S-91257A937 7/8"-14 x 3 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws
High-Strength Grade 8 Steel Hex Head Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Exceptional load-bearing capability with 150,000 psi tensile strength, ideal for high-stress structural connections
- Superior corrosion resistance from zinc yellow-chromate plating, extending service life in harsh environments
- Reliable fine-thread engagement with 7/8"-14 UNF threads and Class 2A fit, ensuring vibration resistance and precise clamping
- Optimized torque transmission via external hex drive and 1 5/16" head width, facilitating secure installation with standard tools
- Enhanced durability from Grade 8 steel and Rockwell C33 hardness, resisting wear under repetitive loads
- Versatile partial threading allowing unthreaded shank sections for shear strength in bolted joints
- Regulatory compliance assurance meeting ASME, SAE, RoHS 3, and REACH standards for global industrial use
Professional Applications & Engineering Value
This Grade 8 hex head screw delivers critical performance in heavy machinery, structural steel frameworks, and high-vibration equipment. The UNF fine threading maintains clamp load integrity under dynamic stresses, while the zinc yellow-chromate finish prevents galvanic corrosion in outdoor or chemical-exposed settings. Engineered with partial threading, it provides an unthreaded bearing surface for improved shear resistance in bolted connections. The external hex drive and large head profile enable high-torque installation without stripping, making it indispensable for construction, mining, and transportation applications where joint failure is not an option.
Specification Summary & Compliance
Manufactured to ASME B18.2.1 and SAE J429 specifications with Class 2A thread fit tolerances. The 7/8"-14 UNF thread form ensures interchangeability with standard components. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Material certification includes Rockwell C33 hardness and 150,000 psi minimum tensile strength verification.
