S-91128A133 0.688" ID Square Washers

Key Features & Benefits at a Glance

• Enhanced load distribution with a large 4" square surface area, reducing surface pressure and preventing material damage in heavy-duty applications.
• Superior corrosion resistance from the black-oxide steel finish, extending service life in demanding industrial environments.
• Exceptional hardness and durability with a Rockwell 15N80 rating, ensuring the washer maintains its shape and function under high stress.
• Precise compatibility with 5/8" screws thanks to the 0.688" inner diameter, providing a secure and reliable fit.
• Robust structural integrity from a substantial 0.235-0.265" thickness, offering reliable performance in high-vibration and load-bearing scenarios.
• Compliance with major environmental regulations including RoHS 3 and REACH, ensuring safe use in regulated industries and global markets.
• Ideal for inch-based assembly systems, designed to meet the needs of industrial applications using standard imperial measurements.

Professional Applications & Engineering Value

This heavy-duty square washer is engineered to solve critical challenges in industrial fastening, such as joint failure and surface indentation. The black-oxide steel construction provides a protective layer that resists rust and wear, making it suitable for outdoor machinery, construction equipment, and automotive assemblies where exposure to moisture and harsh conditions is common. Its large 4" square design and substantial thickness ensure maximum load distribution, which is vital for preventing bolt loosening and distributing clamp load over a wider area. This is particularly valuable in structural applications, such as steel framing or heavy machinery, where maintaining joint integrity under dynamic loads is essential. The precise 0.688" ID ensures a perfect match for 5/8" screws, reducing installation errors and enhancing overall assembly reliability.

Specification Summary & Compliance

This washer features an inner diameter of 0.688" and a thickness range of 0.235-0.265", manufactured to standard inch system tolerances for consistent performance. It is made from black-oxide steel with a hardness of Rockwell 15N80, ensuring durability and resistance to deformation. The product is fully compliant with RoHS 3 (2015/863/EU) under exemption 6(a) for lead in steel alloys and REACH (EC 1907/2006) as of January 17, 2023, meeting stringent environmental and safety standards for industrial use.