Product
Product Details
Copper Sealing Washers
Copper Sealing Washers
Pricing: US$ 15.80 / Kilogram (FOB India | MOQ: 25 Kg | Custom dimensions on request)
Electrical Accessories India manufactures and exports copper sealing washers conforming to DIN 7603, BS 4518, ASME B16.21, and IS 2016 standards. Produced from high-conductivity electrolytic tough pitch (ETP) copper C11000, oxygen-free copper C10100, and phosphorus-deoxidized copper C12200, these copper gasket washers are engineered for high-pressure hydraulic fittings, electrical terminal sealing, pipe flanges, instrumentation connections, transformer drain plugs, compressor valve plates, and industrial fastener sealing. With inherent corrosion resistance, excellent ductility for cold-seating, and reliable electrical conductivity, copper sealing washers are the specification-grade choice for electrical OEMs, EPC contractors, power utilities, industrial OEMs, and export distributors across North America, Europe, the Middle East, and Asia-Pacific.
Product Overview – Copper Sealing Washers
Copper sealing washers—also referenced in engineering specifications as copper crush washers, copper gasket washers, copper bonded sealing washers, copper annealed washers, copper flat sealing washers, copper drain plug washers, copper banjo washers, copper pipe sealing rings, and copper joint rings—constitute a critical precision-stamped sub-category within the broader copper parts and components range. These components are stamped or machined from copper sheet or rod stock and soft-annealed to ensure maximum malleability for cold-seating against mating surfaces.
Sealing Mechanism and Functional Design
Copper sealing washers function through controlled plastic deformation (crush sealing) when torqued against a mating port, fitting, or flange face. The annealed copper conforms microscopically to surface irregularities, eliminating leak paths for hydraulic fluid, compressed air, gas, oil, and water. The sealing principle is identical to that used in banjo bolt connections, hydraulic hose adaptors, transformer inspection covers, compressor valve seats, diesel injection system return pipes, instrumentation manifold blocks, and high-pressure test rig connections. Hardness after annealing is typically 40–60 HV, enabling reliable sealing at bolt torques compatible with standard steel or brass fasteners.
Electrical Connectivity and EMI Sealing
In electrical enclosures, switchgear cabinets, and HT/LT terminal boxes, copper sealing washers provide simultaneous mechanical sealing and low-resistance electrical bonding. When used under terminal bolts, grounding studs, cable gland backplates, and panel earth studs, they ensure uninterrupted conductive contact, reducing contact resistance to below 1 mΩ. This dual function—gasket and electrical bond washer—is specified in IEC 61439, IEC 60529 (IP65/IP66 panel sealing), railway rolling stock EMI bonding (IEC 62236), and telecom shelter grounding (TIA-607). Copper’s ≥98% IACS conductivity ensures negligible voltage drop across joints in bus-bar assemblies and earthing systems.
Raw Material Grades and Traceability
All copper sealing washers are manufactured from prime copper strip or sheet conforming to ASTM B152, BS EN 13599, DIN EN 1652, or IS 191. Standard grades: C10100 (OFHC, oxygen-free high conductivity), C11000 (ETP, electrolytic tough pitch), C12200 (DHP, phosphorus-deoxidized high residual). Each batch is traceable to mill test certificates (MTCs) verifying chemical composition, tensile strength, elongation, hardness, and electrical conductivity. Material identification via heat number, lot number, and batch record ensures full supply-chain traceability per EN 10204 Type 2.2 or 3.1 upon request.
Dimensional Range and Tolerance
Standard copper sealing washers are available in metric sizes M6 through M100 (inner diameter) and imperial pipe sizes 1/4″ NPS through 4″ NPS. Thickness ranges from 0.5 mm to 3.0 mm standard; non-standard thicknesses to 6 mm are produced against customer drawings. Dimensional tolerances conform to DIN 7603 Class A (±0.1 mm on ID/OD) and ASME B16.21 (face-to-face thickness ±0.05 mm). Stamped washers are produced with burr-free sheared edges; machined washers are produced on CNC lathes or multi-spindle automatics for tighter concentricity (TIR ≤ 0.05 mm).
Surface Treatment Options
Copper sealing washers are supplied in soft-annealed bright copper finish (as-standard), pickled and passivated (acid-cleaned), tin-plated (ASTM B545, 2–5 μm), silver-plated (ASTM B700, 3–8 μm), nickel-plated (ASTM B689, 3–8 μm), and PTFE-coated variants for chemical resistance. Annealing (soft/fully annealed per ASTM B152 temper designation ‘O61’) is performed in controlled-atmosphere belt furnaces to prevent oxidation and maintain surface quality. RoHS 2-compliant and REACH-compliant surface treatments are standard.
