S-91128A337 0.938" ID Square Washers

Key Features & Benefits at a Glance

• Enhanced load distribution with 4" square design to prevent surface damage and fastener loosening under heavy loads
• Superior corrosion resistance from black-oxide steel finish for extended service life in harsh industrial environments
• Precise 0.938" inner diameter ensures perfect fit and alignment with 7/8" screws, reducing installation time
• Exceptional hardness rating (Rockwell 15N80) maintains structural integrity under high-pressure applications
• Consistent thickness control (0.235-0.265") provides reliable performance and uniform clamping force
• Full regulatory compliance with RoHS 3 and REACH standards for safe global industrial use
• Heavy-duty construction delivers maximum durability for demanding machinery and structural applications

Professional Applications & Engineering Value

This 4" square washer in black-oxide steel addresses critical engineering challenges in heavy industrial applications where standard washers fail. The large square surface area significantly improves load distribution, preventing surface indentation and fastener sinkage in soft materials while maintaining joint integrity under vibration and dynamic loads. The black-oxide surface treatment provides essential corrosion protection without dimensional changes, making it ideal for outdoor equipment, structural steel connections, and machinery subjected to environmental exposure. With precise 0.938" ID matching standard 7/8" screw sizes, installation efficiency improves while eliminating misalignment issues that compromise assembly quality in construction, manufacturing, and heavy equipment maintenance applications.

Specification Summary & Compliance

Manufactured to inch system standards with 0.938" inner diameter and 0.235-0.265" thickness for consistent performance. The black-oxide steel construction meets industrial hardness requirements at Rockwell 15N80. Fully compliant with RoHS 3 (2015/863/EU) under exemption 6(a) for lead as steel alloying element and REACH (EC 1907/2006) regulations (SVHC list as of 01/17/2023), ensuring environmental responsibility and global market acceptance for industrial fastener applications.