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Item detailsMaterials, dimensions, what is in the box
Copper sealing washers made from 100% pure annealed copper provide a soft, malleable seal for marine, automotive, plumbing, and instrumentation applications. These copper washers come in packs of 10 pieces in your selected size, with metric options from M3 through M20. Choose the inner diameter, outer diameter, and thickness that match your connection.
Annealing softens the metal so it can deform under compression to help seal the joint. These flat washers offer heat and corrosion resistance for demanding environments. Use copper washers for brake lines, automotive fuel systems, marine engine fittings, gauge connections, plumbing, HVAC, and refrigeration equipment. They are also suitable as copper washers for hydraulic fittings and for connections carrying oil, fuel, water, or gas.
Before ordering, confirm all three dimensions rather than relying on the nominal size alone. Thickness options are 1, 1.5, and 2 mm, depending on the selected variant. The washers arrive ready to use, with no additional processing required. They can be reused if they have not been over-compressed.
Specifications
Material
100% pure annealed copper
Style
Flat sealing washer
Metric Size Options
M3, M4, M5, M6, M8, M10, M12, M14, M16, M18, M20
Thickness Options
Approximately 0.039, 0.059, or 0.079 inches (0.10, 0.15, or 0.20 cm), depending on size
In the Box
10 washers in your selected size, in clearly labeled sealed packaging
Reuse
Can be reused if not over-compressed
What problem does it solve?
A poorly sealed plumbing connection can mean unwanted drips and extra cleanup. For kitchen plumbing connections that require a flat copper sealing washer, these annealed copper washers offer a soft, compressible seal at the joint.
Choosing the right fit helps take the guesswork out of replacing a washer. These metric copper washers are available in specific sizes, with 10 matching pieces per pack, so you can keep spares together for another repair. Check the connection’s required dimensions before selecting your pack.
The problem in numbers
The average household's leaks can waste more than 10,000 gallons of water each year. (U.S. Environmental Protection Agency, WaterSense, Fix a Leak Week fact sheet, 2023)
Ten percent of homes have leaks that waste at least 90 gallons of water per day. (U.S. Environmental Protection Agency, WaterSense, Fix a Leak Week fact sheet, 2023)
Household leaks can waste nearly 1 trillion gallons of water annually nationwide. (U.S. Environmental Protection Agency, WaterSense, Fix a Leak Week fact sheet, 2023)
Household leaks make properly sealed plumbing connections worth attention. These annealed copper washers can help seal compatible joints that require a flat copper washer, but they are not a fix for every household leak.
Why choose this one?
Choose these metric copper sealing washers for their pure copper construction, annealed softness, and range of dimensional options. Their flat design combines a malleable sealing surface with resistance to heat and corrosion, making them useful across marine fittings, automotive systems, and plumbing connections.
You can select from M3–M20 sizes and three thicknesses, depending on the variant, rather than settle for a single standard thickness. Each pack contains 10 pieces of your chosen size in labeled, sealed packaging, making it easy to identify the dimensions when you need a replacement.
What exactly do you get?
Your package contains 10 pure annealed copper flat washers, all in the size you select, packed in a clearly labeled sealed package. Size choices include M3, M4, M5, M6, M8, M10, M12, M14, M16, M18, and M20, with specific inner diameter, outer diameter, and thickness combinations.
Thickness choices are 1, 1.5, or 2 mm, depending on the size. For example, a 10mm copper washer is available with a 16, 18, or 20 mm outer diameter. Each washer serves as a flat sealing ring for a matching connection; choose the dimensions required for your application.
Frequently asked questions
Straight answers about the materials, care and everyday use — no fine print.
What are these washers made from?
These copper washers are made from 100% pure annealed copper. The copper sealing washers are soft and malleable, allowing the metal to deform under compression at a sealing joint.
What comes in each pack?
You receive 10 copper washers in your selected size, supplied in clearly labeled sealed packaging. Each pack contains matching copper sealing washers with the dimensions you choose.
Which metric sizes can I choose?
These copper washers are available in M3, M4, M5, M6, M8, M10, M12, M14, M16, M18, and M20 options. Choose your copper sealing washers by the full inner diameter, outer diameter, and thickness combination.
What thickness options are available?
The copper washers come in 1, 1.5, and 2 mm thickness options, depending on the size. When selecting copper sealing washers, check the complete variant dimensions to find the thickness you need.
Are these suitable for automotive brake systems?
These copper washers are intended for automotive brake and fuel systems, among other applications. When choosing copper washers for brake lines, match the washer dimensions to your connection's requirements.
Can I use them for plumbing or hydraulic connections?
Yes, these copper washers are designed for plumbing and hydraulic systems. Choose copper washers for hydraulic fittings by checking the required inner diameter, outer diameter, and thickness.
Are they suitable for marine equipment?
Yes, these copper washers are intended for marine engines and fittings. The copper sealing washers combine annealed softness with corrosion resistance for use in demanding conditions.
Can they be used in hot environments?
These copper washers are designed for high-heat environments. The copper sealing washers are also intended for HVAC and refrigeration equipment, alongside other sealing applications.
Do they need additional processing before use?
No additional processing is required for these copper washers. The copper sealing washers are already annealed and ready to use in a connection that requires their selected dimensions.
Can these washers be reused?
These copper washers can be reused if they have not been over-compressed. That condition matters because the soft copper sealing washers deform under compression to create their seal.
Which fluids or gases are they intended for?
These copper washers are recommended for oil, fuel, water, and gas systems. Applications for the copper sealing washers include plumbing, automotive systems, instrumentation, and gauge connections.
What dimensional options are available for a 10 mm inner diameter?
The copper washers with a 10 mm inner diameter come with 16, 18, or 20 mm outer diameters. These copper sealing washers offer 1, 1.5, or 2 mm thicknesses across those combinations, so select all three dimensions carefully.
