S-91205A668 3/8"-16 x 4" ASME B18.3, ASTM A574 Alloy Steel Thread-Locking Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Permanent nylon patch thread locker provides vibration resistance from -70° to 250°F, maintaining secure connections in fluctuating thermal environments.
• Class 3A thread fit offers superior precision and tighter tolerances for improved assembly accuracy and reduced loosening.
• Black-oxide finish on alloy steel enhances corrosion resistance and durability, extending service life in harsh industrial settings.
• Partially threaded design with 1-1/4" engagement allows for controlled clamping force and easier alignment in assemblies.
• ASME B18.3 and ASTM A574 compliance guarantees consistent quality and interoperability with standardized components.
• 5/16" hex drive socket head enables high-torque installation with common tools, speeding up maintenance and reducing labor time.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address critical challenges in heavy machinery, automotive, and aerospace sectors where vibration loosening and material fatigue are common. The UNC coarse thread design ensures quick assembly and disassembly, while the nylon patch thread locker secures fasteners against shocks and thermal cycles without requiring additional adhesives. With a Rockwell C37 hardness and high tensile strength, it withstands dynamic loads in equipment frames, actuators, and structural joints, minimizing downtime. Ideal for partially threaded applications, it provides precise thread engagement control, preventing over-tightening and ensuring uniform stress distribution in industrial assembly lines.

Specification Summary & Compliance

This screw adheres to Class 3A thread fit for precise UNC coarse threading (3/8"-16) and meets ASME B18.3 specifications under ASTM A574. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material integrity. The black-oxide surface treatment enhances durability, while the dimensional accuracy supports consistent performance in regulated industries.