--- title: "What Are Copper Sealing Washers (DIN 7603 A) Used For?" description: "Copper Sealing Washers (DIN 7603 A) (DIN 7603) are used for sealing a threaded fitting against fluid pressure by crushing a soft metal ring between two machi…" url: https://engineeringhardware.com/applications/copper-sealing-washers-din-7603/ source: Engineering Hardware & Fasteners --- # What Are Copper Sealing Washers (DIN 7603 A) Used For? Washers · DIN 7603 · Application guide Typical applications, the industries that specify copper sealing washers (din 7603 a), and how to choose the right size, material and finish for the joint. Copper Sealing Washers (DIN 7603 A) are used for sealing a threaded fitting against fluid pressure by crushing a soft metal ring between two machined faces. They are manufactured to DIN 7603, and selection is driven by the nominal diameter, the fit and tolerance the assembly requires, and the service environment. - **Primary duty:** Sealing a threaded fitting against fluid pressure by crushing a soft metal ring between two machined faces - **Governing standard:** DIN 7603 - **Nominal diameter range:** 6 mm to 20 mm - **Category:** Washers Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation. ![What Are Copper Sealing Washers (DIN 7603 A) Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/08/Sealing-Washers.webp) The primary duty of Copper Sealing Washers (DIN 7603 A) is sealing a threaded fitting against fluid pressure by crushing a soft metal ring between two machined faces. Below: the sectors that specify them in volume, the checklist used to select the right size and material for the application, installation notes, and the known limits of the type. Stocked across roughly 6 mm to 20 mm, they cover general to heavy-duty work. ## Typical Applications for Copper Sealing Washers (DIN 7603 A) The most common settings where these are specified: - **Maintenance & repair (MRO):** a stocked size for servicing existing plant where the original fastener spec must be matched. - **Fabrication & metalwork:** bench and on-site assembly of steel frames, enclosures and weldments. - **Bolted structural joints:** spreading load over soft or oversized holes and protecting the surface. - **Vibration applications:** spring and serrated types that maintain tension under cyclic load. - **Timber & soft materials:** large-OD types that prevent pull-through. 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This product spans 6 mm–20 mm; check the full table below for the exact dimensions of each size. - **Type & OD:** Select flat for load spreading, spring/serrated for anti-loosening, or fender/large-OD for soft or oversized holes. - **Environment:** For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient. - **Standard:** This product is supplied to DIN 7603. Quoting the standard on your order guarantees interchangeable dimensions between suppliers. ## Installation & Assembly Practice - Place the washer under the rotating element (usually the nut) so tightening does not score the surface. - Chamfered-hole side of a hardened washer faces the bolt head fillet. - On serrated-flange hardware, do not add a plain washer — it defeats the serrations. ## Common Selection Mistakes with Copper Sealing Washers (DIN 7603 A) - Relying on a spring washer for locking on class 8.8+ joints — at high preload it flattens and adds nothing. - Choosing an OD too small for soft material, so the head pulls through or embeds. ## Where Copper Sealing Washers (DIN 7603 A) Are Not the Right Choice A washer does not replace a locking feature on its own in severe vibration, and a spring washer adds little clamp on high-strength joints. Custom manufacturing · Made to drawing ## Need a copper sealing washers (din 7603 a) outside the standard range? Bore, outside diameter, thickness, temper and finish are the variables here — there is no thread to specify, so the fit and the bearing area are what the drawing has to pin down. Made by stamping or punching. Minimum order from 2,000 pieces; samples within 7 days of drawing approval. [Custom washer manufacturing](https://engineeringhardware.com/custom/washers/)[Send a drawing](https://engineeringhardware.com/custom/washers/#rfq) ## Technical Drawing Dimensioned line drawing of 6.0 Copper Sealing Washers (DIN 7603 A) to DIN 7603. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Outer diameter d2 (mm):** 10.0 - **Thickness t (mm):** 1.0 - **Material:** Cu-DHP - **Condition:** Soft annealed - **Max temperature (u00b0C):** 250 - **Re-use:** Single use ## Dimensions & Specifications (DIN 7603) | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness t (mm) | Material | Condition | Max temperature (u00b0C) | Reference standard | Re-use | | --- | --- | --- | --- | --- | --- | --- | --- | | 6.0 | 10.0 | 1.0 | Cu-DHP | Soft annealed | 250 | DIN 7603 | Single use | | 8.0 | 12.0 | 1.0 | Cu-DHP | Soft annealed | 250 | DIN 7603 | Single use | | 10.0 | 14.0 | 1.5 | Cu-DHP | Soft annealed | 250 | DIN 7603 | Single use | | 12.0 | 16.0 | 1.5 | Cu-DHP | Soft annealed | 250 | DIN 7603 | Single use | | 14.0 | 20.0 | 1.5 | Cu-DHP | Soft annealed | 250 | DIN 7603 | Single use | | 16.0 | 22.0 | 2.0 | Cu-DHP | Soft annealed | 250 | DIN 7603 | Single use | | 20.0 | 26.0 | 2.0 | Cu-DHP | Soft annealed | 250 | DIN 7603 | Single use | Inside the plant ## Manufactured in our own plant This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided. 1. ![Wire rod feeding into a cold heading machine](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 01 **Cold heading** Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail. Head dimensions and under-head radius checked at set-up and per shift. 2. ![Thread rolling machine producing bolt threads](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 02 **Thread rolling** Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch. Go / no-go ring gauges to ISO 965 tolerance class 6g. 3. ![Baskets of bolts staged for heat treatment](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 03 **Heat treatment** Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it. Core hardness and tensile tested per lot to ISO 898-1. 4. ![Zinc plated bolts in a treatment basket](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 04 **Surface treatment** Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list. Coating thickness and neutral salt spray hours to ISO 9227. ## Frequently Asked Questions ### Which industries use Copper Sealing Washers (DIN 7603 A)? They are commonly specified in bolted structural joints, vibration applications and timber & soft materials, among other sectors. ### How do I choose the right size of Copper Sealing Washers (DIN 7603 A)? Match the nominal size to the mating thread or hole. This product is available from 6 mm to 20 mm; the full dimension table on this page lists each size. ### Do Copper Sealing Washers (DIN 7603 A) actually stop bolts loosening? Spring and serrated washers help maintain tension under light vibration, but for critical joints a prevailing-torque locking nut or adhesive is more reliable. Flat washers mainly spread load and protect the surface. ### What material should Copper Sealing Washers (DIN 7603 A) be for outdoor use? For damp, coastal or chemical environments specify A4 (316) stainless or a suitably coated steel. For indoor or dry use, A2 (304) stainless or zinc-plated steel is normally adequate. ### Can I get a quote for Copper Sealing Washers (DIN 7603 A) in the size and material I need? Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time. ## Related Pages Product page: [Copper Sealing Washers (DIN 7603 A) — specifications & sizes](https://engineeringhardware.com/fastener/copper-sealing-washers-din-7603/) ### Copper Sealing Washers (DIN 7603 A) Specification Guides ### Related Fastener Applications