S-91128A152 0.343" ID Square Washers

Key Features & Benefits at a Glance

• Enhanced corrosion resistance from the black-oxide steel finish, extending service life in demanding environments
• Superior load distribution due to the 2" square design, preventing surface damage and loosening under vibration
• Precise fit for 5/16" screws with a 0.343" inner diameter, ensuring secure fastening and reducing assembly errors
• Reliable mechanical strength backed by Rockwell B40 hardness, maintaining shape under high pressure
• Compliance with global environmental standards including RoHS 3 and REACH, ensuring safe use in regulated industries
• Consistent dimensional accuracy with thickness ranging from 0.054" to 0.066", providing uniform performance in batch applications

Professional Applications & Engineering Value

This black-oxide steel square washer is engineered to address common industrial challenges such as fastener corrosion and joint failure. The square shape offers a larger bearing surface compared to round washers, effectively distributing clamp load in structural assemblies, machinery frames, and heavy equipment. The black-oxide coating provides a protective layer against rust and mild chemicals, making it ideal for outdoor construction, automotive, and manufacturing applications where exposure to moisture is a concern. With its Rockwell B40 hardness, it resists deformation under torque, ensuring long-term reliability in high-vibration environments. Designed for use with 5/16" screws in inch-system applications, it simplifies inventory management for North American and global engineering projects requiring durable, precision washers.

Specification Summary & Compliance

This washer meets standard inch-system dimensions with an inner diameter of 0.343" and thickness tolerance of 0.054–0.066". It conforms to general industrial thread and fit standards for 5/16" screw sizes. The product is manufactured in compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it is free of restricted hazardous substances and safe for use in various sectors.