A sealing washer at industrial catalog level starts from €0.12 excl. tax for the PLASTEM CVRAK round plastic ring (PA, natural colour) with 5–6.4 mm internal diameter, 12–17 mm OD and 2.7–13.4 mm thickness [S1]. At the opposite end of the consumer-grade retail tier, a Honda 90481-001-020 sealing washer (10.2 mm) lists at US $5.00 new on the eBay aftermarket channel [S6].
Sealing washers split into two functional families that price very differently: (a) thread-port sealing elements — copper, aluminium or bonded-elastomer crush rings sold against DIN 7603 A dimensions [S2] — and (b) cover/cap rings — plastic PA or PE protector rings fitted under screw caps [S1]. The 99.8%-feedback Goodridge metric copper crush washer (M10–M18, ID 10–18.2 mm, thickness 1.0–2.0 mm) was listed at GBP 1.98 per piece on eBay with 239 units sold and 69 in stock at capture [S4], while the 1/4″ BSPP bonded-Buna sealing washer for hydraulic gauge ports sat at US $2.19 with a 98.9% positive rating [S3].
Material & construction grades and what each costs
PLASTEM's CVRAK is moulded in PA (polyamide / nylon) in natural colour and is described as a ring that "has to be assembled to the Screw caps Ref. CVAKR" to cover a wide range of screw-head diameters [S1]. Its price band starts at €0.12 excl. tax per piece and the related PLASTEM finishing-plug family ranges from €0.02 (round plug RO series, LDPE) to €0.49 (finned plug CACP series, thermoplastic) [S1] — a useful proxy for how cheap commodity plastic mouldings remain at catalog scale.
For threaded-port sealing, the VIPA spa part 8056689160940 is a flat, round copper/aluminium sealing washer built to DIN 7603 A, with internal diameter 4–42 mm, external diameter 7.5–50 mm and thickness 1–6 mm [S2]. DIN 7603 A is the standard designation for solid copper sealing rings used on screw plugs and threaded unions in hydraulic and pneumatic circuits; copper-aluminium combinations trade off deformability (aluminium crushes softer, copper recovers better on reuse). At retail, the Goodridge metric M10–M18 copper crush washer listing showed six size options from 10 mm ID × 2.0 mm thick up to 18.2 mm ID × 2.0 mm thick, with 12.2 mm ID × 1.5 mm and 14.3 mm ID × 1.2 mm being the most popular seller options [S4].
Standards, dimensions and cross-spec compatibility
DIN 7603 A governs the copper/aluminium crush-washer family that VIPA spa lists [S2]; the standard defines type A as a solid sealing ring without a chamfer, used against machined flat faces on banjo bolts, drain plugs and gauge ports. Inside that envelope, the metric ID range observed in the S2 catalog entry (4–42 mm) lines up with the metric Goodridge retail offering (M10–M18, ID 10–18.2 mm) [S4], and the imperial retail tier (1/4″ BSPP with Buna seal, 98.9% positive) [S3] covers the same hydraulic gauge-port application in a different unit system.
Bonded-seal washers — a metal carrier with an elastomer face vulcanised to it — are typically built around a 1/4″, 3/8″ or 1/2″ BSPP / NPT / JIC port and are specified for higher-pressure hydraulic work where a plain copper crush ring would creep [S3]. The Fragola 999126 nylon sealing washer for 6 AN fittings (set of 10) is a different design point again: nylon is used where the fluid is compatible (race fuel, oil, coolant) and the pressure class is moderate, with the elastomer-free construction removing a temperature ceiling imposed by a bonded O-ring [S5]. PLASTEM's CVRAK sits outside the sealing-pressure family entirely: it is a PA cover ring, not a pressure-containing seal, with thickness up to 13.4 mm designed to sit under a screw cap and mask the head of a fastener [S1].
Decision matrix: which washer to specify
Use this four-axis comparison as a starting point before quoting: (1) function — pressure-containing thread seal vs cosmetic/cover ring; (2) material — copper, aluminium, bonded elastomer, PA, nylon; (3) standard — DIN 7603 A solid ring vs proprietary bonded seal vs non-standard cover; (4) sourcing channel — industrial OEM catalog (VIPA, PLASTEM) vs retail/e-commerce (Goodridge, Fragola, Honda OEM). Plastic cover rings like the PLASTEM CVRAK in PA are the right pick where the requirement is aesthetic or dust-/scratch-protection under a cap [S1] — the sealing washer encyclopedia entry covers this category.