Industry Procurement Terms and Equivalents
Copper sealing washers are procured globally under equivalent trade terms: copper crush rings, copper soft-annealed washers, copper hydraulic washers, copper drain washers, copper fibre-free gasket rings, copper O-ring backup washers, copper banjo sealing washers, copper manifold seals, copper pipe fitting washers, copper pressure test port seals, and copper instrument calibration port washers. Custom non-standard dimensions are accepted against customer CAD files (DXF, DWG, STEP) with prototypes in 5–7 working days.
Applications in Electrical and Industrial Systems
Key application areas include: transformer oil drain plug seals, HT/LT cable gland sealing rings, electrical panel IP65 bolt seals, bus-bar clamping washers, hydraulic power unit (HPU) fittings in oil & gas electrical installations, compressed air lines in power plant instrumentation, diesel generator set fuel system connections, marine switchgear cable entry seals, and locomotive/metro traction electrical cabinet bonding washers. Copper sealing washers are additionally specified in process instrumentation (Rosemount, Yokogawa, Emerson transmitters) port sealing and industrial robot cable management systems.
Key Features
- Soft-annealed to 40–60 HV for reliable crush sealing at rated bolt torque
- High conductivity: ≥98% IACS (C11000) to ≥100% IACS (C10100)
- Manufactured to DIN 7603 / BS 4518 / ASME B16.21 / IS 2016
- Size range: M6 to M100 (metric); 1/4″ to 4″ NPS (imperial)
- Thickness: 0.5 mm to 6.0 mm (standard 1.0 mm, 1.5 mm, 2.0 mm stocked)
- RoHS 2 and REACH compliant; EN 10204 3.1 MTCs available
- 100% dimensional inspection; AQL 1.0 sampling per ISO 2859
- Operating temperature: –200°C to +250°C (continuous)
Crush Sealing and Pressure Performance
The primary performance criterion for copper sealing washers is the ability to achieve and maintain a leak-tight joint under defined bolt torque and system pressure. Annealed C11000 copper sealing washers achieve reliable sealing at hydraulic pressures up to 700 bar (10,000 PSI) when correctly installed against hardened steel or stainless steel mating surfaces. Sealing performance is validated per SAE J1231 (hydraulic fittings), ISO 8434-1 (metallic tube end fittings), and EN 14592 (wood screw sealing—dimensional reference). Re-seating capability is available in thicker (≥2 mm) washers that can be re-annealed and reused. Pressure ratings are provided in our product data sheets for each standard size.
Electrical Bonding Performance
When specified as electrical bond washers under grounding studs, earthing terminal bolts, and enclosure earth points, copper sealing washers conforming to IEC 61439-1 Annex F (mechanical and electrical connection requirements) deliver contact resistance below 1 mΩ at 10 A DC measurement current. This performance is critical for fault current dissipation in switchgear assemblies, compliance with IEEE Std 80 (grounding of AC substations), and EMC bonding per MIL-STD-461. Conductivity is verified by eddy-current test per ASTM E1004 on random samples from each production batch, with results recorded on the quality docket.
Temperature and Chemical Resistance
Copper sealing washers resist sustained service temperatures from cryogenic (–200°C, suitable for LNG plant electrical instrumentation fittings) to +250°C (suitable for steam trap instrumentation and heat exchanger fittings). They resist oxidizing acids at low concentrations, seawater (marine electrical installations), alkali environments, and petroleum-based hydraulic fluids (ISO VG 32–68). They are not recommended for ammonia-based systems (stress corrosion cracking susceptibility) or concentrated nitric acid environments, where PTFE-encapsulated copper or monel options should be considered. Chemical resistance data is provided in our technical datasheet.
Dimensional Accuracy and Quality Control
Stamped copper sealing washers are produced on progressive compound dies achieving dimensional repeatability within ±0.1 mm (DIN 7603 Class A). Concentricity between bore and OD is within TIR 0.15 mm for stamped washers and TIR 0.05 mm for CNC-machined washers. Thickness uniformity is ±0.05 mm across each washer face. 100% visual inspection is performed for burrs, cracks, and surface defects. Dimensional sampling per AQL 1.0 (ISO 2859-1) uses calibrated go/no-go gauges and digital micrometers traceable to NABL-accredited standards.
