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Copper Sealing Washers
Copper Sealing Washers
Copper sealing washers are annealed copper rings designed to deform (crush) under bolt tightening torque, creating a reliable metal-to-metal seal against fluid or gas leakage. Also known as copper crush washers, copper bonded washers, copper sealing rings, copper drain plug washers, copper hydraulic sealing washers, copper banjo washers, copper compression washers, and copper seal rings, these components are manufactured from soft-annealed Cu-DHP (C12200) and Cu-ETP (C11000) copper by Electrical Accessories India. Applied in hydraulic fittings, pneumatic connections, oil drain plugs, refrigeration line connectors, banjo bolt assemblies, fuel system connections, and high-pressure fluid systems.
Product Overview
Copper Crush Washers and Drain Plug Seals
Copper crush washers, also called copper drain plug washers, copper sump plug sealing washers, copper oil drain seals, copper banjo sealing washers, copper compression seals, and copper gearbox drain seals, are flat annealed copper rings used to seal threaded connections in oil sumps, gearboxes, hydraulic manifolds, and fuel systems. When the bolt or plug is tightened, the soft copper ring deforms to fill microscopic surface irregularities in the mating metal faces, creating a reliable metal-to-metal seal. Available in standard metric DIN 7603-A (copper) and BS 4825 sizes, as well as custom inner and outer diameters for OEM applications.
Copper Hydraulic and Pneumatic Sealing Washers
Copper hydraulic sealing washers, copper high-pressure sealing rings, copper banjo bolt washers, copper pipe union sealing washers, copper compression fittings sealing rings, and copper face-seal washers are used in hydraulic systems, pneumatic circuits, fluid power equipment, and high-pressure piping. They seal between banjo bolt heads and fluid port faces, between union fittings, and in compression fitting assemblies. Operating pressures up to 700 bar (10,000 psi) are sealed by thick copper crush washers in hydraulic fittings. Cu-DHP is preferred over Cu-ETP for hydraulic applications due to better formability and weldability.
Copper Refrigeration and HVAC Sealing Washers
Copper refrigeration sealing washers, copper flare fitting washers, copper refrigerant line sealing rings, copper AC pipe joint seals, and copper HVAC sealing gaskets are used in refrigeration and air conditioning system piping connections. They seal refrigerant (R410A, R32, R22, R134a) within screwed fittings, flare connections, and access valve assemblies. Cu-DHP copper is compatible with all common refrigerants and does not contribute to oil contamination. Manufactured to ASHRAE, EN 1037, and DIN 8978 dimensional standards for refrigeration fittings.
Copper Banjo Washers and OEM Sealing Rings
Copper banjo washers, copper banjo sealing rings, and copper dowty seals are used in banjo bolt assemblies for brake fluid lines, power steering, fuel injection rails, and hydraulic control systems. Two washers are used — one each side of the banjo fitting — creating a sealed through-bore path. These are manufactured to OEM dimensional specifications from DIN 7603-A copper. Standard metric thread OD copper banjo washers from M6 to M22 are available from stock; non-standard OD, ID, and thickness are manufactured to customer drawing.
Copper Sealing Washers for Electrical Enclosures
Copper sealing washers are also used under cable gland locknuts, conduit fitting locknuts, and cable entry fittings to seal the entry point against moisture, dust, and gas ingress. These copper sealing rings are softer than the enclosure material and conform to the surface under locknut torque to create an IP-rated seal. Used in ATEX, IP65, and IP66-rated enclosures where metallic sealing is preferred over rubber gaskets for chemical resistance or high-temperature applications.
Key Features
- Soft-annealed Cu-DHP and Cu-ETP copper — maximum conformability and sealing performance
- Standard metric sizes per DIN 7603-A: M6 to M40 bolt threads
- Custom OD/ID/thickness to OEM specification
- Pressure ratings up to 700 bar depending on configuration
- Compatible with hydraulic oil, diesel, petrol, refrigerant, compressed air, water
- Reusable with re-annealing; single-use recommended for critical applications
- RoHS, REACH compliant; full material documentation
- Bare copper standard; nickel-plated available for corrosive fluid applications
Sealing Mechanism and Performance
Copper crush washers seal by plastic deformation of the soft annealed copper under bolt tightening torque. The copper conforms to the surface topography of the mating faces (typically steel), filling scratches and machining marks with copper. Recommended seating stress: 200–400 MPa (copper yield stress 200–250 MPa for annealed Cu-ETP). At this stress level, the copper extrudes into surface features creating a leak-tight seal. For re-sealing after removal, the washer must be re-annealed (heated to 400°C and air-cooled) to restore ductility, or replaced. Single-use replacement is standard practice for critical seals.
