S-91257A951 7/8"-14 x 9" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Maximum Load-Bearing Capacity: Grade 8 classification and 150,000 psi tensile strength ensure reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior Corrosion Protection: Zinc yellow-chromate plating provides excellent resistance to rust and environmental degradation, extending service life in harsh industrial conditions.
• Precise Thread Engagement: UNF fine thread with Class 2A fit offers superior vibration resistance and secure fastening in critical assemblies.
• Optimized Strength-to-Weight Ratio: Partial threading design concentrates material where needed most, providing maximum grip length without unnecessary weight.
• Enhanced Installation Efficiency: Standard 1 5/16" hex head with external drive allows for high-torque application using common tools, speeding up assembly processes.
• Rigorous Quality Assurance: Manufactured to ASME B18.2.1 and SAE J429 specifications, ensuring dimensional accuracy and consistent performance across batches.
• Environmental Compliance: Meets RoHS 3 and REACH regulations, making them suitable for use in regulated industries and international markets.

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers exceptional engineering value in demanding industrial applications where high tensile strength and corrosion resistance are critical. The 7/8"-14 UNF fine thread configuration provides superior clamping force distribution, making it ideal for heavy machinery, structural steel connections, and high-vibration equipment where Class 2A thread fit ensures precise engagement and prevents loosening under dynamic loads. The zinc yellow-chromate plating creates a protective barrier that withstands exposure to moisture, chemicals, and outdoor elements, significantly extending maintenance intervals in construction, mining, and transportation equipment. The partial threading design optimizes the screw's performance by providing maximum thread engagement in the critical load-bearing section while reducing weight and material usage. These industrial hex screws are engineered to maintain integrity under extreme pressure, with Rockwell C33 hardness ensuring durability against wear and deformation in repetitive assembly applications.

Specification Summary & Compliance

This fastener maintains Class 2A thread fit tolerance per UNF standards, ensuring precise dimensional accuracy and compatibility with standard nuts. Manufacturing complies with ASME B18.2.1 and SAE J429 specifications for hex head screws, guaranteeing consistent quality and performance. The product is fully compliant with RoHS 3 (2015/863/EU) restrictions on hazardous substances and REACH (EC 1907/2006) regulations concerning chemical safety, making it suitable for use in environmentally conscious applications and international markets.