S-90311A174 5/16"-18 ASME B18.3 Shoulder Screws

Key Features & Benefits at a Glance

• Vibration-resistant secure fastening with permanent nylon patch thread locker, maintaining integrity from -50° to 250°F for reliable performance in dynamic environments.
• Superior corrosion resistance due to 316 stainless steel construction, ideal for harsh industrial, marine, and chemical-exposed applications.
• High load-bearing capacity with 70,000 psi tensile strength and 35,000 psi shear strength, ensuring durability under heavy mechanical stress.
• Precise alignment and smooth rotation from the precision shoulder (3/8" diameter, 1 1/4" length) with tight tolerances for accurate component positioning.
• Easy installation and removal using the hex drive (3/16") and standard socket head, combined with a knurled head for improved grip during handling.
• Consistent thread engagement with Class 3A UNC coarse threads, providing secure fits and reducing the risk of cross-threading in assembly.
• Compliance with industry standards including ASME B18.3, RoHS, and REACH, ensuring safety, quality, and environmental responsibility.

Professional Applications & Engineering Value

This 5/16"-18 UNC shoulder screw is engineered to address critical challenges in industrial assembly, where vibration loosening and misalignment can compromise machinery integrity. The nylon patch thread locker provides a permanent locking mechanism, eliminating the need for additional adhesives and reducing maintenance in equipment like rotating shafts, pivoting joints, and precision guides. Made from 316 stainless steel, it offers excellent resistance to corrosion from moisture, chemicals, and saltwater, making it suitable for marine, food processing, and pharmaceutical applications. The knurled head and hex drive facilitate quick installation, while the precision shoulder ensures accurate alignment of components, minimizing wear and extending service life in high-stress environments.

Specification Summary & Compliance

This shoulder screw adheres to Class 3A thread fit for precise UNC coarse threading, with shoulder diameter tolerance of -0.004" to -0.002" and length tolerance of -0.005" to 0.005" to ensure dimensional accuracy. It conforms to ASME B18.3 manufacturing specifications and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing it is free from hazardous substances and safe for various industrial uses.