Material and Fluid Compatibility
Cu-DHP (C12200) is compatible with mineral hydraulic oils (ISO VG 32–100), automotive diesel, petrol (gasoline), engine oil, ATF, refrigerants (R410A, R32, R22, R134a, R404A), compressed air, natural gas, and water. Copper is not recommended for ammonia, acetylene, or acids. For aggressive chemical fluid sealing, nickel-plated copper washers or alternative materials (aluminium, PTFE) should be specified. Cu-DHP is the preferred grade for all plumbing and hydraulic applications per BS 2872 and ASTM B280.
Dimensional Standards
DIN 7603-A: standard copper sealing ring with flat section. DIN 7603-B: copper sealing ring with internally ribbed section for higher pressure sealing. DIN 7603-C: composite (copper-NBR) sealing washer (not purely copper — available from our stock also). BS 4825: copper pipe fitting sealing washers. Custom OD, ID, and thickness for OEM applications manufactured to drawing. Inner diameter tolerance: +0.3/+0.5 mm on bolt OD. Outer diameter tolerance: ±0.3 mm. Thickness tolerance: ±0.05 mm.
Thickness and Section Options
Thin sealing washers (0.5–1.0 mm): used for low-pressure fittings and electrical enclosure sealing. Standard sealing washers (1.0–2.5 mm): DIN 7603-A for most hydraulic and drain plug applications. Heavy sealing washers (2.5–6.0 mm): for high-pressure hydraulic fittings and industrial piping. Ribbed/flanged sections provide higher seating pressure at the sealing OD for enhanced leak resistance. Chamfered-ID washers are used in banjo fittings where the washer must locate on the banjo bolt shank.
Re-annealing and Reuse
Cu-DHP and Cu-ETP copper sealing washers can be re-annealed and reused after removal. Re-annealing process: heat to 400–500°C until dull red, then air-cool (do not quench). This restores full soft annealed ductility. After re-annealing, the washer is inspected for cracks and deformation; if undamaged, it seals as effectively as a new washer. For critical fluid systems, single-use replacement is recommended to eliminate the risk of re-use failure.
Technical Specifications
| Parameter | Specification |
|---|---|
| Base Material | Cu-DHP C12200, Cu-ETP C11000 |
| Temper | Soft annealed (O-temper) |
| Hardness | 40–60 HV (annealed Cu-DHP) |
| Dimensional Standard | DIN 7603-A/B, BS 4825, custom |
| Thread Range | M6 to M40 (DIN 7603); custom for OEM |
| Thickness Range | 0.5 mm to 6.0 mm |
| Max Operating Pressure | Up to 700 bar (hydraulic, depending on configuration) |
| Operating Temperature | -50°C to +180°C (Cu-DHP bare) |
| Surface Finish | Bare copper annealed (standard); nickel-plated available |
Material Grades and International Equivalents
| India IS | USA ASTM/UNS | UK BS EN | Germany DIN | Europe EN | ISO | Common Name |
|---|---|---|---|---|---|---|
| IS 191 Grade 3 | C12200 / ASTM B280 | CW024A / BS EN 1057 | SW-Cu / DIN 1787 | EN CW024A | ISO 1337 | Cu-DHP, Phosphorus Deoxidized Copper |
| IS 191 Grade 1 | C11000 / ASTM B187 | CW004A / BS EN 13601 | E-Cu57 / DIN 1787 | EN CW004A | ISO 1337 | Cu-ETP, Electrolytic Tough Pitch Copper |
Product Types and Variants
DIN 7603-A flat section copper sealing rings (M6–M40); DIN 7603-B ribbed copper sealing rings; banjo bolt copper washers (M6–M22); oil drain plug copper washers; refrigeration fitting sealing washers; hydraulic fitting face-seal washers; cable gland sealing washers; custom OEM sealing rings to drawing; re-annealable sealing washer kits.
Applications in Industry
Oil sump and gearbox drain plug sealing; hydraulic system manifold fittings; banjo bolt assemblies (brakes, power steering, fuel injection); refrigeration and air conditioning system connections; pneumatic system fittings; fuel system connections; natural gas piping connections; cable gland and conduit entry sealing; industrial piping sealing; marine engine oil and fuel connections.
