Choosing the right gasket for a spiral duct fitting is critical. Too loose, and air escapes. Too tight or misaligned, and you’ll face installation delays and poor sealing. That’s why accurate gasket dimensions—cut length, thickness, profile, and standards—matter so much.
Spiral fitting EPDM gaskets are engineered to match standard round duct diameters, typically ranging from 100 mm (4") to 1250 mm (50") or more, with cut lengths defined precisely for each pipe size.
Below is a detailed reference based on real-world factory specs and international standards.
Spiral Fitting EPDM Gasket Size Chart
| For Pipe Size (mm) | Total Length (mm) | ISO Tolerance (mm) |
|---|---|---|
| 80 | 220 | ±2.5 |
| 100 | 290 | ±3.2 |
| 125 | 350 | ±3.2 |
| 150 | 425 | ±4.0 |
| 160 | 458 | ±4.0 |
| 180 | 513 | ±4.0 |
| 200 | 570 | ±4.0 |
| 250 | 702 | ±5.0 |
| 315 | 878 | ±5.0 |
| 355 | 991 | ±5.0 |
| 400 | 1112 | ±6.3 |
| 450 | 1280 | ±6.3 |
| 500 | 1422 | ±6.3 |
| 630 | 1776 | ±10.0 |
| 710 | 1960 | ±10.0 |
| 800 | 2214 | ±10.0 |
| 900 | 2498 | ±10.0 |
| 1000 | 2746 | ±12.5 |
| 1250 | 3470 | ±12.5 |
Dimensions of Spiral Fitting EPDM Gaskets
Spiral fitting gaskets with EPDM sealing elements1 are typically designed to meet common spiral duct and flange standards such as SMACNA2, ASME B16.203, and ASME B16.21.
Typical Size Range
- Diameter: Available for duct sizes from 100 mm (4") to 900 mm (36")4 or larger depending on the project.
- Thickness: Usually 3–6 mm5, depending on gasket profile and system requirements.
- Profile: Double-legged EPDM strip with a 180° hemmed edge6, factory-attached to the fitting for stability and compression integrity.
Dimensional Standards Reference
- Spiral wound gaskets7 under ASME B16.20 allow ±0.13 mm thickness variation for metal and filler layers.
- Inner diameters have tighter tolerances, often ±0.8 mm for NPS sizes 3 and above.
- Full-face EPDM gaskets8 for flanges per ASME B16.21 typically have 1/8" (3.2 mm) thickness and follow pipe sizes from ½" up to 24" or more.
Application Notes
- Temperature range: EPDM gaskets in spiral fittings perform from -22°F to 212°F (-30°C to 100°C)—ideal for standard HVAC airflow systems.
- Factory-installed: Most spiral fittings come with the EPDM gasket already attached to ensure a fast and accurate seal during installation.
- Leakage class: Designed to meet SMACNA Class 39 air leakage standards when properly installed.
Summary
| Specification | Typical Range / Notes |
|---|---|
| Diameter Range | 100 mm (4") – 1250 mm (50") and larger available |
| Total Lengths | 220 mm to 3470 mm, depending on pipe diameter |
| Thickness | 3–6 mm EPDM seal profile |
| Gasket Profile10 | Double-legged with 180° hemmed edge for spiral ducts |
| Dimensional Standards11 | ASME B16.20 / B16.21, SMACNA guidelines |
| Temperature Range12 | -22°F to 212°F (-30°C to 100°C) |
| Tolerance | ISO dimensional tolerances from ±2.5 mm to ±12.5 mm |
For exact sizing and application-specific advice, always refer to the gasket manufacturer’s technical datasheet or request a quote with your duct’s outer diameter and pressure class.
What affects the dimension?
- Pipe outer diameter13: This defines the required gasket cut length (circumference).
- Gasket width and thickness14: Typically between 6–12 mm wide and 2–4 mm thick, depending on groove depth and fitting type.
- Tolerance15: Cut length tolerance ensures sealing reliability and dimensional fit. ISO standards help maintain consistency and performance.
Where are spiral EPDM gaskets16 used?
- Circular HVAC ducts
- Spiral flanged fittings
- Ventilation fan connections
- Duct-to-plenum joints
- Cleanroom or industrial ventilation lines
They’re designed to compress slightly when the duct and fitting are fastened, creating a secure, air-tight joint17 with minimal airflow loss.
Final advice
Always match your EPDM spiral fitting gasket to the actual pipe diameter—not just the nominal duct size. At Julong Rubber, we provide these gaskets with precise cut lengths and tight ISO tolerances18 for reliable sealing performance. If you’re unsure about your size, send us your duct OD, and we’ll help you select the correct part.
Conclusion
Spiral fitting EPDM gaskets are dimensioned to wrap precisely around ventilation ducts from 80 mm to 1250 mm in diameter. Choosing the correct length with proper tolerance ensures a secure, durable seal in HVAC systems.
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Learning about EPDM sealing elements can help you understand their benefits and uses in various sealing applications. ↩
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Understanding SMACNA standards can enhance your knowledge of quality and compliance in ductwork applications. ↩
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Exploring ASME B16.20 will provide insights into the specifications and standards for gasket design and performance. ↩
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Understanding standard duct sizes is crucial for proper HVAC installation and efficiency. Explore this link for detailed information. ↩
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Knowing the thickness of duct materials helps in selecting the right components for your HVAC system. Check this resource for insights. ↩
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A hemmed edge can enhance the durability and performance of duct fittings. Discover more about its benefits in this informative article. ↩
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Explore this link to understand the specifications and applications of Spiral wound gaskets, crucial for ensuring effective sealing in various systems. ↩
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Learn about the benefits and uses of EPDM gaskets in HVAC systems, which are essential for maintaining efficiency and performance. ↩
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Discover the details of the SMACNA Class 3 air leakage standard to ensure compliance and efficiency in your HVAC installations. ↩
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Exploring gasket profiles can help you choose the most effective sealing solution for spiral ducts, improving efficiency and reducing leaks. ↩
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Familiarizing yourself with dimensional standards helps ensure compliance and compatibility in industrial settings, enhancing system reliability. ↩
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Understanding the temperature range is crucial for selecting the right gasket for HVAC systems, ensuring durability and performance. ↩
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Understanding the significance of pipe outer diameter can enhance your gasket installation process and ensure better sealing. ↩
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Exploring this topic will provide insights into optimizing gasket dimensions for improved sealing efficiency. ↩
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Learning about tolerance in gasket manufacturing can help ensure reliable sealing and compliance with industry standards. ↩
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Explore this link to understand the various applications and benefits of spiral EPDM gaskets in HVAC systems. ↩
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Learn about the importance of air-tight joints in HVAC systems and how they enhance efficiency and performance. ↩
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Discover the significance of ISO tolerances in ensuring quality and precision in manufacturing processes. ↩
