Rivetking ABUP-4/P500 Blind Rivet Backup Washer Size 4

Product Description

The RIVETKING ABUP-4/P500 is a Size 4 aluminum round backup washer designed for use with blind rivets. Backup washers distribute the clamping load of a rivet across a wider surface area, reducing the risk of pull-through on thin or soft base materials. This washer features a 0.125-inch inside diameter sized to accept a standard 1/8-inch rivet shank, a 0.375-inch outside diameter, and a 0.0625-inch thickness. Constructed from aluminum, it offers corrosion resistance and light weight suited to sheet metal, HVAC panel, and general fabrication applications. Each package contains 500 pieces.

This backup washer is used wherever a blind rivet is installed into a material that requires additional bearing surface on the blind side. Common applications include light-gauge sheet metal assembly, ductwork fabrication, enclosure and panel construction, and other fastening tasks where material tear-out is a concern. The aluminum construction makes it appropriate for applications where galvanic compatibility with aluminum rivets is required. Installers working in HVAC, electrical enclosure assembly, and general sheet metal trades will find this washer suitable for production and field repair work alike.

Key Features

• Size 4 designation compatible with standard 1/8-inch diameter blind rivets
• 0.375-inch outside diameter provides a wider load-bearing footprint on the blind side
• 0.0625-inch thickness keeps the washer low-profile within the joint stack
• Aluminum construction resists corrosion and avoids galvanic issues when used with aluminum rivets
• Round washer geometry centers consistently around the rivet shank during installation
• 500-piece package quantity suits production runs and high-volume field work

Compatibility

Designed for use with Size 4 blind rivets having a 1/8-inch shank diameter. Suitable as a blind-side backup washer in sheet metal, panel, and ductwork fastening applications where standard material thickness alone does not provide adequate pull-through resistance.

Installation Notes

Slip the backup washer onto the rivet shank before inserting the rivet through the workpiece, positioning the washer against the blind side of the material. Set the rivet with a standard hand or pneumatic rivet tool appropriate for the rivet size. Ensure the base material and washer remain flush and properly aligned before setting to achieve full clamping load distribution. No special tools beyond a standard rivet setting tool are required for installation.