Custom Engineering and Special Configurations
Custom copper sealing washer geometries include: square-bore banjo washers, tabbed anti-rotation washers, multi-hole pattern sealing flanges, profiled-face (serrated or grooved) sealing washers, and oversized OD washers for soft-seat valve applications. Non-standard alloys such as C14500 (tellurium copper, free-machining), C17200 (beryllium copper, high-strength), and C19400 (iron-bearing copper) are available for specialized applications. Low-volume prototypes (100 pieces minimum) are accepted for qualification testing by OEM customers. Full reverse-engineering from sample parts or sketches is offered within 3–5 working days.
Packaging and Export Compliance
Copper sealing washers are packed in moisture-barrier VCI polybags, labelled with part number, lot number, material grade, and quantity, then placed in corrugated cartons. Export packing complies with ISPM-15 phytosanitary requirements. Gross weight, net weight, dimension markings, and COO (Country of Origin: India) are printed on each outer carton. Shipments are accompanied by commercial invoice, packing list, certificate of origin (Chamber of Commerce), EN 10204 MTC, and RoHS/REACH compliance declaration. Air and sea freight options via FedEx, DHL, and consolidated sea freight are available.
Technical Specifications
| Parameter | Specification |
|---|---|
| Product | Copper Sealing Washer / Copper Crush Washer |
| Standards | DIN 7603, BS 4518, ASME B16.21, IS 2016, SAE J1231 |
| Material Grades | C10100, C11000, C12200 (see table below) |
| Inner Diameter Range (Metric) | M6 to M100 (6 mm to 100 mm bore) |
| Inner Diameter Range (Imperial) | 1/4″ NPS to 4″ NPS |
| Thickness Range | 0.5 mm to 6.0 mm (standard: 1.0, 1.5, 2.0 mm) |
| OD Tolerance | ±0.1 mm (DIN 7603 Class A); ±0.05 mm (machined) |
| Hardness (annealed) | 40–60 HV (Vickers) |
| Conductivity | 98–101% IACS |
| Tensile Strength (annealed) | 200–250 MPa |
| Elongation (annealed) | ≥ 45% |
| Operating Temperature | –200°C to +250°C |
| Max Sealing Pressure | Up to 700 bar (hydraulic, with correct installation) |
| Surface Finish | Bright annealed / Tin-plated / Silver-plated / Nickel-plated |
| Packing | VCI polybag + carton; bulk bag on request |
| Lead Time | 2–3 weeks standard; express in 1 week (subject to stock) |
| Pricing | US$ 15.80 / Kilogram (FOB India) |
Copper Raw Material Grades and International Equivalents
| UNS (USA) | EN (Europe) | BS (UK) | DIN (Germany) | IS (India) | JIS (Japan) | Description |
|---|---|---|---|---|---|---|
| C10100 | CW008A | C101 | E-Cu99.99 | — | C1011 | Oxygen-Free High Conductivity (OFHC) |
| C11000 | CW004A | C101 | E-Cu58 ETP | ETP Copper | C1100 | Electrolytic Tough Pitch (ETP) |
| C12200 | CW024A | C106 | SF-Cu | DHP Copper | C1220 | Phosphorus Deoxidized (DHP) |
| C14500 | CW118C | C109 | CuTeP | — | C1450 | Tellurium Copper (Free-Machining) |
Product Types and Variants
| Type | Standard | Size Range | Typical Use |
|---|---|---|---|
| Flat Sealing Washer (Stamped) | DIN 7603 Form A | M6–M64 | Hydraulic fittings, pipe unions, drain plugs |
| Flat Sealing Washer (Machined) | DIN 7603 Form A / BS 4518 | M6–M100 | High-precision instrumentation, valve bodies |
| Banjo Sealing Washer | DIN 7603 / SAE J1231 | M6–M22 | Banjo bolt connections, brake lines, fuel rails |
| Bonded Sealing Washer | BS 4518 / ISO 11926 | M6–M36 | Hydraulic adaptor ports, manifold blocks |
| Oversized OD Sealing Washer | Customer drawing | Custom | Large-bore valve seats, heat exchanger covers |
| Profiled/Serrated Washer | Customer drawing | M8–M48 | High-vibration electrical connections, bus-bar joints |
| Square/Rectangular Sealing Washer | Customer drawing | Custom | Rectangular port sealing, custom enclosures |
Applications by Industry
| Industry | Application |
|---|---|
| Power Transmission and Distribution | Transformer drain plug seals, bushing gasket rings, cable box entry seals |
| Oil and Gas / Petrochemical | Hydraulic power unit (HPU) fitting seals, instrument manifold port seals, wellhead electrical bonding washers |
| Renewable Energy (Solar/Wind) | Inverter terminal sealing washers, cable management gland seals, earthing clamp washers |
| Railways and Metro | OHE fitting seals, locomotive hydraulic system washers, EMI bonding washers in rolling stock |
| Marine and Offshore | Hull fitting seals, sea valve bonding washers, shore-power cable entry seals |
