What is a vent pipe gasket and why use EPDM?

When a vent pipe system leaks, it’s usually not the pipe that fails—it’s the gasket. Over time, poor sealing leads to gas leakage, condensation problems, and system imbalance. I’ve helped many clients avoid these issues by choosing the right gasket material upfront.

A vent pipe gasket is a sealing component placed between pipe ends or fittings in exhaust, drainage, or flue gas systems. EPDM is the best choice for these gaskets because it resists weather, heat, and chemical attack while staying flexible for years.

Whether it’s a chimney flue, HVAC exhaust¹, or DWV system, proper sealing depends on both the gasket shape and its material. Let’s look at what a vent gasket does and why EPDM² outperforms others in this role.

What does a vent pipe gasket³ do?

A vent pipe gasket is installed between pipe joints or flanged fittings in a venting system. Its main job is to create an airtight and watertight seal while still allowing pressure relief or flow of gases. This prevents leakage of exhaust fumes, moisture, or vapors.

It’s used in systems like chimney ducts, boiler flue pipes, bathroom vents, and industrial gas lines—places where escaping gas or steam can cause safety or efficiency problems.

Main applications include:

• HVAC exhaust ducting
• Flue gas vent lines
• Drain-waste-vent (DWV) systems
• Boiler or water heater ventilation
• Chimney and stack connections

In most of these uses, the gasket must hold up against pressure fluctuation, acidic condensates, and outdoor exposure.

Why is EPDM the preferred material?

EPDM (ethylene propylene diene monomer) is a synthetic rubber with excellent all-around resistance to weather, heat, steam, and many chemicals. I often recommend it for any vent system that faces UV, ozone, or temperature swings.

EPDM gaskets offer reliable sealing in outdoor or corrosive environments, maintain elasticity, and prevent leaks caused by aging or chemical attack.

Key reasons to choose EPDM:

• ✅ Wide operating range⁴: -34°C to 110°C (-30°F to 230°F)
• ✅ Superior resistance⁵ to ozone, UV, steam, and diluted acids
• ✅ Flexible and elastic—fills surface gaps and irregularities
• ✅ Long-lasting—resists hardening, shrinking, and cracking
• ✅ Safe and non-toxic⁶—suitable for domestic or commercial buildings

Many of our EPDM vent gaskets⁷ at Julong are also pre-lubricated with talc or a dry-film agent, which helps with faster installation and reduces the chance of tearing during compression.

What issues does EPDM help prevent?

Using the wrong rubber—like NBR or low-cost SBR—can lead to serious problems in vent systems. These materials often harden, crack, or degrade when exposed to sunlight or acidic condensates.

EPDM prevents premature gasket failure caused by thermal cycling, UV exposure, and chemical attack. It stays soft and elastic where other rubbers fail.

Problems EPDM helps avoid:

• Flue gas leakage due to shrinkage or cracking
• Backdrafts caused by pressure imbalance
• Moisture entry leading to mold or corrosion
• Costly service calls for failed gaskets
• Code violations from improper sealing

A customer of mine switched to EPDM in a rooftop HVAC vent application after experiencing seasonal failures with NBR gaskets. The EPDM version has now lasted four winters without any issues, even with snow, sun, and high heat from vented air.

Summary: Why choose EPDM for vent pipe gaskets?

Here’s a quick overview of what makes EPDM the best material:

At Julong, we manufacture molded EPDM gaskets that meet EN and ASTM standards for vent systems. These products are trusted by European ventilation and flue manufacturers for reliable, compliant sealing.

Conclusion

A vent pipe gasket ensures your exhaust or drainage system stays sealed, safe, and compliant. EPDM is the best material thanks to its durability, chemical resistance, flexibility, and ability to perform in harsh environments.