EPDM Flat Gasket

A flat gasket is the most fundamental sealing geometry in fluid systems — and EPDM is its most capable partner wherever water, steam, or outdoor exposure is involved. Engineered for water inlet fittings, tap connectors, pipe flanges, and pump housings, these EPDM flat gaskets and washer rings deliver reliable compression sealing across a 50–70 Shore…

Specifications

Product Type:

Flat Gasket / Washer Ring

Base Polymer:

Ethylene Propylene Diene Monomer (EPDM)

Structure:

Solid flat; annular (washer) geometry

Color: 

Black (standard); gray, white, custom on request

Surface Finish:

Smooth, calendered; lathe-cut: square-edge precision finish

Standards & Compliance: 

Hardness:

50–70 Shore A (±5)

Tensile Strength: 

≥ 20 kN/m

Elongation at Break:

≥ 280%

Tear Strength:

≥ 20 kN/m

Recommended Service Temperature:

−45°C to +150°C

Hot Air Aging:

120°C × 72h: hardness change ≤ ±8 Shore A; tensile change ≤ −20%

Low‑Temperature Brittleness: 

≤ −45°C

Typical Applications:

Water inlet flat washer, tap connector gasket, pipe flange ring seal, pump housing flat gasket, appliance fitting seal

Description:

EPDM’s fundamental advantage for flat gaskets is structural: its saturated polymer backbone — ethylene and propylene units with a small percentage of diene monomer as crosslink sites — leaves virtually no reactive double bonds exposed to the sealing medium. In flat gasket geometry, where the sealing face is permanently in contact with the fluid, that matters more than it does for covered profiles or enclosed O-rings. Ozone, UV radiation, and water vapor have nothing to attack.

For water-contact applications, EPDM retains mechanical properties reliably through extended hot-water immersion at up to 150°C — hydrothermal stability that most commodity elastomers cannot match. At 50–70 Shore A, the compound is firm enough to resist cold-flow under bolt-load or spring-clip compression, yet compliant enough to conform to minor surface irregularities on cast or machined fittings. Reliable. Even at −45°C.

Typical Industry Applications

Proven performance across demanding manufacturing environments.

Industry Typical Use Cases
Automotive & Motorcycle Coolant hose end washers, radiator drain plug gaskets, battery vent flat seals
Construction & Architecture Pipe flange ring seals, faucet body flat washers, water meter connector gaskets
Home Appliances Washing machine inlet valve washers, dishwasher water inlet flat gaskets, steam iron water-tank seals
Lighting & LED Outdoor luminaire housing face seals (weatherproofing, not direct water-contact)
Electronics & Industrial Machinery Pump housing flat gaskets, hydraulic manifold face seals, coolant circuit flat washers

Chemical Resistance Table:

Chemical / Medium Resistance Notes
Cold water (≤ 40°C) ✅ Excellent Long-term immersion; minimal swell
Hot water (40–100°C) ✅ Excellent Preferred elastomer for potable water fittings
Steam (low pressure, ≤ 0.5 MPa) ✅ Excellent Stable up to 150°C with peroxide cure
Steam (high pressure, > 1 MPa) ✓ Good Temperature-dependent; verify against compound grade
Ozone & UV ✅ Excellent Saturated backbone; outdoor service rated
Dilute sulfuric acid (< 30%) ✓ Good Suitable for drain and wastewater contact
Dilute sodium hydroxide ✓ Good Compatible at typical domestic concentrations
Ethanol / isopropanol ✓ Good Minor swell possible at high concentrations
Ketones (acetone, MEK) ⚠ Limited Moderate swell; short incidental contact only
Vegetable / animal oils ✓ Good Suitable for food-adjacent appliance applications
Petroleum mineral oil ✗ Not recommended Significant swelling; specify NBR or FKM instead
Gasoline / diesel fuel ✗ Not recommended Not suitable for hydrocarbon fuel sealing
Aromatic solvents (toluene, xylene) ✗ Not recommended Severe swelling; incompatible
Chlorinated solvents (TCE, DCM) ✗ Not recommended Aggressive attack; no contact
Phosphate ester hydraulic fluid ✅ Excellent EPDM preferred over NBR for this fluid class

 

In-House Quality Assurance & Testing:

At Micune Rubber, batch-to-batch consistency is guaranteed through our ISO-9001 certified Quality Management System. Every rubber compound and custom extrusion undergoes rigorous evaluation in our dedicated testing laboratory before shipment. We utilise industry-standard baseline testing, including Mooney Viscometers to measure compound viscosity and Torque Rheometers to verify exact vulcanisation characteristics. This ensures every material formulation strictly adheres to your required specifications and processing parameters.

Mooney Viscometer

Mooney Viscometer

abrasive testing machine

Abrasive Testing Machine

Burn-in Chamber

Burn-in Chamber

Torque Rheometer

Torque-Rheometer

RFQ:

For die-cut rubber gaskets, standard production tolerances on OD and ID are ±0.2 mm for parts under 100 mm diameter, widening proportionally on larger flanges; thickness follows RMA commercial-grade sheet tolerance at ±0.2–0.3 mm depending on sheet gauge. Lathe-cut washers achieve ±0.1 mm or tighter on OD/ID with slice-width (thickness) repeatability of ±0.1 mm. If a fitting has a recessed groove or a tight bore, lathe-cut is the appropriate process to specify.

SGS test reports dated March 2026 confirm full compliance with EU RoHS Directive (2011/65/EU + 2015/863/EU) and AfPS GS 2019:01 PAHs limits on the black EPDM compound; all regulated substances returned not detected. Reports are issued on the compound’s revision cycle and are available for download upon request.

Hardness can be formulated from 40 to 80 Shore A within the same EPDM base polymer; the 50–70 Shore A window covers the majority of appliance and plumbing fitting requirements. Non-black colors — gray, white, red, or custom — are achievable with alternative filler and pigment systems, subject to minimum compound quantities. Non-standard OD/ID combinations or non-circular outlines are quoted against a customer 2D drawing, with new die or tube extrusion specification as appropriate.

Die-cut samples from existing compound stock are typically ready within 7–10 business days after drawing confirmation. Lathe-cut samples from a new tube extrusion require 10–15 business days, as the tube must be extruded, cured, and ground to OD before slicing. If the target hardness requires a new compound formulation, allow an additional 5–7 days for mix-and-test before sample production begins.

MOQ for die-cut rubber gaskets is typically 1,000–5,000 pieces depending on part diameter and sheet utilization; lathe-cut washers start at 500 pieces for standard OD/ID combinations. Parts are packaged in polybag-and-carton format with lot number labeling for IQC traceability. Shipment is from Zengcheng, Guangzhou by air freight, sea LCL/FCL, or express courier — based on order volume and destination lead-time requirements.

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