| Industrial Machinery | Hydraulic cylinder port seals, pneumatic circuit sealing, motor terminal box sealing |
| Process Instrumentation | Transmitter impulse pipe seals, calibration port washers, gauge root valve washers |
| Aerospace and Defence | Hydraulic actuator port seals, EMI bonding washers, weapon system hydraulic line seals |
Manufacturing Process
Copper sealing washers are produced through a controlled multi-step manufacturing process. (1) Raw Material Incoming Inspection: copper strip/sheet is tested by ICP spectroscopy for chemical composition, eddy-current test for conductivity, and tensile test per ASTM E8 before release to production. (2) Blanking and Piercing: progressive compound dies on 40–200-tonne mechanical presses stamp the OD and bore simultaneously, achieving burr-free shear edges with rollover radius ≤ 0.05 mm. Die clearance is set to 4–6% of material thickness for copper. (3) Annealing: washers are soft-annealed in a controlled-atmosphere (nitrogen/hydrogen) belt furnace at 350–500°C for 15–30 minutes, followed by accelerated air cooling. Post-anneal hardness is verified per ASTM E92 (Vickers) to confirm 40–60 HV. (4) Pickling and Surface Cleaning: acid pickling (10% sulfuric acid, ambient temperature) removes oxide scale; water rinse and drying follow. (5) Plating (where specified): barrel or rack electroplating for tin, nickel, or silver per customer specifications; plating thickness measured by XRF per ASTM B568. (6) Inspection: 100% visual inspection, dimensional sampling per AQL 1.0 (ISO 2859-1), and conductivity spot-check. (7) Packing and Dispatch: VCI polybag, count-labeled inner bags, carton, and full export documentation.
Quality Standards and Certifications
| Standard / Certification | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| DIN 7603 | Sealing washers for pipe fittings – dimensions and materials |
| BS 4518 | Metric dimensions of gaskets for pipe flanges |
| ASTM B152 | Copper sheet, strip, plate, and rolled bar – chemical composition |
| BS EN 13599 | Copper and copper alloy strip for electrical purposes |
| EN 10204 Type 2.2 / 3.1 | Material test certificate (test report / inspection certificate) |
| RoHS 2 (2011/65/EU) | Restriction of hazardous substances in surface treatments |
| REACH (EC No. 1907/2006) | Chemical compliance for plating and surface treatment agents |
| ASTM B117 | Salt spray/corrosion testing for plated variants (500 h) |
| ISO 2859-1 (AQL 1.0) | Sampling procedures for attribute inspection |
Why Choose Electrical Accessories India for Copper Sealing Washers?
Electrical Accessories India brings over two decades of precision copper parts manufacturing experience to the copper sealing washer segment. Our production facility operates dedicated copper blanking and piercing presses, controlled-atmosphere annealing furnaces, in-house electroplating lines, and NABL-traceable dimensional inspection equipment. We supply: EN 10204 3.1 material test certificates with every order; AQL 1.0 incoming and outgoing inspection; custom engineering against OEM drawings within 5–7 working days for prototypes and 2–3 weeks for production quantities; competitive pricing at US$ 15.80/kg FOB India; ISPM-15 compliant export packaging; and dedicated export documentation for clients in USA, UK, Germany, UAE, Australia, Canada, Singapore, South Africa, France, Italy, and Spain. Third-party inspection by SGS, Bureau Veritas, or TÜV can be arranged at additional cost.
Frequently Asked Questions (FAQ)
Q1. What is the minimum order quantity for copper sealing washers?
Standard MOQ is 25 kg for catalogue sizes in C11000 ETP copper. For custom non-standard sizes or special alloys (C10100 OFHC, C14500 tellurium copper), MOQ is 50 kg. Sample orders of 0.5–2 kg are accepted for OEM qualification at nominal sample charges.
Q2. What is the difference between stamped and machined copper sealing washers?
Stamped (blanked) washers are produced on progressive dies and are economical for high-volume standard sizes; dimensional tolerance is DIN 7603 Class A (±0.1 mm). Machined washers are produced on CNC lathes for tighter tolerances (±0.02 mm), better concentricity (TIR ≤ 0.05 mm), and non-standard profiles such as profiled faces, serrations, or stepped bores. Machined washers are preferred for precision instrumentation, valve bodies, and GIS interfaces.