Manufacturing Process
- Copper strip procurement — Cu-DHP ASTM B280 / BS EN 1057 with MTC
- Incoming inspection — composition (XRF), hardness (must be annealed)
- Blanking and punching — progressive die or single-hit blanking of OD and ID
- Annealing — full soft anneal at 400–500°C, air-cool to ensure O-temper
- Deburring — gentle barrel deburring; burr <0.05 mm to avoid stress concentration
- Visual inspection — check for cracks, deformation, surface defects
- Packing — individual poly bags or bulk packs with desiccant; export carton
- Documentation — MTC, dimensional report, REACH/RoHS compliance certificates
Quality Standards and Certifications
Material: ASTM B280, BS EN 1057, IS 191. Dimensions: DIN 7603-A/B, BS 4825. ISO 9001:2015 QMS. REACH and RoHS compliance. EN 10204 Type 3.1 material test certificates standard.
Why Choose Electrical Accessories India
Electrical Accessories India manufactures copper sealing washers in all standard DIN and BS sizes at its Jamnagar facility. Our annealing process ensures the required soft temper for reliable sealing under clamping torque. We maintain stock of Cu-DHP strip in standard thicknesses for fast turnaround. Custom OEM dimensions are manufactured to drawing with short lead times. Full material, dimensional, and compliance documentation is provided with every shipment.
Frequently Asked Questions (FAQ)
What is a copper crush washer?
A copper crush washer is a flat annealed copper ring that deforms under bolt tightening to create a metal-to-metal seal against fluid leakage. The soft copper plastically deforms to conform to surface irregularities, creating a leak-tight seal at the mating faces.
What is the difference between Cu-ETP and Cu-DHP for sealing washers?
Cu-DHP is recommended for hydraulic and plumbing sealing washers because its phosphorus content prevents oxygen-related embrittlement and makes it suitable for welding and brazing. Cu-ETP is used for electrical sealing washers where high conductivity is also needed. For pure sealing applications, Cu-DHP is the standard choice.
Can copper sealing washers be reused?
Yes, after re-annealing. Heat to 400–500°C (dull red), then air-cool. This restores full soft annealed condition. For critical sealing applications, single-use replacement is recommended. Never reuse a cracked or excessively deformed washer.
What pressure can copper sealing washers withstand?
Well-designed copper crush seals in hydraulic fittings can withstand operating pressures up to 700 bar (10,000 psi). Actual pressure capability depends on seating stress, surface finish of mating parts, and washer cross-section. DIN 7603-B ribbed washers provide higher pressure capability than DIN 7603-A flat section.
What fluids are compatible with copper sealing washers?
Mineral hydraulic oil, diesel, petrol, engine oil, ATF, most refrigerants, compressed air, water, natural gas. Not recommended for ammonia, acetylene, or strong acids.
What DIN standard covers copper sealing washers?
DIN 7603-A (flat copper sealing ring) and DIN 7603-B (ribbed copper sealing ring) are the primary standards. For refrigeration fittings, DIN 8978 and ASHRAE standards apply. BS 4825 covers copper sealing washers in UK plumbing fittings.
What is the minimum order quantity?
Standard DIN 7603-A sizes: 200 pieces minimum. Custom OEM dimensions: 500 pieces. Sample quantities of 25–50 pieces available for qualification.
Are copper sealing washers available with nickel plating?
Yes. Nickel-plated copper sealing washers (3–8 μm electroplated nickel) are available for applications in mildly aggressive fluids, high-temperature service, or where the copper appearance is aesthetically objectionable. Contact us for availability.
Equivalent Terms – Multilingual Reference
| Language | Term 1 | Term 2 | Term 3 |
|---|---|---|---|
| Spanish | Arandela de sellado de cobre | Arandela de aplastamiento de cobre | Junta de cobre para hidráulica |
| Russian | Медная уплотнительная шайба | Медная обжимная шайба | Медное уплотнительное кольцо |
| French | Rondelle d’étanchéité en cuivre | Joint cuivre de vidange | Bague d’étanchéité cuivre |
| Portuguese | Arruela de vedação de cobre | Arruela de esmagamento de cobre | Junta de cobre hidráulica |
| Italian | Rondella di tenuta in rame | Rondella di schiacciamento in rame | Guarnizione di tenuta in rame |
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Indicative Pricing
Copper Items: US$ 15.80 per kilogram, CIF USA Port
Prices are indicative and subject to change based on quantity, specification, alloy grade, and market conditions. Contact us with your RFQ for a firm quotation.
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