S-91257A936 7/8"-14 x 3 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional strength and durability: Grade 8 classification with 150,000 psi tensile strength and Rockwell C33 hardness ensures reliable performance in high-stress applications.
• Superior corrosion resistance: Zinc yellow-chromate plating provides a robust protective barrier, extending service life in harsh industrial environments.
• Precise thread engagement: UNF fine thread with Class 2A fit offers excellent vibration resistance and secure fastening in critical assemblies.
• Optimized load distribution: Partially threaded design concentrates strength where needed while reducing weight and material usage.
• Easy installation and removal: External hex drive with standard 1 5/16" head width accommodates common tools for efficient maintenance operations.
• Regulatory compliance assurance: Meets ASME B18.2.1 and SAE J429 specifications, along with RoHS 3 and REACH environmental standards.
• Versatile industrial application: Right-hand thread direction and 3 1/2" length make it suitable for construction, heavy machinery, and structural fastening needs.

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions where failure is not an option. The 7/8"-14 UNF fine thread configuration provides superior resistance to loosening under vibration, making it ideal for heavy machinery, structural steel connections, and industrial equipment subjected to dynamic loads. The zinc yellow-chromate plated steel construction combats corrosion in demanding environments, from manufacturing facilities to outdoor construction sites. With 150,000 psi tensile strength and Rockwell C33 hardness, this partially threaded fastener maintains integrity under extreme tension while the external hex drive ensures straightforward installation and maintenance access. These industrial fasteners are engineered to withstand the rigorous demands of construction, automotive, and heavy equipment applications where reliability and compliance with industry standards are paramount.

Specification Summary & Compliance

This heavy-duty hex head screw features precision Class 2A thread fit with 7/8"-14 UNF fine threading and partial threading extending a minimum of 2 inches. Manufactured to ASME B18.2.1 and SAE J429 specifications, it ensures dimensional accuracy and mechanical performance. The fastener is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, meeting the latest standards for hazardous substance restrictions and chemical safety.