Gibraltar Z9201SS Extra Thick Flat Washer 5/16 in 18-8 Ss

Product Description

The GIBRALTAR Z9201SS is an extra thick flat washer designed for use with 5/16 inch fasteners. Manufactured from Grade 18-8 stainless steel with a plain finish, this washer delivers corrosion resistance suitable for wet, outdoor, and chemically active environments. The extra thick profile — at 3/16 inches — provides greater load distribution and bearing surface compared to standard flat washers. With an inside diameter of 11/32 inches and an outside diameter of 3/4 inches, it seats properly on 5/16 inch screw and bolt assemblies. Plumbers, HVAC technicians, electricians, and general contractors reach for 18-8 stainless hardware when installations demand long-term resistance to rust and staining.

This washer suits residential and light commercial fastener applications where standard washers lack the thickness or surface area needed under bolt heads or nuts. Common install scenarios include equipment mounting, pipe hangers, structural bracketing, and panel attachment where fastener pull-through or surface damage is a concern. The plain finish means no coating to chip or flake in high-humidity or submerged conditions. Sold individually, this washer fits within multi-fastener assemblies or single-point repair jobs alike.

Key Features

• Extra thick profile at 3/16 inches for increased load distribution and reduced fastener pull-through
• Grade 18-8 stainless steel construction for corrosion and stain resistance
• Inside diameter of 11/32 inches fits 5/16 inch screw and bolt shanks
• Outside diameter of 3/4 inches provides broad bearing surface
• Plain finish — no coating to degrade in wet or chemically active environments
• Rockwell hardness C36-C42 for reliable performance under clamping loads

Compatibility

Designed for use with 5/16 inch screws and bolts in standard inch-measurement fastener assemblies where an extra thick flat washer is specified.

Installation Notes

Install using standard hand tools appropriate for the fastener size. Power down or de-energize any equipment before servicing fastener assemblies in electrical or HVAC panels. Verify washer seating is flush against the mating surface before torquing the fastener to avoid cocking or uneven load distribution. When used in stainless steel assemblies, ensure mating fasteners are also stainless to prevent galvanic corrosion between dissimilar metals.