Compliance

This fastener adheres to ASME B18.2.1 and SAE J429 Grade 5 specifications, ensuring dimensional accuracy and mechanical properties. Threads are manufactured to UNF fine thread standards with a Class 2A fit for consistent engagement. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free of hazardous substances and safe for use in regulated industries.