S-90128A138 5/16"-18 x 1 3/8" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior corrosion resistance from zinc plating protects against rust and extends service life in harsh industrial environments.
• Precise Class 3A thread fit provides tighter tolerances for secure, vibration-resistant assemblies with minimal backlash.
• High hardness rating (Rockwell C37) offers excellent wear resistance, maintaining thread integrity through repeated use.
• Standard hex drive design with 1/4" drive size allows for easy installation and removal using common tools.
• Partially threaded shank enables precise clamping force control where full threading isn't required.
• Compliance with major standards including ASTM A574 ensures consistent quality and material reliability.

Professional Applications & Engineering Value

These zinc-plated alloy steel socket head cap screws deliver critical performance advantages for demanding industrial applications. The UNC coarse thread spacing provides faster assembly and better resistance to vibration loosening in heavy machinery, automotive components, and structural frameworks. The Class 3A thread fit ensures precise engagement with mating parts, eliminating play in precision equipment while the 170,000 psi tensile strength handles extreme dynamic loads without deformation. The right-hand thread direction with standard socket head profile facilitates installation in confined spaces where wrench clearance is limited, making these fasteners ideal for maintenance operations and OEM manufacturing across multiple sectors.

Specification Summary & Compliance

This socket head cap screw features 5/16"-18 UNC coarse threads with Class 3A thread fit for precision assembly. Dimensions include 1 3/8" length with minimum thread length of 1 1/8" and standard head diameter of 15/32". Manufactured to ASTM A574 specifications from zinc-plated alloy steel, these screws are fully RoHS 3 (2015/863/EU) compliant and REACH (EC 1907/2006) compliant, meeting international environmental and safety standards for industrial use.