S-91128A115 0.438" ID Square Washers

Key Features & Benefits at a Glance

• Superior load distribution with 2" square design for maximum surface contact and reduced surface pressure
• Enhanced corrosion resistance through black-oxide steel coating for extended service life in harsh environments
• Precise fitment with 0.438" ID specifically engineered for 3/8" screw applications
• Exceptional hardness rating of Rockwell 15N80 ensures dimensional stability under heavy loads
• Consistent performance maintained through controlled thickness range of 0.235-0.265"
• Regulatory compliance with RoHS 3 and REACH standards for safe industrial use
• Durable steel construction provides reliable performance in demanding applications

Professional Applications & Engineering Value

This black-oxide steel square washer delivers critical engineering solutions for industrial applications where standard washers fall short. The 2" width provides significantly larger bearing surface compared to round washers, effectively distributing clamping forces and preventing material deformation in structural connections. The black-oxide surface treatment creates a protective barrier against oxidation and corrosion, making these square washers ideal for outdoor construction, heavy machinery, and manufacturing equipment exposed to environmental elements. Engineered specifically for 3/8" screw size applications, these washers ensure precise fitment while the Rockwell 15N80 hardness maintains dimensional integrity under sustained vibration and load conditions common in industrial settings.

Specification Summary & Compliance

Manufactured to inch system standards with precise 0.438" inner diameter and thickness tolerance of 0.235-0.265". Constructed from steel with black-oxide finish for corrosion protection and meeting Rockwell 15N80 hardness specifications. Fully compliant with RoHS 3 (2015/863/EU) under exemption 6(a) for lead as an alloying element in steel and REACH (EC 1907/2006) regulations current as of January 17, 2023, ensuring environmental and safety standards for industrial use.