S-91257A447 5/16"-24 x 5 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional strength for demanding applications with Grade 8 classification, providing a tensile strength of 150,000 psi to withstand extreme loads and prevent failure.
• Superior corrosion resistance in harsh environments due to the zinc yellow-chromate plating, extending the fastener's service life and reducing maintenance needs.
• Reliable, precision threading for secure fastening featuring a 5/16"-24 UNF fine thread with Class 2A fit, ensuring consistent engagement and vibration resistance.
• High durability and wear resistance from Rockwell C33 hardness, making it suitable for high-stress industrial applications without deforming.
• Optimized for heavy-duty assembly with a 5 1/2" length and partial threading, offering flexibility in grip range and concentrated strength where needed.
• Easy installation and removal with an external hex drive and standard 1/2" head width, allowing for high torque application with common tools.
• Compliance with industry standards meeting ASME B18.2.1 and SAE J429 specifications, ensuring interoperability and reliability in professional settings.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical challenges in heavy machinery, construction, and automotive assemblies where high tensile strength and corrosion resistance are paramount. The steel material combined with zinc yellow-chromate plating provides a robust barrier against rust and chemical exposure, reducing downtime in corrosive environments. Its 5/16"-24 UNF fine thread and Class 2A thread fit ensure precise, vibration-resistant connections, preventing loosening under dynamic loads. The partially threaded design concentrates strength on the shank, ideal for applications requiring clamping force without full threading. By meeting ASME B18.2.1 standards, it guarantees consistency and safety in critical industrial fastening scenarios, from structural frames to engine components.

Specification Summary & Compliance

This fastener adheres to Class 2A thread fit tolerances for consistent engagement and is manufactured in accordance with ASME B18.2.1 and SAE J429 specifications. It features a 5/16"-24 UNF fine thread with a minimum thread length of 7/8" and is compliant with RoHS and REACH environmental regulations, ensuring safe and sustainable use in global industrial markets.