Q3. Which copper grade is recommended for high-pressure hydraulic sealing?
C11000 ETP copper (soft-annealed) is the most widely specified grade for hydraulic sealing washers due to its combination of ductility (≥45% elongation), moderate strength (200–250 MPa), and 98% IACS conductivity. For cryogenic applications (LNG plant), C12200 DHP copper is preferred due to its resistance to hydrogen embrittlement. For free-machining custom profiles, C14500 tellurium copper is used.
Q4. Can copper sealing washers be re-used?
Single-use is recommended for safety-critical hydraulic sealing applications, as the washer deforms plastically during first installation. However, thicker (≥2 mm) copper sealing washers can be re-annealed (350–450°C, 15–20 min in air, followed by quench) to restore ductility and reused in lower-pressure applications. For electrical bonding applications (non-sealing use), re-use is acceptable provided the washer surface is free from deep scratches or gouges.
Q5. What surface finish is recommended for marine or offshore installations?
Tin-plated (ASTM B545, 5 μm minimum) copper sealing washers are recommended for marine, coastal, and offshore environments. Nickel-plated variants are used where higher hardness or elevated temperature resistance is needed. For electrical bonding in offshore switchgear, silver-plated washers (ASTM B700, 5–8 μm) are preferred to maintain oxidation-free low-resistance contact.
Q6. Do you supply EN 10204 3.1 material test certificates?
Yes. EN 10204 Type 3.1 inspection certificates from the copper strip/sheet manufacturer are standard on all production orders above 25 kg. Type 3.2 (third-party witnessed inspection) is available on request from SGS, Bureau Veritas, or TÜV at additional cost. NABL-accredited chemical analysis reports are available for orders above 100 kg.
Q7. What is the lead time for custom-size copper sealing washers?
Standard catalogue sizes (M6–M36, 1.0–2.0 mm thickness, C11000 ETP): 2–3 weeks. Custom non-standard sizes require die manufacturing (first-off): 3–5 weeks for die fabrication plus 1–2 weeks production. Prototype machined washers (custom profiles) can be supplied in 5–7 working days.
Q8. Are copper sealing washers suitable for potable water systems?
Yes, copper is approved for potable water systems per WRAS (UK), NSF/ANSI 61 (USA), and AS/NZS 4020 (Australia) when used without prohibited surface treatments. Plain (unplated) C11000 ETP and C12200 DHP copper sealing washers are approved for drinking water fittings, water meter connections, and plumbing fixture sealing applications.
Q9. Can you produce copper sealing washers to ASME B16.21 for pipeline flanges?
Yes. We produce copper ring gaskets and sealing washers to ASME B16.21 in Class 150, 300, 600, 900, 1500, and 2500 pressure classes, in sizes NPS 1/2 through NPS 24. Full-face and raised-face profiles are available. These are used for transformer oil flange connections, heat exchanger covers, and electrical equipment inspection covers.
Q10. What documentation is supplied with export shipments?
Standard export documentation package includes: commercial invoice, packing list, certificate of origin (Chamber of Commerce attested), EN 10204 material test certificate, RoHS/REACH compliance declaration, product data sheet, and dimensional inspection report. Fumigation certificate (ISPM-15) for wooden packing is included. Letter of credit (LC) and DA/DP payment terms are accepted for established buyers.
Multilingual Equivalent Terms
| Language | Equivalent Terms |
|---|---|
| Spanish | Arandelas de sellado de cobre, Arandelas de cobre de aplastamiento, Juntas de cobre para tuberías |
| Russian | Медные уплотнительные шайбы, Медные прокладки-шайбы, Медные крановые шайбы |
| French | Rondelles d’étanchéité en cuivre, Joints rondelle en cuivre, Rondelles de compression en cuivre |
| Portuguese | Arruelas de vedação de cobre, Arruelas de cobre para tubulações, Juntas de vedação de cobre |
| Italian | Rondelle di tenuta in rame, Guarnizioni a rondella in rame, Rondelle di compressione in rame |
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Request a Quote – Copper Sealing Washers
Electrical Accessories India | Manufacturer & Exporter of Copper Sealing Washers and Precision Copper Parts
Email: info@elecaccs.com | Website: elecaccs.com
Price: US$ 15.80 / Kilogram (FOB India)
Lead Time: 2–3 weeks | MOQ: 25 Kg | Custom configurations accepted
Submit your drawing, purchase specification, or dimensional requirements to receive a detailed technical quotation within 24 business hours. We serve clients across India, USA, UK, Germany, UAE, Australia, Canada, Singapore, South Africa, France, Italy, and Spain.