Gibraltar Z8852 M12 Extra Thick Flat Washer Black Oxide

Product Description

The GIBRALTAR Z8852 is an M12 extra thick flat washer made from case-hardened steel with a black oxide finish. It features a 13mm inside diameter, a 26mm outside diameter, and a 5mm thickness, making it substantially thicker than standard flat washers. The black oxide finish provides mild corrosion resistance and reduces light reflection in finished assemblies. Constructed from 1010 case-hardened steel, this washer delivers hardness at the surface while maintaining toughness at the core. It is used by mechanical technicians, millwrights, maintenance professionals, and tradespeople wherever an M12 fastener requires increased load distribution or added clamping depth.

This washer is suited for industrial, commercial, and heavy-duty mechanical assemblies that call for metric fasteners. The extra thickness is useful in applications where standard washers would deform under high clamp loads or where additional standoff is required between a fastener and the mating surface. Common applications include structural connections, machinery mounting, and fabrication work requiring metric hardware. The black oxide finish makes it appropriate for both interior and exposed assemblies where mild surface protection is needed.

Key Features

• Extra thick at 5mm, providing greater load distribution than standard flat washers
• Case-hardened 1010 steel construction for surface hardness and core toughness
• Black oxide finish for mild corrosion resistance and a low-reflectance appearance
• 13mm inside diameter sized for M12 fasteners
• 26mm outside diameter for broad bearing surface coverage
• Metric dimensioning consistent with ISO fastener systems

Compatibility

Designed for use with M12 metric screws and bolts in industrial, commercial, and mechanical assembly applications requiring an extra thick flat washer.

Installation Notes

Installation is performed by hand or with standard wrenches as part of a bolted assembly. Ensure the mating fastener is M12 and that the bearing surfaces are clean and free of debris before seating the washer. Do not use this washer as a substitute for a hardened load-indicating or structural washer in safety-critical connections without verifying the appropriate specification. Follow applicable mechanical and structural codes for the installation environment.