S-91253A725 1/2"-13 x 3 1/4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 130,000 psi ensures reliable performance under heavy loads and vibration, reducing the risk of fastener failure in demanding applications.
• Superior corrosion resistance provided by the black-oxide coating on alloy steel, extending the screw's service life in various industrial environments.
• Precise Class 3A thread fit guarantees secure, tight connections with minimal play, enhancing assembly integrity and reducing the need for re-tightening.
• Robust Rockwell C39 hardness offers excellent wear resistance, maintaining thread form and drive integrity through repeated use and installation.
• Convenient 5/16" hex drive allows for high-torque installation with standard tools, speeding up assembly and reducing labor time.
• 82° countersink angle and flat head design enable a flush finish when installed, providing a smooth surface and improved aesthetic for assembled products.
• Compliance with major industry standards including ASTM F835, RoHS 3, and REACH ensures product reliability, safety, and environmental responsibility for global supply chains.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial fastening, these 1/2"-13 UNC flat head screws are ideal for machinery, structural frames, and equipment assembly where high tensile strength and vibration resistance are critical. The black-oxide alloy steel construction provides a durable barrier against rust and corrosion, making them suitable for both indoor and moderately harsh environments. The coarse UNC thread and partial threading design ensure rapid installation and strong grip in a wide range of materials, from steel to cast iron. The hex drive facilitates easy installation in confined spaces, reducing assembly time while maintaining torque integrity. These screws deliver consistent performance in applications requiring flush mounting and reliable, long-term fastening solutions, minimizing maintenance needs and downtime.

Specification Summary & Compliance

This screw features a 1/2"-13 UNC coarse thread with a Class 3A thread fit for precision engagement, and a partially threaded shank with a minimum thread length of 1-1/2". Dimensions include a 3-1/4" length, 0.938" head diameter, and 82° countersink angle. It is manufactured from alloy steel with a black-oxide surface treatment, and meets ASTM F835 specifications for mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it is free of restricted substances and safe for use in regulated markets.