Gibraltar Z9201U Flat Washer 5/16 in Steel Black Oxide

Product Description

The GIBRALTAR Z9201U is a standard flat washer designed for use with 5/16-inch screws and fasteners. Manufactured from steel with a black oxide finish, this washer distributes load across the fastener head or nut to reduce surface damage and prevent loosening under vibration. The black oxide coating provides moderate corrosion resistance and a consistent dark appearance. With an inside diameter of 0.344 inches, an outside diameter of 0.828 inches, and a thickness of 0.188 inches, the Z9201U meets standard dimensional tolerances for general mechanical and structural assembly work. It is installed by electricians, plumbers, HVAC technicians, and general tradespeople wherever a standard steel flat washer is required.

This washer is suited for residential and light commercial fastening applications. It is commonly used in equipment mounting, panel assembly, ductwork attachment, pipe hangers, and general structural connections where a 5/16-inch fastener is specified. The steel construction and black oxide finish make it appropriate for indoor and semi-protected environments. Sold individually, with a minimum order quantity of 5 units.

Key Features

• Standard flat washer profile for 5/16-inch screw size
• Steel construction for reliable load distribution and durability
• Black oxide finish provides moderate corrosion resistance and a uniform dark appearance
• Inside diameter of 0.344 inches fits 5/16-inch fastener shafts with standard clearance
• Outside diameter of 0.828 inches and thickness of 0.188 inches meet standard washer dimensions
• Inch measurement system; UNSPSC Code 31161807

Compatibility

Designed as a standard flat washer for use with 5/16-inch screws and bolts in general mechanical, structural, and trade-service assembly applications.

Installation Notes

Install using standard hand tools; seat the washer flush against the mating surface before torquing the fastener. For electrical or mechanical enclosures, confirm the washer material and finish are appropriate for the environmental exposure rating of the installation. Always follow applicable codes and equipment manufacturer fastener specifications when selecting washers for structural or safety-critical connections.