S-91257A961 1"-8 x 4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Load-Bearing Capacity: With a tensile strength of 150,000 psi, this screw reliably handles high-stress applications without failure.
• Superior Corrosion Resistance: Zinc yellow-chromate plating provides durable protection against rust and environmental degradation in harsh industrial settings.
• High Hardness for Longevity: Rockwell C33 hardness ensures the screw maintains its structural integrity and resists wear over repeated use.
• Secure Fastening with Coarse Threads: 1"-8 UNC coarse threads offer quick installation and strong holding power in a variety of materials.
• Optimized for Heavy-Duty Use: Grade 8 classification and partial threading deliver robust performance where high strength and precise engagement are critical.
• Wide Compatibility: Meets ASME B18.2.1 standards, ensuring reliable interchangeability and fit in professional assemblies.
• Environmental and Safety Compliance: RoHS 3 and REACH compliant, making it suitable for regulated industries and global supply chains.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical challenges in heavy machinery, construction, and automotive sectors where fastener failure can lead to costly downtime or safety hazards. The steel material combined with zinc yellow-chromate plating resists corrosion in outdoor or chemically aggressive environments, extending service life. The 1"-8 UNC coarse thread design ensures rapid assembly and reliable grip in soft or coarse substrates, reducing installation time while maintaining high tensile strength. Its external hex drive and partially threaded shank allow for precise torque application and reduced risk of thread damage, making it ideal for structural connections, equipment frames, and load-bearing supports that demand unwavering reliability and compliance with ASME B18.2.1 specifications.

Specification Summary & Compliance

This screw features a 1"-8 UNC coarse thread with Class 2A fit for consistent dimensional accuracy and ease of assembly. It is manufactured to meet ASME B18.2.1 and SAE J429 Grade 8 standards, ensuring high strength and reliability. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting safe and sustainable usage in industrial applications.