MTS Assorted Copper Flat Washers 110-Piece

The MTS 110-piece Copper Washer Assortment is an essential kit for mechanics, plumbers, and DIY enthusiasts. Copper washers are "crush" washers; they are softer than steel, allowing them to deform slightly when tightened to create a 100% leak-proof, metal-to-metal seal. This kit provides a range of popular sizes in a partitioned, re-sealable plastic case for easy organization.

Contents & Sizes

While specific contents can vary slightly by batch, this 110-piece imperial/metric hybrid set typically includes the following 6 popular sizes:

• 1/4" (approx. 6mm): 30 Pieces
• 5/16" (approx. 8mm): 25 Pieces
• 3/8" (approx. 10mm): 20 Pieces
• 7/16" (approx. 11mm): 15 Pieces
• 1/2" (approx. 12.5mm): 10 Pieces
• 5/8" (approx. 16mm): 10 Pieces

Key Features

• Superior Sealing: The malleability of copper allows it to fill micro-imperfections in the mating surfaces, making it the industry standard for high-pressure fluid lines.
• Corrosion Resistance: Copper naturally resists rust and degradation, making these washers ideal for applications exposed to water, oil, fuel, and hydraulic fluids.
• Thermal & Electrical Conductivity: Unlike rubber or fiber washers, copper handles extreme heat (engines/exhausts) and can be used in electrical grounding applications.
• High Pressure Tolerance: Capable of maintaining a seal under the intense vibration and pressure found in automotive braking and hydraulic systems.

Common Applications

• Automotive: Sump plugs (oil drain bolts), brake line banjo bolts, fuel injectors, and cooling system fittings.
• Plumbing: Sealing taps, valves, and compression fittings where a durable, non-perishable seal is required.
• Hydraulics: Used on tractor and heavy machinery hose connections to prevent high-pressure leaks.
• Electrical: Serving as conductive spacers or terminals in battery and alternator connections.

Usage Tip: "The One-Use Rule"

Copper washers are technically single-use components in critical applications. Once they have been "crushed" to form a seal, they work-harden and lose their malleability. If you remove a bolt that has a copper washer, it is best practice to replace it with a fresh one from this kit to ensure a leak-free reassembly.