Gibraltar Z8860 M20 Extra Thick Flat Washer Black Oxide

Product Description

The GIBRALTAR Z8860 is an extra thick flat washer designed for M20 screw applications requiring greater load distribution and surface protection. Manufactured from case-hardened 1010 steel with a black oxide finish, this washer delivers solid corrosion resistance and hardness suitable for high-load fastening assemblies. It measures 21 mm inside diameter, 35 mm outside diameter, and 5 mm thick, conforming to metric sizing standards. Weighing 0.05 pounds, the Z8860 is a compact but durable hardware component used by mechanical contractors, millwrights, and industrial maintenance technicians working with metric fastener systems.

This washer is suited for structural and mechanical assemblies where standard flat washers lack sufficient bearing surface or thickness. The extra thick profile helps prevent fastener pull-through on softer base materials and distributes clamp load more evenly across the joint. It is appropriate for use in commercial and industrial settings, including machinery mounting, steel fabrication, and heavy equipment maintenance where metric M20 hardware is specified.

Key Features

• Extra thick 5 mm profile provides increased load distribution compared to standard flat washers
• Case-hardened 1010 steel construction resists deformation under high clamp loads
• Black oxide finish offers moderate corrosion resistance and a clean, low-reflectance appearance
• 21 mm inside diameter fits M20 fasteners precisely within metric tolerance
• 35 mm outside diameter delivers a broad bearing surface for improved joint integrity

Compatibility

Designed as a metric-standard replacement or supplemental flat washer for M20 screw and bolt assemblies in industrial, structural, and mechanical applications.

Installation Notes

Installation is performed by mechanical contractors, millwrights, or maintenance technicians using standard metric hand tools and torque wrenches. Always de-energize or depressurize any connected system before beginning fastener service. Verify that the washer seating surface is clean and free of debris before tightening to avoid uneven load distribution. Do not substitute this washer in applications requiring washers with specific hardness or dimensional certifications unless confirmed compatible with the joint design.