For a hydraulic gauge port at 1/4″ BSPP a bonded-Buna metal-carrier seal (US $2.19 retail, 98.9% feedback) [S3] is the cheapest DIN-comparable solution; for a banjo bolt on a brake or fuel system the solid copper crush washer to DIN 7603 A (GBP 1.98 retail, 239 sold) [S4] is the conventional choice. If the assembly is a high-vibration fastener that needs pre-load control, step up to a spring washer pair rather than relying on a flat sealing ring — that role is different, even when both parts are stacked under the same nut. AN-fitting race hardware typically uses nylon or aluminium crush rings such as the Fragola 999126 (set of 10) [S5] because the elastomer-free design tolerates the higher temperatures seen near an engine bay.
Real use cases and price-per-piece benchmarks
Three reference price points anchor the market as of mid-2025 captures: PLASTEM CVRAK PA ring from €0.12 per piece at OEM quantity [S1]; Goodridge metric copper crush washer at GBP 1.98 per piece retail with active stock turnover (69 in stock, 239 sold) [S4]; 1/4″ BSPP bonded Buna seal at US $2.19 per piece retail with 98.9% positive feedback [S3]. The PLASTEM CVRAK range of internal diameter (5–6.4 mm) and external diameter (12–17 mm) [S1] is consistent with a cap-covering ring for M3–M5 screw heads, not a pressure-containing port seal.
Aftermarket automotive and motorcycle channels push the per-piece ceiling higher because SKUs are low-volume and pattern-specific: the Honda 90481-001-020 sealing washer (10.2 mm) at US $5.00 new [S6] is sold as a single-piece spare part on eBay rather than a bulk industrial item. This is the same pattern visible in special cement TCO — unit price is driven as much by packaging, channel and minimum-order quantity as by raw material.
Limitations, failure modes and sourcing traps
Three failure modes dominate field complaints on sealing washers. First, copper crush washers over-torque and crack rather than deform, especially above the standard's recommended bolt preload — the standard pattern is to replace, not re-use, a DIN 7603 A ring once the bolt has been loosened [S2]. Second, bonded Buna seals leak when the elastomer is exposed to a fluid outside its chemical-compatibility window (aromatic fuels, aggressive synthetic oils) or when the temperature rating of the elastomer (typically -40 °C to +120 °C for NBR/Buna, higher for FKM) is exceeded [S3]. Third, plastic PA or PE cover rings like the PLASTEM CVRAK [S1] are not pressure seals and must never be substituted for a DIN 7603 A ring on a hydraulic port — they will extrude.
On sourcing, the cheapest catalog price is not the lowest landed cost: a 1/4″ BSPP bonded-Buna seal at US $2.19 [S3] is sold with indicative pricing that excludes delivery, customs duties and installation accessories, and customs handling fees can apply on cross-border retail shipments [S3][S4]. Industrial OEM channels such as PLASTEM (France) and VIPA spa (Italy) publish €-denominated prices excluding tax and require an RFQ for non-listed sizes [S1][S2]. The cross-reference of metric DIN 7603 A sizes at VIPA spa (ID 4–42 mm) [S2] and Goodridge retail (ID 10–18.2 mm) [S4] is the easiest way to confirm a metric thread before ordering.
Standards reference and how to read the spec line
For a copper/aluminium sealing washer, the spec line should read: standard = DIN 7603 A; form = type A solid ring; material = Cu (or Cu/Al) per DIN 7603; ID = thread nominal + small clearance; thickness = typically 1.0–2.0 mm for M10–M18 metric [S2][S4]. For a bonded seal, the spec line should additionally name the elastomer (NBR/Buna, FKM/Viton, EPDM), the carrier material (zinc-plated steel, stainless steel) and the port thread standard (BSPP, NPT, JIC, ORB). The 1/4″ BSPP retail washer in [S3] is a representative bonded-seal example at the 1/4″ port size.
For a plastic cap-covering ring such as the PLASTEM CVRAK [S1], the spec line is fundamentally different: it names the material (PA, LDPE), the colour, the ID/OD range, and the mating cap reference (PLASTEM CVAKR screw cap). These rings are specified against an assembly drawing, not a pressure or temperature rating, because they carry no pressure load. Buyers comparing listings should reject any supplier that quotes a pressure rating on a plastic cover ring — that signals a misread of the part. Where a linear guide or a capping sealing machine is in the bill of materials, the sealing washer spec line still has to be drawn from the same materials-and-standards logic.
Trackable signals for the next sourcing cycle: the PLASTEM CVRAK PA ring is listed "from €0.12 excl. tax" with the same envelope as the related LDPE plug family (€0.02–€0.49) [S1], so the catalog pricing for plastic cover rings has been stable across the 2024–2025 captures; DIN 7603 A copper washers from VIPA spa [S2] and from Goodridge retail [S4] both surface in the €1.50–€2.50 per-piece band, and the Honda OEM pattern part at US $5.00 [S6] sits as the high-water mark for single-piece aftermarket SKUs. Any future price move above 10% on the copper DIN 7603 A line is the signal worth watching, since copper is the dominant raw-material driver.